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Metal-Ion Optical Fingerprinting Sensor Selection via an Analyte Classification and Feature Selection Algorithm
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Analytical Chemistry

Cite this: Anal. Chem. 2025, XXXX, XXX, XXX-XXX
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https://doi.org/10.1021/acs.analchem.4c06762
Published March 27, 2025

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Abstract

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Accurate analyte classification remains a significant challenge in sensor technologies. We present the Analyte Classification and Feature Selection Algorithm (ACFSA), a computational tool designed to identify optimal sensor combinations from unique fingerprint patterns for analyte classification. We applied the ACFSA to a library of peptide-corona-functionalized single-walled carbon nanotubes (SWCNTs), developed as a near-infrared fluorescent, semiselective fingerprinting sensor set for detecting heavy metal ions. Inspired by natural metal-ion complexation sites, each SWCNT sensor in this library features a unique peptide sequence containing various amino acids for metal binding, revealing diverse optical response patterns to the various metal ions tested. The sensor library was further diversified using different SWCNT chiralities and photochemical modifications of the peptide coronae. The ACFSA was applied to the screening data of the fluorescence response of the 30 resulting SWCNT-peptide sensors to five metal-ion analytes. Through iterative dimensionality reduction and rational sensor selection, the algorithm identified the optimal fingerprinting sensors as a minimal two-sensor set with a 0.02% classification error. The final output of the ACFSA is thus an analyte classifier that serves as a unique analyte fingerprint pattern for the selected sensors. The developed peptide-SWCNT system serves as an effective proof-of-concept, illustrating the potential of our platform as a generally applicable tool for fingerprinting analytes and optimal sensor set selection in other sensor–analyte screening experiments.

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Developing biomedical or biochemical sensors relies on achieving specific and selective analyte recognition. (1) Typically, molecular recognition is facilitated by macromolecules forming three-dimensional binding pockets, providing unique binding interaction with the analyte, (2) e.g., via hydrogen bonds, π–π stacking, or electronic interactions for metal complexation. (3−6) Natural recognition units include, for example, aptamers, (7) antibodies, (8) or the active site of enzymes. (9) Recent efforts in developing sensor recognition agents have demonstrated that synthetic (bio)-macromolecules and polymers, which form a molecular corona around the surface of nanoparticle sensors, adapt conformations that can enhance selectivity to certain analytes. (10−14)
Various polymers, as well as synthetic nucleic acid or peptide sequences, have been reported to form selective coronae for nanosensors, (15) offering greater stability and reduced biodegradation compared to natural biomolecules. (8) Further, using molecules without a priori inherent selectivity to the analytes allows for an extensive pool of potential sensor candidates for various analytes. (16−21) Despite recent efforts for computational modeling of structure and functionality, (10,22,23) as well as advancements in directed evolution, (24−26) identifying a corona phase for selective sensing for a certain analyte still requires an extensive screening process. Although these sensors show high selectivity, matching the specificity of natural binding sites like aptamers or antibodies remains challenging. (27)
To enhance sensing accuracy, a fingerprinting approach using multiple sensors with distinct corona phases can be employed instead of relying on a single sensor. (18,20,28) A fingerprint platform comprises multiple sensors that generate unique optical or electronic response patterns for each analyte. For an efficient and cost-effective platform, minimizing the sensor count while maintaining high identification accuracy is ideal. Achieving this requires screening a large pool of potential sensors, as a broader selection increases the likelihood of identifying an optimal minimal sensor set.
During this optimization process, the response of all potential sensors to all analytes must be recorded through a comprehensive screening process, resulting in a multidimensional data set, from which the optimal set of sensors must be selected via complex data analysis techniques. Thus, fingerprinting different analytes with multiple sensors can essentially be considered a multidimensional data classification task. One common approach to handling multidimensional data is principal component analysis (PCA), (29) which transforms the data into a reduced dimensionality space. (20) For multiple sensor applications, PCA ideally produces distinct response-data clusters for each analyte, (30) which can then be used to generate an analyte classifier using methods like Bayesian optimal decision lines, (31) or Voronoi tessellation diagrams. (32) By comparing new measurement data against the resulting classifier, unknown analytes can be accurately identified. (33)
Many sensor platforms used in biomedicine rely on optical nanoparticles, enabling noninvasive and real-time analyte detection. (34) A prime example of such optical nanosensors is single-walled carbon nanotubes (SWCNTs), which are carbon nanomaterials that can be thought of as graphene sheets rolled up into tubes. (35) Their roll-up vector determines the diameter, as well as the chemical and electronic properties of the resulting SWCNT (n,m)-chirality. (35−37) Semiconducting SWCNT chiralities allow for fluorescence emission in the near-infrared (NIR) wavelength range and fluorescence excitation in the visible to NIR range. (38) Due to their fluorescence emission in the transparency window of biological tissue, they find widespread application in fluorescence sensing and imaging in biomedicine and bioengineering. (39−41) The concept of functionalized SWCNTs as optical sensors has been developed for various applications, including the detection of enzymes, (42−47) RNA, lipids, and proteins; (11,48−50) small molecules, (49,51−54) pathogens, (16,20) and reactive oxygen species, (55,56) as well as multiple biomedical imaging and sensing applications. (38,57−61)
The SWCNTs’ optical properties also depend on the surface functionalization, which can be purely noncovalent or, include covalent modifications via the introduction of defect sites. (62) The former maintains the sp2 lattice structure and is typically performed using macromolecules such as single-stranded DNA, (63) surfactants, (64) amphiphilic polymers, (45,65−67) proteins, (68) and suitable peptides (16,69) that can bind the graphene lattice of the SWCNTs via hydrophobic interactions or π–π stacking.
When an analyte binds to the SWCNT corona phase, it can alter the polarity and dielectric environment, affecting the SWCNTs’ fluorescence emission wavelength and/or intensity., (58,62,70) Furthermore, studies have shown that individual (n,m)-chiralities can respond differently to a specific analyte, even when functionalized with the same corona phase. (71) Thus, the fluorescence modulations of the SWCNTs have been found to be chirality-dependent, (72,73) which enables SWCNT mixtures to function as multiple optical sensors, identifiable by their specific excitation and emission wavelengths – an advantage over other optical nanosensors.
The development of transition metal-ion sensors is crucial due to the significant effects of these metals on the environment and human health. (74) Elevated levels of lead, copper, or chromium in living organisms can lead to enzymatic dysfunction and contribute to diseases like cancer and neurodegenerative disorders. (75) Most metal-ion detectors rely on chelating molecules that form metal-specific binding sites, (5,76−78) but their synthesis and stability pose challenges. (5) Notably, previous studies have demonstrated the modulation of SWCNT fluorescence by divalent metal ions through DNA conformational changes on the nanotube surface. (79−81) Building on these insights, the ability to enrich the sensing toolbox and identify an optimal, minimal set of sensors from a multidimensional data set while minimizing sensor redundancy could significantly enhance the scalability of fingerprinting platforms for metal-ion detection. Previously, we functionalized SWCNTs with fluorenylmethoxycarbonyl (Fmoc)-tyrosine, polymerized into a melanin-like material that presents quinone and catechol groups that are known to have metal chelation properties. (3,82) While this system produced an optical response, it could not distinguish between different metals. (3)
In proteins and enzymes with metal-ion reaction centers, metal-binding sides are formed by the interplay of different amino acids, each with specific side-chain functional groups, such as amine groups in lysine or the carboxyl groups in glutamic acid. (83,84) Similarly, SWCNTs functionalized with peptide coronas could enhance metal-ion recognition or classification. Modifying peptide sequences and corona chemistry, and using various SWCNT chiralities, would enable the construction of an extensive sensor library, from which an optimal fingerprinting set can be selected through data processing algorithms.
This work presents an optical fingerprinting sensor platform tested on transition metal-ions, where sensors are selected through an algorithmic iterative process, utilizing fluorescent SWCNTs functionalized with diverse peptide corona phases. Five Fmoc-peptides (Fmoc-FFFFYXYXY) were designed, each consisting of a phenylalanine chain (FFFF) and an alternating sequence of tyrosine (Y) and a variable amino acid (X). While the Fmoc-FFFF chain facilitates binding to the SWCNTs by π–π stacking, (85) the alternating sequence YXYXY contains tyrosine to provide the same functionality exploited in our previous work, (3) and functional groups such as guanidino, carboxyl, amine, and thiol, provided by four varying amino acids (arginine, glutamic acid, lysine, cysteine). Glycine, which lacks a side chain, was also included for comparison and for enriching the sensor library. Together, these functional groups, along with tyrosine and amide bonds, provide a range of potential sites for metal complexation (Scheme 1a). To further diversify the peptide library, the SWCNT-Fmoc-peptides underwent photochemical oxidization, yielding ten SWCNT-Fmoc-peptide sensors, including the oxidized and nonoxidized forms. By monitoring three chiralities in each SWCNT-peptide sample at their respective fluorescence excitation and emission wavelengths, we established a library of 30 potential sensors. The fluorescence intensity changes upon exposure to five metal ions – copper (Cu2+), nickel (Ni2+), chromium (Cr3+), lead (Pb2+), and mercury (Hg2+) – demonstrated that both the peptide corona phase and the SWCNT chirality influence the sensor response, resulting in a rich, multidimensional data set (Scheme 1b). To identify an optimal fingerprinting sensor set, we developed a selection and classification algorithm, namely Analyte Classification and Feature Selection Algorithm (ACFSA), which iteratively selects sensors via PCA-based dimensionality reduction, k-means clustering, and Chi-Squared feature selection (Scheme 1c). The iterative selection scheme runs until only one sensor remains or when a predefined accuracy threshold is met. This flexible methodology can be applied to other corona phase sensor–analyte screening experiments, facilitating the identification of the most effective fingerprinting sensor systems for analyte classification with higher detection certainty.

Scheme 1

Scheme 1. SWCNTs Suspended by Fmoc-Peptides as Fingerprinting Sensorsa
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a(a) Corona phase peptide sequence and the varying amino acids side chains. (b) Fmoc-peptide and oxidized Fmoc-peptide functionalized SWCNTs interact with metal-ions, leading to different fluorescence responses. (c) The ACFSA algorithm finds an optimal sensor set for analyte classification

Experimental Section

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Suspension of SWCNT with Fmoc-Peptides

Fmoc-peptides (15 mg, ABclonal) were dissolved in 1 mL of water, with solubility adjustments using NaOH or DMSO as needed (see the Supporting Information for additional details). HiPCO SWCNTs (2 mg, NanoIntegris) were dispersed in these solutions via tip sonication (4 W, 60 min, on ice). The suspensions were centrifuged twice (21,130 rcf, 1.5 h), filtered (Amicon, MWCO 100 kDa), and washed to remove excess peptides and equilibrate pH. The concentrations of the SWCNT-Fmoc-peptides suspension were determined using the extinction coefficient ε632 nm = 0.036 L mg–1 cm–1, (86) and found to be between 100 mg L–1 and 300 mg L–1.

UV Oxidation

The SWCNT-peptide suspensions (10 mL, 50 mg L–1) were transferred into an 8 cm diameter glass Petri dish, and irradiated by λ = 254 nm UV light (Vilber, 6W) from above at a 4 cm distance for 90 min. Peptide oxidation was characterized via fluorescence (λex = 280 nm and λem = 300–600 nm; and λex = 320 nm and λem = 350–600 nm) using a plate reader (SPARK, Tecan).

Transmission Electron Microscopy

SWCNTs-peptide suspensions (30 μL at 10 mg L–1) were dropped onto a carbon-coated grid and dried. The samples were stained by 30 μL of 2% (w/v) uranyl acetate solution, and then imaged using a JEM-1400plus TEM (JEOL, Japan) operating at 80 kV. Images were recorded using the SIS Megaview III camera and iTEM, the TEM imaging platform (Olympus).

NIR Fluorescence Spectroscopy

Spectra were acquired using an inverted microscope (Olympus IX73) with a supercontinuum laser (NKT-photonics, 20 mW) with a bandwidth filter (Super-K varia) and spectrograph (HRS-300, Teledyne Princeton Instruments). Excitation–emission maps covered 500–840 nm (2 nm steps). For measuring the fluorescence response with the metals, the SWCNT-peptide suspensions (1 mg L–1) were incubated with metal-ions (Cu2+, Ni2+, Cr3+, Pb2+, Hg2+) at 300 μM for 15 min. NIR fluorescence was measured at excitation wavelengths 570, 660, and 730 nm, targeting SWCNT chiralities (6,5), (7,5), and (9,4) (see the Supporting Information for additional details).

Sensor Response Analysis and Analyte Classification and Feature Selection Algorithm (ACFSA)

The peaks of the respective chiralities were fitted with a Lorentzian distribution function (MATLAB) and the relative intensity changes of the sensors to the different metal analytes were analyzed via the algorithm. A detailed description of the algorithm and a discussion of its performance is given in Section SIII.

Results and Discussion

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Sensor Synthesis and Characterization

To explore the potential of fluorenylmethoxycarbonyl (Fmoc)-protected peptides as effective corona phases of SWCNTs for transition metal-ion sensing, we utilized the peptide sequence Fmoc-FFFFYXYXY, consisting of phenylalanine (Phe, F), tyrosine (Tyr, Y), and a variable amino acid (X), which is either arginine (Arg, R), glutamic acid (Glu, E), lysine (Lys, K), cysteine (Cys, C) or glycine (Gly, G) (Scheme 1a and Figure S1). These peptides were designed to provide functional groups through tyrosine and the variable amino acids, i.e., guanidine-, amine-, carboxyl-, hydroxyl-, and thiol-groups, to form a corona phase that can complex metal-ions. (3,83,87) Glycine was included as an amino acid without an additional side chain. Further, the Fmoc-FFFF-tail facilitated the attachment of the Fmoc-peptide to the SWCNTs and their dispersion in water. Notably, without the additional phenylalanine-chain, the Fmoc-peptides showed very low efficiency as SWCNT dispersants (Figure S2).
Figure 1a shows the absorption spectrum of SWCNTs successfully functionalized with Fmoc-FFFFYCYCY via direct tip sonication (SWCNT-Cys). The spectra of SWCNT-Cys along with the remaining Fmoc-peptide functionalized SWCNTs (SWCNT-Arg, SWCNT-Glu, SWCNT-Lys, and SWCNT-Gly) are shown in the Supporting Information (Figure S3). For all Fmoc-peptides, defined peaks corresponding to the SWCNTs’ E11 and E22 electronic transitions are clearly observed, indicating successful suspensions. Additionally, the peak at around 270 nm corresponds to the Fmoc-group, confirming the presence of the Fmoc-peptides in the corona phase of the SWCNTs after filtering the samples from excess Fmoc-peptides. However, the SWCNT surface coverage by the Fmoc-peptides varies depending on the peptide sequence, as evident from the different UV absorption of the Fmoc-group (Figure S3). SWCNT-Arg, for example, contains the least amount of Fmoc-peptide per milligram of SWCNTs, while SWCNT-Cys has the highest amount. These variations in the SWCNT surface coverage suggest different affinities of each peptide to the SWCNT surface and potential electrostatic repulsion between the Fmoc-peptides molecules. Nevertheless, all five SWCNT-peptide suspensions were stable in water for several weeks.

Figure 1

Figure 1. Functionalization, oxidation, and characterization of SWCNT-peptides. (a) UV–vis–NIR absorption spectrum of SWCNT-Cys, diluted 1:20 in water. Inset: NIR absorption of the SWCNTs-Cys. (b) Fluorescence emission spectra of SWCNT-Cys at three different excitation wavelengths: 570 nm (black), 660 nm (orange), and 730 nm (blue). Emission peaks of the three chiralities measured at these excitation wavelengths are marked with arrows corresponding to the (6,5), (7,5), and (9,4) chiralities, respectively. (c) Normalized excitation–emission map of SWCNT-Cys. The three chiralities shown in (b) are highlighted in circles. (d) Absorption spectra of SWCNT-Cys before (blue) and after UV-oxidation to SWCNT-CysOx (orange). Inset: Fmoc-peptides in solution before and after oxidation, following the precipitation of the SWCNTs with DMSO. (e) Normalized fluorescence emission of the peptides before (blue) and after (orange) UV-oxidation of SWCNT-Cys measured at excitation wavelengths of 280 nm (left) and 320 nm (right). (f) Normalized excitation–emission map of SWCNT-CysOx.

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HiPCO SWCNTs combine several different chiralities within a single SWCNT sample, with each chirality characterized by its band gap energy, resulting in distinct fluorescence excitation and emission wavelengths. Further, it has been observed that each chirality can exhibit a distinct fluorescence response to analytes binding to their corona, influenced by the different curvature and surface coverage of the SWCNTs., (36,71,72) Consequently, every SWCNT-chirality in our SWCNT-peptide sample can be considered an independent sensor. For our measurements, we selected three different chiralities, namely the (6,5), (7,5), and (9,4) chiralities, which are excited at λex = 570, 660, and 730 nm, respectively, and show fluorescence emission at around λem = 995, 1050, and 1130 nm, respectively (Figures 1b, c and S4). While various chiralities could be considered, we selected three that provide maximal spectral separation and minimal peak overlap, ensuring reliable and distinguishable fluorescence responses, making them well-suited for robust sensor analysis.
To further extend our SWCNT-peptide sensor library, we chose to photochemically oxidize the tyrosine-containing peptide corona of the SWCNTs via UV irradiation. Tyrosine and tyrosine-containing peptides that undergo photochemical oxidation are known to form dimers of dityrosine and, in some cases, to further oxidize to melanin-like derivatives. (88,89) The resulting variations of the SWCNT corona are expected to affect analyte recognition (11) through the modification of the corona phase morphology and the formation of metal-chelating catechol and quinone groups. (90) In a previous study, Fmoc-tyrosine that underwent enzymatic oxidative polymerization via tyrosinase to a melanin-like material demonstrated improved stability as a SWCNT dispersant and enhanced performance in metal sensing attributed to the formation of metal-scavenging functional groups like catechols and quinones. (3) Nevertheless, due to the more complex peptide structure in the current study, we chose photochemical oxidation instead of enzymatic oxidation.
For the oxidation of the Fmoc-peptide corona of the SWCNTs, we exposed the suspensions to UV light (254 nm) and monitored the reaction via absorption and fluorescence spectroscopy. Compared to SWCNT-Cys, the oxidized suspension after UV irradiation, onward referred to by the suffix Ox, SWCNT-CysOx, showed a slight increase in absorption below 500 nm, consistent with the observable browning of the Fmoc-peptide solution due to tyrosine oxidation also reported in previous works (Figure 1d). (3,90) Additionally, the fluorescence emission of the peptide in the SWCNT-Cys suspension before and after UV-oxidation exhibited a decrease in the fluorescence intensity of tyrosine (λex = 280 nm, λem = 320 nm) and an increase in the fluorescence intensity at λem = 420 nm, associated with the formation of dityrosine and its oxidized derivatives (Figure 1e). (89) Similar results were obtained for the other suspensions, while for SWCNT-Arg, coloration was hardly observed, probably due to a lower amount of Fmoc-peptides in the corona phase of this particular sensor compared to the other sensors (Figure S5). The excitation–emission map of SWCNT-CysOx confirms that the fluorescence properties of the SWCNTs are maintained after UV-oxidation (Figures 1f and S4). Additional Raman spectroscopy analysis (Figure S6) comparing the spectra of each sensor before and after oxidation revealed no significant changes in the D band peak (around 1350 cm–1), confirming that the sp2 structure of the nanotubes remained intact. This suggests that the oxidation process was limited to the Fmoc-peptides, leaving the carbon nanotube chemical structure unaltered. As examples, TEM images of SWCNT-Lys and SWCNT-LysOx suspensions (Figure S7), and of SWCNT-Cys and SWCNT-CysOx suspensions (Figure S8) illustrate the SWCNT-peptide dispersion, as well as the changes in nanotube diameter and/or morphology following oxidation/polymerization.
Through the oxidation of the five Fmoc-peptides and the resulting chemically and structurally modified coronae, we obtain ten different SWCNT-peptide sensors. Further, by leveraging the different chiralities present in each SWCNT suspension, specifically focusing on the fluorescence response of three chiralities, (6,5), (7,5), and (9,4), we effectively increase the sensor library to a total of 30 distinct sensors.

SWCNT-Peptide Metal-Ion Fingerprinting

To develop a fluorescence fingerprinting sensor platform, each sensor’s response to each analyte must be characterized. By ensuring sufficient variability in fluorescence signals, a subset of sensors could be selected to generate a unique fingerprint for each analyte. To monitor the fluorescence response, each SWCNT-peptide sensor was exposed to the transition metal-ions Cu2+, Ni2+, Cr3+, Pb2+, and Hg2+ (300 μM)3 and measured in quintuplicates. The intensity changes were recorded at three different excitation wavelengths, 570, 660, and 730 nm, corresponding to the (6,5), (7,5), and (9,4) chiralities, respectively. Figure 2a shows the fluorescence emission spectra of one Fmoc-peptide sensor, SWCNT-Glu, excited at 570 nm, with the relative fluorescence response of the corresponding (6,5) chirality to the metal-ions. Notably, the sensor exhibited distinct fluorescence responses to each metal-ion: Ni2+, Cr3+, and Pb2+ induced varying degrees of intensity increase, with Ni2+ showing the highest increase, while Cu2+ and Hg2+ caused a decrease in intensity. The nature of the intensity change, whether an increase or decrease, remains an area of active research. (39) Nevertheless, previous works reported that the fluorescence intensity decrease upon Cu2+ and Hg2+ might be attributed to quenching. (3,91) Further, the modulation of the SWCNT fluorescence by metal ions might also be partly attributed to conformational changes in the corona phase of the nanotube, which could lead to changes in the accessible SWCNT surface area to solvent. (68,70,78,79,92)

Figure 2

Figure 2. Fluorescence response of the SWCNT-peptide sensor in the presence of 300 μM of metal-ions. (a) Normalized fluorescence emission spectra of SWCNT-Glu, excited at 570 nm, before (dotted black line) and after the addition of metal-ions, Cu2+ (orange), Ni2+ (yellow), Cr3+ (purple), Pb2+ (green), and Hg2+ (blue). The dashed rectangle marks the peak of (6,5) chirality. The bar plot shows the relative fluorescence response for each metal-ion. N = 5. (b) Normalized fluorescence intensity of the (6,5) chirality of SWCNT-Glu, SWCNT-GluOx, and SWCNT-Cys before (dotted black line) and after the addition of metals-ions, Cu2+ (orange), Ni2+ (yellow), Cr3+ (purple), Pb2+ (green), and Hg2+ (blue). (c) Bar plot of the relative fluorescence response of the (6,5) chirality of all the SWCNT-peptide sensors in the presence of the metal-ions. Error bars represent the standard deviation of N = 5 measurements. (d) Normalized fluorescence emission spectra of SWCNT-CysOx in water (dotted lines) and after the addition of Ni2+ (continuous lines), measured at three excitation wavelengths: 570 nm (black), 660 nm (orange), and 730 nm (blue), corresponding to the excitation wavelengths of the (6,5), (7,5), and (9,4) chiralities, respectively. Arrows mark the peaks of the respective chiralities. (e) Normalized fluorescence intensity of the (6,5), (7,5), and (9,4) chirality of SWCNT-CysOx before (dotted lines) and after the addition of Ni2+ (continuous lines).

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Achieving a fingerprinting sensor system requires variations in the SWCNT-peptide sensor responses to the different analytes. Indeed, by comparing the fluorescence response of the (6,5) chirality of three sensors, SWCNT-Glu, SWCNT-GluOx, and SWCNT-Cys, we observed a corona-specific response toward the different metal analytes (Figure 2b). Additionally, the comparison between the responses of SWCNT-Glu and SWCNT-GluOx demonstrates that peptide oxidation leads to variations in fluorescence intensity response to metal addition, confirming the creation of independent sensors via chemical modifications of the peptide corona through the oxidation process. While the precise molecular structure of the peptides after oxidation may exhibit heterogeneous morphologies, making it challenging to fully characterize, oxidation is expected to lead to the formation of catechol and quinone groups. (90) These functional groups have metal chelation properties, which may contribute to the fluorescence response mechanism of the SWCNT-peptide complexes. (90,93) The relative fluorescence intensity changes of the (6,5) chirality of all ten SWCNT-peptide samples show different response patterns for each metal-ion, thereby generating an analyte-specific fingerprint (Figure 2c).
HiPCO SWCNT samples contain a mixture of different chiralities within a single suspension, where the differences in their optical properties enable us to treat each chirality as a single sensor probed by its distinct excitation and emission wavelengths. (71,72,94−97) The fluorescence response of SWCNT-CysOx in the presence of Ni2+ measured at three different excitation wavelengths corresponding to the three chiralities (6,5), (7,5), and (9,4), exemplifies this point (Figure 2d), showing a turn-off response of the (6,5) chirality, no significant change of the (7,5) chirality, and a turn-on response for the (9,4) chirality (Figure 2e). These results demonstrate that each chirality of a SWCNT-peptide sample can have a distinct response to a particular analyte and, thus, can be regarded as an independent sensor. Figure S9 shows the bar plots for the relative fluorescence intensity changes of all the SWCNT-peptide sensors in response to the metal-ions for all three chiralities. To facilitate a clearer comparison between the fluorescence response of SWCNT-peptide sensors before and after oxidation, the data has been reordered in Figure S10, allowing for easier visual assessment of oxidation-induced changes. Additionally, in Figure S11, the data has been restructured to group the responses by sensor rather than by metal ion, emphasizing the variability in each sensor’s response across different metal ions.
In our sensing model, it is reasonable to expect that the variations in the fluorescence responses of the SWCNT-peptide sensors toward the analytes are due to the different binding affinities of metal-ions to the functional groups offered by the peptide-coronae or different wrapping conformations adopted by the corona phases. We observe that the sensor response is not clearly correlated with the Fmoc-peptide coverage per SWCNTs, suggesting that a higher peptide loading does not automatically produce a higher fluorescence response to metal-ions (Figure S12a). Furthermore, the zeta potential of the SWCNT-peptide sensors does not show a clear correlation with metal adsorption either (Figure S12b). Specifically, a negative zeta potential does not consistently lead to a higher fluorescence response by adsorbing more positively charged metal-ions. These findings suggest that the peptide structure variations play a key role in modulating fluorescence responses beyond simple electrostatic interactions or peptide surface coverage. Additionally, the observed variability in fluorescence responses across different SWCNT-peptide sensors reinforces the complexity of nonspecific sensing mechanisms and highlights the challenge of predicting sensor performance based solely on peptide sequence or theoretical considerations. This further emphasizes the need for experimental screening and data-driven approaches in sensor optimization for analyte classification.

Sensor Set Optimization

To create a cost and time-efficient sensor platform, minimizing the number of sensors needed to identify a specific analyte is beneficial. For example, identifying Ni2+ does not require all 30 sensors, but rather, a subset of a small number of sensors can be sufficient to achieve a distinctive fingerprint. A turn-on response of the (9,4) chirality of SWCNT-GlyOx suggests the presence of either Ni2+ or Pb2+, as the other metal-ions would induce a decrease in the fluorescence intensity (Figure 3a). A subsequent experiment with the (7,5) chirality of SWCNT-Cys showing a small turn-on response in the fluorescence intensity would point toward Ni2+ since Pb2+ would have induced a fluorescence intensity decrease (Figure 3b). An additional experiment with the (7,5) chirality of SWCNT-Glu showing a significant turn-on response would confirm the presence of Ni2+ rather than Pb2+, as the latter would have caused only a slight increase in the emission intensity (Figure 3c). Therefore, to identify Ni2+ out of the five metal-ions, only two or three sensors would be sufficient. In our example, two sensors, SWCNT-GlyOx-(9,4) and SWCNT-Cys-(7,5), can identify the analyte, and a third sensor, SWCNT-Glu-(7,5), would simply increase the certainty of the sensing experiment.

Figure 3

Figure 3. Example of an analyte identification procedure using several sensors. (a) The (9,4) chirality of SWCNT-GlyOx shows an intensity increase in response to the analyte, indicating Ni2+ or Pb2+. (b) A turn-on response of the (7,5) chirality of SWCNT-Cys excludes Pb2+. (c) Significant turn-on response of the (7,5) chirality of SWCNT-Glu further confirms Ni2+, in contrast to a minor turn-on response that would indicate Pb2+. All barplots N = 5.

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Manually identifying an optimal sensor set for fingerprinting all five metal ions is complex and time-consuming. To streamline this process, we developed the Analyte Classification and Feature Selection Algorithm (ACFSA) that can perform the optimal sensor selection and results in an analyte classification pattern as a fingerprint that can be applied to identify analytes in similar measurement conditions (Figure 4a).

Figure 4

Figure 4. Analyte Classification and Feature Selection algorithm (ACFSA) for reducing the number of fingerprinting sensors and producing an analyte classification scheme. (a) Simplified flowchart of the algorithm. (b) 2D principal component representations of the data for all 30 sensors (colored shapes), including the 95% uncertainty ellipses of the clustering method (dashed lines). (c) 2D principal component representations of the data for the selected two sensors (colored shapes), including the 95% uncertainty ellipses of the clustering method (dashed lines). (d) The Voronoi classifier in the 2D principal components space for all 30 sensors (left) and for the selected two sensors (right) with the same color scheme as above. Points show the cluster center, and lines are defined by the intercluster distance. (e) The average intercluster distance, ⟨D⟩ (blue circles), the adjusted Rand index, ARI (black diamond), and the Voronoi classifier error (orange dots) for the remaining sensors.

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ACFSA is a feature selection algorithm where features correspond to sensors. The input data is the experimentally measured fluorescence response of the SWCNT-peptide sensors upon metal-ion addition. In our experiments, we measured the responses in 5 repetitions for the 30 SWCNT-peptide sensors and 5 different metal analytes (Figure S9). First, principal component analysis (PCA) reduces data dimensionality to two components, with PC1 and PC2 explaining 89% and 4.5% variability, respectively. Then, k-means clustering groups the data into five clusters, corresponding to the metal analytes, relying on the knowledge that the number of clusters k equals the number of analytes. The 95% confidence eclipses are computed under a Gaussian assumption for each cluster, with main axes also computed by the PCA algorithm (Figure 4b), (98) and cluster labels were assigned using the Kuhn-Munkres algorithm. (99,100) Further, the clustering performance of the algorithm was evaluated against the ground truth data using the adjusted Rand index (ARI), which measures the cluster similarity between the k-means and the ground truth data, (101) where a perfect match would result in an ARI of 1, (100%), as observed in our results.
After clustering, the algorithm checks if a stopping condition is met, which can be a desired number of sensors or a desired clustering performance (ARI). If not, the algorithm proceeds to the feature (sensor) selection and elimination step, where one sensor per iteration is eliminated based on a Chi-squared feature ranking. (102) The process repeats with the remaining sensors until the condition is satisfied. Figure 4c shows the PCA and clustering for the final two selected sensors. PC1 and PC2 of the selected sensors explain 99.5% and 0.5% of the data variability, respectively, and the data is separated into five clusters differentiated mainly by their PC1 values, while PC2 is nearly redundant. Despite using only two sensors, clustering achieves 100% ARI, confirming that this minimal set is sufficient for accurate classification.
Based on the selected sensors and their response pattern, an output analyte classifier was constructed utilizing the updated cluster centers to create a nearest neighbor Voronoi diagram. (33) Figure 4d shows the Voronoi analyte classifiers for the sensor sets, for all 30 sensors, and for the two remaining sensors after sensor selection, shown in Figure 4b and c. The classifier areas for each analyte in the diagram were determined by the intercluster distance D between the centers of the k-means clusters. To identify an unknown analyte, its sensor response should be transformed using PCA, retaining the top two components for comparison with the classifier. Notably, a higher sensor count increases intercluster distance in the Voronoi diagram, reducing the error of mismatching an analyte in the classifier.
To quantify the performance of the ACFSA and the expected classifier error, we monitored the ARI, the average intercluster distance ⟨D⟩, and the classifier error for the remaining sensor set after each iteration, starting from the entire 30 sensors set. The classification performance was quantified as a function of the number of surviving sensors, which experimentalists could use as a design principle given the desired accuracy (Figure 4e). A detailed description of the ACFSA is given in the Supporting Information, while further analysis of the results follows. Our data shows 100% ARI accuracy in each ACFSA iteration, as clustering aligns with ground truth and all data points fall within their respective cluster. This high accuracy stems from five-repetition measurements and a low ∼3% standard deviation per SWCNT-peptide sensor. To evaluate the robustness of our method in simulating real-world scenarios where unknown samples may be analyzed, we tested an artificial data set with 50 repetitions per measurement and a 4-fold increase in standard deviation compared to the original data for each sensor. This simulation, designed to mimic conditions with greater measurement error and variability, resulted in larger, overlapping clusters, with some ground truth data falling outside the 95% confidence ellipse of the clusters. Despite these challenges, the ARI accuracy remained high at around 90% across all sensors (with an expected decrease during the elimination process), demonstrating the potential of our classification approach even under more variable and uncertain conditions to classify unknown samples (Figure S13).
We also compared randomized feature selection with the Chi-squared method in the ACFSA (Figures S14 and S15). The randomized approach required six sensors for 100% ARI, while Chi-squared needed only two. This highlights the advantage of statistical selection, further validating the ACFSA’s effectiveness.
The sensor elimination reduces intercluster distance ⟨D⟩, increasing the likelihood of classification errors, which measure the overlap between each Gaussian distribution associated with a cluster and the neighboring Voronoi tiles. We quantified this by calculating ⟨D⟩ and the resulting classification error from the Voronoi classifiers’ data (Figure 4e), applying the ACFSA until only one sensor remained. The Pearson correlation (ρ = −0.5) confirmed a negative correlation between ⟨D⟩ and error. Thus, the intercluster distance is a useful metric for classification accuracy. With one sensor (SWCNT-Gly-(6,5)), the classification error was 1.6%, but with two sensors (SWCNT-Gly-(6,5) and SWCNT-GlyOx-(6,5)), it dropped to 0.02%, while ARI remained 100%.
For sensor selection, it is recommended to set a rational stopping condition. This condition, instead of a certain number of sensors, can be a minimum ARI, or a maximum classification error. To gain further understanding of the ACFSA on different data sets, we examined the algorithm for various subsets of our data, i.e., only oxidized for the three chiralities, only nonoxidized for the three chiralities, and single chirality SWCNT-peptide sensors, yielding a different surviving sensor set for each data subset when we apply a stopping condition of ARI = 100% and a classification error of <1% (Table S1 and Figures S16–S21). The lowest classification error (0.02%) was achieved using the full 30-sensor data set, while restricted initial sets resulted in higher errors and sometimes required more sensors, emphasizing the value of diverse screening data. This analysis highlights the trade-off between classification accuracy and experimental efficiency. While using all 30 sensors ensures the lowest error rate, it is not always practical due to increased complexity and resource demands. By optimizing for a minimal yet effective sensor set, we balance classification performance with experimental feasibility, demonstrating that a smaller, well-selected subset can achieve comparable accuracy with significantly reduced effort. Pearson correlation coefficients for the intercluster distance and classifier error are detailed in Table S2.
Analyzing the elimination process, we observed key trends in feature (sensor) selection. The Chi-squared single-feature elimination method ensures sensors are removed systematically rather than randomly. Instead, sensor measurements are uniformly discretized into ten values (predictor variables), which are compared against the cluster labels (response variable) using a contingency table. The Chi-squared test follows for each sensor, measuring the statistical dependency between its discretized values and the response variable, compared to the null hypothesis of independence. This sensor ranking reflects the relative importance of each predictor on the ACFSA resulting labels (Table S1, Figures 4e, and S16–S21). Nevertheless, the ARI can increase during elimination in some iterations (Figures S19d, S20d, and S21d), which may occur if one sensor data contains additional experimentally induced noise such that the two main PCA components do not necessarily lead to better data classification as the total data uncertainty increases. After this sensor is eliminated, the classification accuracy can improve.
As expected, a higher number of sensors in the fingerprinting set results in a higher intercluster distance of the classifiers and, therefore, in a smaller classification error. Clustering performance depends on the quality of the initial screening data, i.e., sufficient sensor response variability, sufficient repetitions, and low standard deviation of the measurement. A diverse sensor set improves these conditions, as shown by the different subsets of our sensor data. The ACFSA efficiently analyzes complete data sets within minutes, which makes it feasible for larger sets. A complexity analysis estimates that the ACFSA, with O(n4) complexity and assuming a single run for 30 features takes two minutes, can process approximately 300 sensors in 2 weeks (see the Time complexity analysis section in the SI). Given the experimental challenge of handling 300 sensors, the ACFSA remains a valuable tool for sensor selection.
We applied the ACFSA to a binary response set, considering only fluorescence trends, which are either turn-on or turn-off responses. In this framework, an increase in intensity was assigned a value of +1, whereas a decrease was assigned −1. We further assume that this response trend remains consistent across concentrations within the sensors’ dynamic range, thereby removing direct concentration dependence. This allows for classification based on relative fluorescence change direction rather than intensity magnitudes. The constructed PCA, in this case, thus removes concentration dependency (Figure S22a). The binary classifier successfully classified chromium, partly classified between nickel and lead due to some overlap, but was unable to distinguish copper from mercury due to their identical negative response profiles (Figure S22b). This approach demonstrates the classification potential, with expanded measurements across more concentrations potentially enabling full analyte classification (see more details in the Supporting Information).

Sensor Robustness and Practical Considerations

To further explore concentration-dependent responses, we analyzed SWCNT-Gly-(6,5), the most effective classification sensor (Figure S23). We found detection limits of 3.0 × 10–9 M for copper, 7.2 × 10–5 M for chromium, 7.1 × 10–7 M for mercury, 8.1 × 10–6 M for lead, and 3.6 × 10–5 M for nickel. While detection limits varied, the fingerprinting patterns remained stable across concentrations, supporting the sensors’ utility for classification tasks across varying concentrations and broader data set applications. Importantly, to achieve quantification or classification of various concentration values, a complete data set covering the concentration range of interest would need to be systematically acquired and analyzed using the ACFSA algorithm. To test functionality in different environments, we analyzed SWCNT-Gly-(6,5) in serum and mineral water (Figure S24). Both showed distinct fingerprinting patterns, likely due to interactions with serum components or dissolved minerals. These results suggest that peptide-SWCNT sensors can adapt across matrices with matrix-specific adjustments. Extending the application of these sensors to additional environments with different interfering substances would require a dedicated set of fingerprinting experiments to generate environment-specific data sets. Ultimately, the same algorithm used for sensor selection in this study would be applied to the newly tested data sets, enabling an optimized identification of minimal sensor sets tailored to the respective conditions.
To assess batch-to-batch variability, we tested the SWCNT-Arg and SWCNT-Glu sensors across three peptide batches, including de novo sensor synthesis and fluorescence response measurements (Figure S25). While fluorescence intensity variations of up to 20% were observed, the overall fingerprinting pattern remained stable. This suggests that while batch-specific data sets may be required, the overall classification performance of the system is maintained across batches.
To assess the stability of the sensors over time, we conducted both short-term and long-term stability experiments. The fluorescence signal of all sensors was monitored under continuous laser irradiation for 9 h (Figure S26), demonstrating stable responses with only minor drifts observed in SWCNT-ArgOx. Additionally, we retested the same SWCNT-Gly sensor batch after 6 months, stored at 4 °C (Figure S27), confirming that while relative intensity variations of 10–20% were present, the overall fingerprinting pattern remained intact. Furthermore, the suspension showed no aggregation after these 6 months (Figure S28), indicating long-term colloidal stability. These results suggest that the sensors can be reliably used over extended periods without loss of functionality.
These analyses highlight the adaptability of the peptide-SWCNT sensor system for broader analyte classification and sensor selection across diverse conditions.

Conclusion

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We developed a comprehensive approach to synthesize Fmoc-peptide functionalized SWCNTs with varying amino acids in the peptide sequence, as the corona phase, to generate a near-infrared fluorescent sensor library for transition metal-ion fingerprinting and classification via a dedicated algorithmic framework. The Fmoc-peptides stabilized SWCNT suspensions in water while maintaining their NIR fluorescence. UV exposure induced photochemical polymerization and oxidation of the tyrosine side chains, leading to structural and chemical changes in the peptide corona, thus extending the SWCNT-peptide sensor library to 30 sensors. The fluorescence response patterns of three different chiralities, (6,5), (7,5), and (9,4), of the SWCNT-peptide sensors to transition metal-ions, Cu2+, Ni2+, Cr3+, Pb2+, and Hg2+, were used for constructing a fingerprint library for the five analytes.
To efficiently navigate this extensive library and identify the most effective set suitable as a fingerprinting sensor platform for metal-ion classification, we developed the Analyte Classification and Feature Selection Algorithm. The algorithm performs iterative sensor selection and elimination until a stopping condition is met, yielding an analyte classifier as output with a corresponding Voronoi diagram for analyte classification. The algorithm also provides information on the selection process, including the intercluster distance ⟨D⟩, ARI data, and Voronoi classifier error, which can be used to analyze the quality of any sensor set. Future work may improve the ACFSA scheme by considering other feature selection algorithms, such as genetic algorithms, (103,104) or by including more than two leading components for the PCA step before clustering the data.
Starting from the full 30 sensors library and setting stopping conditions of a maximum 1% classification error and ARI of 100%, in a few minutes of runtime, the ACFSA selected the sensors SWCNT-Gly-(6,5) and SWCNT-GlyOx-(6,5), which achieved the classification of the five analytes, with a classification error of 0.02%. Manual sensor selection, in contrast, would require iteratively analyzing fluorescence patterns, discarding redundant sensors, and reevaluating classification accuracy – a significantly more time-consuming and impractical process that becomes exponentially more complex as the sensor library grows, highlighting the efficiency of the ACFSA framework in automating sensor selection with speed, accuracy, and scalability. Testing on artificially generated data sets with larger variance confirmed robustness, maintaining 90% ARI even under increased uncertainty.
Our results demonstrated concentration-independent classification for chromium, and partial classification for nickel and lead. Additionally, SWCNT-Gly, the last sensor to remain in the elimination process, maintained the fingerprint patterns across concentrations, meaning that the fluorescence response trend – whether an increase (turn-on) or a decrease (turn-off) in intensity – remained the same for each metal-ion at all tested concentrations. The limits of detection varied from the nanomolar range for copper to the micromolar range for nickel. These results underscore the potential for extending this approach to more comprehensive data sets that include a wide range of analyte concentrations.
The methodology and algorithm developed here can be generalized and applied to other corona phase sensor–analyte screening experiments. This capability offers a powerful tool for analyzing multidimensional data obtained from these experiments, optimizing sensor selection, and enhancing analyte classification’s overall accuracy and efficiency across various applications. The flexibility and adaptability of this approach pave the way for future advancements in fingerprinting sensor technology and its application to classifying diverse molecular analytes.

Supporting Information

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.analchem.4c06762.

  • Supporting experimental section; molecular structure of the Fmoc-peptides; stability photograph; absorption and fluorescence spectra of the SWCNT-peptide suspensions; absorption and fluorescence spectra of SWCNT-peptide oxidation; Raman spectra of the SWCNTs-peptides before and after oxidation; TEM images; relative fluorescence intensity changes of the sensors with each metal at three different chiralities per metal and per peptide; correlation between the fluorescence response vs peptide load or Zeta potential; detailed explanation and performance analysis for all sensor subsets of the analyte classification and feature selection algorithm; ACFSA time complexity analysis; ACFSA implementation with simulated data. ACFSA with randomized feature selection; Pearson correlation coefficients for the intercluster distance with the classifier error ρ(⟨D⟩,error), and for the ARI with the classifier error table; ACFSA implementation with experimental data; PCA results for binary responses of the 30 sensors and five metal-ions; calibration curves and limit of detection for SWCNT-Gly sensor and the five metal-ions; relative fluorescence response of SWCNT-Gly to the metal-ions in serum and mineral water; sensor stability (PDF)

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Author Information

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  • Corresponding Author
    • Gili Bisker - Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 6997801, Israel;  Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv 6997801, Israel;  Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv 6997801, Israel;  Center for Light-Matter Interaction, Tel Aviv University, Tel Aviv 6997801, Israel;  Orcidhttps://orcid.org/0000-0003-2592-7956;  Email: [email protected]
  • Authors
  • Author Contributions

    The manuscript was written through the contributions of all authors. All authors have given approval to the final version of the manuscript.

  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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G.B. acknowledges the support of the Zuckerman STEM Leadership Program, the ERC NanoNonEq 101039127, the Israel Science Foundation (Grant no. 196/22), the Ministry of Science, Technology, and Space, Israel (Grants no. 3-17426 and 1001818370), the Marian Gertner Institute for Medical Nanosystems at Tel Aviv University, the Air Force Office of Scientific Research (AFOSR) under award number FA9550-20-1-0426, the Army Research Office (ARO) under Grant Number W911NF-21-1-0101, and the Naomi Prawer Kadar Foundation. G.P. thanks the Marian Gertner Institute for Medical Nanosystems at Tel Aviv University for the fellowship for excellent graduate students. M.F. acknowledges the support of The Yitzhak and Chaya Weinstein Research Institute for Signal Processing. The authors thank Dr. Ayala Lampel for valuable discussions.

References

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    Zhang, L.; Yang, Y.; Tan, J.; Yuan, Q. Chemically Modified Nucleic Acid Biopolymers Used in Biosensing. Mater. Chem. Front. 2020, 4 (5), 1315– 1327,  DOI: 10.1039/D0QM00026D
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    Shumeiko, V.; Zaken, Y.; Hidas, G.; Paltiel, Y.; Bisker, G.; Shoseyov, O. Peptide-Encapsulated Single-Wall Carbon Nanotube-Based Near-Infrared Optical Nose for Bacteria Detection and Classification. IEEE Sens. J. 2022, 22 (7), 6277– 6287,  DOI: 10.1109/JSEN.2022.3152622
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    Peptide-encapsulated single-wall carbon nanotube-based near-infrared optical nose for bacteria detection and classification
    Shumeiko, Vlad; Zaken, Yuval; Hidas, Guy; Paltiel, Yossi; Bisker, Gili; Shoseyov, Oded
    IEEE Sensors Journal (2022), 22 (7), 6277-6287CODEN: ISJEAZ; ISSN:1558-1748. (Institute of Electrical and Electronics Engineers)
    Sense of smell has been used as a diagnostic tool for almost entire human history. While successful examples of the use of the human nose for diagnostics are rare in modern history, there are ample reports of use of animals to diagnose various medical conditions. Bacterial infections often result in strong odors. In recent years, electronic noses (e-nose) and optical noses (o-nose) are of high interest in diagnostics and classificationof bacterial infections.Artificial olfactory sensors can perform noninvasively, immediately at the point of care, do not require extensive sample handling, and promise to be highly cost-effective. This manuscript demonstrates the development of a near-IR optical sniffer comprised of peptide-encapsulated (6,5) single-wall carbon nanotubes (SWCNTs) for bacteria detection and classification. Sixteen different peptides that include tyrosine in different proportions and positions were synthesized. The ability of these peptides to disperse SWCNTs in water was tested, and the intensity of the resultant optical signal was evaluated. Overall, longer peptides provided better dispersion as compared to shorter peptides. Addn. of the fluorenylmethyloxycarbonylchloride (Fmoc) group to pos. charged peptides tested in the current study significantly improved SWCNT dispersion and signal intensity. The sensors successfully distinguished between the odor of sterile growth medium, Escherichia coli, and Klebsiella pneumoniae. Moreover, we demonstrated the possibility of using the developed sensors for antibiotics susceptibility testing. The sensors provided results in real-time, enabledmultiple-usage, and operated at room temp.
  17. 17
    Zong, C.; Fang, L.; Song, F.; Wang, A.; Wan, Y. Fluorescent Fingerprint Bacteria by Multi-Channel Magnetic Fluorescent Nanosensor. Sens. Actuators, B 2019, 289, 234– 241,  DOI: 10.1016/j.snb.2019.03.091
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    Fluorescent fingerprint bacteria by multi-channel magnetic fluorescent nanosensor
    Zong, Chengli; Fang, Linyi; Song, Fengge; Wang, Aimin; Wan, Yi
    Sensors and Actuators, B: Chemical (2019), 289 (), 234-241CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)
    Bacteria lies at the root of many infectious and non-infectious diseases. To control and prevent those diseases, there is an urgent need for the rapid and affordable microbial sensing techniques to aid the point-of-care bacterial identification. Here, we report the design and performance of a Multichannel Magnetic Fluorescent Nose (dMFN) for bacteria detection. The system consists of a magnetic nanoparticle conjugated with three different fluorescent proteins (FPs). Upon interacting with bacteria, characteristic levels of the three FPs can be displaced, which are dependent on the binding strength among quaternized magnetic nanoparticles, FPs and bacteria. These characteristic fluorescent responses are bacteria specific, repeatable and can be differentiated by Linear Discriminant Anal. (LDA). The technique is employed for bacterial identity study with a first discriminant of 89.7% within 30 min. We further used dMFN platform for antibiotic screening, the eleven drugs can be distinguished with a first discriminant of 95.2% for E. coli and 97.6% for S. aureu. The generally applicable platform offers a simple tool for the rapid diagnosis and drug screening of pathogens without preprocessing steps.
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    Amir, D.; Hendler-Neumark, A.; Wulf, V.; Ehrlich, R.; Bisker, G. Oncometabolite Fingerprinting Using Fluorescent Single-Walled Carbon Nanotubes. Adv. Mater. Interfaces 2022, 9, 2101591,  DOI: 10.1002/admi.202101591
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    Oncometabolite Fingerprinting Using Fluorescent Single-Walled Carbon Nanotubes
    Amir, Dean; Hendler-Neumark, Adi; Wulf, Verena; Ehrlich, Roni; Bisker, Gili
    Advanced Materials Interfaces (2022), 9 (4), 2101591CODEN: AMIDD2; ISSN:2196-7350. (Wiley-VCH Verlag GmbH & Co. KGaA)
    The prodn. of oncometabolites is the direct result of mutagenesis in key cellular metabolic enzymes, appearing typically in cancers such as glioma, leukemia, and glioblastoma. Once accumulated, oncometabolites promote cancerous transformations by interfering with important cellular functions. Hence, the ability to sense and quantify oncometabolites is essential for cancer research and clin. diagnosis. Here, the authors present a near-IR optical nanosensor for a known oncometabolite, D-2-hydroxyglutarate (D2HG), discovered in a screening of a library of fluorescent single-walled carbon nanotubes (SWCNTs) functionalized with ssDNA. The screening reveals (ATTT)7-SWCNT as a sensor for D2HG, exhibiting a fluorescence intensity increase upon the interaction with D2HG. The fluorescence response of the sensor does not appear to be attributed to basic chem. features of the target analytes tested, and is shown to discriminate D2HG from other related metabolites, including its enantiomer L-2-hydroxyglutarate. Further, the fluorescence modulation is dependent on the analyte concn. and the SWCNT chirality, showing up to 40.7% and 28.2% increase of the (6,5)-chirality peak and the (9,5)- and (8,7)-chirality joint peak, at 572 and 730 nm excitation, resp., in the presence of 10 mM D2HG. This work opens new opportunities for mol. recognition of oncometabolites which can advance basic cancer metab. research.
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    Kim, M.; Chen, C.; Wang, P.; Mulvey, J. J.; Yang, Y.; Wun, C.; Antman-Passig, M.; Luo, H.-B.; Cho, S.; Long-Roche, K.; Ramanathan, L. V.; Jagota, A.; Zheng, M.; Wang, Y.; Heller, D. A. Detection of Ovarian Cancer via the Spectral Fingerprinting of Quantum-Defect-Modified Carbon Nanotubes in Serum by Machine Learning. Nat. Biomed. Eng. 2022, 6 (3), 267– 275,  DOI: 10.1038/s41551-022-00860-y
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    Detection of ovarian cancer via the spectral fingerprinting of quantum-defect-modified carbon nanotubes in serum by machine learning
    Kim, Mijin; Chen, Chen; Wang, Peng; Mulvey, Joseph J.; Yang, Yoona; Wun, Christopher; Antman-Passig, Merav; Luo, Hong-Bin; Cho, Sun; Long-Roche, Kara; Ramanathan, Lakshmi V.; Jagota, Anand; Zheng, Ming; Wang, YuHuang; Heller, Daniel A.
    Nature Biomedical Engineering (2022), 6 (3), 267-275CODEN: NBEAB3; ISSN:2157-846X. (Nature Portfolio)
    Serum biomarkers are often insufficiently sensitive or specific to facilitate cancer screening or diagnostic testing. In ovarian cancer, the few established serum biomarkers are highly specific, yet insufficiently sensitive to detect early-stage disease and to impact the mortality rates of patients with this cancer. Here we show that a disease fingerprint acquired via machine learning from the spectra of near-IR fluorescence emissions of an array of carbon nanotubes functionalized with quantum defects detects high-grade serous ovarian carcinoma in serum samples from symptomatic individuals with 87sensitivity at 98specificity (compared with 84sensitivity at 98specificity for the current best clin. screening test, which uses measurements of cancer antigen 125 and transvaginal ultrasonog.). We used 269 serum samples to train and validate several machine-learning classifiers for the discrimination of patients with ovarian cancer from those with other diseases and from healthy individuals. The predictive values of the best classifier could not be attained via known protein biomarkers, suggesting that the array of nanotube sensors responds to unidentified serum biomarkers.
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    Nißler, R.; Bader, O.; Dohmen, M.; Walter, S. G.; Noll, C.; Selvaggio, G.; Groß, U.; Kruss, S. Remote near Infrared Identification of Pathogens with Multiplexed Nanosensors. Nat. Commun. 2020, 11 (1), 5995,  DOI: 10.1038/s41467-020-19718-5
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    Remote near infrared identification of pathogens with multiplexed nanosensors
    Nissler, Robert; Bader, Oliver; Dohmen, Maria; Walter, Sebastian G.; Noll, Christine; Selvaggio, Gabriele; Gross, Uwe; Kruss, Sebastian
    Nature Communications (2020), 11 (1), 5995CODEN: NCAOBW; ISSN:2041-1723. (Nature Research)
    Infectious diseases are worldwide a major cause of morbidity and mortality. Fast and specific detection of pathogens such as bacteria is needed to combat these diseases. Optimal methods would be non-invasive and without extensive sample-taking/processing. Here, we developed a set of near IR (NIR) fluorescent nanosensors and used them for remote fingerprinting of clin. important bacteria. The nanosensors are based on single-walled carbon nanotubes (SWCNTs) that fluoresce in the NIR optical tissue transparency window, which offers ultra-low background and high tissue penetration. They are chem. tailored to detect released metabolites as well as specific virulence factors (lipopolysaccharides, siderophores, DNases, proteases) and integrated into functional hydrogel arrays with 9 different sensors. These hydrogels are exposed to clin. isolates of 6 important bacteria (Staphylococcus aureus, Escherichia coli,...) and remote (≥25 cm) NIR imaging allows to identify and distinguish bacteria. Sensors are also spectrally encoded (900 nm, 1000 nm, 1250 nm) to differentiate the two major pathogens P. aeruginosa as well as S. aureus and penetrate tissue (>5 mm). This type of multiplexing with NIR fluorescent nanosensors enables remote detection and differentiation of important pathogens and the potential for smart surfaces.
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    Morrison, K.; Tincher, M.; Rothchild, A.; Yehl, K. Fingerprinting DNAzyme Cross-Reactivity for Pattern-Based Detection of Heavy Metals. Anal. Chem. 2024, 96 (29), 11780– 11789,  DOI: 10.1021/acs.analchem.4c01331
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    Ebrahim-Habibi, M.-B.; Ghobeh, M.; Mahyari, F. A.; Rafii-Tabar, H.; Sasanpour, P. An Investigation into Non-Covalent Functionalization of a Single-Walled Carbon Nanotube and a Graphene Sheet with Protein G: A Combined Experimental and Molecular Dynamics Study. Sci. Rep. 2019, 9 (1), 1273,  DOI: 10.1038/s41598-018-37311-1
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    Sultana, N.; Dewey, H. M.; Arellano, A. G.; Budhathoki-Uprety, J. Understanding the Molecular Assemblies of Single Walled Carbon Nanotubes and Tailoring Their Photoluminescence for the Next-Generation Optical Nanosensors. Chem. Mater. 2024, 36 (9), 4034– 4053,  DOI: 10.1021/acs.chemmater.4c00232
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    Lambert, B. P.; Taheri, A.; Wu, S.-J.; Gillen, A. J.; Kashaninejad, M.; Boghossian, A. A. Directed Evolution of Nanosensors for the Detection of Mycotoxins. bioRxiv 2023,  DOI: 10.1101/2023.06.13.544576
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    An, S.; Suh, Y.; Kelich, P.; Lee, D.; Vukovic, L.; Jeong, S. Directed Evolution of Near-Infrared Serotonin Nanosensors with Machine Learning-Based Screening. Nanomaterials 2024, 14 (3), 247,  DOI: 10.3390/nano14030247
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    Jeong, S.; Yang, D.; Beyene, A. G.; Del Bonis-O’Donnell, J. T.; Gest, A. M. M.; Navarro, N.; Sun, X.; Landry, M. P. High-Throughput Evolution of near-Infrared Serotonin Nanosensors. Sci. Adv. 2019, 5 (12), eaay3771  DOI: 10.1126/sciadv.aay3771
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    Antibody production, design and use for biosensor-based applications
    Conroy, Paul J.; Hearty, Stephen; Leonard, Paul; O'Kennedy, Richard J.
    Seminars in Cell & Developmental Biology (2009), 20 (1), 10-26CODEN: SCDBFX; ISSN:1084-9521. (Elsevier Ltd.)
    A review. Currently, the reliable detection and quantification of a multitude of different analytes is crucial in many applications and settings. Biosensors have revolutionised diagnostics for use in point-of-care testing (POC), the detection of food and environmental contaminants, biol. warfare agents, illicit drugs and human/animal disease markers. Antibodies continue to play a pivotal role in many sensor devices due to their exquisite specificity for their cognate antigens. In this review current biosensor platforms employing antibodies for mol. recognition are briefly described. The use of mol. biol. techniques for the generation and improvement of antibodies is critically examd. Such recombinant antibodies possess improved attributes for use in biosensor development in terms of design, stability, affinity and specificity.
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    Yoon, M.; Shin, S.; Lee, S.; Kang, J.; Gong, X.; Cho, S.-Y. Scalable Photonic Nose Development through Corona Phase Molecular Recognition. ACS Sens. 2024, 9 (12), 6311– 6319,  DOI: 10.1021/acssensors.4c02327
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    Bigdeli, A.; Ghasemi, F.; Golmohammadi, H.; Abbasi-Moayed, S.; Nejad, M. A. F.; Fahimi-Kashani, N.; Jafarinejad, S.; Shahrajabian, M.; Hormozi-Nezhad, M. R. Nanoparticle-Based Optical Sensor Arrays. Nanoscale 2017, 9 (43), 16546– 16563,  DOI: 10.1039/C7NR03311G
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    Nanoparticle-based optical sensor arrays
    Bigdeli, Arafeh; Ghasemi, Forough; Golmohammadi, Hamed; Abbasi-Moayed, Samira; Nejad, M. Amin Farahmand; Fahimi-Kashani, Nafiseh; Jafarinejad, Somayeh; Shahrajabian, Maryam; Hormozi-Nezhad, M. Reza
    Nanoscale (2017), 9 (43), 16546-16563CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)
    As in many other methods that have integrated nanoparticles (NPs), the chem. nose/tongue strategy has also progressed greatly since the entrance of NPs into this field. The fascinating tunable physicochem. properties of NPs have made them powerful candidates for array-based sensing platforms and have enabled the development of real-time, sensitive and portable systems that are able to target complex mixts. of analytes. In particular, the unique optical properties of NPs have a key role in providing promising array-based sensing approaches. This review will describe the main aspects and processes of most common NP-based optical sensor arrays. The fundamental steps in the design of a sensor array together with details of each step would be provided. The review begins with the principles of optical sensor arrays and presents the concept of cross-reactivity as the main criterion in the selection of sensing elements. Changes in the absorption and emission properties of the assembled sensing elements are categorized into two main classes of optical signals (colorimetric and fluorometric). Popular chemometric methods used for analyzing the data acquired by a sensor array have also been briefly introduced. On the basis of the objective and the desired application, different types of plasmonic and fluorescent NP that possess unique opto-phys. properties have been presented as available choices in the design of sensing elements. The vast no. of applications of NP-based optical sensor arrays published throughout the literature have then been reviewed according to their mechanism of interaction and the type of optical signal. Finally, the remaining challenges and future directions in this topic have been highlighted.
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    Coto-García, A. M.; Sotelo-González, E.; Fernández-Argüelles, M. T.; Pereiro, R.; Costa-Fernández, J. M.; Sanz-Medel, A. Nanoparticles as Fluorescent Labels for Optical Imaging and Sensing in Genomics and Proteomics. Anal. Bioanal. Chem. 2011, 399 (1), 29– 42,  DOI: 10.1007/s00216-010-4330-3
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    Fundamental Electronic Properties and Applications of Single-Walled Carbon Nanotubes
    Ouyang, Min; Huang, Jin-Lin; Lieber, Charles M.
    Accounts of Chemical Research (2002), 35 (12), 1018-1025CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)
    Recent scanning tunneling microscopy studies of the intrinsic electronic properties of single-walled carbon nanotubes (SWNTs) are overviewed in this Account. A brief theor. treatment of the electronic properties of SWNTs is developed, and then the effects of finite curvature and broken symmetry on electronic properties, the unique 1-dimensional energy dispersion in nanotubes, the interaction between local spins and carriers in metallic nanotubes systems, and the at. structure and electronic properties of intramol. junctions are described. The implications of these studies for understanding fundamental 1-dimensional physics and future nanotube device applications are also discussed.
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    Bachilo, S. M.; Strano, M. S.; Kittrell, C.; Hauge, R. H.; Smalley, R. E.; Weisman, R. B. Structure-Assigned Optical Spectra of Single-Walled Carbon Nanotubes. Science 2002, 298 (5602), 2361– 2366,  DOI: 10.1126/science.1078727
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    Structure-Assigned Optical Spectra of Single-Walled Carbon Nanotubes
    Bachilo, Sergei M.; Strano, Michael S.; Kittrell, Carter; Hauge, Robert H.; Smalley, Richard E.; Weisman, R. Bruce
    Science (Washington, DC, United States) (2002), 298 (5602), 2361-2366CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
    Spectrofluorometric measurements on single-walled carbon nanotubes (SWNTs) isolated in aq. surfactant suspensions have revealed distinct electronic absorption and emission transitions for more than 30 different semiconducting nanotube species. By combining these fluorimetric results with resonance Raman data, each optical transition has been mapped to a specific (n,m) nanotube structure. Optical spectroscopy can thereby be used to rapidly det. the detailed compn. of bulk SWNT samples, providing distributions in both tube diam. and chiral angle. The measured transition frequencies differ substantially from simple theor. predictions. These deviations may reflect combinations of trigonal warping and excitonic effects.
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    Kharlamova, M. V.; Burdanova, M. G.; Paukov, M. I.; Kramberger, C. Synthesis, Sorting, and Applications of Single-Chirality Single-Walled Carbon Nanotubes. Materials 2022, 15 (17), 5898,  DOI: 10.3390/ma15175898
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    Jain, A.; Homayoun, A.; Bannister, C. W.; Yum, K. Single-walled Carbon Nanotubes as Near-infrared Optical Biosensors for Life Sciences and Biomedicine. Biotechnol. J. 2015, 10 (3), 447– 459,  DOI: 10.1002/biot.201400168
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    Single-walled carbon nanotubes as near-infrared optical biosensors for life sciences and biomedicine
    Jain, Astha; Homayoun, Aida; Bannister, Christopher W.; Yum, Kyungsuk
    Biotechnology Journal (2015), 10 (3), 447-459CODEN: BJIOAM; ISSN:1860-6768. (Wiley-VCH Verlag GmbH & Co. KGaA)
    Single-walled carbon nanotubes that emit photostable near-IR fluorescence have emerged as near-IR optical biosensors for life sciences and biomedicine. Since the discovery of their near-IR fluorescence, researchers have engineered single-walled carbon nanotubes to function as an optical biosensor that selectively modulates its fluorescence upon binding of target mols. Here we review the recent advances in the single-walled carbon nanotube-based optical sensing technol. for life sciences and biomedicine. We discuss the structure and optical properties of single-walled carbon nanotubes, the mechanisms for mol. recognition and signal transduction in single-walled carbon nanotube complexes, and the recent development of various single-walled carbon nanotube-based optical biosensors. We also discuss the opportunities and challenges to translate this emerging technol. into biomedical research and clin. use, including the biol. safety of single-walled carbon nanotubes. The advances in single-walled carbon nanotube-based near-IR optical sensing technol. open up a new avenue for in vitro and in vivo biosensing with high sensitivity and high spatial resoln., beneficial for many areas of life sciences and biomedicine.
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    Nißler, R.; Ackermann, J.; Ma, C.; Kruss, S. Prospects of Fluorescent Single-Chirality Carbon Nanotube-Based Biosensors. Anal. Chem. 2022, 94 (28), 9941– 9951,  DOI: 10.1021/acs.analchem.2c01321
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    Zhang, Y.; Guo, J.; Tang, Z.; Tang, C.; Li, Y.; Tao, X.; Zhou, B.; Chen, W.; Guo, L.; Tang, K.; Liang, T. Recent Developments and Trends of Biosensors Based on Carbon Nanotubes for Biomedical Diagnosis Applications: A Review. Biosens Bioelectron X 2024, 17, 100424,  DOI: 10.1016/j.biosx.2023.100424
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    Acharya, R.; Patil, T. V.; Dutta, S. D.; Lee, J.; Ganguly, K.; Kim, H.; Randhawa, A.; Lim, K.-T. Single-Walled Carbon Nanotube-Based Optical Nano/Biosensors for Biomedical Applications: Role in Bioimaging, Disease Diagnosis, and Biomarkers Detection. Adv. Mater. Technol. 2024, 9 (20), 2400279,  DOI: 10.1002/admt.202400279
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    Yaari, Z.; Cheung, J. M.; Baker, H. A.; Frederiksen, R. S.; Jena, P. V.; Horoszko, C. P.; Jiao, F.; Scheuring, S.; Luo, M.; Heller, D. A. Nanoreporter of an Enzymatic Suicide Inactivation Pathway. Nano Lett. 2020, 20 (11), 7819– 7827,  DOI: 10.1021/acs.nanolett.0c01858
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    Nanoreporter of an Enzymatic Suicide Inactivation Pathway
    Yaari, Zvi; Cheung, Justin M.; Baker, Hanan A.; Frederiksen, Rune S.; Jena, Prakrit V.; Horoszko, Christopher P.; Jiao, Fang; Scheuring, Simon; Luo, Minkui; Heller, Daniel A.
    Nano Letters (2020), 20 (11), 7819-7827CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    Enzymic suicide inactivation, a route of permanent enzyme inhibition, is the mechanism of action for a wide array of pharmaceuticals. Here, we developed the first nanosensor that selectively reports the suicide inactivation pathway of an enzyme. The sensor is based on modulation of the near-IR fluorescence of an enzyme-bound carbon nanotube. The nanosensor responded selectively to substrate-mediated suicide inactivation of the tyrosinase enzyme via bathochromic shifting of the nanotube emission wavelength. Mechanistic investigations revealed that singlet oxygen generated by the suicide inactivation pathway induced the response. We used the nanosensor to quantify the degree of enzymic inactivation by measuring response rates to small mol. tyrosinase modulators. This work resulted in a new capability of interrogating a specific route of enzymic death. Potential applications include drug screening and hit-validation for compds. that elicit or inhibit enzymic inactivation and single-mol. measurements to assess population heterogeneity in enzyme activity.
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    Kallmyer, N. E.; Abdennadher, M. S.; Agarwal, S.; Baldwin-Kordick, R.; Khor, R. L.; Kooistra, A. S.; Peterson, E.; McDaniel, M. D.; Reuel, N. F. Inexpensive Near-Infrared Fluorimeters: Enabling Translation of NIR-Based Assays to the Field. Anal. Chem. 2021, 93 (11), 4800– 4808,  DOI: 10.1021/acs.analchem.0c03732
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    Dong, J.; Lee, M. A.; Rajan, A. G.; Rahaman, I.; Sun, J. H.; Park, M.; Salem, D. P.; Strano, M. S. A Synthetic Mimic of Phosphodiesterase Type 5 Based on Corona Phase Molecular Recognition of Single-Walled Carbon Nanotubes. Proc. Natl. Acad. Sci. U. S. A. 2020, 117 (43), 26616– 26625,  DOI: 10.1073/pnas.1920352117
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    A synthetic mimic of phosphodiesterase type 5 based on corona phase molecular recognition of single-walled carbon nanotubes
    Dong, Juyao; Lee, Michael A.; Rajan, Ananth Govind; Rahaman, Imon; Sun, Jessica H.; Park, Minkyung; Salem, Daniel P.; Strano, Michael S.
    Proceedings of the National Academy of Sciences of the United States of America (2020), 117 (43), 26616-26625CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
    Mol. recognition binding sites that specifically identify a target mol. are essential for life science research, clin. diagnoses, and therapeutic development. Corona phase mol. recognition is a technique introduced to generate synthetic recognition at the surface of a nanoparticle corona, but it remains an important question whether such entities can achieve the specificity of natural enzymes and receptors. In this work, we generate and screen a library of 24 amphiphilic polymers, preselected for mol. recognition and based on functional monomers including methacrylic acid, acrylic acid, and styrene, iterating upon a poly(methacrylic acid-co-styrene) motif. When complexed to a single-walled carbon nanotube, some of the resulting corona phases demonstrate binding specificity remarkably similar to that of phosphodiesterase type 5 (PDE5), an enzyme that catalyzes the hydrolysis of secondary messenger. The corona phase binds selectively to a PDE5 inhibitor, Vardenafil, as well as its mol. variant, but not to other potential off-target inhibitors. Our work herein examines the specificity and sensitivity of polymer 'mutations' to the corona phase, as well as direct competitions with the native binding PDE5. Using structure perturbation, corona surface characterization, and mol. dynamics simulations, we show that the mol. recognition is assocd. with the unique three-dimensional configuration of the corona phase formed at the nanotube surface. This work conclusively shows that corona phase mol. recognition can mimic key aspects of biol. recognition sites and drug targets, opening up possibilities for pharmaceutical and biol. applications.
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    Wulf, V.; Slor, G.; Rathee, P.; Amir, R. J.; Bisker, G. Dendron–Polymer Hybrids as Tailorable Responsive Coronae of Single-Walled Carbon Nanotubes. ACS Nano 2021, 15 (12), 20539– 20549,  DOI: 10.1021/acsnano.1c09125
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    Dendron-Polymer Hybrids as Tailorable Responsive Coronae of Single-Walled Carbon Nanotubes
    Wulf, Verena; Slor, Gadi; Rathee, Parul; Amir, Roey J.; Bisker, Gili
    ACS Nano (2021), 15 (12), 20539-20549CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    Functional composite materials that can change their spectral properties in response to external stimuli have a plethora of applications in fields ranging from sensors to biomedical imaging. One of the most promising types of materials used to design spectrally active composites are fluorescent single-walled carbon nanotubes (SWCNTs), noncovalently functionalized by synthetic amphiphilic polymers. These coated SWCNTs can exhibit modulations in their fluorescence spectra in response to interactions with target analytes. Hence, identifying new amphiphiles with interchangeable building blocks that can form individual coronae around the SWCNTs and can be tailored for a specific application is of great interest. This study presents highly modular amphiphilic polymer-dendron hybrids, composed of hydrophobic dendrons and hydrophilic polyethylene glycol (PEG) that can be synthesized with a high degree of structural freedom, for suspending SWCNTs in aq. soln. Taking advantage of the high mol. precision of these PEG-dendrons, we show that precise differences in the chem. structure of the hydrophobic end groups of the dendrons can be used to control the interactions of the amphiphiles with the SWCNT surface. These interactions can be directly related to differences in the intrinsic near-IR fluorescence emission of the various chiralities in a SWCNT sample. Utilizing the susceptibility of the PEG-dendrons toward enzymic degrdn., we demonstrate the ability to monitor enzymic activity through changes in the SWCNT fluorescent signal. These findings pave the way for a rational design of functional SWCNTs, which can be used for optical sensing of enzymic activity in the near-IR spectral range.
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    Basu, S.; Hendler-Neumark, A.; Bisker, G. Rationally Designed Functionalization of Single-Walled Carbon Nanotubes for Real-Time Monitoring of Cholinesterase Activity and Inhibition in Plasma. Small 2024, 20, 2309481,  DOI: 10.1002/smll.202309481
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    Basu, S.; Hendler-Neumark, A.; Bisker, G. Monitoring Enzyme Activity Using Near-Infrared Fluorescent Single-Walled Carbon Nanotubes. ACS Sens. 2024, 9 (5), 2237– 2253,  DOI: 10.1021/acssensors.4c00377
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    Williams, R. M.; Harvey, J. D.; Budhathoki-Uprety, J.; Heller, D. A. Glutathione-S-Transferase Fusion Protein Nanosensor. Nano Lett. 2020, 20 (10), 7287– 7295,  DOI: 10.1021/acs.nanolett.0c02691
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    Glutathione-S-transferase Fusion Protein Nanosensor
    Williams, Ryan M.; Harvey, Jackson D.; Budhathoki-Uprety, Januka; Heller, Daniel A.
    Nano Letters (2020), 20 (10), 7287-7295CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    Fusion protein tags are widely used to capture and track proteins in research and industrial bioreactor processes. Quantifying fusion-tagged proteins normally requires several purifn. steps coupled with classical protein assays. Here, the authors developed a broadly applicable nanosensor platform that quantifies glutathione-S-transferase (GST) fusion proteins in real-time. The authors synthesized a glutathione-DNA-carbon nanotube system to study glutathione-GST interactions via semiconducting single-walled carbon nanotube (SWCNT) photoluminescence. SWCNT fluorescence wavelength and intensity modulation occurred specifically in response to GST and GST-fusions. The sensor response was dependent on SWCNT structure, wherein mod(n - m, 3) = 1 nanotube wavelength and intensity responses correlated with nanotube diam. distinctly from mod(n - m, 3) = 2 SWCNT responses. The authors also found broad functionality of this sensor to diverse GST-tagged proteins. This work comprises the first label-free optical sensor for GST and has implications for the assessment of protein expression in situ, including in imaging and industrial bioreactor settings.
  49. 49
    Ehrlich, R.; Hendler-Neumark, A.; Wulf, V.; Amir, D.; Bisker, G. Optical Nanosensors for Real-Time Feedback on Insulin Secretion by Β-Cells. Small 2021, 17 (30), 2101660,  DOI: 10.1002/smll.202101660
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    Optical nanosensors for real-time feedback on insulin secretion by beta-cells
    Ehrlich, Roni; Hendler-Neumark, Adi; Wulf, Verena; Amir, Dean; Bisker, Gili
    Small (2021), 17 (30), 2101660CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)
    Quantification of insulin is essential for diabetes research in general, and for the study of pancreatic β-cell function in particular. Herein, fluorescent single-walled carbon nanotubes (SWCNT) are used for the recognition and real-time quantification of insulin. Two approaches for rendering the SWCNT sensors for insulin are compared, using surface functionalization with either a natural insulin aptamer with known affinity to insulin, or a synthetic lipid-poly(ethylene glycol) (PEG) (C16-PEG(2000Da)-Ceramide), both of which show a modulation of the emitted fluorescence in response to insulin. Although the PEGylated-lipid has no prior affinity to insulin, the response of C16-PEG(2000Da)-Ceramide-SWCNTs to insulin is more stable and reproducible compared to the insulin aptamer-SWCNTs. The SWCNT sensors successfully detect insulin secreted by β-cells within the complex environment of the conditioned media. The insulin is quantified by comparing the SWCNTs fluorescence response to a std. calibration curve, and the results are found to be in agreement with an ELISA. This novel anal. tool for real time quantification of insulin secreted by β-cells provides new opportunities for rapid assessment of β-cell function, with the ability to push forward many aspects of diabetes research.
  50. 50
    Pinals, R. L.; Ledesma, F.; Yang, D.; Navarro, N.; Jeong, S.; Pak, J. E.; Kuo, L.; Chuang, Y.-C.; Cheng, Y.-W.; Sun, H.-Y.; Landry, M. P. Rapid SARS-CoV-2 Spike Protein Detection by Carbon Nanotube-Based Near-Infrared Nanosensors. Nano Lett. 2021, 21 (5), 2272– 2280,  DOI: 10.1021/acs.nanolett.1c00118
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    50
    Rapid SARS-CoV-2 spike protein detection by carbon nanotube-based near-infrared nanosensors
    Pinals, Rebecca L.; Ledesma, Francis; Yang, Darwin; Navarro, Nicole; Jeong, Sanghwa; Pak, John E.; Kuo, Lili; Chuang, Yung-Chun; Cheng, Yu-Wei; Sun, Hung-Yu; Landry, Markita P.
    Nano Letters (2021), 21 (5), 2272-2280CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    To effectively track and eliminate COVID-19, it is crit. to develop tools for rapid and accessible diagnosis of actively infected individuals. Here, we introduce a single-walled carbon nanotube (SWCNT)-based optical sensing approach toward this end. We construct a nanosensor based on SWCNTs noncovalently functionalized with ACE2, a host protein with high binding affinity for the SARS-CoV-2 spike protein. The presence of the SARS-CoV-2 spike protein elicits a robust, 2-fold nanosensor fluorescence increase within 90 min of spike protein exposure. We characterize the nanosensor stability and sensing mechanism and passivate the nanosensor to preserve sensing response in saliva and viral transport medium. We further demonstrate that these ACE2-SWCNT nanosensors retain sensing capacity in a surface-immobilized format, exhibiting a 73% fluorescence turn-on response within 5 s of exposure to 35 mg/L SARS-CoV-2 virus-like particles. Our data demonstrate that ACE2-SWCNT nanosensors can be developed into an optical tool for rapid SARS-CoV-2 detection.
  51. 51
    Gillen, A. J.; Siefman, D. J.; Wu, S.-J.; Bourmaud, C.; Lambert, B.; Boghossian, A. A. Templating Colloidal Sieves for Tuning Nanotube Surface Interactions and Optical Sensor Responses. J. Colloid Interface Sci. 2020, 565, 55– 62,  DOI: 10.1016/j.jcis.2019.12.058
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    Templating colloidal sieves for tuning nanotube surface interactions and optical sensor responses
    Gillen, Alice J.; Siefman, Daniel J.; Wu, Shang-Jung; Bourmaud, Claire; Lambert, Benjamin; Boghossian, Ardemis A.
    Journal of Colloid and Interface Science (2020), 565 (), 55-62CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)
    Surfactants offer a tunable approach for modulating the exposed surface area of a nanoparticle. They further present a scalable and cost-effective means for suspending single-walled carbon nanotubes (SWCNTs), which have demonstrated practical use as fluorescence sensors. Though surfactant suspensions show record quantum yields for SWCNTs in aq. solns., they lack the selectivity that is vital for optical sensing. We present a new method for controlling the selectivity of optical SWCNT sensors through colloidal templating of the exposed surface area. Colloidal nanotube sensors were obtained using various concns. of sodium cholate, and their performances were compared to DNA-SWCNT optical sensors. Sensor responses were measured against a library of bioanalytes, including neurotransmitters, amino acids, and sugars. We report an intensity response towards dopamine and serotonin for all sodium cholate-suspended SWCNT concns. We further identify a selective, 14.1 nm and 10.3 nm wavelength red-shifting response to serotonin for SWCNTs suspended in 1.5 and 0.5 mM sodium cholate, resp. Through controlled, adsorption-based tuning of the nanotube surface, this study demonstrates the applicability of sub-crit. colloidal suspensions to achieve selectivities exceeding those previously reported for DNA-SWCNT sensors.
  52. 52
    Beyene, A. G.; Delevich, K.; Del Bonis-O’Donnell, J. T.; Piekarski, D. J.; Lin, W. C.; Thomas, A. W.; Yang, S. J.; Kosillo, P.; Yang, D.; Prounis, G. S.; Wilbrecht, L.; Landry, M. P. Imaging Striatal Dopamine Release Using a Nongenetically Encoded near Infrared Fluorescent Catecholamine Nanosensor. Sci. Adv. 2019, 5 (7), eaaw3108  DOI: 10.1126/sciadv.aaw3108
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    Dinarvand, M.; Elizarova, S.; Daniel, J.; Kruss, S. Imaging of Monoamine Neurotransmitters with Fluorescent Nanoscale Sensors. ChemPluschem 2020, 85 (7), 1465– 1480,  DOI: 10.1002/cplu.202000248
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    Imaging of Monoamine Neurotransmitters with Fluorescent Nanoscale Sensors
    Dinarvand, Meshkat; Elizarova, Sofia; Daniel, James; Kruss, Sebastian
    ChemPlusChem (2020), 85 (7), 1465-1480CODEN: CHEMM5; ISSN:2192-6506. (Wiley-VCH Verlag GmbH & Co. KGaA)
    A review. Cells use biomols. to convey information. For instance, neurons communicate by releasing chems. called neurotransmitters, including several monoamines. The information transmitted by neurons is, in part, coded in the type and amt. of neurotransmitter released, the spatial distribution of release sites, the frequency of release events, and the diffusion range of the neurotransmitter. Therefore, quant. information about neurotransmitters at the (sub)cellular level with high spatiotemporal resoln. is needed to understand how complex cellular networks function. So far, various anal. methods have been developed and used to detect neurotransmitter secretion from cells. However, each method has limitations with respect to chem., temporal and spatial resoln. In this review, we focus on emerging methods for optical detection of neurotransmitter release and discuss fluorescent sensors/probes for monoamine neurotransmitters such as dopamine and serotonin. We focus on the latest advances in near IR fluorescent carbon nanotube-based sensors and engineered fluorescent proteins for monoamine imaging, which provide high spatial and temporal resoln. suitable for examg. the release of monoamines from cells in cellular networks.
  54. 54
    Lee, M. A.; Wang, S.; Jin, X.; Bakh, N. A.; Nguyen, F. T.; Dong, J.; Silmore, K. S.; Gong, X.; Pham, C.; Jones, K. K.; Muthupalani, S.; Bisker, G.; Son, M.; Strano, M. S. Implantable Nanosensors for Human Steroid Hormone Sensing In Vivo Using a Self-Templating Corona Phase Molecular Recognition. Adv. Healthcare Mater. 2020, 9 (21), 2000429,  DOI: 10.1002/adhm.202000429
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    54
    Implantable Nanosensors for Human Steroid Hormone Sensing In Vivo Using a Self-Templating Corona Phase Molecular Recognition
    Lee, Michael A.; Wang, Song; Jin, Xiaojia; Bakh, Naveed Ali; Nguyen, Freddy T.; Dong, Juyao; Silmore, Kevin S.; Gong, Xun; Pham, Crystal; Jones, Kelvin K.; Muthupalani, Sureshkumar; Bisker, Gili; Son, Manki; Strano, Michael S.
    Advanced Healthcare Materials (2020), 9 (21), 2000429CODEN: AHMDBJ; ISSN:2192-2640. (Wiley-VCH Verlag GmbH & Co. KGaA)
    Dynamic measurements of steroid hormones in vivo are crit., but steroid sensing is currently limited by the availability of specific mol. recognition elements due to the chem. similarity of these hormones. In this work, a new, self-templating synthetic approach is applied using corona phase mol. recognition (CoPhMoRe) targeting the steroid family of mols. to produce near IR fluorescent, implantable sensors. A key limitation of CoPhMoRe has been its reliance on library generation for sensor screening. This problem is addressed with a self-templating strategy of polymer design, using the examples of progesterone and cortisol sensing based on a styrene and acrylic acid copolymer library augmented with an acrylated steroid. The pendant steroid attached to the corona backbone is shown to self-template the phase, providing a unique CoPhMoRE design strategy with high efficacy. The resulting sensors exhibit excellent stability and reversibility upon repeated analyte cycling. It is shown that mol. recognition using such constructs is viable even in vivo after sensor implantation into a murine model by employing a poly (ethylene glycol) diacrylate (PEGDA) hydrogel and porous cellulose interface to limit nonspecific absorption. The results demonstrate that CoPhMoRe templating is sufficiently robust to enable a new class of continuous, in vivo biosensors.
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    Safaee, M. M.; Gravely, M.; Roxbury, D. A Wearable Optical Microfibrous Biomaterial with Encapsulated Nanosensors Enables Wireless Monitoring of Oxidative Stress. Adv. Funct. Mater. 2021, 31 (13), 2006254,  DOI: 10.1002/adfm.202006254
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    A Wearable Optical Microfibrous Biomaterial with Encapsulated Nanosensors Enables Wireless Monitoring of Oxidative Stress
    Safaee, Mohammad Moein; Gravely, Mitchell; Roxbury, Daniel
    Advanced Functional Materials (2021), 31 (13), 2006254CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)
    In an effort to facilitate personalized medical approaches, the continuous and noninvasive monitoring of biochem. information using wearable technologies can enable a detailed understanding of an individual's physiol. Reactive oxygen species (ROS) are a class of oxygen-contg. free radicals that function in a wide range of biol. processes. In wound healing applications, the continuous monitoring of ROS through a wearable diagnostics platform is essential for the prevention of chronicity and pathogenic infection. Here, a versatile one-step procedure is utilized to fabricate optical core-shell microfibrous textiles incorporating single-walled carbon nanotubes (SWCNTs) for the real-time optical monitoring of hydrogen peroxide concns. in in vitro wounds. The environmentally sensitive and non-photobleachable fluorescence of SWCNTs enables continuous analyte monitoring without decay in signal over time. The existence of multiple chiralities of SWCNTs emitting near-IR fluorescence with narrow bandwidths allows a ratiometric signal readout invariant to the excitation source distance and exposure time. The individual fibers encapsulate the SWCNT nanosensors for at least 21 days without apparent loss in structural integrity. Moreover, the microfibrous textiles are utilized to spatially resolve peroxide concns. using a camera and further integrated into com. wound bandages without significant degrdn. in their optical properties.
  56. 56
    Wu, H.; Nißler, R.; Morris, V.; Herrmann, N.; Hu, P.; Jeon, S.-J.; Kruss, S.; Giraldo, J. P. Monitoring Plant Health with Near-Infrared Fluorescent H 2 O 2 Nanosensors. Nano Lett. 2020, 20 (4), 2432– 2442,  DOI: 10.1021/acs.nanolett.9b05159
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    Hofferber, E. M.; Stapleton, J. A.; Iverson, N. M. Review─Single Walled Carbon Nanotubes as Optical Sensors for Biological Applications. J. Electrochem. Soc. 2020, 167 (3), 037530,  DOI: 10.1149/1945-7111/ab64bf
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    Review-single walled carbon nanotubes as optical sensors for biological applications
    Hofferber, Eric M.; Stapleton, Joseph A.; Iverson, Nicole M.
    Journal of the Electrochemical Society (2020), 167 (3), 037530CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)
    A review. Since the discovery of the band gap fluorescence from single walled carbon nanotubes (SWNT) many advancements have been made towards the use of these unique fluorophores as optical biosensors in vitro, ex vivo in vivo. Attention has been given to these pure carbon structures due to their photostability, tunable properties, and bright near IR emission that falls in the tissue transparency window. This review highlights some of the major advancements in the field of SWNT biosensors over the last two decades with a focus given to recent advances in biol. applications.
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    Farrera, C.; Torres Andón, F.; Feliu, N. Carbon Nanotubes as Optical Sensors in Biomedicine. ACS Nano 2017, 11 (11), 10637– 10643,  DOI: 10.1021/acsnano.7b06701
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    Carbon Nanotubes as Optical Sensors in Biomedicine
    Farrera, Consol; Torres Andon, Fernando; Feliu, Neus
    ACS Nano (2017), 11 (11), 10637-10643CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    A review. Single-walled carbon nanotubes (SWCNTs) have become potential candidates for a wide range of medical applications including sensing, imaging, and drug delivery. Their photophys. properties (i.e., the capacity to emit in the near-IR), excellent photostability, and fluorescence, which is highly sensitive to the local environment, make SWCNTs promising optical probes in biomedicine. In this Perspective, the authors discuss the existing strategies for and challenges of using carbon nanotubes for medical diagnosis based on intracellular sensing as well as their biocompatibility and degradability. Finally, the authors highlight the potential improvements of this nanotechnol. and future directions in the field of carbon nanotubes for biomedical applications.
  59. 59
    Hendler-Neumark, A.; Wulf, V.; Bisker, G. In Vivo Imaging of Fluorescent Single-Walled Carbon Nanotubes within C. Elegans Nematodes in the near-Infrared Window. Mater. Today Bio. 2021, 12, 100175,  DOI: 10.1016/j.mtbio.2021.100175
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    59
    In vivo imaging of fluorescent single-walled carbon nanotubes within C. elegans nematodes in the near-infrared window
    Hendler-Neumark, Adi; Wulf, Verena; Bisker, Gili
    Materials Today Bio (2021), 12 (), 100175CODEN: MTBAC2; ISSN:2590-0064. (Elsevier Ltd.)
    Caenorhabditis elegans (C. elegans) nematodes serve as a model organism for eukaryotes, esp. due to their genetic similarity. Although they have many advantages like their small size and transparency, their autofluorescence in the entire visible wavelength range poses a challenge for imaging and tracking fluorescent proteins or dyes using std. fluorescence microscopy. Herein, near-IR (NIR) fluorescent single-walled carbon nanotubes (SWCNTs) are utilized for in vivo imaging within the gastrointestinal track of C. elegans. The SWCNTs are biocompatible, and do not affect the worms' viability nor their reprodn. ability. The worms do not show any autofluorescence in the NIR range, thus enabling the spectral sepn. between the SWCNT NIR fluorescence and the strong autofluorescence of the worm gut granules. The worms are fed with ssDNA-SWCNT which are visualized mainly in the intestine lumen. The NIR fluorescence is used in vivo to track the contraction and relaxation in the area of the pharyngeal valve at the anterior of the terminal bulb. These biocompatible, non-photobleaching, NIR fluorescent nanoparticles can advance in vivo imaging and tracking within C. elegans and other small model organisms by overcoming the signal-to-noise challenge stemming from the wide-range visible autofluorescence.
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    Nandi, S.; Caicedo, K.; Cognet, L. When Super-Resolution Localization Microscopy Meets Carbon Nanotubes. Nanomaterials 2022, 12 (9), 1433,  DOI: 10.3390/nano12091433
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    When Super-Resolution Localization Microscopy Meets Carbon Nanotubes
    Nandi, Somen; Caicedo, Karen; Cognet, Laurent
    Nanomaterials (2022), 12 (9), 1433CODEN: NANOKO; ISSN:2079-4991. (MDPI AG)
    A review. We recently assisted in a revolution in the realm of fluorescence microscopy triggered by the advent of super-resoln. techniques that surpass the classic diffraction limit barrier. By providing optical images with nanometer resoln. in the far field, super-resoln. microscopy (SRM) is currently accelerating our understanding of the mol. organization of bio-specimens, bridging the gap between cellular observations and mol. structural knowledge, which was previously only accessible using electron microscopy. SRM mainly finds its roots in progress made in the control and manipulation of the optical properties of (single) fluorescent mols. The flourishing development of novel fluorescent nanostructures has recently opened the possibility of assocg. super-resoln. imaging strategies with nanomaterials' design and applications. In this review article, we discuss some of the recent developments in the field of super-resoln. imaging explicitly based on the use of nanomaterials. As an archetypal class of fluorescent nanomaterial, we mainly focus on single-walled carbon nanotubes (SWCNTs), which are photoluminescent emitters at near-IR (NIR) wavelengths bearing great interest for biol. imaging and for information optical transmission. Whether for fundamental applications in nanomaterial science or in biol., we show how super-resoln. techniques can be applied to create nanoscale images "in", "of" and "with" SWCNTs.
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    Kleiner, S.; Wulf, V.; Bisker, G. Single-Walled Carbon Nanotubes as near-Infrared Fluorescent Probes for Bio-Inspired Supramolecular Self-Assembled Hydrogels. J. Colloid Interface Sci. 2024, 670, 439– 448,  DOI: 10.1016/j.jcis.2024.05.098
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    Ackermann, J.; Metternich, J. T.; Herbertz, S.; Kruss, S. Biosensing with Fluorescent Carbon Nanotubes. Angew. Chem., Int. Ed. 2022, 61 (18), e202112372  DOI: 10.1002/anie.202112372
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    Biosensing with Fluorescent Carbon Nanotubes
    Ackermann, Julia; Metternich, Justus T.; Herbertz, Svenja; Kruss, Sebastian
    Angewandte Chemie, International Edition (2022), 61 (18), e202112372CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
    A review. Biosensors are powerful tools for modern basic research and biomedical diagnostics. Their development requires substantial input from the chem. sciences. Sensors or probes with an optical readout, such as fluorescence, offer rapid, minimally invasive sensing of analytes with high spatial and temporal resoln. The near-IR (NIR) region is beneficial because of the reduced background and scattering of biol. samples (tissue transparency window) in this range. In this context, single-walled carbon nanotubes (SWCNTs) have emerged as versatile NIR fluorescent building blocks for biosensors. Here, we provide an overview of advances in SWCNT-based NIR fluorescent mol. sensors. We focus on chem. design strategies for diverse analytes and summarize insights into the photophysics and mol. recognition. Furthermore, different application areas are discussed-from chem. imaging of cellular systems and diagnostics to in vivo applications and perspectives for the future.
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    De Los Santos, Z. A.; Lin, Z.; Zheng, M. Optical Detection of Stereoselective Interactions with DNA-Wrapped Single-Wall Carbon Nanotubes. J. Am. Chem. Soc. 2021, 143 (49), 20628– 20632,  DOI: 10.1021/jacs.1c11372
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    Optical Detection of Stereoselective Interactions with DNA-Wrapped Single-Wall Carbon Nanotubes
    De los Santos, Zeus A.; Lin, Zhiwei; Zheng, Ming
    Journal of the American Chemical Society (2021), 143 (49), 20628-20632CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    DNA-wrapped carbon nanotubes have been explored increasingly as sensitive near-IR fluorescence probes for biomols. However, notably missing in previous studies is an inquiry on stereoselective interactions between DNA-wrapped carbon nanotubes and biomols. Here, enantiopure (+) and (-)(6,5), and (-)(8,3) as well as achiral (11,0) carbon nanotubes wrapped with specific resolving DNA sequences are used to demonstrate their stereoselective detection of amino acid enantiomers. Furthermore, stereoselective sensing abilities are found to be retained by dispersions contg. a multitude of chiral nanotube structures. The fluorescence response profiles of six different DNA-wrapped carbon nanotube dispersions to nine std. amino acids, and their enantiomers, demonstrate that DNA-wrapped carbon nanotubes are exquisitely sensitive to the stereoconfiguration and side-chain functionality of amino acids in a manner that is dependent on both DNA sequence and nanotube chirality. Implications of our findings are discussed in the context of developing a machine learning-aided multiplexed biosensing scheme called a mol. perceptron.
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    Blanch, A. J.; Lenehan, C. E.; Quinton, J. S. Optimizing Surfactant Concentrations for Dispersion of Single-Walled Carbon Nanotubes in Aqueous Solution. J. Phys. Chem. B 2010, 114 (30), 9805– 9811,  DOI: 10.1021/jp104113d
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    Optimizing Surfactant Concentrations for Dispersion of Single-Walled Carbon Nanotubes in Aqueous Solution
    Blanch, Adam J.; Lenehan, Claire E.; Quinton, Jamie S.
    Journal of Physical Chemistry B (2010), 114 (30), 9805-9811CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)
    The sonication-centrifugation technique is commonly used for dispersing single-walled carbon nanotubes (SWCNTs) in aq. surfactant solns. However, the methodologies and materials used for this purpose are widely varied, and few dispersive agents were studied systematically. This work describes a systematic study into the ability of some known (and some less common) surfactants and polymers to disperse SWCNTs fabricated by two different techniques. UV-visible-NIR absorbance spectra of their supernatant solns. showed that the smaller ionic surfactants were generally more effective dispersants, with larger polymer and surfactant mols. exhibiting a reduced performance for ensembles of carbon nanotubes of smaller av. diam. Optimal surfactant concns. were established for dispersions of carbon nanotubes produced by the elec. arc method in aq. solns. of sodium dodecylbenzene sulfonate, sodium deoxycholate, Triton X-405, Brij S-100, Pluronic F-127, and polyvinylpyrrolidone. This optimum value was detd. as the point at which the relative concn. of nanotubes dispersed is maximized, before flocculation-inducing attractive depletion interactions begin to dominate. The aggregation state of carbon nanotubes dispersed in sodium dodecylbenzene sulfonate was probed by AFM at different stages of rebundling, showing the length dependence of these effects.
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    Gerstman, E.; Hendler-Neumark, A.; Wulf, V.; Bisker, G. Monitoring the Formation of Fibrin Clots as Part of the Coagulation Cascade Using Fluorescent Single-Walled Carbon Nanotubes. ACS Appl. Mater. Interfaces 2023, 15 (18), 21866– 21876,  DOI: 10.1021/acsami.3c00828
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    65
    Monitoring the Formation of Fibrin Clots as Part of the Coagulation Cascade Using Fluorescent Single-Walled Carbon Nanotubes
    Gerstman, Efrat; Hendler-Neumark, Adi; Wulf, Verena; Bisker, Gili
    ACS Applied Materials & Interfaces (2023), 15 (18), 21866-21876CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
    Blood coagulation is a crit. defense mechanism against bleeding that results in the conversion of liq. blood into a solid clot through a complicated cascade, which involves multiple clotting factors. One of the final steps in the coagulation pathway is the conversion of fibrinogen to insol. fibrin mediated by thrombin. Because coagulation disorders can be life-threatening, the development of novel methods for monitoring the coagulation cascade dynamics is of high importance. Here, we use near-IR (NIR)-fluorescent single-walled carbon nanotubes (SWCNTs) to image and monitor fibrin clotting in real time. Following the binding of fibrinogen to a tailored SWCNT platform, thrombin transforms the fibrinogen into fibrin monomers, which start to polymerize. The SWCNTs are incorporated within the clot and can be clearly visualized in the NIR-fluorescent channel, where the signal-to-noise ratio is improved compared to bright-field imaging in the visible range. Moreover, the diffusion of individual SWCNTs within the fibrin clot gradually slows down after the addn. of thrombin, manifesting a coagulation rate that depends on both fibrinogen and thrombin concns. Our platform can open new opportunities for coagulation disorder diagnostics and allow for real-time monitoring of the coagulation cascade with a NIR optical signal output in the biol. transparency window.
  66. 66
    Budhathoki-Uprety, J.; Harvey, J. D. D.; Isaac, E.; Williams, R. M. M.; Galassi, T. V. V.; Langenbacher, R. E. E.; Heller, D. A. A. Polymer Cloaking Modulates the Carbon Nanotube Protein Corona and Delivery into Cancer Cells. J. Mater. Chem. B 2017, 5 (32), 6637– 6644,  DOI: 10.1039/C7TB00695K
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    Polymer cloaking modulates the carbon nanotube protein corona and delivery into cancer cells
    Budhathoki-Uprety, Januka; Harvey, Jackson D.; Isaac, Elizabeth; Williams, Ryan M.; Galassi, Thomas V.; Langenbacher, Rachel E.; Heller, Daniel A.
    Journal of Materials Chemistry B: Materials for Biology and Medicine (2017), 5 (32), 6637-6644CODEN: JMCBDV; ISSN:2050-7518. (Royal Society of Chemistry)
    Carbon nanotube-based mol. probes, imaging agents, and biosensors in cells and in vivo continue to garner interest as investigational tools and clin. devices due to their unique photophys. properties. Surface chem. modulation of nanotubes plays a crit. role in detg. stability and interaction with biol. systems both in vitro and in vivo. Among the many parameters that influence the biol. fate of nanomaterials, surface charge is particularly influential due to direct electrostatic interactions with components of the cell membrane as well as proteins in the serum, which coat the nanoparticle surface in a protein corona and alter nanoparticle-cell interactions. Here, we modulated functional moieties on a helical polycarbodiimide polymer backbone that non-covalently suspended the nanotubes in aq. media. By derivatizing the polymer with either primary amine or carboxylic acid side chains, we obtained nanotube complexes that present net surface charges of opposite polarity at physiol. pH. Using these materials, we found that the uptake of carbon nanotubes in these cells is highly dependent on charge, with cationic nanotubes efficiently internalized into cells compared to the anionic nanotubes. Furthermore, we found that serum proteins drastically influenced cell uptake of the anionic nanotubes, while the effect was not prominent for the cationic nanotubes. Our findings have implications for improved engineering of drug delivery devices, mol. probes, and biosensors.
  67. 67
    Fernandes, R. M. F.; Dai, J.; Regev, O.; Marques, E. F.; Furó, I. Block Copolymers as Dispersants for Single-Walled Carbon Nanotubes: Modes of Surface Attachment and Role of Block Polydispersity. Langmuir 2018, 34 (45), 13672– 13679,  DOI: 10.1021/acs.langmuir.8b02658
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    Block Copolymers as Dispersants for Single-Walled Carbon Nanotubes: Modes of Surface Attachment and Role of Block Polydispersity
    Fernandes, Ricardo M. F.; Dai, Jing; Regev, Oren; Marques, Eduardo F.; Furo, Istvan
    Langmuir (2018), 34 (45), 13672-13679CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)
    When using amphiphilic polymers to exfoliate and disperse carbon nanotubes in water, the balance between the hydrophobic and hydrophilic moieties is crit. and nontrivial. Here, we investigate the mode of surface attachment of a triblock copolymer, Pluronics F127, composed of a central hydrophobic polypropylene oxide block flanked by hydrophilic polyethylene oxide blocks, onto single-walled carbon nanotubes (SWNTs). Crucially, we analyze the compn. in dispersant of both the as-obtained dispersion (the supernatant) and the ppt.-contg. undispersed materials. For this, we combine the carefully obtained data from 1H NMR peak intensities and self-diffusion and thermogravimetric anal. The mol. motions behind the obsd. NMR features are clarified. We find that the hydrophobic blocks attach to the dispersed SWNT surface and remain significantly immobilized leading to 1H NMR signal loss. On the other hand, the hydrophilic blocks remain highly mobile and thus readily detectable by NMR. The dispersant is shown to possess significant block polydispersity that has a large effect on dispersibility. Polymers with large hydrophobic blocks adsorb on the surface of the carbonaceous particles that ppt., indicating that although a larger hydrophobic block is good for enhancing adsorption, it may be less effective in dispersing the tubes. A model is also proposed that consistently explains our observations in SWNT dispersions and some contradicting findings obtained previously in carbon nanohorn dispersions. Overall, our findings help elucidating the mol. picture of the dispersion process for SWNTs and are of interest when looking for more effective (i.e., well-balanced) polymeric dispersants.
  68. 68
    Antonucci, A.; Kupis-Rozmysłowicz, J.; Boghossian, A. A. Noncovalent Protein and Peptide Functionalization of Single-Walled Carbon Nanotubes for Biodelivery and Optical Sensing Applications. ACS Appl. Mater. Interfaces 2017, 9 (13), 11321– 11331,  DOI: 10.1021/acsami.7b00810
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    Noncovalent Protein and Peptide Functionalization of Single-Walled Carbon Nanotubes for Biodelivery and Optical Sensing Applications
    Antonucci, Alessandra; Kupis-Rozmyslowicz, Justyna; Boghossian, Ardemis A.
    ACS Applied Materials & Interfaces (2017), 9 (13), 11321-11331CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
    A review. The exquisite structural and optical characteristics of single-walled carbon nanotubes (SWCNTs), combined with the tunable specificities of proteins and peptides, can be exploited to strongly benefit technologies with applications in fields ranging from biomedicine to industrial biocatalysis. The key to exploiting the synergism of these materials is designing protein/peptide-SWCNT conjugation schemes that preserve biomol. activity while keeping the near-IR optical and electronic properties of SWCNTs intact. Since sp2 bond-breaking disrupts the optoelectronic properties of SWCNTs, noncovalent conjugation strategies are needed to interface biomols. to the nanotube surface for optical biosensing and delivery applications. An underlying understanding of the forces contributing to protein and peptide interaction with the nanotube is thus necessary to identify the appropriate conjugation design rules for specific applications. This article explores the mol. interactions that govern the adsorption of peptides and proteins on SWCNT surfaces, elucidating contributions from individual amino acids as well as secondary and tertiary protein structure and conformation. Various noncovalent conjugation strategies for immobilizing peptides, homopolypeptides, and sol. and membrane proteins on SWCNT surfaces are presented, highlighting studies focused on developing near-IR optical sensors and mol. scaffolds for self-assembly and biochem. anal. The anal. presented herein suggests that though direct adsorption of proteins and peptides onto SWCNTs can be principally applied to drug and gene delivery, in vivo imaging and targeting, or cancer therapy, nondirect conjugation strategies using artificial or natural membranes, polymers, or linker mols. are often better suited for biosensing applications that require conservation of biomol. functionality or precise control of the biomol.'s orientation. These design rules are intended to provide the reader with a rational approach to engineering biomol.-SWCNT platforms, broadening the breadth and accessibility of both wild-type and engineered biomols. for SWCNT-based applications.
  69. 69
    Tsyboulski, D. A.; Bakota, E. L.; Witus, L. S.; Rocha, J.-D. R.; Hartgerink, J. D.; Weisman, R. B. Self-Assembling Peptide Coatings Designed for Highly Luminescent Suspension of Single-Walled Carbon Nanotubes. J. Am. Chem. Soc. 2008, 130 (50), 17134– 17140,  DOI: 10.1021/ja807224x
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    Self-Assembling Peptide Coatings Designed for Highly Luminescent Suspension of Single-Walled Carbon Nanotubes
    Tsyboulski, Dmitri A.; Bakota, Erica L.; Witus, Leah S.; Rocha, John-David R.; Hartgerink, Jeffrey D.; Weisman, R. Bruce
    Journal of the American Chemical Society (2008), 130 (50), 17134-17140CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    A series of self-assembling multidomain peptides have been designed, synthesized, and tested for their ability to individually suspend single-walled carbon nanotubes (SWCNTs) in water while preserving strong near-IR nanotube luminescence. Photometric and spectral measurements on individual SWCNTs revealed that emission in the common biocompatible coating agents Pluronic F127, ss-DNA, and BSA is approx. an order of magnitude weaker than in the bioincompatible ionic surfactant SDBS. By contrast, one of the engineered peptides gave SWCNT emission ∼40% as intense as in SDBS. A strong inverse correlation was also found between the spectral line widths of coated SWCNTs and the efficiency of their emission. Peptides with rationally designed self-assembly properties appear to be promising coatings that may enable SWCNT optical sensing applications in biol. environments.
  70. 70
    Heller, D. A.; Pratt, G. W.; Zhang, J.; Nair, N.; Hansborough, A. J.; Boghossian, A. A.; Reuel, N. F.; Barone, P. W.; Strano, M. S. Peptide Secondary Structure Modulates Single-Walled Carbon Nanotube Fluorescence as a Chaperone Sensor for Nitroaromatics. Proc. Natl. Acad. Sci. U. S. A. 2011, 108 (21), 8544– 8549,  DOI: 10.1073/pnas.1005512108
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    Peptide secondary structure modulates single-walled carbon nanotube fluorescence as a chaperone sensor for nitroaromatics
    Heller, Daniel A.; Pratt, George W.; Zhang, Jingqing; Nair, Nitish; Hansborough, Adam J.; Boghossian, Ardemis A.; Reuel, Nigel F.; Barone, Paul W.; Strano, Michael S.
    Proceedings of the National Academy of Sciences of the United States of America (2011), 108 (21), 8544-8549, S8544/1-S8544/8CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
    A class of peptides from the bombolitin family, not previously identified for nitroarom. recognition, allows near-IR fluorescent single-walled carbon nanotubes to transduce specific changes in their conformation. In response to the binding of specific nitroarom. species, such peptide-nanotube complexes form a virtual "chaperone sensor," which reports modulation of the peptide secondary structure via changes in single-walled carbon nanotubes, near-IR photoluminescence. A split-channel microscope constructed to image quantized spectral wavelength shifts in real time, in response to nitroarom. adsorption, results in the first single-nanotube imaging of solvatochromic events. The described indirect detection mechanism, as well as an addnl. exciton quenching-based optical nitroarom. detection method, illustrate that functionalization of the carbon nanotube surface can result in completely unique sites for recognition, resolvable at the single-mol. level.
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    Matsukawa, Y.; Umemura, K. Chirality Luminescent Properties of Single-Walled Carbon Nanotubes during Redox Reactions. Opt. Mater. 2021, 112, 110748,  DOI: 10.1016/j.optmat.2020.110748
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    Chirality luminescent properties of single-walled carbon nanotubes during redox reactions
    Matsukawa, Yuji; Umemura, Kazuo
    Optical Materials (Amsterdam, Netherlands) (2021), 112 (), 110748CODEN: OMATET; ISSN:0925-3467. (Elsevier B.V.)
    In this study, we focused on the presence of SWNTs with different chiralities within the same SWNT powder, and we investigated the correlation between the rate of change of the emission intensity due to redox reactions and SWNT chirality. We measured the redox change rate of chirality, which was difficult to detect because of the low emission intensity, by increasing the exposure time during (PL) measurement. 0.5 mg of SWNT powder and 1 mL of (dsDNA) stock soln. were mixed and sonicated using a probe-type sonicator on ice. Hydrogen peroxide (H2O2; final concn.: 0.03%) was added to this dispersion for oxidn., and then, a catechin aq. soln. (final concn. 1.5μg/mL) was added to the soln. to measure PL. The exposure time was 90 s to obtain sufficient emission intensity. The measurement results showed that the magnitude of the rate of change of the PL intensity due to redox reaction was different for each chirality. Focusing on the (8,6) and (9,4) chiralities, which showed a large rate of change, the PL intensity decreased by 57.4% and 54.6% from the initial state, resp., when H2O2 was added. Subsequently, these values increased by 1024% and 558% with the addn. of a catechin aq. soln., resp. Furthermore, from the comparison of the PL detection results and optical response characteristics of each chirality, it was obsd. that the rate of change of the PL intensity of SWNTs during redox reactions using H2O2 and catechin had the strongest correlation with the SWNT diam.
  72. 72
    Salem, D. P.; Landry, M. P.; Bisker, G.; Ahn, J.; Kruss, S.; Strano, M. S. Chirality Dependent Corona Phase Molecular Recognition of DNA-Wrapped Carbon Nanotubes. Carbon 2016, 97, 147– 153,  DOI: 10.1016/j.carbon.2015.08.075
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    Chirality dependent corona phase molecular recognition of DNA-wrapped carbon nanotubes
    Salem, Daniel P.; Landry, Markita P.; Bisker, Gili; Ahn, Jiyoung; Kruss, Sebastian; Strano, Michael S.
    Carbon (2016), 97 (), 147-153CODEN: CRBNAH; ISSN:0008-6223. (Elsevier Ltd.)
    Corona phase mol. recognition (CoPhMoRe) is a phenomenon whereby a polymer or surfactant corona phase wrapped around a nanoparticle selectively recognizes a particular mol. The method can potentially generate non-biol., synthetic mol. recognition sites, analogous to antibodies, for a broad range of biomedical applications, including new types of sensors, lab. and clin. assays, as well as inhibitors and targeted therapeutics. In this work, we utilize near IR fluorescent single-walled carbon nanotubes (SWNTs) wrapped with specific single stranded DNA sequences to explore the (n,m) chirality dependence of CoPhMoRe. Specific DNA oligonucleotide sequences are known to recognize and interact uniquely with certain (n,m) SWNTs enabling their enrichment in ion exchange chromatog. We explore the CoPhMoRe effect using corona phases constructed from a library of 24 such sequences, screening against a biomol. panel that includes common neurotransmitters, amino acids, saccharides and riboflavin. Example sequences include (ATT)4, (TAT)4 and (ATTT)3 which recognize (7,5), (6,5) and (8,4) SWNTs, resp. We find that these recognition sequences indeed form CoPhMoRe phases that are distinct among SWNT chiralities, and appear to pack more densely as to exclude analyte adsorption on the chirality they recognize. These results have encouraging implications for the controlled design of CoPhMoRe phases for biomedical applications.
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    Choi, J. H.; Strano, M. S. Solvatochromism in Single-Walled Carbon Nanotubes. Appl. Phys. Lett. 2007, 90 (22), 88– 91,  DOI: 10.1063/1.2745228
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    Järup, L. Hazards of Heavy Metal Contamination. Br. Med. Bull. 2003, 68 (1), 167– 182,  DOI: 10.1093/bmb/ldg032
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    Hazards of heavy metal contamination
    Jarup Lars
    British medical bulletin (2003), 68 (), 167-82 ISSN:0007-1420.
    The main threats to human health from heavy metals are associated with exposure to lead, cadmium, mercury and arsenic. These metals have been extensively studied and their effects on human health regularly reviewed by international bodies such as the WHO. Heavy metals have been used by humans for thousands of years. Although several adverse health effects of heavy metals have been known for a long time, exposure to heavy metals continues, and is even increasing in some parts of the world, in particular in less developed countries, though emissions have declined in most developed countries over the last 100 years. Cadmium compounds are currently mainly used in re-chargeable nickel-cadmium batteries. Cadmium emissions have increased dramatically during the 20th century, one reason being that cadmium-containing products are rarely re-cycled, but often dumped together with household waste. Cigarette smoking is a major source of cadmium exposure. In non-smokers, food is the most important source of cadmium exposure. Recent data indicate that adverse health effects of cadmium exposure may occur at lower exposure levels than previously anticipated, primarily in the form of kidney damage but possibly also bone effects and fractures. Many individuals in Europe already exceed these exposure levels and the margin is very narrow for large groups. Therefore, measures should be taken to reduce cadmium exposure in the general population in order to minimize the risk of adverse health effects. The general population is primarily exposed to mercury via food, fish being a major source of methyl mercury exposure, and dental amalgam. The general population does not face a significant health risk from methyl mercury, although certain groups with high fish consumption may attain blood levels associated with a low risk of neurological damage to adults. Since there is a risk to the fetus in particular, pregnant women should avoid a high intake of certain fish, such as shark, swordfish and tuna; fish (such as pike, walleye and bass) taken from polluted fresh waters should especially be avoided. There has been a debate on the safety of dental amalgams and claims have been made that mercury from amalgam may cause a variety of diseases. However, there are no studies so far that have been able to show any associations between amalgam fillings and ill health. The general population is exposed to lead from air and food in roughly equal proportions. During the last century, lead emissions to ambient air have caused considerable pollution, mainly due to lead emissions from petrol. Children are particularly susceptible to lead exposure due to high gastrointestinal uptake and the permeable blood-brain barrier. Blood levels in children should be reduced below the levels so far considered acceptable, recent data indicating that there may be neurotoxic effects of lead at lower levels of exposure than previously anticipated. Although lead in petrol has dramatically decreased over the last decades, thereby reducing environmental exposure, phasing out any remaining uses of lead additives in motor fuels should be encouraged. The use of lead-based paints should be abandoned, and lead should not be used in food containers. In particular, the public should be aware of glazed food containers, which may leach lead into food. Exposure to arsenic is mainly via intake of food and drinking water, food being the most important source in most populations. Long-term exposure to arsenic in drinking-water is mainly related to increased risks of skin cancer, but also some other cancers, as well as other skin lesions such as hyperkeratosis and pigmentation changes. Occupational exposure to arsenic, primarily by inhalation, is causally associated with lung cancer. Clear exposure-response relationships and high risks have been observed.
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    Barnham, K. J.; Bush, A. I. Biological Metals and Metal-Targeting Compounds in Major Neurodegenerative Diseases. Chem. Soc. Rev. 2014, 43, 6727,  DOI: 10.1039/C4CS00138A
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    Biological metals and metal-targeting compounds in major neurodegenerative diseases
    Barnham, Kevin J.; Bush, Ashley I.
    Chemical Society Reviews (2014), 43 (19), 6727-6749CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
    A review. Multiple abnormalities occur in the homeostasis of essential endogenous brain biometals in age-related neurodegenerative disorders, Alzheimer's disease, Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis. As a result, metals both accumulate in microscopic proteinopathies, and can be deficient in cells or cellular compartments. Therefore, bulk measurement of metal content in brain tissue samples reveal only the "tip of the iceberg", with most of the important changes occurring on a microscopic and biochem. level. Each of the major proteins implicated in these disorders interacts with biol. transition metals. Tau and the amyloid protein precursor have important roles in normal neuronal iron homeostasis. Changes in metal distribution, cellular deficiencies, or sequestration in proteinopathies all present abnormalities that can be cor. in animal models by small mols. These biochem. targets are more complex than the simple excess of metals that are targeted by chelators. In this review we illustrate some of the richness in the science that has developed in the study of metals in neurodegeneration, and explore its novel pharmacol.
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    Tofan, L.; Wenkert, R. Chelating Polymers with Valuable Sorption Potential for Development of Precious Metal Recycling Technologies. Rev. Chem. Eng. 2022, 38 (2), 167– 183,  DOI: 10.1515/revce-2019-0075
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    Guo, S.-Y.; Hou, P.-X.; Zhang, F.; Liu, C.; Cheng, H.-M. Gas Sensors Based on Single-Wall Carbon Nanotubes. Molecules 2022, 27 (17), 5381,  DOI: 10.3390/molecules27175381
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    Gas Sensors Based on Single-Wall Carbon Nanotubes
    Guo, Shu-Yu; Hou, Peng-Xiang; Zhang, Feng; Liu, Chang; Cheng, Hui-Ming
    Molecules (2022), 27 (17), 5381CODEN: MOLEFW; ISSN:1420-3049. (MDPI AG)
    A review. Single-wall carbon nanotubes (SWCNTs) have a high aspect ratio, large surface area, good stability and unique metallic or semiconducting elec. cond., they are therefore considered a promising candidate for the fabrication of flexible gas sensors that are expected to be used in the Internet of Things and various portable and wearable electronics. In this review, we first introduce the sensing mechanism of SWCNTs and the typical structure and key parameters of SWCNT-based gas sensors. We then summarize research progress on the design, fabrication, and performance of SWCNT-based gas sensors. Finally, the principles and possible approaches to further improving the performance of SWCNT-based gas sensors are discussed.
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    Gong, X.; Cho, S.-Y.; Kuo, S.; Ogunlade, B.; Tso, K.; Salem, D. P.; Strano, M. S. Divalent Metal Cation Optical Sensing Using Single-Walled Carbon Nanotube Corona Phase Molecular Recognition. Anal. Chem. 2022, 94 (47), 16393– 16401,  DOI: 10.1021/acs.analchem.2c03648
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    Divalent Metal Cation Optical Sensing Using Single-Walled Carbon Nanotube Corona Phase Molecular Recognition
    Gong, Xun; Cho, Soo-Yeon; Kuo, Sydney; Ogunlade, Babatunde; Tso, Kathryn; Salem, Daniel P.; Strano, Michael S.
    Analytical Chemistry (Washington, DC, United States) (2022), 94 (47), 16393-16401CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
    Colloidal single-walled carbon nanotubes (SWCNTs) offer a promising platform for the nanoscale engineering of mol. recognition. Optical sensors have been recently designed through the modification of noncovalent corona phases (CPs) of SWCNTs through a phenomenon known as corona phase mol. recognition (CoPhMoRe). In CoPhMoRe constructs, DNA CPs are of great interest due to the breadth of the design space and our ability to control these mols. with sequence specificity at scale. Utilizing these constructs for metal ion sensing is a natural extension of this technol. due to DNA's well-known coordination chem. Addnl., understanding metal ion interactions of these constructs allows for improved sensor design for use in complex aq. environments. In this work, we study the interactions between a panel of 9 dil. divalent metal cations and 35 DNA CPs under the most controlled exptl. conditions for SWCNT optical sensing to date. We found that best practices for the study of colloidal SWCNT analyte responses involve mitigating the effects of ionic strength, diln. kinetics, laser power, and analyte response kinetics. We also discover that SWCNT with DNA CPs generally offers two unique sensing states at pH 6 and 8. The combined set of sensors in this work allowed for the differentiation of Hg2+, Pb2+, Cr2+, and Mn2+. Finally, we implemented Hg2+ sensing in the context of portable detection within fish tissue ext., demonstrating nanomolar level detection.
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    Heller, D. A.; Jeng, E. S.; Yeung, T.-K.; Martinez, B. M.; Moll, A. E.; Gastala, J. B.; Strano, M. S. Optical Detection of DNA Conformational Polymorphism on Single-Walled Carbon Nanotubes. Science 2006, 311 (5760), 508– 511,  DOI: 10.1126/science.1120792
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    Optical Detection of DNA Conformational Polymorphism on Single-Walled Carbon Nanotubes
    Heller, Daniel A.; Jeng, Esther S.; Yeung, Tsun-Kwan; Martinez, Brittany M.; Moll, Anthonie E.; Gastala, Joseph B.; Strano, Michael S.
    Science (Washington, DC, United States) (2006), 311 (5760), 508-511CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
    The transition of DNA secondary structure from an analogous B to Z conformation modulates the dielec. environment of the single-walled carbon nanotube (SWNT) around which it is adsorbed. The SWNT band-gap fluorescence undergoes a red shift when an encapsulating 30-nucleotide oligomer is exposed to counter ions that screen the charged backbone. The transition is thermodynamically identical for DNA on and off the nanotube, except that the propagation length of the former is shorter by five-sixths. The magnitude of the energy shift is described by using an effective medium model and the DNA geometry on the nanotube sidewall. The authors demonstrate the detection of the B-Z change in whole blood, tissue, and from within living mammalian cells.
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    Jin, H.; Jeng, E. S.; Heller, D. A.; Jena, P. V.; Kirmse, R.; Langowski, J.; Strano, M. S. Divalent Ion and Thermally Induced DNA Conformational Polymorphism on Single-Walled Carbon Nanotubes. Macromolecules 2007, 40 (18), 6731– 6739,  DOI: 10.1021/ma070608t
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    Divalent Ion and Thermally Induced DNA Conformational Polymorphism on Single-walled Carbon Nanotubes
    Jin, Hong; Jeng, Esther S.; Heller, Daniel A.; Jena, Prakrit V.; Kirmse, Robert; Langowski, Joerg; Strano, Michael S.
    Macromolecules (Washington, DC, United States) (2007), 40 (18), 6731-6739CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)
    Various sequences of single and double stranded DNA can wrap and colloidally stabilize single- walled carbon nanotubes in soln. The binding of divalent ions to these complexes results in a 10 meV emission energy red-shift of the photoluminescence of the nanotube. In this work, this optical modulation is linked to specific secondary structure changes in the adsorbed DNA. Dynamic light scattering is used to rule out aggregation and inter-particle effects. It is obsd. that the transition can also be induced thermally over the temp. range between 0 and 50 °C without ion addn. Interestingly, we find evidence of the dissocn. of a DNA duplex at the surface, as confirmed using both selective dialysis and DNA electrophoresis on a 20% PAGE gel. Consistent with several observations is a mechanism that proceeds via a competitive, stepwise process of partial desorption of the DNA along the length of SWNT. A two-state math. model quant. describes the equil. for various divalent ions binding to DNA adsorbed at the nanotube surface.
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    Gillen, A. J.; Kupis-Rozmysłowicz, J.; Gigli, C.; Schuergers, N.; Boghossian, A. A. Xeno Nucleic Acid Nanosensors for Enhanced Stability Against Ion-Induced Perturbations. J. Phys. Chem. Lett. 2018, 9 (15), 4336– 4343,  DOI: 10.1021/acs.jpclett.8b01879
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    Xeno Nucleic Acid Nanosensors for Enhanced Stability Against Ion-Induced Perturbations
    Gillen, Alice J.; Kupis-Rozmyslowicz, Justyna; Gigli, Carlo; Schuergers, Nils; Boghossian, Ardemis A.
    Journal of Physical Chemistry Letters (2018), 9 (15), 4336-4343CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)
    The omnipresence of salts in biofluids creates a pervasive challenge in designing sensors suitable for in vivo applications. Fluctuations in ion concns. have been shown to affect the sensitivity and selectivity of optical sensors based on single-walled carbon nanotubes wrapped with single-stranded DNA (ssDNA-SWCNTs). We herein observe fluorescence wavelength shifting for ssDNA-SWCNT-based optical sensors in the presence of divalent cations at concns. above 3.5 mM. In contrast, no shifting was obsd. for concns. up to 350 mM for sensors bioengineered with increased rigidity using xeno nucleic acids (XNAs). Transient fluorescence measurements reveal distinct optical transitions for ssDNA- and XNA-based wrappings during ion-induced conformation changes, with XNA-based sensors showing increased permanence in conformational and signal stability. This demonstration introduces synthetic biol. as a complementary means for enhancing nanotube optoelectronic behavior, unlocking previously unexplored possibilities for developing nanobioengineered sensors with augmented capabilities.
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    Andjelkovic, M.; Vancamp, J.; Demeulenaer, B.; Depaemelaere, G.; Socaciu, C.; Verloo, M.; Verhe, R. Iron-Chelation Properties of Phenolic Acids Bearing Catechol and Galloyl Groups. Food Chem. 2006, 98 (1), 23– 31,  DOI: 10.1016/j.foodchem.2005.05.044
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    Iron-chelation properties of phenolic acids bearing catechol and galloyl groups
    Andjelkovic, Mirjana; Van Camp, John; De Meulenaer, Bruno; Depaemelaere, Griet; Socaciu, Carmen; Verloo, Marc; Verhe, Roland
    Food Chemistry (2006), 98 (1), 23-31CODEN: FOCHDJ; ISSN:0308-8146. (Elsevier B.V.)
    In this study, the capacity of 7 phenolic acids and hydroxytyrosol for complex formation with iron was quantified. A metal-chelation mechanism was described by means of spectrophotometry and calcg. the binding consts. of the complexes. The influence of phosphate buffer, Hepes buffer, Tris buffer and water on this mechanism was investigated. UV-Vis absorption spectroscopy showed that the absorption of phenolic acids changes upon the addn. of Fe2+, which resulted in several shifts of their spectra. These bathochromic shifts were analyzed and evaluated by calcg. binding consts. Furthermore, in the presence of different concns. of EDTA (0-1 mM), a redn. of the consts. was obsd. However, not all of the phenolic compds. assessed here showed complex formation, those not bearing catechol or galloyl moiety like vanillic acid, syringic acid and ferulic acid, did not show any complex formation. The ability of the phenolic compds. which chelate iron have been ranked in line with the binding consts. in ascending order rendering the protocatechuic acid (1.43 M-1) the weakest chelator, followed by hydroxytyrosol (2.66 M-1), gallic acid (4.78 M-1), caffeic acid (8.12 M-1) and chlorogenic acid (20.13 M-1) as the strongest chelator.
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    Irankunda, R.; Camaño Echavarría, J. A.; Paris, C.; Stefan, L.; Desobry, S.; Selmeczi, K.; Muhr, L.; Canabady-Rochelle, L. Metal-Chelating Peptides Separation Using Immobilized Metal Ion Affinity Chromatography: Experimental Methodology and Simulation. Separations 2022, 9 (11), 370,  DOI: 10.3390/separations9110370
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    Yang, M.; Song, W. J. Diverse Protein Assembly Driven by Metal and Chelating Amino Acids with Selectivity and Tunability. Nat. Commun. 2019, 10 (1), 5545,  DOI: 10.1038/s41467-019-13491-w
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    Diverse protein assembly driven by metal and chelating amino acids with selectivity and tunability
    Yang, Minwoo; Song, Woon Ju
    Nature Communications (2019), 10 (1), 5545CODEN: NCAOBW; ISSN:2041-1723. (Nature Research)
    Proteins are versatile natural building blocks with highly complex and multifunctional architectures, and self-assembled protein structures have been created by the introduction of covalent, noncovalent, or metal-coordination bonding. Here, we report the robust, selective, and reversible metal coordination properties of unnatural chelating amino acids as the sufficient and dominant driving force for diverse protein self-assembly. Bipyridine-alanine is genetically incorporated into a D3 homohexamer. Depending on the position of the unnatural amino acid, 1-directional, cryst. and noncryst. 2-directional, combinatory, and hierarchical architectures are effectively created upon the addn. of metal ions. The length and shape of the structures is tunable by altering conditions related to thermodn. and kinetics of metal-coordination and subsequent reactions. The cryst. 1-directional and 2-directional biomaterials retain their native enzymic activities with increased thermal stability, suggesting that introducing chelating ligands provides a specific chem. basis to synthesize diverse protein-based functional materials while retaining their native structures and functions.
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  • Abstract

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    Scheme 1

    Scheme 1. SWCNTs Suspended by Fmoc-Peptides as Fingerprinting Sensorsa
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    a(a) Corona phase peptide sequence and the varying amino acids side chains. (b) Fmoc-peptide and oxidized Fmoc-peptide functionalized SWCNTs interact with metal-ions, leading to different fluorescence responses. (c) The ACFSA algorithm finds an optimal sensor set for analyte classification

    Figure 1

    Figure 1. Functionalization, oxidation, and characterization of SWCNT-peptides. (a) UV–vis–NIR absorption spectrum of SWCNT-Cys, diluted 1:20 in water. Inset: NIR absorption of the SWCNTs-Cys. (b) Fluorescence emission spectra of SWCNT-Cys at three different excitation wavelengths: 570 nm (black), 660 nm (orange), and 730 nm (blue). Emission peaks of the three chiralities measured at these excitation wavelengths are marked with arrows corresponding to the (6,5), (7,5), and (9,4) chiralities, respectively. (c) Normalized excitation–emission map of SWCNT-Cys. The three chiralities shown in (b) are highlighted in circles. (d) Absorption spectra of SWCNT-Cys before (blue) and after UV-oxidation to SWCNT-CysOx (orange). Inset: Fmoc-peptides in solution before and after oxidation, following the precipitation of the SWCNTs with DMSO. (e) Normalized fluorescence emission of the peptides before (blue) and after (orange) UV-oxidation of SWCNT-Cys measured at excitation wavelengths of 280 nm (left) and 320 nm (right). (f) Normalized excitation–emission map of SWCNT-CysOx.

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    Figure 2

    Figure 2. Fluorescence response of the SWCNT-peptide sensor in the presence of 300 μM of metal-ions. (a) Normalized fluorescence emission spectra of SWCNT-Glu, excited at 570 nm, before (dotted black line) and after the addition of metal-ions, Cu2+ (orange), Ni2+ (yellow), Cr3+ (purple), Pb2+ (green), and Hg2+ (blue). The dashed rectangle marks the peak of (6,5) chirality. The bar plot shows the relative fluorescence response for each metal-ion. N = 5. (b) Normalized fluorescence intensity of the (6,5) chirality of SWCNT-Glu, SWCNT-GluOx, and SWCNT-Cys before (dotted black line) and after the addition of metals-ions, Cu2+ (orange), Ni2+ (yellow), Cr3+ (purple), Pb2+ (green), and Hg2+ (blue). (c) Bar plot of the relative fluorescence response of the (6,5) chirality of all the SWCNT-peptide sensors in the presence of the metal-ions. Error bars represent the standard deviation of N = 5 measurements. (d) Normalized fluorescence emission spectra of SWCNT-CysOx in water (dotted lines) and after the addition of Ni2+ (continuous lines), measured at three excitation wavelengths: 570 nm (black), 660 nm (orange), and 730 nm (blue), corresponding to the excitation wavelengths of the (6,5), (7,5), and (9,4) chiralities, respectively. Arrows mark the peaks of the respective chiralities. (e) Normalized fluorescence intensity of the (6,5), (7,5), and (9,4) chirality of SWCNT-CysOx before (dotted lines) and after the addition of Ni2+ (continuous lines).

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    Figure 3

    Figure 3. Example of an analyte identification procedure using several sensors. (a) The (9,4) chirality of SWCNT-GlyOx shows an intensity increase in response to the analyte, indicating Ni2+ or Pb2+. (b) A turn-on response of the (7,5) chirality of SWCNT-Cys excludes Pb2+. (c) Significant turn-on response of the (7,5) chirality of SWCNT-Glu further confirms Ni2+, in contrast to a minor turn-on response that would indicate Pb2+. All barplots N = 5.

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    Figure 4

    Figure 4. Analyte Classification and Feature Selection algorithm (ACFSA) for reducing the number of fingerprinting sensors and producing an analyte classification scheme. (a) Simplified flowchart of the algorithm. (b) 2D principal component representations of the data for all 30 sensors (colored shapes), including the 95% uncertainty ellipses of the clustering method (dashed lines). (c) 2D principal component representations of the data for the selected two sensors (colored shapes), including the 95% uncertainty ellipses of the clustering method (dashed lines). (d) The Voronoi classifier in the 2D principal components space for all 30 sensors (left) and for the selected two sensors (right) with the same color scheme as above. Points show the cluster center, and lines are defined by the intercluster distance. (e) The average intercluster distance, ⟨D⟩ (blue circles), the adjusted Rand index, ARI (black diamond), and the Voronoi classifier error (orange dots) for the remaining sensors.

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      Carter, Kyle P.; Young, Alexandra M.; Palmer, Amy E.
      Chemical Reviews (Washington, DC, United States) (2014), 114 (8), 4564-4601CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
      This review focuses on fluorescent sensors for transition metals commonly found in biol. organisms. The authors start this review by giving a basic overview of fluorescence imaging and sensor design, followed by a crit. anal. of parameters and properties to consider when using sensors in biol. systems. The authors then present a historical perspective of how the field has evolved. While this review focuses on transition metals, the authors discuss some of the key advances/milestones achieved in the development of fluorescent Ca2+ indicators as these helped lay the groundwork for much of the subsequent work developing sensors for transition metals. Finally, the authors highlight progress in sensor development for biol. metals, emphasizing recent advances, while including a discussion of the most widely used sensors. To demonstrate what kind of measurements can be made and what kind of information can be learned from using fluorescent sensors, the authors review several applications of sensors for defining metal homeostasis and dynamics in cells or organisms. The authors would also like to call readers' attention to several excellent prior reviews that focus on different aspects of sensor development.
    6. 6
      El-Safty, S. A.; Prabhakaran, D.; Ismail, A. A.; Matsunaga, H.; Mizukami, F. Nanosensor Design Packages: A Smart and Compact Development for Metal Ions Sensing Responses. Adv. Funct. Mater. 2007, 17 (18), 3731– 3745,  DOI: 10.1002/adfm.200700447
      There is no corresponding record for this reference.
    7. 7
      Cho, E. J.; Lee, J.-W.; Ellington, A. D. Applications of Aptamers as Sensors. Annu. Rev. Anal Chem. 2009, 2 (1), 241– 264,  DOI: 10.1146/annurev.anchem.1.031207.112851
      7
      Applications of aptamers as sensors
      Cho, Eun Jeong; Lee, Joo-Woon; Ellington, Andrew D.
      Annual Review of Analytical Chemistry (2009), 2 (), 241-264CODEN: ARACFU; ISSN:1936-1327. (Annual Reviews Inc.)
      A review. Aptamers are ligand-binding nucleic acids whose affinities and selectivities can rival those of antibodies. They have been adapted to anal. applications not only as alternatives to antibodies, but as unique reagents in their own right. In particular, aptamers can be readily site-specifically modified during chem. or enzymic synthesis to incorporate particular reporters, linkers, or other moieties. Also, aptamer secondary structures can be engineered to undergo analyte-dependent conformational changes, which, in concert with the ability to specifically place chem. agents, opens up a wealth of possible signal transduction schemas, irresp. of whether the detection modality is optical, electrochem., or mass based. Finally, because aptamers are nucleic acids, they are readily adapted to sequence- (and hence signal-) amplification methods. However, application of aptamers without a basic knowledge of their biochem. or tech. requirements can cause serious anal. difficulties.
    8. 8
      Byrne, B.; Stack, E.; Gilmartin, N.; O’Kennedy, R. Antibody-Based Sensors: Principles, Problems and Potential for Detection of Pathogens and Associated Toxins. Sensors 2009, 9 (6), 4407– 4445,  DOI: 10.3390/s90604407
      8
      Antibody-based sensors: principles, problems and potential for detection of pathogens and associated toxins
      Byrne, Barry; Stack, Edwina; Gilmartin, Niamh; O'Kennedy, Richard
      Sensors (2009), 9 (6), 4407-4445CODEN: SENSC9; ISSN:1424-8220. (Molecular Diversity Preservation International)
      A review. Antibody-based sensors permit the rapid and sensitive anal. of a range of pathogens and assocd. toxins. A crit. assessment of the implementation of such formats is provided, with ref. to their principles, problems and potential for 'on-site' anal. Particular emphasis is placed on the detection of foodborne bacterial pathogens, such as Escherichia coli and Listeria monocytogenes, and addnl. examples relating to the monitoring of fungal pathogens, viruses, mycotoxins, marine toxins and parasites are also provided.
    9. 9
      Nguyen, H. H.; Lee, S. H.; Lee, U. J.; Fermin, C. D.; Kim, M. Immobilized Enzymes in Biosensor Applications. Materials 2019, 12 (1), 121,  DOI: 10.3390/ma12010121
      9
      Immobilized enzymes in biosensor applications
      Nguyen, Hoang Hiep; Lee, Sun Hyeok; Lee, Ui Jin; Fermin, Cesar D.; Kim, Moonil
      Materials (2019), 12 (1), 121CODEN: MATEG9; ISSN:1996-1944. (MDPI AG)
      Enzyme-based biosensing devices have been extensively developed over the last few decades, and have proven to be innovative techniques in the qual. and quant. anal. of a variety of target substrates over a wide range of applications. Distinct advantages that enzyme-based biosensors provide, such as high sensitivity and specificity, portability, cost-effectiveness, and the possibilities for miniaturization and point-of-care diagnostic testing make them more and more attractive for research focused on clin. anal., food safety control, or disease monitoring purposes. Therefore, this review article investigates the operating principle of enzymic biosensors utilizing electrochem., optical, thermistor, and piezoelec. measurement techniques and their applications in the literature, as well as approaches in improving the use of enzymes for biosensors.
    10. 10
      Zhang, J.; Landry, M. P.; Barone, P. W.; Kim, J.-H.; Lin, S.; Ulissi, Z. W.; Lin, D.; Mu, B.; Boghossian, A. A.; Hilmer, A. J.; Rwei, A.; Hinckley, A. C.; Kruss, S.; Shandell, M. A.; Nair, N.; Blake, S.; Şen, F.; Şen, S.; Croy, R. G.; Li, D.; Yum, K.; Ahn, J.-H.; Jin, H.; Heller, D. A.; Essigmann, J. M.; Blankschtein, D.; Strano, M. S. Molecular Recognition Using Corona Phase Complexes Made of Synthetic Polymers Adsorbed on Carbon Nanotubes. Nat. Nanotechnol. 2013, 8 (12), 959– 968,  DOI: 10.1038/nnano.2013.236
      10
      Molecular recognition using corona phase complexes made of synthetic polymers adsorbed on carbon nanotubes
      Zhang, Jingqing; Landry, Markita P.; Barone, Paul W.; Kim, Jong-Ho; Lin, Shangchao; Ulissi, Zachary W.; Lin, Dahua; Mu, Bin; Boghossian, Ardemis A.; Hilmer, Andrew J.; Rwei, Alina; Hinckley, Allison C.; Kruss, Sebastian; Shandell, Mia A.; Nair, Nitish; Blake, Steven; Sen, Fatih; Sen, Selda; Croy, Robert G.; Li, Deyu; Yum, Kyungsuk; Ahn, Jin-Ho; Jin, Hong; Heller, Daniel A.; Essigmann, John M.; Blankschtein, Daniel; Strano, Michael S.
      Nature Nanotechnology (2013), 8 (12), 959-968CODEN: NNAABX; ISSN:1748-3387. (Nature Publishing Group)
      Understanding mol. recognition is of fundamental importance in applications such as therapeutics, chem. catalysis and sensor design. The most common recognition motifs involve biol. macromols. such as antibodies and aptamers. The key to biorecognition consists of a unique three-dimensional structure formed by a folded and constrained bioheteropolymer that creates a binding pocket, or an interface, able to recognize a specific mol. Here, we show that synthetic heteropolymers, once constrained onto a single-walled carbon nanotube by chem. adsorption, also form a new corona phase that exhibits highly selective recognition for specific mols. To prove the generality of this phenomenon, we report three examples of heteropolymer-nanotube recognition complexes for riboflavin, L-thyroxine and oestradiol. In each case, the recognition was predicted using a two-dimensional thermodn. model of surface interactions in which the dissocn. consts. can be tuned by perturbing the chem. structure of the heteropolymer. Moreover, these complexes can be used as new types of spatiotemporal sensors based on modulation of the carbon nanotube photoemission in the near-IR, as we show by tracking riboflavin diffusion in murine macrophages.
    11. 11
      Bisker, G.; Dong, J.; Park, H. D.; Iverson, N. M.; Ahn, J.; Nelson, J. T.; Landry, M. P.; Kruss, S.; Strano, M. S. Protein-Targeted Corona Phase Molecular Recognition. Nat. Commun. 2016, 7 (1), 10241,  DOI: 10.1038/ncomms10241
      11
      Protein-targeted corona phase molecular recognition
      Bisker, Gili; Dong, Juyao; Park, Hoyoung D.; Iverson, Nicole M.; Ahn, Jiyoung; Nelson, Justin T.; Landry, Markita P.; Kruss, Sebastian; Strano, Michael S.
      Nature Communications (2016), 7 (), 10241CODEN: NCAOBW; ISSN:2041-1723. (Nature Publishing Group)
      Corona phase mol. recognition (CoPhMoRe) uses a heteropolymer adsorbed onto and templated by a nanoparticle surface to recognize a specific target analyte. This method has not yet been extended to macromol. analytes, including proteins. Herein we develop a variant of a CoPhMoRe screening procedure of single-walled carbon nanotubes (SWCNT) and use it against a panel of human blood proteins, revealing a specific corona phase that recognizes fibrinogen with high selectivity. In response to fibrinogen binding, SWCNT fluorescence decreases by >80% at satn. Sequential binding of the three fibrinogen nodules is suggested by selective fluorescence quenching by isolated sub-domains and validated by the quenching kinetics. The fibrinogen recognition also occurs in serum environment, at the clin. relevant fibrinogen concns. in the human blood. These results open new avenues for synthetic, non-biol. antibody analogs that recognize biol. macromols., and hold great promise for medical and clin. applications.
    12. 12
      Denizli, A. Molecular Imprinting for Nanosensors and Other Sensing ApplicationsElsevier2021 1– 417
      There is no corresponding record for this reference.
    13. 13
      Adampourezare, M.; Nikzad, B.; Nasrollahzadeh, S.; Asadpour-Zeynali, K.; de la Guardia, M.; Ezzati Nazhad Dolatabadi, J.; Zhang, F.; Mahdi Jafari, S. Polysaccharide-Based Sensors and Nanosensors: A Review of Recent Progress and Challenges. Microchem. J. 2024, 204, 110944,  DOI: 10.1016/j.microc.2024.110944
      There is no corresponding record for this reference.
    14. 14
      Nocerino, V.; Miranda, B.; Tramontano, C.; Chianese, G.; Dardano, P.; Rea, I.; De Stefano, L. Plasmonic Nanosensors: Design, Fabrication, and Applications in Biomedicine. Chemosensors 2022, 10 (5), 150,  DOI: 10.3390/chemosensors10050150
      There is no corresponding record for this reference.
    15. 15
      Zhang, L.; Yang, Y.; Tan, J.; Yuan, Q. Chemically Modified Nucleic Acid Biopolymers Used in Biosensing. Mater. Chem. Front. 2020, 4 (5), 1315– 1327,  DOI: 10.1039/D0QM00026D
      There is no corresponding record for this reference.
    16. 16
      Shumeiko, V.; Zaken, Y.; Hidas, G.; Paltiel, Y.; Bisker, G.; Shoseyov, O. Peptide-Encapsulated Single-Wall Carbon Nanotube-Based Near-Infrared Optical Nose for Bacteria Detection and Classification. IEEE Sens. J. 2022, 22 (7), 6277– 6287,  DOI: 10.1109/JSEN.2022.3152622
      16
      Peptide-encapsulated single-wall carbon nanotube-based near-infrared optical nose for bacteria detection and classification
      Shumeiko, Vlad; Zaken, Yuval; Hidas, Guy; Paltiel, Yossi; Bisker, Gili; Shoseyov, Oded
      IEEE Sensors Journal (2022), 22 (7), 6277-6287CODEN: ISJEAZ; ISSN:1558-1748. (Institute of Electrical and Electronics Engineers)
      Sense of smell has been used as a diagnostic tool for almost entire human history. While successful examples of the use of the human nose for diagnostics are rare in modern history, there are ample reports of use of animals to diagnose various medical conditions. Bacterial infections often result in strong odors. In recent years, electronic noses (e-nose) and optical noses (o-nose) are of high interest in diagnostics and classificationof bacterial infections.Artificial olfactory sensors can perform noninvasively, immediately at the point of care, do not require extensive sample handling, and promise to be highly cost-effective. This manuscript demonstrates the development of a near-IR optical sniffer comprised of peptide-encapsulated (6,5) single-wall carbon nanotubes (SWCNTs) for bacteria detection and classification. Sixteen different peptides that include tyrosine in different proportions and positions were synthesized. The ability of these peptides to disperse SWCNTs in water was tested, and the intensity of the resultant optical signal was evaluated. Overall, longer peptides provided better dispersion as compared to shorter peptides. Addn. of the fluorenylmethyloxycarbonylchloride (Fmoc) group to pos. charged peptides tested in the current study significantly improved SWCNT dispersion and signal intensity. The sensors successfully distinguished between the odor of sterile growth medium, Escherichia coli, and Klebsiella pneumoniae. Moreover, we demonstrated the possibility of using the developed sensors for antibiotics susceptibility testing. The sensors provided results in real-time, enabledmultiple-usage, and operated at room temp.
    17. 17
      Zong, C.; Fang, L.; Song, F.; Wang, A.; Wan, Y. Fluorescent Fingerprint Bacteria by Multi-Channel Magnetic Fluorescent Nanosensor. Sens. Actuators, B 2019, 289, 234– 241,  DOI: 10.1016/j.snb.2019.03.091
      17
      Fluorescent fingerprint bacteria by multi-channel magnetic fluorescent nanosensor
      Zong, Chengli; Fang, Linyi; Song, Fengge; Wang, Aimin; Wan, Yi
      Sensors and Actuators, B: Chemical (2019), 289 (), 234-241CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)
      Bacteria lies at the root of many infectious and non-infectious diseases. To control and prevent those diseases, there is an urgent need for the rapid and affordable microbial sensing techniques to aid the point-of-care bacterial identification. Here, we report the design and performance of a Multichannel Magnetic Fluorescent Nose (dMFN) for bacteria detection. The system consists of a magnetic nanoparticle conjugated with three different fluorescent proteins (FPs). Upon interacting with bacteria, characteristic levels of the three FPs can be displaced, which are dependent on the binding strength among quaternized magnetic nanoparticles, FPs and bacteria. These characteristic fluorescent responses are bacteria specific, repeatable and can be differentiated by Linear Discriminant Anal. (LDA). The technique is employed for bacterial identity study with a first discriminant of 89.7% within 30 min. We further used dMFN platform for antibiotic screening, the eleven drugs can be distinguished with a first discriminant of 95.2% for E. coli and 97.6% for S. aureu. The generally applicable platform offers a simple tool for the rapid diagnosis and drug screening of pathogens without preprocessing steps.
    18. 18
      Amir, D.; Hendler-Neumark, A.; Wulf, V.; Ehrlich, R.; Bisker, G. Oncometabolite Fingerprinting Using Fluorescent Single-Walled Carbon Nanotubes. Adv. Mater. Interfaces 2022, 9, 2101591,  DOI: 10.1002/admi.202101591
      18
      Oncometabolite Fingerprinting Using Fluorescent Single-Walled Carbon Nanotubes
      Amir, Dean; Hendler-Neumark, Adi; Wulf, Verena; Ehrlich, Roni; Bisker, Gili
      Advanced Materials Interfaces (2022), 9 (4), 2101591CODEN: AMIDD2; ISSN:2196-7350. (Wiley-VCH Verlag GmbH & Co. KGaA)
      The prodn. of oncometabolites is the direct result of mutagenesis in key cellular metabolic enzymes, appearing typically in cancers such as glioma, leukemia, and glioblastoma. Once accumulated, oncometabolites promote cancerous transformations by interfering with important cellular functions. Hence, the ability to sense and quantify oncometabolites is essential for cancer research and clin. diagnosis. Here, the authors present a near-IR optical nanosensor for a known oncometabolite, D-2-hydroxyglutarate (D2HG), discovered in a screening of a library of fluorescent single-walled carbon nanotubes (SWCNTs) functionalized with ssDNA. The screening reveals (ATTT)7-SWCNT as a sensor for D2HG, exhibiting a fluorescence intensity increase upon the interaction with D2HG. The fluorescence response of the sensor does not appear to be attributed to basic chem. features of the target analytes tested, and is shown to discriminate D2HG from other related metabolites, including its enantiomer L-2-hydroxyglutarate. Further, the fluorescence modulation is dependent on the analyte concn. and the SWCNT chirality, showing up to 40.7% and 28.2% increase of the (6,5)-chirality peak and the (9,5)- and (8,7)-chirality joint peak, at 572 and 730 nm excitation, resp., in the presence of 10 mM D2HG. This work opens new opportunities for mol. recognition of oncometabolites which can advance basic cancer metab. research.
    19. 19
      Kim, M.; Chen, C.; Wang, P.; Mulvey, J. J.; Yang, Y.; Wun, C.; Antman-Passig, M.; Luo, H.-B.; Cho, S.; Long-Roche, K.; Ramanathan, L. V.; Jagota, A.; Zheng, M.; Wang, Y.; Heller, D. A. Detection of Ovarian Cancer via the Spectral Fingerprinting of Quantum-Defect-Modified Carbon Nanotubes in Serum by Machine Learning. Nat. Biomed. Eng. 2022, 6 (3), 267– 275,  DOI: 10.1038/s41551-022-00860-y
      19
      Detection of ovarian cancer via the spectral fingerprinting of quantum-defect-modified carbon nanotubes in serum by machine learning
      Kim, Mijin; Chen, Chen; Wang, Peng; Mulvey, Joseph J.; Yang, Yoona; Wun, Christopher; Antman-Passig, Merav; Luo, Hong-Bin; Cho, Sun; Long-Roche, Kara; Ramanathan, Lakshmi V.; Jagota, Anand; Zheng, Ming; Wang, YuHuang; Heller, Daniel A.
      Nature Biomedical Engineering (2022), 6 (3), 267-275CODEN: NBEAB3; ISSN:2157-846X. (Nature Portfolio)
      Serum biomarkers are often insufficiently sensitive or specific to facilitate cancer screening or diagnostic testing. In ovarian cancer, the few established serum biomarkers are highly specific, yet insufficiently sensitive to detect early-stage disease and to impact the mortality rates of patients with this cancer. Here we show that a disease fingerprint acquired via machine learning from the spectra of near-IR fluorescence emissions of an array of carbon nanotubes functionalized with quantum defects detects high-grade serous ovarian carcinoma in serum samples from symptomatic individuals with 87sensitivity at 98specificity (compared with 84sensitivity at 98specificity for the current best clin. screening test, which uses measurements of cancer antigen 125 and transvaginal ultrasonog.). We used 269 serum samples to train and validate several machine-learning classifiers for the discrimination of patients with ovarian cancer from those with other diseases and from healthy individuals. The predictive values of the best classifier could not be attained via known protein biomarkers, suggesting that the array of nanotube sensors responds to unidentified serum biomarkers.
    20. 20
      Nißler, R.; Bader, O.; Dohmen, M.; Walter, S. G.; Noll, C.; Selvaggio, G.; Groß, U.; Kruss, S. Remote near Infrared Identification of Pathogens with Multiplexed Nanosensors. Nat. Commun. 2020, 11 (1), 5995,  DOI: 10.1038/s41467-020-19718-5
      20
      Remote near infrared identification of pathogens with multiplexed nanosensors
      Nissler, Robert; Bader, Oliver; Dohmen, Maria; Walter, Sebastian G.; Noll, Christine; Selvaggio, Gabriele; Gross, Uwe; Kruss, Sebastian
      Nature Communications (2020), 11 (1), 5995CODEN: NCAOBW; ISSN:2041-1723. (Nature Research)
      Infectious diseases are worldwide a major cause of morbidity and mortality. Fast and specific detection of pathogens such as bacteria is needed to combat these diseases. Optimal methods would be non-invasive and without extensive sample-taking/processing. Here, we developed a set of near IR (NIR) fluorescent nanosensors and used them for remote fingerprinting of clin. important bacteria. The nanosensors are based on single-walled carbon nanotubes (SWCNTs) that fluoresce in the NIR optical tissue transparency window, which offers ultra-low background and high tissue penetration. They are chem. tailored to detect released metabolites as well as specific virulence factors (lipopolysaccharides, siderophores, DNases, proteases) and integrated into functional hydrogel arrays with 9 different sensors. These hydrogels are exposed to clin. isolates of 6 important bacteria (Staphylococcus aureus, Escherichia coli,...) and remote (≥25 cm) NIR imaging allows to identify and distinguish bacteria. Sensors are also spectrally encoded (900 nm, 1000 nm, 1250 nm) to differentiate the two major pathogens P. aeruginosa as well as S. aureus and penetrate tissue (>5 mm). This type of multiplexing with NIR fluorescent nanosensors enables remote detection and differentiation of important pathogens and the potential for smart surfaces.
    21. 21
      Morrison, K.; Tincher, M.; Rothchild, A.; Yehl, K. Fingerprinting DNAzyme Cross-Reactivity for Pattern-Based Detection of Heavy Metals. Anal. Chem. 2024, 96 (29), 11780– 11789,  DOI: 10.1021/acs.analchem.4c01331
      There is no corresponding record for this reference.
    22. 22
      Ebrahim-Habibi, M.-B.; Ghobeh, M.; Mahyari, F. A.; Rafii-Tabar, H.; Sasanpour, P. An Investigation into Non-Covalent Functionalization of a Single-Walled Carbon Nanotube and a Graphene Sheet with Protein G: A Combined Experimental and Molecular Dynamics Study. Sci. Rep. 2019, 9 (1), 1273,  DOI: 10.1038/s41598-018-37311-1
      There is no corresponding record for this reference.
    23. 23
      Sultana, N.; Dewey, H. M.; Arellano, A. G.; Budhathoki-Uprety, J. Understanding the Molecular Assemblies of Single Walled Carbon Nanotubes and Tailoring Their Photoluminescence for the Next-Generation Optical Nanosensors. Chem. Mater. 2024, 36 (9), 4034– 4053,  DOI: 10.1021/acs.chemmater.4c00232
      There is no corresponding record for this reference.
    24. 24
      Lambert, B. P.; Taheri, A.; Wu, S.-J.; Gillen, A. J.; Kashaninejad, M.; Boghossian, A. A. Directed Evolution of Nanosensors for the Detection of Mycotoxins. bioRxiv 2023,  DOI: 10.1101/2023.06.13.544576
      There is no corresponding record for this reference.
    25. 25
      An, S.; Suh, Y.; Kelich, P.; Lee, D.; Vukovic, L.; Jeong, S. Directed Evolution of Near-Infrared Serotonin Nanosensors with Machine Learning-Based Screening. Nanomaterials 2024, 14 (3), 247,  DOI: 10.3390/nano14030247
      There is no corresponding record for this reference.
    26. 26
      Jeong, S.; Yang, D.; Beyene, A. G.; Del Bonis-O’Donnell, J. T.; Gest, A. M. M.; Navarro, N.; Sun, X.; Landry, M. P. High-Throughput Evolution of near-Infrared Serotonin Nanosensors. Sci. Adv. 2019, 5 (12), eaay3771  DOI: 10.1126/sciadv.aay3771
      There is no corresponding record for this reference.
    27. 27
      Conroy, P. J.; Hearty, S.; Leonard, P.; O’Kennedy, R. J. Antibody Production, Design and Use for Biosensor-Based Applications. Semin. Cell. Dev. Biol. 2009, 20 (1), 10– 26,  DOI: 10.1016/j.semcdb.2009.01.010
      27
      Antibody production, design and use for biosensor-based applications
      Conroy, Paul J.; Hearty, Stephen; Leonard, Paul; O'Kennedy, Richard J.
      Seminars in Cell & Developmental Biology (2009), 20 (1), 10-26CODEN: SCDBFX; ISSN:1084-9521. (Elsevier Ltd.)
      A review. Currently, the reliable detection and quantification of a multitude of different analytes is crucial in many applications and settings. Biosensors have revolutionised diagnostics for use in point-of-care testing (POC), the detection of food and environmental contaminants, biol. warfare agents, illicit drugs and human/animal disease markers. Antibodies continue to play a pivotal role in many sensor devices due to their exquisite specificity for their cognate antigens. In this review current biosensor platforms employing antibodies for mol. recognition are briefly described. The use of mol. biol. techniques for the generation and improvement of antibodies is critically examd. Such recombinant antibodies possess improved attributes for use in biosensor development in terms of design, stability, affinity and specificity.
    28. 28
      Yoon, M.; Shin, S.; Lee, S.; Kang, J.; Gong, X.; Cho, S.-Y. Scalable Photonic Nose Development through Corona Phase Molecular Recognition. ACS Sens. 2024, 9 (12), 6311– 6319,  DOI: 10.1021/acssensors.4c02327
      There is no corresponding record for this reference.
    29. 29
      Jolliffe, I. T. Principal Component Analysis: A Beginner’s Guide ─ I. Introduction and Application. Weather 1990, 45 (10), 375– 382,  DOI: 10.1002/j.1477-8696.1990.tb05558.x
      There is no corresponding record for this reference.
    30. 30
      Bigdeli, A.; Ghasemi, F.; Golmohammadi, H.; Abbasi-Moayed, S.; Nejad, M. A. F.; Fahimi-Kashani, N.; Jafarinejad, S.; Shahrajabian, M.; Hormozi-Nezhad, M. R. Nanoparticle-Based Optical Sensor Arrays. Nanoscale 2017, 9 (43), 16546– 16563,  DOI: 10.1039/C7NR03311G
      30
      Nanoparticle-based optical sensor arrays
      Bigdeli, Arafeh; Ghasemi, Forough; Golmohammadi, Hamed; Abbasi-Moayed, Samira; Nejad, M. Amin Farahmand; Fahimi-Kashani, Nafiseh; Jafarinejad, Somayeh; Shahrajabian, Maryam; Hormozi-Nezhad, M. Reza
      Nanoscale (2017), 9 (43), 16546-16563CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)
      As in many other methods that have integrated nanoparticles (NPs), the chem. nose/tongue strategy has also progressed greatly since the entrance of NPs into this field. The fascinating tunable physicochem. properties of NPs have made them powerful candidates for array-based sensing platforms and have enabled the development of real-time, sensitive and portable systems that are able to target complex mixts. of analytes. In particular, the unique optical properties of NPs have a key role in providing promising array-based sensing approaches. This review will describe the main aspects and processes of most common NP-based optical sensor arrays. The fundamental steps in the design of a sensor array together with details of each step would be provided. The review begins with the principles of optical sensor arrays and presents the concept of cross-reactivity as the main criterion in the selection of sensing elements. Changes in the absorption and emission properties of the assembled sensing elements are categorized into two main classes of optical signals (colorimetric and fluorometric). Popular chemometric methods used for analyzing the data acquired by a sensor array have also been briefly introduced. On the basis of the objective and the desired application, different types of plasmonic and fluorescent NP that possess unique opto-phys. properties have been presented as available choices in the design of sensing elements. The vast no. of applications of NP-based optical sensor arrays published throughout the literature have then been reviewed according to their mechanism of interaction and the type of optical signal. Finally, the remaining challenges and future directions in this topic have been highlighted.
    31. 31
      Stork, D. G.; Hart, P. E.; D, R. O. Pattern Classification; Wiley, 2000.
      There is no corresponding record for this reference.
    32. 32
      Pourbahrami, S.; Balafar, M. A.; Khanli, L. M.; Kakarash, Z. A. A Survey of Neighborhood Construction Algorithms for Clustering and Classifying Data Points. Comput. Sci. Rev. 2020, 38, 100315,  DOI: 10.1016/j.cosrev.2020.100315
      There is no corresponding record for this reference.
    33. 33
      Okabe, A.; Boots, B.; Sugihara, K. Nearest Neighbourhood Operations with Generalized Voronoi Diagrams: A Review. Int. J. Geogr. Inf. Syst. 1994, 8 (1), 43– 71,  DOI: 10.1080/02693799408901986
      There is no corresponding record for this reference.
    34. 34
      Coto-García, A. M.; Sotelo-González, E.; Fernández-Argüelles, M. T.; Pereiro, R.; Costa-Fernández, J. M.; Sanz-Medel, A. Nanoparticles as Fluorescent Labels for Optical Imaging and Sensing in Genomics and Proteomics. Anal. Bioanal. Chem. 2011, 399 (1), 29– 42,  DOI: 10.1007/s00216-010-4330-3
      There is no corresponding record for this reference.
    35. 35
      Ouyang, M.; Huang, J.-L.; Lieber, C. M. Fundamental Electronic Properties and Applications of Single-Walled Carbon Nanotubes. Acc. Chem. Res. 2002, 35 (12), 1018– 1025,  DOI: 10.1021/ar0101685
      35
      Fundamental Electronic Properties and Applications of Single-Walled Carbon Nanotubes
      Ouyang, Min; Huang, Jin-Lin; Lieber, Charles M.
      Accounts of Chemical Research (2002), 35 (12), 1018-1025CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)
      Recent scanning tunneling microscopy studies of the intrinsic electronic properties of single-walled carbon nanotubes (SWNTs) are overviewed in this Account. A brief theor. treatment of the electronic properties of SWNTs is developed, and then the effects of finite curvature and broken symmetry on electronic properties, the unique 1-dimensional energy dispersion in nanotubes, the interaction between local spins and carriers in metallic nanotubes systems, and the at. structure and electronic properties of intramol. junctions are described. The implications of these studies for understanding fundamental 1-dimensional physics and future nanotube device applications are also discussed.
    36. 36
      Bachilo, S. M.; Strano, M. S.; Kittrell, C.; Hauge, R. H.; Smalley, R. E.; Weisman, R. B. Structure-Assigned Optical Spectra of Single-Walled Carbon Nanotubes. Science 2002, 298 (5602), 2361– 2366,  DOI: 10.1126/science.1078727
      36
      Structure-Assigned Optical Spectra of Single-Walled Carbon Nanotubes
      Bachilo, Sergei M.; Strano, Michael S.; Kittrell, Carter; Hauge, Robert H.; Smalley, Richard E.; Weisman, R. Bruce
      Science (Washington, DC, United States) (2002), 298 (5602), 2361-2366CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
      Spectrofluorometric measurements on single-walled carbon nanotubes (SWNTs) isolated in aq. surfactant suspensions have revealed distinct electronic absorption and emission transitions for more than 30 different semiconducting nanotube species. By combining these fluorimetric results with resonance Raman data, each optical transition has been mapped to a specific (n,m) nanotube structure. Optical spectroscopy can thereby be used to rapidly det. the detailed compn. of bulk SWNT samples, providing distributions in both tube diam. and chiral angle. The measured transition frequencies differ substantially from simple theor. predictions. These deviations may reflect combinations of trigonal warping and excitonic effects.
    37. 37
      Kharlamova, M. V.; Burdanova, M. G.; Paukov, M. I.; Kramberger, C. Synthesis, Sorting, and Applications of Single-Chirality Single-Walled Carbon Nanotubes. Materials 2022, 15 (17), 5898,  DOI: 10.3390/ma15175898
      There is no corresponding record for this reference.
    38. 38
      Jain, A.; Homayoun, A.; Bannister, C. W.; Yum, K. Single-walled Carbon Nanotubes as Near-infrared Optical Biosensors for Life Sciences and Biomedicine. Biotechnol. J. 2015, 10 (3), 447– 459,  DOI: 10.1002/biot.201400168
      38
      Single-walled carbon nanotubes as near-infrared optical biosensors for life sciences and biomedicine
      Jain, Astha; Homayoun, Aida; Bannister, Christopher W.; Yum, Kyungsuk
      Biotechnology Journal (2015), 10 (3), 447-459CODEN: BJIOAM; ISSN:1860-6768. (Wiley-VCH Verlag GmbH & Co. KGaA)
      Single-walled carbon nanotubes that emit photostable near-IR fluorescence have emerged as near-IR optical biosensors for life sciences and biomedicine. Since the discovery of their near-IR fluorescence, researchers have engineered single-walled carbon nanotubes to function as an optical biosensor that selectively modulates its fluorescence upon binding of target mols. Here we review the recent advances in the single-walled carbon nanotube-based optical sensing technol. for life sciences and biomedicine. We discuss the structure and optical properties of single-walled carbon nanotubes, the mechanisms for mol. recognition and signal transduction in single-walled carbon nanotube complexes, and the recent development of various single-walled carbon nanotube-based optical biosensors. We also discuss the opportunities and challenges to translate this emerging technol. into biomedical research and clin. use, including the biol. safety of single-walled carbon nanotubes. The advances in single-walled carbon nanotube-based near-IR optical sensing technol. open up a new avenue for in vitro and in vivo biosensing with high sensitivity and high spatial resoln., beneficial for many areas of life sciences and biomedicine.
    39. 39
      Nißler, R.; Ackermann, J.; Ma, C.; Kruss, S. Prospects of Fluorescent Single-Chirality Carbon Nanotube-Based Biosensors. Anal. Chem. 2022, 94 (28), 9941– 9951,  DOI: 10.1021/acs.analchem.2c01321
      There is no corresponding record for this reference.
    40. 40
      Zhang, Y.; Guo, J.; Tang, Z.; Tang, C.; Li, Y.; Tao, X.; Zhou, B.; Chen, W.; Guo, L.; Tang, K.; Liang, T. Recent Developments and Trends of Biosensors Based on Carbon Nanotubes for Biomedical Diagnosis Applications: A Review. Biosens Bioelectron X 2024, 17, 100424,  DOI: 10.1016/j.biosx.2023.100424
      There is no corresponding record for this reference.
    41. 41
      Acharya, R.; Patil, T. V.; Dutta, S. D.; Lee, J.; Ganguly, K.; Kim, H.; Randhawa, A.; Lim, K.-T. Single-Walled Carbon Nanotube-Based Optical Nano/Biosensors for Biomedical Applications: Role in Bioimaging, Disease Diagnosis, and Biomarkers Detection. Adv. Mater. Technol. 2024, 9 (20), 2400279,  DOI: 10.1002/admt.202400279
      There is no corresponding record for this reference.
    42. 42
      Yaari, Z.; Cheung, J. M.; Baker, H. A.; Frederiksen, R. S.; Jena, P. V.; Horoszko, C. P.; Jiao, F.; Scheuring, S.; Luo, M.; Heller, D. A. Nanoreporter of an Enzymatic Suicide Inactivation Pathway. Nano Lett. 2020, 20 (11), 7819– 7827,  DOI: 10.1021/acs.nanolett.0c01858
      42
      Nanoreporter of an Enzymatic Suicide Inactivation Pathway
      Yaari, Zvi; Cheung, Justin M.; Baker, Hanan A.; Frederiksen, Rune S.; Jena, Prakrit V.; Horoszko, Christopher P.; Jiao, Fang; Scheuring, Simon; Luo, Minkui; Heller, Daniel A.
      Nano Letters (2020), 20 (11), 7819-7827CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      Enzymic suicide inactivation, a route of permanent enzyme inhibition, is the mechanism of action for a wide array of pharmaceuticals. Here, we developed the first nanosensor that selectively reports the suicide inactivation pathway of an enzyme. The sensor is based on modulation of the near-IR fluorescence of an enzyme-bound carbon nanotube. The nanosensor responded selectively to substrate-mediated suicide inactivation of the tyrosinase enzyme via bathochromic shifting of the nanotube emission wavelength. Mechanistic investigations revealed that singlet oxygen generated by the suicide inactivation pathway induced the response. We used the nanosensor to quantify the degree of enzymic inactivation by measuring response rates to small mol. tyrosinase modulators. This work resulted in a new capability of interrogating a specific route of enzymic death. Potential applications include drug screening and hit-validation for compds. that elicit or inhibit enzymic inactivation and single-mol. measurements to assess population heterogeneity in enzyme activity.
    43. 43
      Kallmyer, N. E.; Abdennadher, M. S.; Agarwal, S.; Baldwin-Kordick, R.; Khor, R. L.; Kooistra, A. S.; Peterson, E.; McDaniel, M. D.; Reuel, N. F. Inexpensive Near-Infrared Fluorimeters: Enabling Translation of NIR-Based Assays to the Field. Anal. Chem. 2021, 93 (11), 4800– 4808,  DOI: 10.1021/acs.analchem.0c03732
      There is no corresponding record for this reference.
    44. 44
      Dong, J.; Lee, M. A.; Rajan, A. G.; Rahaman, I.; Sun, J. H.; Park, M.; Salem, D. P.; Strano, M. S. A Synthetic Mimic of Phosphodiesterase Type 5 Based on Corona Phase Molecular Recognition of Single-Walled Carbon Nanotubes. Proc. Natl. Acad. Sci. U. S. A. 2020, 117 (43), 26616– 26625,  DOI: 10.1073/pnas.1920352117
      44
      A synthetic mimic of phosphodiesterase type 5 based on corona phase molecular recognition of single-walled carbon nanotubes
      Dong, Juyao; Lee, Michael A.; Rajan, Ananth Govind; Rahaman, Imon; Sun, Jessica H.; Park, Minkyung; Salem, Daniel P.; Strano, Michael S.
      Proceedings of the National Academy of Sciences of the United States of America (2020), 117 (43), 26616-26625CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
      Mol. recognition binding sites that specifically identify a target mol. are essential for life science research, clin. diagnoses, and therapeutic development. Corona phase mol. recognition is a technique introduced to generate synthetic recognition at the surface of a nanoparticle corona, but it remains an important question whether such entities can achieve the specificity of natural enzymes and receptors. In this work, we generate and screen a library of 24 amphiphilic polymers, preselected for mol. recognition and based on functional monomers including methacrylic acid, acrylic acid, and styrene, iterating upon a poly(methacrylic acid-co-styrene) motif. When complexed to a single-walled carbon nanotube, some of the resulting corona phases demonstrate binding specificity remarkably similar to that of phosphodiesterase type 5 (PDE5), an enzyme that catalyzes the hydrolysis of secondary messenger. The corona phase binds selectively to a PDE5 inhibitor, Vardenafil, as well as its mol. variant, but not to other potential off-target inhibitors. Our work herein examines the specificity and sensitivity of polymer 'mutations' to the corona phase, as well as direct competitions with the native binding PDE5. Using structure perturbation, corona surface characterization, and mol. dynamics simulations, we show that the mol. recognition is assocd. with the unique three-dimensional configuration of the corona phase formed at the nanotube surface. This work conclusively shows that corona phase mol. recognition can mimic key aspects of biol. recognition sites and drug targets, opening up possibilities for pharmaceutical and biol. applications.
    45. 45
      Wulf, V.; Slor, G.; Rathee, P.; Amir, R. J.; Bisker, G. Dendron–Polymer Hybrids as Tailorable Responsive Coronae of Single-Walled Carbon Nanotubes. ACS Nano 2021, 15 (12), 20539– 20549,  DOI: 10.1021/acsnano.1c09125
      45
      Dendron-Polymer Hybrids as Tailorable Responsive Coronae of Single-Walled Carbon Nanotubes
      Wulf, Verena; Slor, Gadi; Rathee, Parul; Amir, Roey J.; Bisker, Gili
      ACS Nano (2021), 15 (12), 20539-20549CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      Functional composite materials that can change their spectral properties in response to external stimuli have a plethora of applications in fields ranging from sensors to biomedical imaging. One of the most promising types of materials used to design spectrally active composites are fluorescent single-walled carbon nanotubes (SWCNTs), noncovalently functionalized by synthetic amphiphilic polymers. These coated SWCNTs can exhibit modulations in their fluorescence spectra in response to interactions with target analytes. Hence, identifying new amphiphiles with interchangeable building blocks that can form individual coronae around the SWCNTs and can be tailored for a specific application is of great interest. This study presents highly modular amphiphilic polymer-dendron hybrids, composed of hydrophobic dendrons and hydrophilic polyethylene glycol (PEG) that can be synthesized with a high degree of structural freedom, for suspending SWCNTs in aq. soln. Taking advantage of the high mol. precision of these PEG-dendrons, we show that precise differences in the chem. structure of the hydrophobic end groups of the dendrons can be used to control the interactions of the amphiphiles with the SWCNT surface. These interactions can be directly related to differences in the intrinsic near-IR fluorescence emission of the various chiralities in a SWCNT sample. Utilizing the susceptibility of the PEG-dendrons toward enzymic degrdn., we demonstrate the ability to monitor enzymic activity through changes in the SWCNT fluorescent signal. These findings pave the way for a rational design of functional SWCNTs, which can be used for optical sensing of enzymic activity in the near-IR spectral range.
    46. 46
      Basu, S.; Hendler-Neumark, A.; Bisker, G. Rationally Designed Functionalization of Single-Walled Carbon Nanotubes for Real-Time Monitoring of Cholinesterase Activity and Inhibition in Plasma. Small 2024, 20, 2309481,  DOI: 10.1002/smll.202309481
      There is no corresponding record for this reference.
    47. 47
      Basu, S.; Hendler-Neumark, A.; Bisker, G. Monitoring Enzyme Activity Using Near-Infrared Fluorescent Single-Walled Carbon Nanotubes. ACS Sens. 2024, 9 (5), 2237– 2253,  DOI: 10.1021/acssensors.4c00377
      There is no corresponding record for this reference.
    48. 48
      Williams, R. M.; Harvey, J. D.; Budhathoki-Uprety, J.; Heller, D. A. Glutathione-S-Transferase Fusion Protein Nanosensor. Nano Lett. 2020, 20 (10), 7287– 7295,  DOI: 10.1021/acs.nanolett.0c02691
      48
      Glutathione-S-transferase Fusion Protein Nanosensor
      Williams, Ryan M.; Harvey, Jackson D.; Budhathoki-Uprety, Januka; Heller, Daniel A.
      Nano Letters (2020), 20 (10), 7287-7295CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      Fusion protein tags are widely used to capture and track proteins in research and industrial bioreactor processes. Quantifying fusion-tagged proteins normally requires several purifn. steps coupled with classical protein assays. Here, the authors developed a broadly applicable nanosensor platform that quantifies glutathione-S-transferase (GST) fusion proteins in real-time. The authors synthesized a glutathione-DNA-carbon nanotube system to study glutathione-GST interactions via semiconducting single-walled carbon nanotube (SWCNT) photoluminescence. SWCNT fluorescence wavelength and intensity modulation occurred specifically in response to GST and GST-fusions. The sensor response was dependent on SWCNT structure, wherein mod(n - m, 3) = 1 nanotube wavelength and intensity responses correlated with nanotube diam. distinctly from mod(n - m, 3) = 2 SWCNT responses. The authors also found broad functionality of this sensor to diverse GST-tagged proteins. This work comprises the first label-free optical sensor for GST and has implications for the assessment of protein expression in situ, including in imaging and industrial bioreactor settings.
    49. 49
      Ehrlich, R.; Hendler-Neumark, A.; Wulf, V.; Amir, D.; Bisker, G. Optical Nanosensors for Real-Time Feedback on Insulin Secretion by Β-Cells. Small 2021, 17 (30), 2101660,  DOI: 10.1002/smll.202101660
      49
      Optical nanosensors for real-time feedback on insulin secretion by beta-cells
      Ehrlich, Roni; Hendler-Neumark, Adi; Wulf, Verena; Amir, Dean; Bisker, Gili
      Small (2021), 17 (30), 2101660CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)
      Quantification of insulin is essential for diabetes research in general, and for the study of pancreatic β-cell function in particular. Herein, fluorescent single-walled carbon nanotubes (SWCNT) are used for the recognition and real-time quantification of insulin. Two approaches for rendering the SWCNT sensors for insulin are compared, using surface functionalization with either a natural insulin aptamer with known affinity to insulin, or a synthetic lipid-poly(ethylene glycol) (PEG) (C16-PEG(2000Da)-Ceramide), both of which show a modulation of the emitted fluorescence in response to insulin. Although the PEGylated-lipid has no prior affinity to insulin, the response of C16-PEG(2000Da)-Ceramide-SWCNTs to insulin is more stable and reproducible compared to the insulin aptamer-SWCNTs. The SWCNT sensors successfully detect insulin secreted by β-cells within the complex environment of the conditioned media. The insulin is quantified by comparing the SWCNTs fluorescence response to a std. calibration curve, and the results are found to be in agreement with an ELISA. This novel anal. tool for real time quantification of insulin secreted by β-cells provides new opportunities for rapid assessment of β-cell function, with the ability to push forward many aspects of diabetes research.
    50. 50
      Pinals, R. L.; Ledesma, F.; Yang, D.; Navarro, N.; Jeong, S.; Pak, J. E.; Kuo, L.; Chuang, Y.-C.; Cheng, Y.-W.; Sun, H.-Y.; Landry, M. P. Rapid SARS-CoV-2 Spike Protein Detection by Carbon Nanotube-Based Near-Infrared Nanosensors. Nano Lett. 2021, 21 (5), 2272– 2280,  DOI: 10.1021/acs.nanolett.1c00118
      50
      Rapid SARS-CoV-2 spike protein detection by carbon nanotube-based near-infrared nanosensors
      Pinals, Rebecca L.; Ledesma, Francis; Yang, Darwin; Navarro, Nicole; Jeong, Sanghwa; Pak, John E.; Kuo, Lili; Chuang, Yung-Chun; Cheng, Yu-Wei; Sun, Hung-Yu; Landry, Markita P.
      Nano Letters (2021), 21 (5), 2272-2280CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      To effectively track and eliminate COVID-19, it is crit. to develop tools for rapid and accessible diagnosis of actively infected individuals. Here, we introduce a single-walled carbon nanotube (SWCNT)-based optical sensing approach toward this end. We construct a nanosensor based on SWCNTs noncovalently functionalized with ACE2, a host protein with high binding affinity for the SARS-CoV-2 spike protein. The presence of the SARS-CoV-2 spike protein elicits a robust, 2-fold nanosensor fluorescence increase within 90 min of spike protein exposure. We characterize the nanosensor stability and sensing mechanism and passivate the nanosensor to preserve sensing response in saliva and viral transport medium. We further demonstrate that these ACE2-SWCNT nanosensors retain sensing capacity in a surface-immobilized format, exhibiting a 73% fluorescence turn-on response within 5 s of exposure to 35 mg/L SARS-CoV-2 virus-like particles. Our data demonstrate that ACE2-SWCNT nanosensors can be developed into an optical tool for rapid SARS-CoV-2 detection.
    51. 51
      Gillen, A. J.; Siefman, D. J.; Wu, S.-J.; Bourmaud, C.; Lambert, B.; Boghossian, A. A. Templating Colloidal Sieves for Tuning Nanotube Surface Interactions and Optical Sensor Responses. J. Colloid Interface Sci. 2020, 565, 55– 62,  DOI: 10.1016/j.jcis.2019.12.058
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      Templating colloidal sieves for tuning nanotube surface interactions and optical sensor responses
      Gillen, Alice J.; Siefman, Daniel J.; Wu, Shang-Jung; Bourmaud, Claire; Lambert, Benjamin; Boghossian, Ardemis A.
      Journal of Colloid and Interface Science (2020), 565 (), 55-62CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)
      Surfactants offer a tunable approach for modulating the exposed surface area of a nanoparticle. They further present a scalable and cost-effective means for suspending single-walled carbon nanotubes (SWCNTs), which have demonstrated practical use as fluorescence sensors. Though surfactant suspensions show record quantum yields for SWCNTs in aq. solns., they lack the selectivity that is vital for optical sensing. We present a new method for controlling the selectivity of optical SWCNT sensors through colloidal templating of the exposed surface area. Colloidal nanotube sensors were obtained using various concns. of sodium cholate, and their performances were compared to DNA-SWCNT optical sensors. Sensor responses were measured against a library of bioanalytes, including neurotransmitters, amino acids, and sugars. We report an intensity response towards dopamine and serotonin for all sodium cholate-suspended SWCNT concns. We further identify a selective, 14.1 nm and 10.3 nm wavelength red-shifting response to serotonin for SWCNTs suspended in 1.5 and 0.5 mM sodium cholate, resp. Through controlled, adsorption-based tuning of the nanotube surface, this study demonstrates the applicability of sub-crit. colloidal suspensions to achieve selectivities exceeding those previously reported for DNA-SWCNT sensors.
    52. 52
      Beyene, A. G.; Delevich, K.; Del Bonis-O’Donnell, J. T.; Piekarski, D. J.; Lin, W. C.; Thomas, A. W.; Yang, S. J.; Kosillo, P.; Yang, D.; Prounis, G. S.; Wilbrecht, L.; Landry, M. P. Imaging Striatal Dopamine Release Using a Nongenetically Encoded near Infrared Fluorescent Catecholamine Nanosensor. Sci. Adv. 2019, 5 (7), eaaw3108  DOI: 10.1126/sciadv.aaw3108
      There is no corresponding record for this reference.
    53. 53
      Dinarvand, M.; Elizarova, S.; Daniel, J.; Kruss, S. Imaging of Monoamine Neurotransmitters with Fluorescent Nanoscale Sensors. ChemPluschem 2020, 85 (7), 1465– 1480,  DOI: 10.1002/cplu.202000248
      53
      Imaging of Monoamine Neurotransmitters with Fluorescent Nanoscale Sensors
      Dinarvand, Meshkat; Elizarova, Sofia; Daniel, James; Kruss, Sebastian
      ChemPlusChem (2020), 85 (7), 1465-1480CODEN: CHEMM5; ISSN:2192-6506. (Wiley-VCH Verlag GmbH & Co. KGaA)
      A review. Cells use biomols. to convey information. For instance, neurons communicate by releasing chems. called neurotransmitters, including several monoamines. The information transmitted by neurons is, in part, coded in the type and amt. of neurotransmitter released, the spatial distribution of release sites, the frequency of release events, and the diffusion range of the neurotransmitter. Therefore, quant. information about neurotransmitters at the (sub)cellular level with high spatiotemporal resoln. is needed to understand how complex cellular networks function. So far, various anal. methods have been developed and used to detect neurotransmitter secretion from cells. However, each method has limitations with respect to chem., temporal and spatial resoln. In this review, we focus on emerging methods for optical detection of neurotransmitter release and discuss fluorescent sensors/probes for monoamine neurotransmitters such as dopamine and serotonin. We focus on the latest advances in near IR fluorescent carbon nanotube-based sensors and engineered fluorescent proteins for monoamine imaging, which provide high spatial and temporal resoln. suitable for examg. the release of monoamines from cells in cellular networks.
    54. 54
      Lee, M. A.; Wang, S.; Jin, X.; Bakh, N. A.; Nguyen, F. T.; Dong, J.; Silmore, K. S.; Gong, X.; Pham, C.; Jones, K. K.; Muthupalani, S.; Bisker, G.; Son, M.; Strano, M. S. Implantable Nanosensors for Human Steroid Hormone Sensing In Vivo Using a Self-Templating Corona Phase Molecular Recognition. Adv. Healthcare Mater. 2020, 9 (21), 2000429,  DOI: 10.1002/adhm.202000429
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      Implantable Nanosensors for Human Steroid Hormone Sensing In Vivo Using a Self-Templating Corona Phase Molecular Recognition
      Lee, Michael A.; Wang, Song; Jin, Xiaojia; Bakh, Naveed Ali; Nguyen, Freddy T.; Dong, Juyao; Silmore, Kevin S.; Gong, Xun; Pham, Crystal; Jones, Kelvin K.; Muthupalani, Sureshkumar; Bisker, Gili; Son, Manki; Strano, Michael S.
      Advanced Healthcare Materials (2020), 9 (21), 2000429CODEN: AHMDBJ; ISSN:2192-2640. (Wiley-VCH Verlag GmbH & Co. KGaA)
      Dynamic measurements of steroid hormones in vivo are crit., but steroid sensing is currently limited by the availability of specific mol. recognition elements due to the chem. similarity of these hormones. In this work, a new, self-templating synthetic approach is applied using corona phase mol. recognition (CoPhMoRe) targeting the steroid family of mols. to produce near IR fluorescent, implantable sensors. A key limitation of CoPhMoRe has been its reliance on library generation for sensor screening. This problem is addressed with a self-templating strategy of polymer design, using the examples of progesterone and cortisol sensing based on a styrene and acrylic acid copolymer library augmented with an acrylated steroid. The pendant steroid attached to the corona backbone is shown to self-template the phase, providing a unique CoPhMoRE design strategy with high efficacy. The resulting sensors exhibit excellent stability and reversibility upon repeated analyte cycling. It is shown that mol. recognition using such constructs is viable even in vivo after sensor implantation into a murine model by employing a poly (ethylene glycol) diacrylate (PEGDA) hydrogel and porous cellulose interface to limit nonspecific absorption. The results demonstrate that CoPhMoRe templating is sufficiently robust to enable a new class of continuous, in vivo biosensors.
    55. 55
      Safaee, M. M.; Gravely, M.; Roxbury, D. A Wearable Optical Microfibrous Biomaterial with Encapsulated Nanosensors Enables Wireless Monitoring of Oxidative Stress. Adv. Funct. Mater. 2021, 31 (13), 2006254,  DOI: 10.1002/adfm.202006254
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      A Wearable Optical Microfibrous Biomaterial with Encapsulated Nanosensors Enables Wireless Monitoring of Oxidative Stress
      Safaee, Mohammad Moein; Gravely, Mitchell; Roxbury, Daniel
      Advanced Functional Materials (2021), 31 (13), 2006254CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)
      In an effort to facilitate personalized medical approaches, the continuous and noninvasive monitoring of biochem. information using wearable technologies can enable a detailed understanding of an individual's physiol. Reactive oxygen species (ROS) are a class of oxygen-contg. free radicals that function in a wide range of biol. processes. In wound healing applications, the continuous monitoring of ROS through a wearable diagnostics platform is essential for the prevention of chronicity and pathogenic infection. Here, a versatile one-step procedure is utilized to fabricate optical core-shell microfibrous textiles incorporating single-walled carbon nanotubes (SWCNTs) for the real-time optical monitoring of hydrogen peroxide concns. in in vitro wounds. The environmentally sensitive and non-photobleachable fluorescence of SWCNTs enables continuous analyte monitoring without decay in signal over time. The existence of multiple chiralities of SWCNTs emitting near-IR fluorescence with narrow bandwidths allows a ratiometric signal readout invariant to the excitation source distance and exposure time. The individual fibers encapsulate the SWCNT nanosensors for at least 21 days without apparent loss in structural integrity. Moreover, the microfibrous textiles are utilized to spatially resolve peroxide concns. using a camera and further integrated into com. wound bandages without significant degrdn. in their optical properties.
    56. 56
      Wu, H.; Nißler, R.; Morris, V.; Herrmann, N.; Hu, P.; Jeon, S.-J.; Kruss, S.; Giraldo, J. P. Monitoring Plant Health with Near-Infrared Fluorescent H 2 O 2 Nanosensors. Nano Lett. 2020, 20 (4), 2432– 2442,  DOI: 10.1021/acs.nanolett.9b05159
      There is no corresponding record for this reference.
    57. 57
      Hofferber, E. M.; Stapleton, J. A.; Iverson, N. M. Review─Single Walled Carbon Nanotubes as Optical Sensors for Biological Applications. J. Electrochem. Soc. 2020, 167 (3), 037530,  DOI: 10.1149/1945-7111/ab64bf
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      Review-single walled carbon nanotubes as optical sensors for biological applications
      Hofferber, Eric M.; Stapleton, Joseph A.; Iverson, Nicole M.
      Journal of the Electrochemical Society (2020), 167 (3), 037530CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)
      A review. Since the discovery of the band gap fluorescence from single walled carbon nanotubes (SWNT) many advancements have been made towards the use of these unique fluorophores as optical biosensors in vitro, ex vivo in vivo. Attention has been given to these pure carbon structures due to their photostability, tunable properties, and bright near IR emission that falls in the tissue transparency window. This review highlights some of the major advancements in the field of SWNT biosensors over the last two decades with a focus given to recent advances in biol. applications.
    58. 58
      Farrera, C.; Torres Andón, F.; Feliu, N. Carbon Nanotubes as Optical Sensors in Biomedicine. ACS Nano 2017, 11 (11), 10637– 10643,  DOI: 10.1021/acsnano.7b06701
      58
      Carbon Nanotubes as Optical Sensors in Biomedicine
      Farrera, Consol; Torres Andon, Fernando; Feliu, Neus
      ACS Nano (2017), 11 (11), 10637-10643CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      A review. Single-walled carbon nanotubes (SWCNTs) have become potential candidates for a wide range of medical applications including sensing, imaging, and drug delivery. Their photophys. properties (i.e., the capacity to emit in the near-IR), excellent photostability, and fluorescence, which is highly sensitive to the local environment, make SWCNTs promising optical probes in biomedicine. In this Perspective, the authors discuss the existing strategies for and challenges of using carbon nanotubes for medical diagnosis based on intracellular sensing as well as their biocompatibility and degradability. Finally, the authors highlight the potential improvements of this nanotechnol. and future directions in the field of carbon nanotubes for biomedical applications.
    59. 59
      Hendler-Neumark, A.; Wulf, V.; Bisker, G. In Vivo Imaging of Fluorescent Single-Walled Carbon Nanotubes within C. Elegans Nematodes in the near-Infrared Window. Mater. Today Bio. 2021, 12, 100175,  DOI: 10.1016/j.mtbio.2021.100175
      59
      In vivo imaging of fluorescent single-walled carbon nanotubes within C. elegans nematodes in the near-infrared window
      Hendler-Neumark, Adi; Wulf, Verena; Bisker, Gili
      Materials Today Bio (2021), 12 (), 100175CODEN: MTBAC2; ISSN:2590-0064. (Elsevier Ltd.)
      Caenorhabditis elegans (C. elegans) nematodes serve as a model organism for eukaryotes, esp. due to their genetic similarity. Although they have many advantages like their small size and transparency, their autofluorescence in the entire visible wavelength range poses a challenge for imaging and tracking fluorescent proteins or dyes using std. fluorescence microscopy. Herein, near-IR (NIR) fluorescent single-walled carbon nanotubes (SWCNTs) are utilized for in vivo imaging within the gastrointestinal track of C. elegans. The SWCNTs are biocompatible, and do not affect the worms' viability nor their reprodn. ability. The worms do not show any autofluorescence in the NIR range, thus enabling the spectral sepn. between the SWCNT NIR fluorescence and the strong autofluorescence of the worm gut granules. The worms are fed with ssDNA-SWCNT which are visualized mainly in the intestine lumen. The NIR fluorescence is used in vivo to track the contraction and relaxation in the area of the pharyngeal valve at the anterior of the terminal bulb. These biocompatible, non-photobleaching, NIR fluorescent nanoparticles can advance in vivo imaging and tracking within C. elegans and other small model organisms by overcoming the signal-to-noise challenge stemming from the wide-range visible autofluorescence.
    60. 60
      Nandi, S.; Caicedo, K.; Cognet, L. When Super-Resolution Localization Microscopy Meets Carbon Nanotubes. Nanomaterials 2022, 12 (9), 1433,  DOI: 10.3390/nano12091433
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      When Super-Resolution Localization Microscopy Meets Carbon Nanotubes
      Nandi, Somen; Caicedo, Karen; Cognet, Laurent
      Nanomaterials (2022), 12 (9), 1433CODEN: NANOKO; ISSN:2079-4991. (MDPI AG)
      A review. We recently assisted in a revolution in the realm of fluorescence microscopy triggered by the advent of super-resoln. techniques that surpass the classic diffraction limit barrier. By providing optical images with nanometer resoln. in the far field, super-resoln. microscopy (SRM) is currently accelerating our understanding of the mol. organization of bio-specimens, bridging the gap between cellular observations and mol. structural knowledge, which was previously only accessible using electron microscopy. SRM mainly finds its roots in progress made in the control and manipulation of the optical properties of (single) fluorescent mols. The flourishing development of novel fluorescent nanostructures has recently opened the possibility of assocg. super-resoln. imaging strategies with nanomaterials' design and applications. In this review article, we discuss some of the recent developments in the field of super-resoln. imaging explicitly based on the use of nanomaterials. As an archetypal class of fluorescent nanomaterial, we mainly focus on single-walled carbon nanotubes (SWCNTs), which are photoluminescent emitters at near-IR (NIR) wavelengths bearing great interest for biol. imaging and for information optical transmission. Whether for fundamental applications in nanomaterial science or in biol., we show how super-resoln. techniques can be applied to create nanoscale images "in", "of" and "with" SWCNTs.
    61. 61
      Kleiner, S.; Wulf, V.; Bisker, G. Single-Walled Carbon Nanotubes as near-Infrared Fluorescent Probes for Bio-Inspired Supramolecular Self-Assembled Hydrogels. J. Colloid Interface Sci. 2024, 670, 439– 448,  DOI: 10.1016/j.jcis.2024.05.098
      There is no corresponding record for this reference.
    62. 62
      Ackermann, J.; Metternich, J. T.; Herbertz, S.; Kruss, S. Biosensing with Fluorescent Carbon Nanotubes. Angew. Chem., Int. Ed. 2022, 61 (18), e202112372  DOI: 10.1002/anie.202112372
      62
      Biosensing with Fluorescent Carbon Nanotubes
      Ackermann, Julia; Metternich, Justus T.; Herbertz, Svenja; Kruss, Sebastian
      Angewandte Chemie, International Edition (2022), 61 (18), e202112372CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
      A review. Biosensors are powerful tools for modern basic research and biomedical diagnostics. Their development requires substantial input from the chem. sciences. Sensors or probes with an optical readout, such as fluorescence, offer rapid, minimally invasive sensing of analytes with high spatial and temporal resoln. The near-IR (NIR) region is beneficial because of the reduced background and scattering of biol. samples (tissue transparency window) in this range. In this context, single-walled carbon nanotubes (SWCNTs) have emerged as versatile NIR fluorescent building blocks for biosensors. Here, we provide an overview of advances in SWCNT-based NIR fluorescent mol. sensors. We focus on chem. design strategies for diverse analytes and summarize insights into the photophysics and mol. recognition. Furthermore, different application areas are discussed-from chem. imaging of cellular systems and diagnostics to in vivo applications and perspectives for the future.
    63. 63
      De Los Santos, Z. A.; Lin, Z.; Zheng, M. Optical Detection of Stereoselective Interactions with DNA-Wrapped Single-Wall Carbon Nanotubes. J. Am. Chem. Soc. 2021, 143 (49), 20628– 20632,  DOI: 10.1021/jacs.1c11372
      63
      Optical Detection of Stereoselective Interactions with DNA-Wrapped Single-Wall Carbon Nanotubes
      De los Santos, Zeus A.; Lin, Zhiwei; Zheng, Ming
      Journal of the American Chemical Society (2021), 143 (49), 20628-20632CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      DNA-wrapped carbon nanotubes have been explored increasingly as sensitive near-IR fluorescence probes for biomols. However, notably missing in previous studies is an inquiry on stereoselective interactions between DNA-wrapped carbon nanotubes and biomols. Here, enantiopure (+) and (-)(6,5), and (-)(8,3) as well as achiral (11,0) carbon nanotubes wrapped with specific resolving DNA sequences are used to demonstrate their stereoselective detection of amino acid enantiomers. Furthermore, stereoselective sensing abilities are found to be retained by dispersions contg. a multitude of chiral nanotube structures. The fluorescence response profiles of six different DNA-wrapped carbon nanotube dispersions to nine std. amino acids, and their enantiomers, demonstrate that DNA-wrapped carbon nanotubes are exquisitely sensitive to the stereoconfiguration and side-chain functionality of amino acids in a manner that is dependent on both DNA sequence and nanotube chirality. Implications of our findings are discussed in the context of developing a machine learning-aided multiplexed biosensing scheme called a mol. perceptron.
    64. 64
      Blanch, A. J.; Lenehan, C. E.; Quinton, J. S. Optimizing Surfactant Concentrations for Dispersion of Single-Walled Carbon Nanotubes in Aqueous Solution. J. Phys. Chem. B 2010, 114 (30), 9805– 9811,  DOI: 10.1021/jp104113d
      64
      Optimizing Surfactant Concentrations for Dispersion of Single-Walled Carbon Nanotubes in Aqueous Solution
      Blanch, Adam J.; Lenehan, Claire E.; Quinton, Jamie S.
      Journal of Physical Chemistry B (2010), 114 (30), 9805-9811CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)
      The sonication-centrifugation technique is commonly used for dispersing single-walled carbon nanotubes (SWCNTs) in aq. surfactant solns. However, the methodologies and materials used for this purpose are widely varied, and few dispersive agents were studied systematically. This work describes a systematic study into the ability of some known (and some less common) surfactants and polymers to disperse SWCNTs fabricated by two different techniques. UV-visible-NIR absorbance spectra of their supernatant solns. showed that the smaller ionic surfactants were generally more effective dispersants, with larger polymer and surfactant mols. exhibiting a reduced performance for ensembles of carbon nanotubes of smaller av. diam. Optimal surfactant concns. were established for dispersions of carbon nanotubes produced by the elec. arc method in aq. solns. of sodium dodecylbenzene sulfonate, sodium deoxycholate, Triton X-405, Brij S-100, Pluronic F-127, and polyvinylpyrrolidone. This optimum value was detd. as the point at which the relative concn. of nanotubes dispersed is maximized, before flocculation-inducing attractive depletion interactions begin to dominate. The aggregation state of carbon nanotubes dispersed in sodium dodecylbenzene sulfonate was probed by AFM at different stages of rebundling, showing the length dependence of these effects.
    65. 65
      Gerstman, E.; Hendler-Neumark, A.; Wulf, V.; Bisker, G. Monitoring the Formation of Fibrin Clots as Part of the Coagulation Cascade Using Fluorescent Single-Walled Carbon Nanotubes. ACS Appl. Mater. Interfaces 2023, 15 (18), 21866– 21876,  DOI: 10.1021/acsami.3c00828
      65
      Monitoring the Formation of Fibrin Clots as Part of the Coagulation Cascade Using Fluorescent Single-Walled Carbon Nanotubes
      Gerstman, Efrat; Hendler-Neumark, Adi; Wulf, Verena; Bisker, Gili
      ACS Applied Materials & Interfaces (2023), 15 (18), 21866-21876CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
      Blood coagulation is a crit. defense mechanism against bleeding that results in the conversion of liq. blood into a solid clot through a complicated cascade, which involves multiple clotting factors. One of the final steps in the coagulation pathway is the conversion of fibrinogen to insol. fibrin mediated by thrombin. Because coagulation disorders can be life-threatening, the development of novel methods for monitoring the coagulation cascade dynamics is of high importance. Here, we use near-IR (NIR)-fluorescent single-walled carbon nanotubes (SWCNTs) to image and monitor fibrin clotting in real time. Following the binding of fibrinogen to a tailored SWCNT platform, thrombin transforms the fibrinogen into fibrin monomers, which start to polymerize. The SWCNTs are incorporated within the clot and can be clearly visualized in the NIR-fluorescent channel, where the signal-to-noise ratio is improved compared to bright-field imaging in the visible range. Moreover, the diffusion of individual SWCNTs within the fibrin clot gradually slows down after the addn. of thrombin, manifesting a coagulation rate that depends on both fibrinogen and thrombin concns. Our platform can open new opportunities for coagulation disorder diagnostics and allow for real-time monitoring of the coagulation cascade with a NIR optical signal output in the biol. transparency window.
    66. 66
      Budhathoki-Uprety, J.; Harvey, J. D. D.; Isaac, E.; Williams, R. M. M.; Galassi, T. V. V.; Langenbacher, R. E. E.; Heller, D. A. A. Polymer Cloaking Modulates the Carbon Nanotube Protein Corona and Delivery into Cancer Cells. J. Mater. Chem. B 2017, 5 (32), 6637– 6644,  DOI: 10.1039/C7TB00695K
      66
      Polymer cloaking modulates the carbon nanotube protein corona and delivery into cancer cells
      Budhathoki-Uprety, Januka; Harvey, Jackson D.; Isaac, Elizabeth; Williams, Ryan M.; Galassi, Thomas V.; Langenbacher, Rachel E.; Heller, Daniel A.
      Journal of Materials Chemistry B: Materials for Biology and Medicine (2017), 5 (32), 6637-6644CODEN: JMCBDV; ISSN:2050-7518. (Royal Society of Chemistry)
      Carbon nanotube-based mol. probes, imaging agents, and biosensors in cells and in vivo continue to garner interest as investigational tools and clin. devices due to their unique photophys. properties. Surface chem. modulation of nanotubes plays a crit. role in detg. stability and interaction with biol. systems both in vitro and in vivo. Among the many parameters that influence the biol. fate of nanomaterials, surface charge is particularly influential due to direct electrostatic interactions with components of the cell membrane as well as proteins in the serum, which coat the nanoparticle surface in a protein corona and alter nanoparticle-cell interactions. Here, we modulated functional moieties on a helical polycarbodiimide polymer backbone that non-covalently suspended the nanotubes in aq. media. By derivatizing the polymer with either primary amine or carboxylic acid side chains, we obtained nanotube complexes that present net surface charges of opposite polarity at physiol. pH. Using these materials, we found that the uptake of carbon nanotubes in these cells is highly dependent on charge, with cationic nanotubes efficiently internalized into cells compared to the anionic nanotubes. Furthermore, we found that serum proteins drastically influenced cell uptake of the anionic nanotubes, while the effect was not prominent for the cationic nanotubes. Our findings have implications for improved engineering of drug delivery devices, mol. probes, and biosensors.
    67. 67
      Fernandes, R. M. F.; Dai, J.; Regev, O.; Marques, E. F.; Furó, I. Block Copolymers as Dispersants for Single-Walled Carbon Nanotubes: Modes of Surface Attachment and Role of Block Polydispersity. Langmuir 2018, 34 (45), 13672– 13679,  DOI: 10.1021/acs.langmuir.8b02658
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      Block Copolymers as Dispersants for Single-Walled Carbon Nanotubes: Modes of Surface Attachment and Role of Block Polydispersity
      Fernandes, Ricardo M. F.; Dai, Jing; Regev, Oren; Marques, Eduardo F.; Furo, Istvan
      Langmuir (2018), 34 (45), 13672-13679CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)
      When using amphiphilic polymers to exfoliate and disperse carbon nanotubes in water, the balance between the hydrophobic and hydrophilic moieties is crit. and nontrivial. Here, we investigate the mode of surface attachment of a triblock copolymer, Pluronics F127, composed of a central hydrophobic polypropylene oxide block flanked by hydrophilic polyethylene oxide blocks, onto single-walled carbon nanotubes (SWNTs). Crucially, we analyze the compn. in dispersant of both the as-obtained dispersion (the supernatant) and the ppt.-contg. undispersed materials. For this, we combine the carefully obtained data from 1H NMR peak intensities and self-diffusion and thermogravimetric anal. The mol. motions behind the obsd. NMR features are clarified. We find that the hydrophobic blocks attach to the dispersed SWNT surface and remain significantly immobilized leading to 1H NMR signal loss. On the other hand, the hydrophilic blocks remain highly mobile and thus readily detectable by NMR. The dispersant is shown to possess significant block polydispersity that has a large effect on dispersibility. Polymers with large hydrophobic blocks adsorb on the surface of the carbonaceous particles that ppt., indicating that although a larger hydrophobic block is good for enhancing adsorption, it may be less effective in dispersing the tubes. A model is also proposed that consistently explains our observations in SWNT dispersions and some contradicting findings obtained previously in carbon nanohorn dispersions. Overall, our findings help elucidating the mol. picture of the dispersion process for SWNTs and are of interest when looking for more effective (i.e., well-balanced) polymeric dispersants.
    68. 68
      Antonucci, A.; Kupis-Rozmysłowicz, J.; Boghossian, A. A. Noncovalent Protein and Peptide Functionalization of Single-Walled Carbon Nanotubes for Biodelivery and Optical Sensing Applications. ACS Appl. Mater. Interfaces 2017, 9 (13), 11321– 11331,  DOI: 10.1021/acsami.7b00810
      68
      Noncovalent Protein and Peptide Functionalization of Single-Walled Carbon Nanotubes for Biodelivery and Optical Sensing Applications
      Antonucci, Alessandra; Kupis-Rozmyslowicz, Justyna; Boghossian, Ardemis A.
      ACS Applied Materials & Interfaces (2017), 9 (13), 11321-11331CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
      A review. The exquisite structural and optical characteristics of single-walled carbon nanotubes (SWCNTs), combined with the tunable specificities of proteins and peptides, can be exploited to strongly benefit technologies with applications in fields ranging from biomedicine to industrial biocatalysis. The key to exploiting the synergism of these materials is designing protein/peptide-SWCNT conjugation schemes that preserve biomol. activity while keeping the near-IR optical and electronic properties of SWCNTs intact. Since sp2 bond-breaking disrupts the optoelectronic properties of SWCNTs, noncovalent conjugation strategies are needed to interface biomols. to the nanotube surface for optical biosensing and delivery applications. An underlying understanding of the forces contributing to protein and peptide interaction with the nanotube is thus necessary to identify the appropriate conjugation design rules for specific applications. This article explores the mol. interactions that govern the adsorption of peptides and proteins on SWCNT surfaces, elucidating contributions from individual amino acids as well as secondary and tertiary protein structure and conformation. Various noncovalent conjugation strategies for immobilizing peptides, homopolypeptides, and sol. and membrane proteins on SWCNT surfaces are presented, highlighting studies focused on developing near-IR optical sensors and mol. scaffolds for self-assembly and biochem. anal. The anal. presented herein suggests that though direct adsorption of proteins and peptides onto SWCNTs can be principally applied to drug and gene delivery, in vivo imaging and targeting, or cancer therapy, nondirect conjugation strategies using artificial or natural membranes, polymers, or linker mols. are often better suited for biosensing applications that require conservation of biomol. functionality or precise control of the biomol.'s orientation. These design rules are intended to provide the reader with a rational approach to engineering biomol.-SWCNT platforms, broadening the breadth and accessibility of both wild-type and engineered biomols. for SWCNT-based applications.
    69. 69
      Tsyboulski, D. A.; Bakota, E. L.; Witus, L. S.; Rocha, J.-D. R.; Hartgerink, J. D.; Weisman, R. B. Self-Assembling Peptide Coatings Designed for Highly Luminescent Suspension of Single-Walled Carbon Nanotubes. J. Am. Chem. Soc. 2008, 130 (50), 17134– 17140,  DOI: 10.1021/ja807224x
      69
      Self-Assembling Peptide Coatings Designed for Highly Luminescent Suspension of Single-Walled Carbon Nanotubes
      Tsyboulski, Dmitri A.; Bakota, Erica L.; Witus, Leah S.; Rocha, John-David R.; Hartgerink, Jeffrey D.; Weisman, R. Bruce
      Journal of the American Chemical Society (2008), 130 (50), 17134-17140CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      A series of self-assembling multidomain peptides have been designed, synthesized, and tested for their ability to individually suspend single-walled carbon nanotubes (SWCNTs) in water while preserving strong near-IR nanotube luminescence. Photometric and spectral measurements on individual SWCNTs revealed that emission in the common biocompatible coating agents Pluronic F127, ss-DNA, and BSA is approx. an order of magnitude weaker than in the bioincompatible ionic surfactant SDBS. By contrast, one of the engineered peptides gave SWCNT emission ∼40% as intense as in SDBS. A strong inverse correlation was also found between the spectral line widths of coated SWCNTs and the efficiency of their emission. Peptides with rationally designed self-assembly properties appear to be promising coatings that may enable SWCNT optical sensing applications in biol. environments.
    70. 70
      Heller, D. A.; Pratt, G. W.; Zhang, J.; Nair, N.; Hansborough, A. J.; Boghossian, A. A.; Reuel, N. F.; Barone, P. W.; Strano, M. S. Peptide Secondary Structure Modulates Single-Walled Carbon Nanotube Fluorescence as a Chaperone Sensor for Nitroaromatics. Proc. Natl. Acad. Sci. U. S. A. 2011, 108 (21), 8544– 8549,  DOI: 10.1073/pnas.1005512108
      70
      Peptide secondary structure modulates single-walled carbon nanotube fluorescence as a chaperone sensor for nitroaromatics
      Heller, Daniel A.; Pratt, George W.; Zhang, Jingqing; Nair, Nitish; Hansborough, Adam J.; Boghossian, Ardemis A.; Reuel, Nigel F.; Barone, Paul W.; Strano, Michael S.
      Proceedings of the National Academy of Sciences of the United States of America (2011), 108 (21), 8544-8549, S8544/1-S8544/8CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
      A class of peptides from the bombolitin family, not previously identified for nitroarom. recognition, allows near-IR fluorescent single-walled carbon nanotubes to transduce specific changes in their conformation. In response to the binding of specific nitroarom. species, such peptide-nanotube complexes form a virtual "chaperone sensor," which reports modulation of the peptide secondary structure via changes in single-walled carbon nanotubes, near-IR photoluminescence. A split-channel microscope constructed to image quantized spectral wavelength shifts in real time, in response to nitroarom. adsorption, results in the first single-nanotube imaging of solvatochromic events. The described indirect detection mechanism, as well as an addnl. exciton quenching-based optical nitroarom. detection method, illustrate that functionalization of the carbon nanotube surface can result in completely unique sites for recognition, resolvable at the single-mol. level.
    71. 71
      Matsukawa, Y.; Umemura, K. Chirality Luminescent Properties of Single-Walled Carbon Nanotubes during Redox Reactions. Opt. Mater. 2021, 112, 110748,  DOI: 10.1016/j.optmat.2020.110748
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      Chirality luminescent properties of single-walled carbon nanotubes during redox reactions
      Matsukawa, Yuji; Umemura, Kazuo
      Optical Materials (Amsterdam, Netherlands) (2021), 112 (), 110748CODEN: OMATET; ISSN:0925-3467. (Elsevier B.V.)
      In this study, we focused on the presence of SWNTs with different chiralities within the same SWNT powder, and we investigated the correlation between the rate of change of the emission intensity due to redox reactions and SWNT chirality. We measured the redox change rate of chirality, which was difficult to detect because of the low emission intensity, by increasing the exposure time during (PL) measurement. 0.5 mg of SWNT powder and 1 mL of (dsDNA) stock soln. were mixed and sonicated using a probe-type sonicator on ice. Hydrogen peroxide (H2O2; final concn.: 0.03%) was added to this dispersion for oxidn., and then, a catechin aq. soln. (final concn. 1.5μg/mL) was added to the soln. to measure PL. The exposure time was 90 s to obtain sufficient emission intensity. The measurement results showed that the magnitude of the rate of change of the PL intensity due to redox reaction was different for each chirality. Focusing on the (8,6) and (9,4) chiralities, which showed a large rate of change, the PL intensity decreased by 57.4% and 54.6% from the initial state, resp., when H2O2 was added. Subsequently, these values increased by 1024% and 558% with the addn. of a catechin aq. soln., resp. Furthermore, from the comparison of the PL detection results and optical response characteristics of each chirality, it was obsd. that the rate of change of the PL intensity of SWNTs during redox reactions using H2O2 and catechin had the strongest correlation with the SWNT diam.
    72. 72
      Salem, D. P.; Landry, M. P.; Bisker, G.; Ahn, J.; Kruss, S.; Strano, M. S. Chirality Dependent Corona Phase Molecular Recognition of DNA-Wrapped Carbon Nanotubes. Carbon 2016, 97, 147– 153,  DOI: 10.1016/j.carbon.2015.08.075
      72
      Chirality dependent corona phase molecular recognition of DNA-wrapped carbon nanotubes
      Salem, Daniel P.; Landry, Markita P.; Bisker, Gili; Ahn, Jiyoung; Kruss, Sebastian; Strano, Michael S.
      Carbon (2016), 97 (), 147-153CODEN: CRBNAH; ISSN:0008-6223. (Elsevier Ltd.)
      Corona phase mol. recognition (CoPhMoRe) is a phenomenon whereby a polymer or surfactant corona phase wrapped around a nanoparticle selectively recognizes a particular mol. The method can potentially generate non-biol., synthetic mol. recognition sites, analogous to antibodies, for a broad range of biomedical applications, including new types of sensors, lab. and clin. assays, as well as inhibitors and targeted therapeutics. In this work, we utilize near IR fluorescent single-walled carbon nanotubes (SWNTs) wrapped with specific single stranded DNA sequences to explore the (n,m) chirality dependence of CoPhMoRe. Specific DNA oligonucleotide sequences are known to recognize and interact uniquely with certain (n,m) SWNTs enabling their enrichment in ion exchange chromatog. We explore the CoPhMoRe effect using corona phases constructed from a library of 24 such sequences, screening against a biomol. panel that includes common neurotransmitters, amino acids, saccharides and riboflavin. Example sequences include (ATT)4, (TAT)4 and (ATTT)3 which recognize (7,5), (6,5) and (8,4) SWNTs, resp. We find that these recognition sequences indeed form CoPhMoRe phases that are distinct among SWNT chiralities, and appear to pack more densely as to exclude analyte adsorption on the chirality they recognize. These results have encouraging implications for the controlled design of CoPhMoRe phases for biomedical applications.
    73. 73
      Choi, J. H.; Strano, M. S. Solvatochromism in Single-Walled Carbon Nanotubes. Appl. Phys. Lett. 2007, 90 (22), 88– 91,  DOI: 10.1063/1.2745228
      There is no corresponding record for this reference.
    74. 74
      Järup, L. Hazards of Heavy Metal Contamination. Br. Med. Bull. 2003, 68 (1), 167– 182,  DOI: 10.1093/bmb/ldg032
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      Hazards of heavy metal contamination
      Jarup Lars
      British medical bulletin (2003), 68 (), 167-82 ISSN:0007-1420.
      The main threats to human health from heavy metals are associated with exposure to lead, cadmium, mercury and arsenic. These metals have been extensively studied and their effects on human health regularly reviewed by international bodies such as the WHO. Heavy metals have been used by humans for thousands of years. Although several adverse health effects of heavy metals have been known for a long time, exposure to heavy metals continues, and is even increasing in some parts of the world, in particular in less developed countries, though emissions have declined in most developed countries over the last 100 years. Cadmium compounds are currently mainly used in re-chargeable nickel-cadmium batteries. Cadmium emissions have increased dramatically during the 20th century, one reason being that cadmium-containing products are rarely re-cycled, but often dumped together with household waste. Cigarette smoking is a major source of cadmium exposure. In non-smokers, food is the most important source of cadmium exposure. Recent data indicate that adverse health effects of cadmium exposure may occur at lower exposure levels than previously anticipated, primarily in the form of kidney damage but possibly also bone effects and fractures. Many individuals in Europe already exceed these exposure levels and the margin is very narrow for large groups. Therefore, measures should be taken to reduce cadmium exposure in the general population in order to minimize the risk of adverse health effects. The general population is primarily exposed to mercury via food, fish being a major source of methyl mercury exposure, and dental amalgam. The general population does not face a significant health risk from methyl mercury, although certain groups with high fish consumption may attain blood levels associated with a low risk of neurological damage to adults. Since there is a risk to the fetus in particular, pregnant women should avoid a high intake of certain fish, such as shark, swordfish and tuna; fish (such as pike, walleye and bass) taken from polluted fresh waters should especially be avoided. There has been a debate on the safety of dental amalgams and claims have been made that mercury from amalgam may cause a variety of diseases. However, there are no studies so far that have been able to show any associations between amalgam fillings and ill health. The general population is exposed to lead from air and food in roughly equal proportions. During the last century, lead emissions to ambient air have caused considerable pollution, mainly due to lead emissions from petrol. Children are particularly susceptible to lead exposure due to high gastrointestinal uptake and the permeable blood-brain barrier. Blood levels in children should be reduced below the levels so far considered acceptable, recent data indicating that there may be neurotoxic effects of lead at lower levels of exposure than previously anticipated. Although lead in petrol has dramatically decreased over the last decades, thereby reducing environmental exposure, phasing out any remaining uses of lead additives in motor fuels should be encouraged. The use of lead-based paints should be abandoned, and lead should not be used in food containers. In particular, the public should be aware of glazed food containers, which may leach lead into food. Exposure to arsenic is mainly via intake of food and drinking water, food being the most important source in most populations. Long-term exposure to arsenic in drinking-water is mainly related to increased risks of skin cancer, but also some other cancers, as well as other skin lesions such as hyperkeratosis and pigmentation changes. Occupational exposure to arsenic, primarily by inhalation, is causally associated with lung cancer. Clear exposure-response relationships and high risks have been observed.
    75. 75
      Barnham, K. J.; Bush, A. I. Biological Metals and Metal-Targeting Compounds in Major Neurodegenerative Diseases. Chem. Soc. Rev. 2014, 43, 6727,  DOI: 10.1039/C4CS00138A
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      Biological metals and metal-targeting compounds in major neurodegenerative diseases
      Barnham, Kevin J.; Bush, Ashley I.
      Chemical Society Reviews (2014), 43 (19), 6727-6749CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
      A review. Multiple abnormalities occur in the homeostasis of essential endogenous brain biometals in age-related neurodegenerative disorders, Alzheimer's disease, Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis. As a result, metals both accumulate in microscopic proteinopathies, and can be deficient in cells or cellular compartments. Therefore, bulk measurement of metal content in brain tissue samples reveal only the "tip of the iceberg", with most of the important changes occurring on a microscopic and biochem. level. Each of the major proteins implicated in these disorders interacts with biol. transition metals. Tau and the amyloid protein precursor have important roles in normal neuronal iron homeostasis. Changes in metal distribution, cellular deficiencies, or sequestration in proteinopathies all present abnormalities that can be cor. in animal models by small mols. These biochem. targets are more complex than the simple excess of metals that are targeted by chelators. In this review we illustrate some of the richness in the science that has developed in the study of metals in neurodegeneration, and explore its novel pharmacol.
    76. 76
      Tofan, L.; Wenkert, R. Chelating Polymers with Valuable Sorption Potential for Development of Precious Metal Recycling Technologies. Rev. Chem. Eng. 2022, 38 (2), 167– 183,  DOI: 10.1515/revce-2019-0075
      There is no corresponding record for this reference.
    77. 77
      Guo, S.-Y.; Hou, P.-X.; Zhang, F.; Liu, C.; Cheng, H.-M. Gas Sensors Based on Single-Wall Carbon Nanotubes. Molecules 2022, 27 (17), 5381,  DOI: 10.3390/molecules27175381
      77
      Gas Sensors Based on Single-Wall Carbon Nanotubes
      Guo, Shu-Yu; Hou, Peng-Xiang; Zhang, Feng; Liu, Chang; Cheng, Hui-Ming
      Molecules (2022), 27 (17), 5381CODEN: MOLEFW; ISSN:1420-3049. (MDPI AG)
      A review. Single-wall carbon nanotubes (SWCNTs) have a high aspect ratio, large surface area, good stability and unique metallic or semiconducting elec. cond., they are therefore considered a promising candidate for the fabrication of flexible gas sensors that are expected to be used in the Internet of Things and various portable and wearable electronics. In this review, we first introduce the sensing mechanism of SWCNTs and the typical structure and key parameters of SWCNT-based gas sensors. We then summarize research progress on the design, fabrication, and performance of SWCNT-based gas sensors. Finally, the principles and possible approaches to further improving the performance of SWCNT-based gas sensors are discussed.
    78. 78
      Gong, X.; Cho, S.-Y.; Kuo, S.; Ogunlade, B.; Tso, K.; Salem, D. P.; Strano, M. S. Divalent Metal Cation Optical Sensing Using Single-Walled Carbon Nanotube Corona Phase Molecular Recognition. Anal. Chem. 2022, 94 (47), 16393– 16401,  DOI: 10.1021/acs.analchem.2c03648
      78
      Divalent Metal Cation Optical Sensing Using Single-Walled Carbon Nanotube Corona Phase Molecular Recognition
      Gong, Xun; Cho, Soo-Yeon; Kuo, Sydney; Ogunlade, Babatunde; Tso, Kathryn; Salem, Daniel P.; Strano, Michael S.
      Analytical Chemistry (Washington, DC, United States) (2022), 94 (47), 16393-16401CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
      Colloidal single-walled carbon nanotubes (SWCNTs) offer a promising platform for the nanoscale engineering of mol. recognition. Optical sensors have been recently designed through the modification of noncovalent corona phases (CPs) of SWCNTs through a phenomenon known as corona phase mol. recognition (CoPhMoRe). In CoPhMoRe constructs, DNA CPs are of great interest due to the breadth of the design space and our ability to control these mols. with sequence specificity at scale. Utilizing these constructs for metal ion sensing is a natural extension of this technol. due to DNA's well-known coordination chem. Addnl., understanding metal ion interactions of these constructs allows for improved sensor design for use in complex aq. environments. In this work, we study the interactions between a panel of 9 dil. divalent metal cations and 35 DNA CPs under the most controlled exptl. conditions for SWCNT optical sensing to date. We found that best practices for the study of colloidal SWCNT analyte responses involve mitigating the effects of ionic strength, diln. kinetics, laser power, and analyte response kinetics. We also discover that SWCNT with DNA CPs generally offers two unique sensing states at pH 6 and 8. The combined set of sensors in this work allowed for the differentiation of Hg2+, Pb2+, Cr2+, and Mn2+. Finally, we implemented Hg2+ sensing in the context of portable detection within fish tissue ext., demonstrating nanomolar level detection.
    79. 79
      Heller, D. A.; Jeng, E. S.; Yeung, T.-K.; Martinez, B. M.; Moll, A. E.; Gastala, J. B.; Strano, M. S. Optical Detection of DNA Conformational Polymorphism on Single-Walled Carbon Nanotubes. Science 2006, 311 (5760), 508– 511,  DOI: 10.1126/science.1120792
      79
      Optical Detection of DNA Conformational Polymorphism on Single-Walled Carbon Nanotubes
      Heller, Daniel A.; Jeng, Esther S.; Yeung, Tsun-Kwan; Martinez, Brittany M.; Moll, Anthonie E.; Gastala, Joseph B.; Strano, Michael S.
      Science (Washington, DC, United States) (2006), 311 (5760), 508-511CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
      The transition of DNA secondary structure from an analogous B to Z conformation modulates the dielec. environment of the single-walled carbon nanotube (SWNT) around which it is adsorbed. The SWNT band-gap fluorescence undergoes a red shift when an encapsulating 30-nucleotide oligomer is exposed to counter ions that screen the charged backbone. The transition is thermodynamically identical for DNA on and off the nanotube, except that the propagation length of the former is shorter by five-sixths. The magnitude of the energy shift is described by using an effective medium model and the DNA geometry on the nanotube sidewall. The authors demonstrate the detection of the B-Z change in whole blood, tissue, and from within living mammalian cells.
    80. 80
      Jin, H.; Jeng, E. S.; Heller, D. A.; Jena, P. V.; Kirmse, R.; Langowski, J.; Strano, M. S. Divalent Ion and Thermally Induced DNA Conformational Polymorphism on Single-Walled Carbon Nanotubes. Macromolecules 2007, 40 (18), 6731– 6739,  DOI: 10.1021/ma070608t
      80
      Divalent Ion and Thermally Induced DNA Conformational Polymorphism on Single-walled Carbon Nanotubes
      Jin, Hong; Jeng, Esther S.; Heller, Daniel A.; Jena, Prakrit V.; Kirmse, Robert; Langowski, Joerg; Strano, Michael S.
      Macromolecules (Washington, DC, United States) (2007), 40 (18), 6731-6739CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)
      Various sequences of single and double stranded DNA can wrap and colloidally stabilize single- walled carbon nanotubes in soln. The binding of divalent ions to these complexes results in a 10 meV emission energy red-shift of the photoluminescence of the nanotube. In this work, this optical modulation is linked to specific secondary structure changes in the adsorbed DNA. Dynamic light scattering is used to rule out aggregation and inter-particle effects. It is obsd. that the transition can also be induced thermally over the temp. range between 0 and 50 °C without ion addn. Interestingly, we find evidence of the dissocn. of a DNA duplex at the surface, as confirmed using both selective dialysis and DNA electrophoresis on a 20% PAGE gel. Consistent with several observations is a mechanism that proceeds via a competitive, stepwise process of partial desorption of the DNA along the length of SWNT. A two-state math. model quant. describes the equil. for various divalent ions binding to DNA adsorbed at the nanotube surface.
    81. 81
      Gillen, A. J.; Kupis-Rozmysłowicz, J.; Gigli, C.; Schuergers, N.; Boghossian, A. A. Xeno Nucleic Acid Nanosensors for Enhanced Stability Against Ion-Induced Perturbations. J. Phys. Chem. Lett. 2018, 9 (15), 4336– 4343,  DOI: 10.1021/acs.jpclett.8b01879
      81
      Xeno Nucleic Acid Nanosensors for Enhanced Stability Against Ion-Induced Perturbations
      Gillen, Alice J.; Kupis-Rozmyslowicz, Justyna; Gigli, Carlo; Schuergers, Nils; Boghossian, Ardemis A.
      Journal of Physical Chemistry Letters (2018), 9 (15), 4336-4343CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)
      The omnipresence of salts in biofluids creates a pervasive challenge in designing sensors suitable for in vivo applications. Fluctuations in ion concns. have been shown to affect the sensitivity and selectivity of optical sensors based on single-walled carbon nanotubes wrapped with single-stranded DNA (ssDNA-SWCNTs). We herein observe fluorescence wavelength shifting for ssDNA-SWCNT-based optical sensors in the presence of divalent cations at concns. above 3.5 mM. In contrast, no shifting was obsd. for concns. up to 350 mM for sensors bioengineered with increased rigidity using xeno nucleic acids (XNAs). Transient fluorescence measurements reveal distinct optical transitions for ssDNA- and XNA-based wrappings during ion-induced conformation changes, with XNA-based sensors showing increased permanence in conformational and signal stability. This demonstration introduces synthetic biol. as a complementary means for enhancing nanotube optoelectronic behavior, unlocking previously unexplored possibilities for developing nanobioengineered sensors with augmented capabilities.
    82. 82
      Andjelkovic, M.; Vancamp, J.; Demeulenaer, B.; Depaemelaere, G.; Socaciu, C.; Verloo, M.; Verhe, R. Iron-Chelation Properties of Phenolic Acids Bearing Catechol and Galloyl Groups. Food Chem. 2006, 98 (1), 23– 31,  DOI: 10.1016/j.foodchem.2005.05.044
      82
      Iron-chelation properties of phenolic acids bearing catechol and galloyl groups
      Andjelkovic, Mirjana; Van Camp, John; De Meulenaer, Bruno; Depaemelaere, Griet; Socaciu, Carmen; Verloo, Marc; Verhe, Roland
      Food Chemistry (2006), 98 (1), 23-31CODEN: FOCHDJ; ISSN:0308-8146. (Elsevier B.V.)
      In this study, the capacity of 7 phenolic acids and hydroxytyrosol for complex formation with iron was quantified. A metal-chelation mechanism was described by means of spectrophotometry and calcg. the binding consts. of the complexes. The influence of phosphate buffer, Hepes buffer, Tris buffer and water on this mechanism was investigated. UV-Vis absorption spectroscopy showed that the absorption of phenolic acids changes upon the addn. of Fe2+, which resulted in several shifts of their spectra. These bathochromic shifts were analyzed and evaluated by calcg. binding consts. Furthermore, in the presence of different concns. of EDTA (0-1 mM), a redn. of the consts. was obsd. However, not all of the phenolic compds. assessed here showed complex formation, those not bearing catechol or galloyl moiety like vanillic acid, syringic acid and ferulic acid, did not show any complex formation. The ability of the phenolic compds. which chelate iron have been ranked in line with the binding consts. in ascending order rendering the protocatechuic acid (1.43 M-1) the weakest chelator, followed by hydroxytyrosol (2.66 M-1), gallic acid (4.78 M-1), caffeic acid (8.12 M-1) and chlorogenic acid (20.13 M-1) as the strongest chelator.
    83. 83
      Irankunda, R.; Camaño Echavarría, J. A.; Paris, C.; Stefan, L.; Desobry, S.; Selmeczi, K.; Muhr, L.; Canabady-Rochelle, L. Metal-Chelating Peptides Separation Using Immobilized Metal Ion Affinity Chromatography: Experimental Methodology and Simulation. Separations 2022, 9 (11), 370,  DOI: 10.3390/separations9110370
      There is no corresponding record for this reference.
    84. 84
      Yang, M.; Song, W. J. Diverse Protein Assembly Driven by Metal and Chelating Amino Acids with Selectivity and Tunability. Nat. Commun. 2019, 10 (1), 5545,  DOI: 10.1038/s41467-019-13491-w
      84
      Diverse protein assembly driven by metal and chelating amino acids with selectivity and tunability
      Yang, Minwoo; Song, Woon Ju
      Nature Communications (2019), 10 (1), 5545CODEN: NCAOBW; ISSN:2041-1723. (Nature Research)
      Proteins are versatile natural building blocks with highly complex and multifunctional architectures, and self-assembled protein structures have been created by the introduction of covalent, noncovalent, or metal-coordination bonding. Here, we report the robust, selective, and reversible metal coordination properties of unnatural chelating amino acids as the sufficient and dominant driving force for diverse protein self-assembly. Bipyridine-alanine is genetically incorporated into a D3 homohexamer. Depending on the position of the unnatural amino acid, 1-directional, cryst. and noncryst. 2-directional, combinatory, and hierarchical architectures are effectively created upon the addn. of metal ions. The length and shape of the structures is tunable by altering conditions related to thermodn. and kinetics of metal-coordination and subsequent reactions. The cryst. 1-directional and 2-directional biomaterials retain their native enzymic activities with increased thermal stability, suggesting that introducing chelating ligands provides a specific chem. basis to synthesize diverse protein-based functional materials while retaining their native structures and functions.
    85. 85
      Tournus, F.; Latil, S.; Heggie, M. I.; Charlier, J.-C. π-Stacking Interaction between Carbon Nanotubes and Organic Molecules. Phys. Rev. B 2005, 72 (7), 075431,  DOI: 10.1103/PhysRevB.72.075431
      85
      π-stacking interaction between carbon nanotubes and organic molecules
      Tournus, F.; Latil, S.; Heggie, M. I.; Charlier, J.-C.
      Physical Review B: Condensed Matter and Materials Physics (2005), 72 (7), 075431/1-075431/5CODEN: PRBMDO; ISSN:1098-0121. (American Physical Society)
      The π-stacking interaction between various planar org. mols. is studied within the framework of ab initio calcns. The adsorption of these mols. on the sidewall of the cylindrical C structure induces a small binding energy compared to conventional covalent functionalization. Such a weak interaction is only physisorption and leads to minor and predictable modifications of the electronic structure. These changes in the electronic behavior of the host C nanotube are ruled by the relative positions of the mol. levels of the isolated mol. and both the valence and conduction bands of the perfect tube.
    86. 86
      Kruss, S.; Landry, M. P.; Vander Ende, E.; Lima, B. M. A.; Reuel, N. F.; Zhang, J.; Nelson, J.; Mu, B.; Hilmer, A.; Strano, M. Neurotransmitter Detection Using Corona Phase Molecular Recognition on Fluorescent Single-Walled Carbon Nanotube Sensors. J. Am. Chem. Soc. 2014, 136 (2), 713– 724,  DOI: 10.1021/ja410433b
      86
      Neurotransmitter Detection Using Corona Phase Molecular Recognition on Fluorescent Single-Walled Carbon Nanotube Sensors
      Kruss, Sebastian; Landry, Markita P.; Vander Ende, Emma; Lima, Barbara M. A.; Reuel, Nigel F.; Zhang, Jingqing; Nelson, Justin; Mu, Bin; Hilmer, Andrew; Strano, Michael
      Journal of the American Chemical Society (2014), 136 (2), 713-724CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      Temporal and spatial changes in neurotransmitter concns. are central to information processing in neural networks. Therefore, biosensors for neurotransmitters are essential tools for neuroscience. The authors applied a new technique, corona phase mol. recognition (CoPhMoRe), to identify adsorbed polymer phases on fluorescent single-walled carbon nanotubes (SWCNTs) that allow for the selective detection of specific neurotransmitters, including dopamine. The authors functionalized and suspended SWCNTs with a library of different polymers (n = 30) contg. phospholipids, nucleic acids, and amphiphilic polymers to study how neurotransmitters modulate the resulting band gap, near-IR (nIR) fluorescence of the SWCNT. The authors identified several corona phases that enable the selective detection of neurotransmitters. Catecholamines such as dopamine increased the fluorescence of specific single-stranded DNA- and RNA-wrapped SWCNTs by 58-80% upon addn. of 100 μM dopamine depending on the SWCNT chirality (n,m). In soln., the limit of detection was 11 nM [Kd = 433 nM for (GT)15 DNA-wrapped SWCNTs]. Mechanistic studies revealed that this turn-on response is due to an increase in fluorescence quantum yield and not covalent modification of the SWCNT or scavenging of reactive oxygen species. When immobilized on a surface, the fluorescence intensity of a single DNA- or RNA-wrapped SWCNT is enhanced by a factor of up to 5.39±1.44, whereby fluorescence signals are reversible. The authors' findings indicate that certain DNA/RNA coronae act as conformational switches on SWCNTs, which reversibly modulate the SWCNT fluorescence. These findings suggest that the authors' polymer-SWCNT constructs can act as fluorescent neurotransmitter sensors in the tissue-compatible nIR optical window, which may find applications in neuroscience.
    87. 87
      Joshua Ashaolu, T.; Lee, C. C.; Opeolu Ashaolu, J.; Pourjafar, H.; Jafari, S. M. Metal-Binding Peptides and Their Potential to Enhance the Absorption and Bioavailability of Minerals. Food Chem. 2023, 428, 136678,  DOI: 10.1016/j.foodchem.2023.136678
      There is no corresponding record for this reference.
    88. 88
      Ren, X.; Zou, Q.; Yuan, C.; Chang, R.; Xing, R.; Yan, X. The Dominant Role of Oxygen in Modulating the Chemical Evolution Pathways of Tyrosine in Peptides: Dityrosine or Melanin. Angew. Chem., Int. Ed. 2019, 131 (18), 5930– 5934,  DOI: 10.1002/ange.201814575
      There is no corresponding record for this reference.
    89. 89
      Reid, L. O.; Vignoni, M.; Martins-Froment, N.; Thomas, A. H.; Dántola, M. L. Photochemistry of Tyrosine Dimer: When an Oxidative Lesion of Proteins Is Able to Photoinduce Further Damage. Photochem. Photobiol. Sci. 2019, 18 (7), 1732– 1741,  DOI: 10.1039/c9pp00182d
      There is no corresponding record for this reference.
    90. 90
      Lampel, A.; McPhee, S. A.; Kassem, S.; Sementa, D.; Massarano, T.; Aramini, J. M.; He, Y.; Ulijn, R. V. Melanin-Inspired Chromophoric Microparticles Composed of Polymeric Peptide Pigments. Angew. Chem., Int. Ed. 2021, 60 (14), 7564– 7569,  DOI: 10.1002/anie.202015170
      90
      Melanin-inspired chromophoric microparticles composed of polymeric peptide pigments
      Lampel, Ayala; McPhee, Scott A.; Kassem, Salma; Sementa, Deborah; Massarano, Tlalit; Aramini, James M.; He, Ye; Ulijn, Rein V.
      Angewandte Chemie, International Edition (2021), 60 (14), 7564-7569CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
      Melanin and related polyphenolic pigments are versatile functional polymers that serve diverse aesthetic and protective roles across the living world. These polymeric pigments continue to inspire the development of adhesive, photonic, electronic and radiation-protective materials and coatings. The properties of these structures are dictated by covalent and non-covalent interactions in ways that, despite progress, are not fully understood. It remains a major challenge to direct oxidative polymn. of their precursors (amino acids, (poly-)phenols, thiols) toward specific structures. By taking advantage of supramol. pre-organization of tyrosine-tripeptides and reactive sequestering of selected amino acids during enzymic oxidn., we demonstrate the spontaneous formation of distinct new chromophores with optical properties that are far beyond the range of those found in biol. melanins, in terms of color, UV absorbance and fluorescent emission.
    91. 91
      Settele, S.; Schrage, C. A.; Jung, S.; Michel, E.; Li, H.; Flavel, B. S.; Hashmi, A. S. K.; Kruss, S.; Zaumseil, J. Ratiometric Fluorescent Sensing of Pyrophosphate with Sp3-Functionalized Single-Walled Carbon Nanotubes. Nat. Commun. 2024, 15 (1), 706,  DOI: 10.1038/s41467-024-45052-1
      There is no corresponding record for this reference.
    92. 92
      Pan, J.; Li, F.; Choi, J. H. Single-Walled Carbon Nanotubes as Optical Probes for Bio-Sensing and Imaging. J. Mater. Chem. B 2017, 5 (32), 6511– 6522,  DOI: 10.1039/C7TB00748E
      92
      Single-walled carbon nanotubes as optical probes for bio-sensing and imaging
      Pan, Jing; Li, Feiran; Choi, Jong Hyun
      Journal of Materials Chemistry B: Materials for Biology and Medicine (2017), 5 (32), 6511-6522CODEN: JMCBDV; ISSN:2050-7518. (Royal Society of Chemistry)
      A review. The unique phys. properties of single-walled carbon nanotubes (SWCNTs) have been exploited in novel applications in various fields including electronics and life sciences. Their photoluminescence in the near-IR (NIR) range, where optical interference from biol. tissues is min., has rendered them particularly attractive as optical probes in biol. environments. Herein the authors review the use of the SWCNT NIR emission in bio-sensing and imaging. To interface the insol. carbon nanotubes with an aq. biol. environment, biomaterials and org. polymers have been widely used for noncovalently functionalizing SWCNTs. Such functionalization minimizes the toxicity of carbon nanotubes in biol. and physiol. environments, while maintaining their optical properties. SWCNTs have been demonstrated as both in vitro and in vivo optical sensors, targeting biol. important mols., such as neurotransmitters and cell signaling mols. For optical imaging, functionalized SWCNTs were used as NIR contrast agents for probing cellular processes and imaging plants and small animals. The authors also discuss emerging SWCNT-based super-resoln. schemes. The authors conclude that SWCNTs are promising optical materials for basic life science research, biomedical diagnostics, and therapeutics.
    93. 93
      Wulf, V.; Bichachi, E.; Hendler-Neumark, A.; Massarano, T.; Leshem, A. B.; Lampel, A.; Bisker, G. Multicomponent System of Single-Walled Carbon Nanotubes Functionalized with a Melanin-Inspired Material for Optical Detection and Scavenging of Metals. Adv. Funct. Mater. 2022, 32 (49), 2209688,  DOI: 10.1002/adfm.202209688
      93
      Multicomponent System of Single-Walled Carbon Nanotubes Functionalized with a Melanin-Inspired Material for Optical Detection and Scavenging of Metals
      Wulf, Verena; Bichachi, Ella; Hendler-Neumark, Adi; Massarano, Tlalit; Leshem, Avigail Baruch; Lampel, Ayala; Bisker, Gili
      Advanced Functional Materials (2022), 32 (49), 2209688CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)
      The accumulation of metal ions in organisms and the presence of heavy metals in water cause adverse effects on ecosystems and results in numerous human health issues such as cancer and neurogenerative diseases. Therefore, the development of novel platforms for metal-scavenging and rapid metal detection for in situ applications are of high importance. Here, this challenge is tackled by taking advantage of the metal chelation ability of a melanin-inspired material in combination with the near-IR (NIR) fluorescence response of single-walled carbon nanotubes (SWCNTs) to surface binding. SWCNTs are functionalized by a melanin-like substance, obtained by enzymic oxidative polymn. of a fluorenylmethyloxycarbonyl-tyrosine (FmocY) precursor. The resulting multicomponent system (SWCNT-FmocYOx) serves as a metal-ion scavenging platform that concurrently reports on metal binding with optical signal transduction. Upon binding of a library of mostly divalent transition metal-ions, the fluorescence emission of the functionalized SWCNTs is modulated, showing a concn.-dependent response with a limit of detection in the nanomolar range. Metal-binding and removal from water of up to 98% is further shown via inductively coupled plasma mass spectrometry. The SWCNT-FmocYOx hybrid system presents a novel platform with NIR optical signal for real-time feedback on metal-ion scavenging.
    94. 94
      Barone, P. W.; Baik, S.; Heller, D. A.; Strano, M. S. Near-Infrared Optical Sensors Based on Single-Walled Carbon Nanotubes. Nat. Mater. 2005, 4 (1), 86– 92,  DOI: 10.1038/nmat1276
      94
      Near-infrared optical sensors based on single-walled carbon nanotubes
      Barone, Paul W.; Baik, Seunghyun; Heller, Daniel A.; Strano, Michael S.
      Nature Materials (2005), 4 (1), 86-92CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)
      Mol. detection using near-IR light between 0.9 and 1.3 eV has important biomedical applications because of greater tissue penetration and reduced auto-fluorescent background in thick tissue or whole-blood media. Carbon nanotubes have a tunable near-IR emission that responds to changes in the local dielec. function but remains stable to permanent photobleaching. In this work, we report the synthesis and successful testing of soln.-phase, near-IR sensors, with β-D-glucose sensing as a model system, using single-walled carbon nanotubes that modulate their emission in response to the adsorption of specific biomols. New types of non-covalent functionalization using electron-withdrawing mols. are shown to provide sites for transferring electrons in and out of the nanotube. We also show two distinct mechanisms of signal transduction-fluorescence quenching and charge transfer. The results demonstrate new opportunities for nanoparticle optical sensors that operate in strongly absorbing media of relevance to medicine or biol.
    95. 95
      O’Connell, M. J.; Eibergen, E. E.; Doorn, S. K. Chiral Selectivity in the Charge-Transfer Bleaching of Single-Walled Carbon-Nanotube Spectra. Nat. Mater. 2005, 4 (5), 412– 418,  DOI: 10.1038/nmat1367
      95
      Chiral selectivity in the charge-transfer bleaching of single-walled carbon-nanotube spectra
      O'Connell, Michael J.; Eibergen, Ezra E.; Doorn, Stephen K.
      Nature Materials (2005), 4 (5), 412-418CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)
      Chiral selective reactivity and redox chem. of carbon nanotubes are two emerging fields of nanoscience. These areas hold strong promise for producing methods for isolating nanotubes into pure samples of a single electronic type, and for reversible doping of nanotubes for electronics applications. Here, the authors study the selective reactivity of single-walled carbon nanotubes with org. acceptor mols. The authors observe spectral bleaching of the nanotube electronic transitions consistent with an electron-transfer reaction occurring from the nanotubes to the org. acceptors. The reaction kinetics have a strong chiral dependence, with rates being slowest for large-bandgap species and increasing for smaller-bandgap nanotubes. The chiral-dependent kinetics can be tuned to effectively freeze the reacted spectra at a fixed chiral distribution. Such tunable redox chem. may be important for future applications in reversible noncovalent modification of nanotube electronic properties and in chiral selective sepns.
    96. 96
      Satishkumar, B. C.; Brown, L. O.; Gao, Y.; Wang, C.-C.; Wang, H.-L.; Doorn, S. K. Reversible Fluorescence Quenching in Carbon Nanotubes for Biomolecular Sensing. Nat. Nanotechnol. 2007, 2 (9), 560– 564,  DOI: 10.1038/nnano.2007.261
      96
      Reversible fluorescence quenching in carbon nanotubes for biomolecular sensing
      Satishkumar, B. C.; Brown, Leif O.; Gao, Yuan; Wang, Chun-Chih; Wang, Hsing-Lin; Doorn, Stephen K.
      Nature Nanotechnology (2007), 2 (9), 560-564CODEN: NNAABX; ISSN:1748-3387. (Nature Publishing Group)
      Biosensing applications of single-walled carbon nanotubes have been demonstrated in solid-state device structures. Bioanalyte sensing schemes based on coupling of reversible nanotube fluorescence quenching to redox reactions paired to enzymic peroxide generation have also been pursued. Here the authors show a new approach to highly sensitive nanotube-based optical sensing. Single-walled carbon nanotubes interacting with dye-ligand conjugates-a redox-active dye mol. that is covalently bound to a biol. receptor ligand (such as biotin in this case)-showed fluorescence quenching. Further interaction between the receptor ligand on the conjugates and target analytes (avidin in this case) induced the recovery of the quenched fluorescence, forming the basis of the sensing scheme. Nanomolar sensitivity was attained with high specificity for the target analyte. This is a versatile approach because a wide range of conjugation possibilities exists between the potential receptors and redox quenchers.
    97. 97
      O’Connell, M. J.; Bachilo, S. M.; Huffman, C. B.; Moore, V. C.; Strano, M. S.; Haroz, E. H.; Rialon, K. L.; Boul, P. J.; Noon, W. H.; Kittrell, C.; Ma, J.; Hauge, R. H.; Weisman, R. B.; Smalley, R. E. Band Gap Fluorescence from Individual Single-Walled Carbon Nanotubes. Science 2002, 297 (5581), 593– 596,  DOI: 10.1126/science.1072631
      97
      Band gap fluorescence from individual single-walled carbon nanotubes
      O'Connell, Michael J.; Bachilo, Sergei M.; Huffman, Chad B.; Moore, Valerie C.; Strano, Michael S.; Haroz, Erik H.; Rialon, Kristy L.; Boul, Peter J.; Noon, William H.; Kittrell, Carter; Ma, Jianpeng; Hauge, Robert H.; Weisman, R. Bruce; Smalley, Richard E.
      Science (Washington, DC, United States) (2002), 297 (5581), 593-596CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
      Fluorescence has been obsd. directly across the band gap of semiconducting carbon nanotubes. We obtained individual nanotubes, each encased in a cylindrical micelle, by ultrasonically agitating an aq. dispersion of raw single-walled carbon nanotubes in sodium dodecyl sulfate and then centrifuging to remove tube bundles, ropes, and residual catalyst. Aggregation of nanotubes into bundles otherwise quenches the fluorescence through interactions with metallic tubes and substantially broadens the absorption spectra. At pH less than 5, the absorption and emission spectra of individual nanotubes show evidence of band gap-selective protonation of the side walls of the tube. This protonation is readily reversed by treatment with base or UV light.
    98. 98
      Mardia, K. V.; Kent, J. T.; Taylor, C. C.; Multivariate Analysis, 2nd Edition. In Wiley Series in Probability and Statistics; John Wiley & Sons: Nashville, TN, 2024; Vol. 88.
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      Munkres, J. Algorithms for the Assignment and Transportation Problems. J. Soc. Ind. Appl. Math. 1957, 5 (1), 32– 38,  DOI: 10.1137/0105003
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      Rand, W. M. Objective Criteria for the Evaluation of Clustering Methods. J. Am. Stat. Assoc. 1971, 66 (336), 846– 850,  DOI: 10.1080/01621459.1971.10482356
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      Too, J.; Abdullah, A. R. A New and Fast Rival Genetic Algorithm for Feature Selection. J. Supercomput. 2021, 77 (3), 2844– 2874,  DOI: 10.1007/s11227-020-03378-9
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      Cai, J.; Luo, J.; Wang, S.; Yang, S. Feature Selection in Machine Learning: A New Perspective. Neurocomputing 2018, 300, 70– 79,  DOI: 10.1016/j.neucom.2017.11.077
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  • Supporting Information

    Supporting Information

    The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.analchem.4c06762.

    • Supporting experimental section; molecular structure of the Fmoc-peptides; stability photograph; absorption and fluorescence spectra of the SWCNT-peptide suspensions; absorption and fluorescence spectra of SWCNT-peptide oxidation; Raman spectra of the SWCNTs-peptides before and after oxidation; TEM images; relative fluorescence intensity changes of the sensors with each metal at three different chiralities per metal and per peptide; correlation between the fluorescence response vs peptide load or Zeta potential; detailed explanation and performance analysis for all sensor subsets of the analyte classification and feature selection algorithm; ACFSA time complexity analysis; ACFSA implementation with simulated data. ACFSA with randomized feature selection; Pearson correlation coefficients for the intercluster distance with the classifier error ρ(⟨D⟩,error), and for the ARI with the classifier error table; ACFSA implementation with experimental data; PCA results for binary responses of the 30 sensors and five metal-ions; calibration curves and limit of detection for SWCNT-Gly sensor and the five metal-ions; relative fluorescence response of SWCNT-Gly to the metal-ions in serum and mineral water; sensor stability (PDF)


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