Long-term stability of microbubbles is crucial to their effectiveness. Using a new microfluidic device connecting three T-junction channels of 100 μm in series, stable monodisperse SiQD-loaded bovine serum albumin (BSA) protein microbubbles down to 22.8 ± 1.4 μm in diameter were generated. Fluorescence microscopy confirmed the integration of SiQD on the microbubble surface, which retained the same morphology as those without SiQD. The microbubble diameter and stability in air were manipulated through appropriate selection of T-junction numbers, capillary diameter, liquid flow rate, and BSA and SiQD concentrations. A predictive computational model was developed from the experimental data, and the number of T-junctions was incorporated into this model as one of the variables. It was illustrated that the diameter of the monodisperse microbubbles generated can be tailored by combining up to three T-junctions in series, while the operating parameters were kept constant. Computational modeling of microbubble diameter and stability agreed with experimental data. The lifetime of microbubbles increased with increasing T-junction number and higher concentrations of BSA and SiQD. The present research sheds light on a potential new route employing SiQD and triple T-junctions to form stable, monodisperse, multi-layered, and well-characterized protein and quantum dot-loaded protein microbubbles with enhanced stability for the first time.

Four kinds of hydrophobic magnetic deep eutectic solvents (HMDESs) were prepared and applied to RNA extraction. Based on the HMDESs, a mechanical shaking-assisted liquid–liquid extraction (MSLLE) was developed for the extraction of RNA. Factors that influence the extraction, including the extraction time, temperature, volume of HMDES, buffer types, and pH, were evaluated. After the optimization of all conditions, the RNA extraction efficiency was 82.31 ± 0.02%. RNA can be extracted from complex samples and medicinal yeast by the method proposed in this work and can be recovered from the HMDESs after being extracted.

Incorporation of directing amide groups has been shown to facilitate the topochemical polymerization of 1,3-butadiyne (diacetylene) groups in noncrystalline phases such as gels, amorphous solids, and liquid crystals. It remains challenging to polymerize 1,3-butadiyne-containing alkylthiolate ligands within their self-assembled monolayers on gold nanoparticles (AuNPs), which enhances their stability and adds new optical and electronic properties. Especially smaller AuNPs of sizes below 5 nm in diameter have been reported to display sluggish photopolymerization and are susceptible to photodegradation under UV irradiation. To probe the effectiveness of the amide-directed photopolymerization of 1,3-butadiyne ligands, small AuNPs in the 2–4 nm range were synthesized that contain alkylthiolate ligands with and without amide and 1,3-butadiyne groups. Their photopolymerization and photostability were studied by transmission electron microscopy (TEM), UV–vis spectroscopy, and Raman spectroscopy. AuNP with amide-free 1,3-butadiyne ligands templated the polymerization of the 1,3-butadiyne ligands but fused to large and insoluble particles during the polymerization process. AuNPs with ligands containing both 1,3-butadiyne and amide groups polymerized significantly faster, which slowed down photodegradation. A UV irradiation (254 nm and 176 W/m²) for 5–10 min was found to be optimal for the AuNPs with directing amide groups studied here, although their average core sizes grew from 3.8 to 4.0 nm in diameter and about 20% of the attached 1,3-butadiyne ligands remained unreacted after 10 minutes of irradiation. About 75% of the attached 1,3-butadiyne ligands were already polymerized during the first 5 min of UV irradiation. This decrease in reactivity is reasoned with a fast polymerization of ligands attached to facet sites and slower polymerization rates for ligands attached to edge and corner sites. Unexpectedly, photopolymerization occurred only in the presence of solvent, whereas no polydiacetylene was generated when dry powders of any of the diacetylene-containing gold nanoparticles were irradiated.

Emulsion templating is a method that enables the production of highly porous and interconnected polymer foams called polymerized high internal phase emulsions (PolyHIPEs). Since emulsions are inherently unstable systems, they can be stabilized either by surfactants or by particles (Pickering HIPEs). Surfactant-stabilized HIPEs form materials with an interconnected porous structure, while Pickering HIPEs typically form closed pore materials. In this study, we describe a system that uses submicrometer polymer particles to stabilize the emulsions. Polymers fabricated from these Pickering emulsions exhibit, unlike traditional Pickering emulsions, highly interconnected large pore structures, and we related these structures to arrested coalescence. We describe in detail the morphological properties of this system and their dependence on different production parameters. This production method might provide an interesting alternative to poly-surfactant-stabilized-HIPEs, in particular where the application necessitates large pore structures.

The deliquescence behavior of salt nanocrystals is different from that of bulk crystals. Here, we report the first systematic measurements of the deliquescence relative humidity (DRH) of sodium chloride crystals confined in various nanoporous silica materials with pore diameters ranging from 8 to 89 nm. Deliquescence humidities were determined by water vapor sorption measurements. In comparison to the DRH of bulk NaCl crystals (75.3% RH), the DRH decreases from 73 to 58% as the pore size decreases from 89 to 8 nm. In contrast, according to literature data, the DRH of NaCl aerosol nanoparticles increases with decreasing crystal size. A thermodynamic model approach, based on the combined use of an ion-interaction model, the Laplace equation, and the Kelvin equation, is used to calculate the influence of the confinement in nanopores on the solid–liquid and liquid–vapor phase equilibria. These calculations reveal that the main reason for the decrease in the DRH in nanopores is the concave curvature of the liquid–vapor interface that is formed during deliquescence. The same model approach shows that the increase in DRH of nanosized aerosol particles is due to the convex curvature of the liquid–vapor interface, whereas the effect of increases in solubility with decreasing crystal size is small.

Double polymeric grafted layer is constructed by two steps of chemical reaction, in which two polymers had been used, respectively polydopamine (PDA) film and modified PASS (NH₂–PASS) resin containing amine group, as the interphase in carbon fiber reinforced poly(arylene sulfide sulfone) (PASS) composite (CF/PASS) to work on enhancing the interfacial property. All the test results of chemical components and chemical structures on the carbon fiber surface show that the double polymeric grafted layer was constructed successfully with PDA and NH₂–PASS chains. And obvious characteristics of thin PDA film and a polymer layer can be clearly seen in the morphology of modified carbon fiber. In addition to this, the obvious interphase and change in the thickness of interphase have been observed in the modulus distribution images of CF/PASS. The final superb performance is achieved by PASS composites with a double polymeric grafted layer, 27.2% and 198.6% superior to the original PASS composite for IFSS and ILSS, respectively. Moreover, the result also indicates that constructing a double polymeric grafted layer on a carbon fiber surface is a promising technique to modify carbon fiber for processing high-performance advanced thermoplastic composites and is more environmental friendly as well as convenient.

Jerky is a type of meat product traditionally produced using a hang-drying process to achieve desirable textural properties. Inspired by the jerky processing, we present a strategy for fabricating strong alginate hydrogels with highly anisotropic structures via stretching and drying under constant stress. The tunable stretching process endowed the alginate hydrogels with adjustable mechanical properties and structural features by promoting the orientation and aggregation of the constituent polymers. At a high water content of about 80%, the tensile strength of the obtained hydrogel was increased to 20 MPa, which was 10 times higher than that of the hydrogel without the stretching process. Moreover, these hydrogels can be favorably compared with other common structural materials. This paper introduces a facile strategy to tune the structural alignment and mechanical properties of hydrogels, which will expand the applicability of the natural hydrogels formed by non-covalent interactions.

Phase separation technology has attracted extensive scientific interest because of its intriguing structure changes during the phase separation process. Phase separation inside emulsion droplets in continuous surroundings has been well studied in recent years. Many investigations have also been conducted to study the droplet phase separation phenomena in noncontinuous surroundings. However, studies on the phase separation phenomena and the spreading behavior of suspended droplets at the air–liquid interface were rarely reported. In this study, PEGDA-glycerol suspended Janus droplets with a patchy structure were produced by utilizing solvent evaporation-induced droplet phase separation at the air–liquid interface. By altering the glycerol/PEGDA volume ratio, the initial proportion of ethanol, and the concentration of surfactants, suspended droplets with different morphologies can be achieved, which include filbert-shaped droplets (FSDs), half lotus seedpod single-phase Janus droplets (HLSDs), lotus seedpod single-phase Janus droplets (LSDs), lotus seedpod-shaped droplets (LSSDs), multiple-bulge droplets (MBDs), and half gourd-shaped droplets (HGSDs). A patchy structure was generated at the air–droplet interface, which was attributed to the Marangoni stresses induced by nonuniform evaporation. Furthermore, a modified spreading coefficient theory was constructed and verified to illustrate the phase separation at the air–droplet interface, which was the first research to predict the phase separation phenomena at the air–liquid interface via spreading coefficients theory. Moreover, we studied the factors that led to the droplets being able to float by designing the combined parameters, including three interfacial tensions and the equilibrium contact angles. Therefore, a simple and versatile strategy for creating suspended Janus droplets has been developed for the first time, which holds significant potential in a variety of applications for material synthesis, such as the electrospinning solution behavior when sprayed from the nozzle into the air.

Drainage via stratification in micellar foam films formulated with ionic surfactants shows dramatic changes on salt addition: both the step size and the number of steps in their stepwise thinning diminish. As the stratification process is governed by supramolecular oscillatory structural forces that arise due to confinement-induced structuring of micelles, it is apparent that salt addition reduces the magnitude, periodicity, and decay length of the oscillatory forces. In this contribution, we characterize the changes in micellar size, shape, and interactions on salt addition in bulk solutions using small-angle X-ray scattering (SAXS) to understand and elucidate the influence of salt on stratification in micellar foam films and, more broadly, on the oscillatory structural forces. Adding salt leads to a significant reduction in long-range correlations between micelles and smaller intermicellar distances. These effects manifest as a weakening of the primary peak of the structure factor, ascertained from SAXS spectra, accompanied by its shift to higher wave vectors. Weakened long-range correlations diminish the magnitude and periodicity of the oscillatory disjoining pressure leading to smaller step sizes, fewer steps, and a rich nanoscopic topography, due to the influence of disjoining pressure on the deformable interfaces. The step sizes in stratifying thin films and intermicellar distances in bulk solutions present incongruous values, implying an imperfect analogy with studies on charged nanoparticles with matched and salt concentration-independent values of measured interparticle distances that equal the periodicity of force–distance curves. We anticipate that our findings are significant for multicomponent soft and biological matter containing self-assembled supramolecular structures wherein screened Coulomb interactions govern the self-assembly, interfacial adsorption, interactions, dynamics, and stability.

Many biological surfaces with hierarchical structures exhibit super wetting properties, but a multiscale hierarchical metal surface with superhydrophilic performance is difficult to be fabricated using a simple method. In this work, we report a large area micro/nanotextured superhydrophilic silicon surface fabricated by a laser direct writing technique. The combination of a microscale column structure and randomization-distributed nano-bumps decorated on the column enhances the superhydrophilic properties, with the contact angle reduced substantially from about 46° to 0°, where the droplets are able to spread rapidly within 591 ms. The water wetting orientation can be regulated by controlling the shape of microcolumns on the surface. Moreover, our results show that the fabricated surface with the hierarchical structure has better droplet shape control performance and higher fog collection efficiency compared to a smooth surface. These surfaces have potential applications in heat exchangers, biosensors, cell adhesives, and self-cleaning solar cells.

The feasibility of detecting a trace concentration of multivalent ions based on the ionic current rectification (ICR) of a nanopore when impurity ions might present is assessed. Adopting a bullet-shaped nanopore surface modified with tannic acid as an example, the detection of trace concentrations of Cu²⁺ (target ion) when Fe³⁺ (impurity) is present with K⁺ as background ions under various conditions is simulated. In particular, the influence of the reaction order of the association of target ions and tannic acid on the nanopore performance is examined. We show that the lower the background concentration the better the detection performance. For the examined background concentrations of 1, 10, 100, and 1000 mM, the optimal detection ranges are [0.5, 1000 μM] and [1, 1000 nM] for Cu²⁺ and Fe³⁺, respectively. The detection limits, 0.5 μM for Cu²⁺ and 1 nM for Fe³⁺, are lower than those that can be obtained from conventional instruments, suggesting the potential of applying the present nanopore-based approach. In addition, we also consider the presence of multiple ions, which can occur, for example, in detecting Cu²⁺ (target ion) when Fe³⁺ (impurity) might present or vice versa with K⁺ as background ions. The competitive adsorption of these three kinds of ions can yield complicated ICR behaviors.

Three types of natural rocks─Bentheimer and Berea sandstones, as well as Liège Chalk─have been aged by immersion in a bitumen solution for extended periods of time in two steps, changing the surface conditions from water-wet to oil-wet. NMR relaxation dispersion measurements were carried out on water and oil constituents, with saturated and aromatic molecules considered individually. In order to separate the different relaxation mechanisms discussed in the literature, ¹H and ¹⁹F relaxation times were compared to ²H for fully deuterated liquids: while ²H relaxes predominantly by quadrupolar coupling, which is an intramolecular process, the remaining nuclei relax by dipolar coupling, which potentially consists of intra- and intermolecular contributions. The wettability change becomes evident in an increase of relaxation rates for oil and a corresponding decrease for water. However, this expected behavior dominates only for the spin–lattice relaxation rate R₁ at very low field strengths and for the spin–spin relaxation rate R₂, while high-field longitudinal relaxation shows a much weaker or even reverse trend. This is attributed in part to a change of radical concentration on the pore surface upon coverage of the native rock surface by bitumen as well as by the change of surface chemistry and roughness. EPR and DNP measurements quantify the change of volume vs surface radical concentration in the rocks, and an improved understanding of the role of relaxation via paramagnetic centers is obtained. By means of comparing different fluids and nuclei in combination with a defined wettability change of natural rocks, a refined model for molecular dynamics in conjunction with NMR relaxation dispersion is proposed.

The development of g-C₃N₄-based photocatalysts with abundant active sites is of great significance for photocatalytic reactions. Herein, a smart and robust strategy was presented to fabricate three-dimensional (3D) g-C₃N₄ nanosheet-coated alginate-based hierarchical porous carbon (g-C₃N₄@HPC), including coating melamine on calcium alginate (CA) hydrogel beads, freeze-drying hydrogel beads as well as pyrolysis at high temperatures. The resulting photocatalyst possessed a significantly high surface area and a large amount of interconnected macropores compared with porous carbon without the melamine coating. The unique structural features could effectively inhibit the curling and agglomeration of g-C₃N₄ nanosheets, provide abundant photocatalytic active sites, and promote mass diffusion. Therefore, the g-C₃N₄@HPC composite exhibited remarkable photocatalytic activity and outstanding stability toward the photoreduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH₄ under natural sunlight and simulated visible-light irradiation (λ > 420 nm) using a 300 W xenon lamp. Moreover, the mechanism toward the photocatalytic reaction was extensively studied by quenching experiments and electron spin resonance (ESR) experiments. The results showed that active hydrogen species were able to be achieved by following a dual-channel pathway in the NaBH₄ system, which included photocatalytic reduction of H⁺ ions and photocatalytic oxidation of BH₄^– ions. This work not only opens up a new way to design efficient photocatalysts for various reactions but also provides a reference for an in-depth study of the photoreduction mechanism.

Mixed-phase TiO₂ nanosheets were loaded on superior thin g-C₃N₄ nanosheets by a one-step solvothermal synthesis to form unique two-dimensional (2D)/2D heterostructures, which increased the interface area between TiO₂ and g-C₃N₄, resulting in the easy migration of photogenerated carriers between two components. The rate of photocatalytic reactions increased significantly. Ciprofloxacin, tetracycline hydrochloride, and oxytetracycline hydrochloride were selected as target substances to test the photocatalytic degradation properties of the sample. The photoreduction performance of Cr(VI) was also tested. The results indicate that the photocatalytic degradation rate of antibiotics using TiO₂/g-C₃N₄ heterostructures under visible light irradiation was twice that of g-C₃N₄. It took only 30 min to remove Cr(VI) (20 mg/L) under full solar spectrum irradiation; the photoreduction rate of Cr(VI) is also nearly twice that of pure TiO₂. The improved performance was attributed to the rich active sites brought by mixed-phase TiO₂ nanosheets. The extensive interface made the rapid migration of photogenerated carriers possible. The heterostructures revealed a band gap of 2.81 eV, which is less than that of TiO₂ (3.2 eV), resulting in the increased absorption of visible light. Meanwhile, the mixed phase of TiO₂ was beneficial for the separation of photogenerated carriers.

The efficient isolation and specific discrimination of circulating tumor cells (CTCs) is expected to provide valuable information for understanding tumor metastasis and play an important role in the treatment of cancer patients. In this study, we developed a novel and rapid method for efficient capture and specific identification of cancer cells using hyaluronic acid (HA)-modified SiO₂-coated magnetic beads in a microfluidic chip. First, polyacrylamide-surfaced SiO₂-coated magnetic beads (SiO₂@MBs) were covalently conjugated with HA, and the created HA-modified SiO₂@MBs (HA-SiO₂@MBs) display binding specificity to HeLa cells (a human cervical carcinoma cell line) overexpressing CD44 receptors. After incubating the HA-SiO₂@MBs with cancer cells for 1 h, the mixture of MBs and cells was drawn into a designed microfluidic channel with two inlets and outlets. Through the formation of lamellar flow, cells specifically bound with the HA-SiO₂@MBs can be separated under an external magnetic field with a capture efficiency of up to 92.0%. The developed method is simple, fast, and promising for CTC separation and cancer diagnostics applications.

The aim of the work is to explore structure-relaxivity relationship by observing transverse relaxivity enhancement in magnetic resonance imaging (MRI) of differently organized superparamagnetic complex ensembles of zinc ferrite isotropic/anisotropic nanosystems. We observe that superparamagnetic systems show a correlation of MRI-transverse relaxivity, r₂/r₁, with spatial arrangement of nanoparticles, as well as magnetic easy axes and thermal-energy-dependent anisotropy energy landscape. The presence of highly random/partially aligned easy axes with enhanced anisotropy constant leads to modulation in transverse relaxation. As a result, we achieve highest contrast efficiency in compact ensemble of isotropic nanoparticles and hollow core ensemble. Indeed, core–shell ensemble with combined effect of aligned and randomly oriented easy magnetic axes shows a reduction in MRI contrast efficiency. However, we address a hypothesis for transverse contrast efficiency where we depict the correlation among MRI-transverse contrast efficiency with structural complexity of ensembles, differently arranged primary nanoparticles/magnetic easy axes, anisotropy constant, and collective magnetic behavior. In consequence, we simplify the limitation of quantum mechanical outer-sphere diffusion model of magnetic resonance relaxivity by neglecting the contribution of magnetization and introducing an anisotropy constant contribution with complex structure landscape of easy axes.

Vapor condensation on bioinspired hierarchical nanostructured surfaces with hybrid wettabilities has been investigated using molecular dynamics simulations. A series of hierarchical surfaces consisting of nanocylinder arrays with hydrophilic top and hydrophobic nanopillar arrays are constructed. The results manifest that the condensed nanodroplets undergo three states in the whole water vapor condensation process, and the total condensed atom number on surfaces increases with the increase of nanocylinder diameter (D), which indicates that the introduction of hydrophilic nanocylinders is conducive to improving the condensation performance compared with that on the hydrophobic surface patterned with homogeneous nanopillars. However, the nucleation sites on hierarchical nanostructured surfaces are covered by the condensed nanodroplets at the end of condensation, which suppresses the further enhancement of condensation performance. To solve these problems, we add a collection region close to the edge of the nanostructured surface. It is noticed that the condensed nanodroplets can roll into the collection regions gradually during the condensation process, which keeps the nucleation sites on nanostructured surfaces exposed effectively, especially for the cases of 20 Å ≤ D ≤ 40 Å. Moreover, the cluster number, the total condensed atom number, and the condensation enhancement efficiency on hierarchical nanostructured surfaces with collection regions at 20 Å ≤ D ≤ 40 Å are higher obviously compared with those on surfaces without collection regions. Our study demonstrates that the bioinspired hierarchical nanostructured surface with the collection region is beneficial to boost the vapor condensation performance, which can bring new insights into water vapor condensation.

Rational synthesis of Co-ZIF-67 metal–organic framework (MOF)-derived carbon-supported metal nanoparticles is essential for various energy and environmental applications; however, their catalytic activity toward carbon monoxide (CO) oxidation in various electrolytes is not yet emphasized. Co-ZIF-67-derived hierarchical porous carbon nanosheet-supported Pd nanocrystals (Pd/ZIF-67/C) were prepared using a simple microwave-irradiation approach followed by carbonization and etching. Mechanistically, during microwave irradiation, triethyleneamine provides abundant reducing gases that promote the formation of Pd nanoparticles/Co-N_x in porous carbon nanosheets with the assistance of ethylene glycol and also form a multimodal pore size. The electrocatalytic CO oxidation activity and stability of Pd/ZIF-67/C outperformed those of commercial Pd/C and Pt/C catalysts by (4.2 and 4.4, 4.0 and 2.7, 3.59 and 2.7) times in 0.1 M HClO₄, 0.1 M KOH, and 0.1 M NaHCO₃, respectively, due to the catalytic properties of Pd besides the conductivity of Co-N_x active sites and delicate porous structures of ZIF-67. Notably, using Pd/ZIF-67/C results in a higher CO oxidation activity than Pd/C and Pt/C. This study may pave the way for using MOF-supported multi-metallic nanoparticles for CO oxidation electrocatalysis.

The stability of metal halide perovskite (CsPbX₃, X = Cl, Br, and I) nanocrystals (NCs) is crucial for their practical applications. In this paper, perovskite NCs were synthesized in situ in lead-based metal–organic frameworks (Pb-MOFs: [Pb₂(1,3,5-HBTC)₂(H₂O)₄]·H₂O), and we obtained stable and bright luminescence composites with different colors. Namely, CsPbBr₃@Pb-MOF composites were created by the in situ growth of CsPbBr₃ crystals (NCs) on Pb-MOF, which had high ion resistance, bright photoluminescence (PL), and excellent stability. The composites still had bright luminescence after 11 months of storage. The PL intensity of green-emitting CsPbBr₃@Pb-MOF composites was increased compared with as-prepared CsPbBr₃ NCs. Bright and stable blue- and red-emitting CsPbX₃@Pb-MOF composites were obtained by adjusting the amount of PbX₂ (X = Cl, Br, and I) in the synthesis process. These CsPbX₃ NCs were homogeneously distributed in Pb-MOF substrates. The growth of CsPbX₃ NCs in Pb-MOFs prevented NC aggregation and decreased surface defects against nonradiative recombination during emitting. Thus, the PL lifetime and stability were improved. Furthermore, white light-emission diodes were prepared using three color CsPbX₃@Pb-MOF composites with Commission Internationale de I’Eclairage color coordinates of (0.296, 0.316). This result provided an efficient way to overcome the limitation of chemical solution synthesis and improve the stability of CsPbX₃ NCs.

MicroRNAs (miRNAs) are a family of endogenous noncoding RNAs with the functions of gene regulation, which serve as promising markers for a range of diseases such as diabetic foot ulcers, cancers, etc. In this work, we engineered a roll-to-roll DNA nanomachine for highly sensitive electrochemical detection of miRNA. A dumbbell-structured DNA probe could be transitioned to be wheel-structured conformation upon target recognition, which rolls around track strands on the surface of gold nanoparticles (AuNPs) in the presence of nicking endonuclease. The resulting single strands on AuNPs are activated for the second round of rolling at the DNA-modified electrode interface, leading to the variation of electrochemical responses. The roll-to-roll amplification behavior allows a wide detection range with a limit of detection as low as 10 aM. The practicability is also demonstrated by the application in human serum samples with satisfactory results. It is expected that the proposed electrochemical method offers a new paradigm to develop miRNA assays based on DNA nanotechnology.