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Brownian Motion Governs the Plasmonic Enhancement of Colloidal Upconverting Nanoparticles
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Cite this: Nano Lett. 2024, 24, 12, 3785–3792
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https://doi.org/10.1021/acs.nanolett.4c00379
Published March 18, 2024

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Abstract

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Upconverting nanoparticles are essential in modern photonics due to their ability to convert infrared light to visible light. Despite their significance, they exhibit limited brightness, a key drawback that can be addressed by combining them with plasmonic nanoparticles. Plasmon-enhanced upconversion has been widely demonstrated in dry environments, where upconverting nanoparticles are immobilized, but constitutes a challenge in liquid media where Brownian motion competes against immobilization. This study employs optical tweezers for the three-dimensional manipulation of an individual upconverting nanoparticle, enabling the exploration of plasmon-enhanced upconversion luminescence in water. Contrary to expectation, experiments reveal a long-range (micrometer scale) and moderate (20%) enhancement in upconversion luminescence due to the plasmonic resonances of gold nanostructures. Comparison between experiments and numerical simulations evidences the key role of Brownian motion. It is demonstrated how the three-dimensional Brownian fluctuations of the upconverting nanoparticle lead to an “average effect” that explains the magnitude and spatial extension of luminescence enhancement.

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The unique ability of lanthanide-based upconverting nanoparticles (UCNPs) to convert infrared light into visible light makes them building blocks of modern photonics. UCNPs have been used to enhance the efficiency of solar panels, (1,2) in healthcare, (3−5) and for high-resolution bioimaging (6−8) and remote sensing. (9−11) Their main drawback is a low brightness, owing to the relatively low absorption coefficient of the lanthanide ions and their reduced quantum yield. The brightness of UCNPs has been enhanced by core/shell architectures that minimize nonradiative losses. (12,13) Also, the absorption efficiency can be improved by doping engineering (14−16) and combining UCNPs with plasmonic nanostructures (PNSs). (17−20) The overlap between the plasmon resonance of PNSs and the absorption or emission bands of UCNPs results in enhanced excitation and radiative emission efficiencies, respectively. By optimizing the PNSs or controlling the UCNP–PNS distance, a critical parameter in plasmon-enhanced luminescence, brightness has been improved by up to 2–3 orders of magnitude. (21−26) These improvements were demonstrated in static conditions where the UCNP–PNS distance is controlled and fixed (27−32) Nevertheless, the situation becomes more complex if UCNPs are suspended in an aqueous medium. Brownian motion can introduce continuous fluctuations in the UCNP–PNS distance, competing with plasmon-enhanced luminescence. While plasmon-enhanced upconversion has been showcased in liquid media, (33,34) the potential of using PNSs to improve the brightness of a single colloidal UCNP subjected to Brownian motion remains to be demonstrated. To explore plasmon-enhanced luminescence in a colloidal UCNP, 3D positioning of the UCNP in the proximity of the PNS is required. This manipulation should be contactless to minimally perturb the luminescence properties and Brownian dynamics. Thus, conventional methods, such as tip-assisted manipulation, are ineffective.

Optical tweezers (OTs) are a unique tool for contactless three-dimensional manipulation of individual UCNP in liquid media, allowing single UCNP spectroscopic studies or single-particle sensing in living cells. (35,36) In this work, we use OTs to investigate the plasmon-induced brightness enhancement in a colloidal UCNP subjected to three-dimensional Brownian motion. The magnitude of plasmon-enhanced luminescence in a single UCNP as a function of OT–PNS distance was studied. Comparison between experimental data and simulations shows the role of Brownian motion in limiting the plasmon-enhanced luminescence of a colloidal UCNP.

Optical tweezing of individual UCNPs in the proximity of Au plasmonic nanoparticles (PNPs) is achieved by using a single-beam experimental setup (Figure 1a). A continuous-wave 980 nm laser beam is focused within a microchamber (13 mm diameter, 0.12 mm thickness) containing the colloidal dispersion of UCNPs by using an oil-immersion objective (100×/NA 1.4). The laser creates the OT and excites the upconverting luminescence. The UCNPs are hexagonal NaYF4:Tm3+,Yb3+ nanoparticles with an average size of 43 ± 4 nm (Figure 1b and c, synthesis method provided in section S1, Supporting Information). The 980 nm laser radiation is absorbed by Yb3+ ions, which transfer their energy to nearby Tm3+ ions, ultimately leading to visible emission (see Figure 1d). The OT system is coupled to a charge-coupled device (CCD) camera to visualize the incorporation of UCNPs into the trap by a real-time fluorescence image. The background contribution of the laser is blocked by two short-pass filters to record only the visible luminescence emitted by UCNPs. The microchamber is placed on a motorized stage for scanning the OT in both horizontal and vertical directions. The base of the microchamber is a glass substrate deposited with Au PNPs. Details about the experimental procedures for the deposition of Au PNPs are given in section S2, Supporting Information. Plasmonic enhancement can be induced by overlapping the surface plasmon resonance wavelength of the PNPs (λSPR) with either the excitation or the emission wavelength of the UCNP. These two possibilities were explored by using Au PNPs of different diameters leading to plasmonic resonances at, approximately, 980 and 574 nm (see Figure 2a, b, c and e, f, g, respectively). In the first case (264 nm Au PNPs, λSPR ≅ 980 nm, Figure 2c), a local enhancement of the laser excitation efficiency is expected. In the second case (95 nm Au PNPs, λSPR ≅ 574 nm, Figure 2g), the plasmonic extinction mainly overlaps with the UCNP emission, and the Purcell effect is expected to be dominant. The broad plasmonic band also leads to a residual overlap with the 980 nm excitation radiation (see the gray dashed line in Figure 2g).

Figure 1

Figure 1. (a) Experimental setup used for optical tweezing of a single, colloidal UCNP in the presence of PNPs. (b) Transmission electron microscopy (TEM) image of the UCNPs. (c) Histogram of the size distribution of UCNPs as obtained from the analysis of TEM images. (d) Emission spectrum of the UCNPs under 980 nm excitation.

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Figure 2

Figure 2. Scanning electron microscope images of the PNPs used in this work, with plasmon resonances at 980 and 574 nm (a and e, respectively). Histogram of the size distribution of Au PNPs with plasmon resonances at 980 and 574 nm (b and f, respectively). Extinction spectra of the PNPs showed the plasmon resonances at 980 and 574 nm (c and g, respectively). The gray dashed line indicates the wavelength of the trapping laser (980 nm). (d) Increase in local temperature induced by the PNPs under 980 nm irradiation as a function of the laser power density (red and yellow lines for the Au PNPs with plasmon resonances at 980 and 574 nm, respectively). (h) Fluorescence image of a single optically trapped UCNP on top of the substrate with PNPs with λSPR ≅ 574 nm under 980 nm excitation.

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To study the possible plasmon-enhanced upconversion via a local increase of excitation efficiency (980 nm), we first tried to tweeze a single UCNP in the proximity of Au PNPs with λSPR ≅ 980 nm. No stable tweezing of the UCNP was achieved. We found that when the 980 nm laser power density was below 3 MW/cm2, the generated optical force is not enough to confine the UCNP within the optical trap. For laser power densities ≥3 MW cm–2, the appearance of bubbles at the laser focus makes UCNP trapping impossible (see video S11 in the Supporting Information). Indeed, microbubbles can be generated near PNPs when the laser-induced temperature increase reaches ΔT ≈ 220 K. (37) This local temperature increment is given by: (38)

ΔT=σabsI4πRkwater
(1)
where σabs is the absorption cross-section of PNPs, I is the laser power density, R is the radius of Au PNP, and k is the thermal conductivity of the surrounding medium (water). The calculated scattering, absorption, and extinction spectra of the PNPs are given in section S3, Supporting Information. Figure 2d shows the calculated local temperature increase as a function of the 980 nm laser power density for the two PNPs used in this work. For the PNPs with λSPR ≅ 980 nm, the critical temperature increment leading to bubble formation is achieved when the 980 nm laser power reaches 3.3 MW cm–2, in good agreement with the experimental observations. Thus, calculations and experiments reveal that stable OT of a single UCNP in the proximity of PNPs is not possible when trapping radiation is strongly absorbed by PNPs. In other words, the formation of bubbles avoids exploring the effect of plasmon-enhanced luminescence in a single optically trapped UCNP. It is important to note that when using the 95 nm Au PNPs, the absorption of 980 nm radiation is reduced but not eliminated. Consequently, thermal gradients are created in the surroundings of the optical tweezers, so that the thermophoretic effects cannot be disregarded. Under our experimental conditions, we have found that these effects increase the force acting on the UCNP (see section S4, Supporting Information).

Figure 2d reveals that when the OT wavelength is not resonant with λSPR, OT laser power densities over 7.5 MW cm–2 (well above that required for stable tweezing of a single UCNP) can be used without leading to bubble formation. Indeed, stable OT of a single UCNP in the proximity of PNPs with λSPR ≅ 574 nm is possible in a wide range of 980 nm laser power densities (1.8–9.4 MW cm–2). The real-time fluorescence image of the OT allows us not only to evidence the OT of a single UCNP (bright spot in Figure 2h) but also to monitor the luminescence intensity when the UCNP is scanned in the surroundings of PNPs. To demonstrate the plasmon-enhanced luminescence, we first scanned a single UCNP parallel to the substrate, passing through a region of bare glass (without PNPs) and through a region containing the PNPs (see Figure 3a and Supporting Information, Figure S1). The OT–substrate distance, set by the vertical position of the laser focus, was kept at 100 nm. The analysis of UCNP luminescence intensity reveals a plasmon-enhancement close to 20% (Figure 3c and section S5.1, Supporting Information). Note that, while the upconversion intensity is quite homogeneous when the OT is scanned over the bare glass substrate, it becomes highly inhomogeneous when the OT is scanned on top of the PNPs. This can be explained by the inhomogeneity of PNPs deposited on the glass substrate and by considering that plasmon-enhancement depends on not only the vertical OT-PNP distance but also the in-plane OT-PNP relative position. To further demonstrate the plasmon-enhanced upconversion, we ran a second round of experiments, in which the OT was placed on top of PNPs. The luminescence intensity was registered as a function of the OT–substrate vertical distance (Figure 3b). The upconversion intensity was compared to that obtained when the same experiments were performed on top of a bare glass substrate, where no plasmon enhancement is expected (Figure 3d). While, in the absence of PNPs, the intensity remains independent of the OT–substrate vertical distance, a remarkable dependence on the OT–substrate distance is observed in the presence of the PNPs. In agreement with the experimental results of Figure 3c, the upconversion enhancement is close to 20% larger at the shortest OT–substrate vertical distance. Longer OT–substrate distances lead to reduced plasmon-induced enhancements. For OT–substrate distances above 1500 nm, the upconversion intensity is close to the values measured on the bare glass region; i.e., for this distance, there is no plasmon-enhanced upconversion luminescence.

Figure 3

Figure 3. (a) Schematic representation of the horizontal scan of an optically tweezed UCNP along a substrate partially covered with Au PNPs. (b) Schematic representation of the vertical scan of an optically tweezed UCNP with respect to the substrate with PNPs. (c) Periodic change in the upconversion luminescence intensity during the horizontal scan of a single UCNP along a substrate partially covered with PNPs. (d) Upconversion intensity generated by a tweezed UCNP during a vertical scan. Data obtained in the presence and absence of PNPs are included for comparison. All of the data included in this figure were obtained for a laser power intensity of 4.3 MW cm–2 and for the PNPs with λSPR ≅ 574 nm.

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There are two significant differences between our results and those reported for static UCNP-PNPs systems. First, the plasmon-induced enhancement here is moderate (20%) compared to those reported under “static” conditions (up to several orders of magnitude). Second, our results arise from a long-range effect, extending up to UCNP-PNP separations as large as 1 μm. On the contrary, the plasmon-induced luminescence enhancement had a short-range character (tens of nanometers at maximum) under static conditions. These discrepancies and the mechanisms behind them are discussed next.

The upconversion enhancement observed experimentally may be induced by the Purcell effect (an increase in the local density of photonic states at the emission wavelength) or by the local enhancement of the excitation field. We investigate the possibility of Purcell effect first because the emission wavelength of the UCNPs overlaps the plasmon resonance band of the Au PNPs (λSPR≅574 nm). The position of the UCNP is parametrized in the calculations through its vertical distance to the substrate on which PNPs are deposited (zUCNP in Figure 4a) and the UCNP-PNP in-plane distance (Δx distance in Figure 4a). Figure 4b shows that, at vertical distances above half-wavelength (490 nm), the Purcell factor is 1 so the UCNP emission is not affected by the Purcell effect. However, in the near field of the PNPs (zUCNP < 200 nm), the Purcell factor deviates from unity, becoming strongly dependent on Δx (Figure 4b). Indeed, when the UCNP is optically trapped on top of a PNP (Δx = 0), the Purcell effect decreases the emitted intensity (quenching), whereas when at Δx = 285 nm it yields a ca. 30% increase in the upconversion luminescence (Figure 4b). This dependence on Δx is particularly important in our case. An optically tweezed colloidal UCNP fluctuates continuously within the trap under Brownian motion. The dynamics of the UCNP in the horizontal plane are determined by the radial trap stiffness (kx). As discussed above, the trap stiffness was experimentally estimated by using the hydrodynamic drag method (see Figure 4c and section S5.2 in the Supporting Information). At the laser power used in the experiments of Figure 3 (23 mW, corresponding to a power density of 4.3 MW·cm–2), the force acting on a UCNP is 0.04 pN, corresponding to a kx value of 78 nN/m. According to numerical simulations, the UCNP is weakly confined within the trap for that stiffness (Figure 4d, the simulation was conducted by using the Brownian Disk Lab, (39) see details in section S6, Supporting Information). Indeed, the lateral distance between the UCNP and the longitudinal axis of the trapping beam fluctuates within a Δx ≈ ±0.5 μm range. Under these conditions, the Purcell factor should be averaged within this broad range of in-plane UCNP-PNP relative positions. With such averaging, the enhancement in upconversion intensity caused by the Purcell effect is almost negligible (Figure 4e). Even for deeply subwavelength vertical distances, zUCNP < 100 nm, the calculations reveal an almost negligible Purcell factor (≅ 1.05, Figure 4e). Thus, numerical calculations suggest that the Purcell effect is not the origin of the plasmon-induced enhancement of upconversion luminescence. This conclusion is confirmed by experimental measurements of the fluorescence lifetime. As the Purcell effect affects the spontaneous emission rate, it should induce a shortened luminescence lifetime of the UCNPs. (23,24,29,40−43) We compared the luminescence decay curves (λexc = 980 nm and λem = 650 nm) of the UCNPs in the absence/presence of PNPs (Figure 4f, see measurement method in section S5.3, Supporting Information). The luminescence lifetimes are 443 and 430 μs, respectively. This difference is within the experimental uncertainty (±5% ≈ ±20 μs), and therefore the PNPs cause a negligible change in the radiative decay rate of the UCNPs.

Figure 4

Figure 4. (a) Sketch of the position of the UCNP within the optical trap. Δx sets the horizontal position of the laser focus, referenced to the position on top of the Au PNP. (b) Dependence of the Purcell factor at 580 nm on the vertical direction. Different colors correspond to the vertical scans performed at different positions (different Δx distances) with respect to the Au PNP. (c) Experimentally determined, laser-power-dependent force for optical trapping of a single UCNP on a substrate with PNPs. Solid lines plot linear fits to the experimental data. (d) Brownian motion trajectory of a single optically trapped UCNP within the transverse section of the laser focus (indicated by the black dashed circle). (e) Dependence of the in-plane spatially averaged Purcell effect at 580 nm along the vertical direction. (f) Upconversion luminescence decay curves recorded for an emission wavelength of 650 nm for UCNPs deposited on a glass substrate (gray) and on a glass substrate containing PNPs (orange) under 980 nm excitation. All of the data included were obtained with the PNPs with plasmon resonance at 574 nm.

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Once the Purcell effect is discarded as the mechanism behind the upconversion luminescence enhancement, we evaluate the increase in absorption efficiency induced by the plasmon-enhanced local-field confinement of 980 nm radiation. Numerical simulations provide the electric field distribution of the 980 nm laser beam along the vertical direction, zUCNP, for different vertical positions of the laser focus, zL, both measured from the substrate surface (see sections S3, S7, and S8, Supporting Information). We consider zL to be between 0 and 2000 nm above the substrate. For each focus position, the 980 nm laser intensity is estimated along the z direction, normalizing it to the free-space intensity at each point (I980n). Numerical calculations reveal that the 980 nm intensity is strongly (6-fold) enhanced at positions in proximity (zUCNP < 80 nm) to the substrate (Figure 5a). Remarkably, the laser intensity profile is almost independent of the focus position, as it is fully governed by the plasmonic tail in the vicinity of the PNPs and the oscillations induced by the substrate reflection (note that all of the curves in Figure 5a overlap almost exactly). In our experimental conditions (see Section S9, Supporting Information), the upconversion emission increases linearly with the laser intensity. Thus, the 6-fold enhancement in the excitation intensity predicted numerically (Figure 5a) would lead, at short UCNP–PNP distances, to a 6-fold luminescence enhancement. However, the numerical and experimental data differ both in magnitude and spatial range of luminescence enhancement. The experimental data show a moderate 20% enhancement which extends for hundreds of nanometers in the vertical direction, whereas theoretical calculations predict a 6-fold enhancement that is produced only in very close proximity to PNPs. Note that this comparison between theory and measurements is based on a crude assumption: numerical calculations assume that the UCNP is always placed at the laser focus (this is the only vertical distance we have access to experimentally). In other words, the calculations in Figure 5a assume a deterministic UCNP–PNP distance that is far from the real situation: Brownian motion makes the UCNP vertical position fluctuate continuously. Indeed, simulations indicate that the Brownian-induced fluctuation in the vertical distance can be larger than ΔzUCNP ≈ ±1 μm (Figure 5b and section S6 in the Supporting Information).

Figure 5

Figure 5. (a) Spatial profile of the laser intensity on top of a PNP and along the vertical distance (z, measured from the substrate on which PNPs are deposited) as obtained for different values of zUCNP. The profiles for laser position, zL ranging between 0 and 2000 nm, overlap almost completely. Inset: schematic of the UCNP on top of a Au PNP. (b) Position distribution of a single optically tweezed UCNP caused by Brownian motion within a longitudinal section of the laser beam axis. The black dashed ellipse indicates the Rayleigh range (long axis) and the size of the laser focus (short axis). (c) Dependence of the effective intensity (experienced by the Brownian UCNP) as a function of the OT vertical position, zL, and for half position distribution widths, w, ranging from 450 nm (black) to 1000 nm (orange). Inset: sketch of the UCNP at the on-top position of the Au nanoparticle. (d) Effective 980 nm laser intensity for zL = 0 nm as a function of the width of the UCNP position distribution.

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To take the vertical Brownian motion of the UCNP into account, we refine the theoretical model (see details in Section S10, Supporting Information). We describe the vertical position of the UCNP through a uniform distribution centered at the laser focus, which enables us to explore the intensity profiles in Figure 5a around zL. As shown in the inset of Figure 5c, the half-width of the UCNP position distribution, w, is set to values between 450 and 1000 nm (in accordance with Figure 5b). For zL < w, the lower bound in the distribution width was set by the substrate (the UCNPs cannot trespass it). For each laser focus position, zL, we convolute the calculated 980 nm laser intensity profiles in Figure 5a with the UCNP position distributions for different w. Hence, the laser intensity is estimated by averaging the position distribution experienced by the colloidal (moving) UCNP, I980n. This effective intensity is now a function of both zL and w. Figure 5c shows I980n(zL) curves for w ranging from 450 nm (black) to 1000 nm (orange). The maximum effective intensity enhancement is obtained at zL = 0, I980n (zL = 0), whose value decreases as the width of the UCNP distribution increases (Figure 5d). This simply reflects that the plasmon-induced upconversion enhancement experienced by the UCNP becomes larger as its fluctuation near the PNPs decreases. Although the OT is placed very close to the PNP, the actual UCNP–PNP distance fluctuates, so that the UCNP spends a large fraction of time at positions where the plasmon contribution to the laser intensity is negligible. Indeed, our numerical model reveals that the Brownian position distribution width must be set to 900 nm to reproduce the experimentally obtained plasmon-induced enhancement (ca. 1.17). This is in very good agreement with the position distribution of UCNP within the trap included in Figure 5b.

In summary, we investigated the plasmon-enhanced luminescence in a single colloidal upconverting nanoparticle. By using single-beam optical tweezers, we achieved three-dimensional manipulation of an individual upconverting nanoparticle in the surroundings of plasmonic nanoparticles immobilized on a transparent substrate. Our findings reveal challenges in achieving stable trapping when the trapping radiation overlaps with the plasmon resonance due to bubble formation caused by local heating. When trapping radiation is weakly overlapping with the plasmonic band, three-dimensional scanning of a single upconverting nanoparticle on top of the plasmonic nanoparticles becomes possible. Under these conditions, experimental data revealed a 20% enhancement in the luminescence intensity for small tweezing distances (<1 μm). The comparison between experimental data and numerical simulations dismisses the Purcell effect as the primary cause of luminescence enhancement. Instead, we concluded that the enhancement is attributed to the plasmon-induced local-field confinement, leading to improved absorption efficiency. Numerical simulations and experimental data reveal differences in the magnitude and spatial range of luminescence enhancement under the assumption of deterministic optical tweezing. Once the impact of Brownian motion on UCNP position distribution is considered, and refined theoretical models are proposed for the fluctuation in distance between upconverting and plasmonic nanoparticles, a remarkable agreement between theory and experiments is obtained.

This work provides valuable insights into the challenges and opportunities of using plasmonic substrates to enhance the brightness of colloidal upconverting nanoparticles. The findings contribute to the understanding of the complex interplay among plasmonic effects, optical trapping, and Brownian motion in colloidal systems, paving the way for future advancements in the field of photonics and nanotechnology.

Supporting Information

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.nanolett.4c00379.

  • Synthesis of the UCNPs, fabrication of the plasmonic substrate, experimental details, simulation of Brownian motion, numerical simulation models, and methods (PDF)

  • Bubble formation due to excessive heating (video)

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Author Information

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  • Corresponding Authors
    • Daniel Jaque - Nanomaterials for Bioimaging Group (nanoBIG), Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain;  Institute for Advanced Research in Chemical Sciences, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain;  Orcidhttps://orcid.org/0000-0002-3225-0667;  Email: [email protected]
    • Antonio I. Fernandez Dominguez - Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias, Universidad Autónoma de Madrid, E28049 Madrid, Spain;  Orcidhttps://orcid.org/0000-0002-8082-395X;  Email: [email protected]
    • Andrea Simone Stucchi de Camargo - Federal Institute for Materials Research and Testing (BAM), Berlin 12489, Germany;  Friedrich Schiller University (FSU), Jena 07737, Germany;  Orcidhttps://orcid.org/0000-0001-8352-2573;  Email: [email protected]
    • Patricia Haro-González - Nanomaterials for Bioimaging Group (nanoBIG), Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain;  Instituto Nicolás Cabrera, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain;  Institute for Advanced Research in Chemical Sciences, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain;  Orcidhttps://orcid.org/0000-0002-1568-3794;  Email: [email protected]
  • Authors
    • Fengchan Zhang - Nanomaterials for Bioimaging Group (nanoBIG), Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain;  Instituto Nicolás Cabrera, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain;  Orcidhttps://orcid.org/0000-0003-0751-1009
    • Pedro Ramon Almeida Oiticica - São Carlos Institute of Physics, University of São Paulo (USP), 13566-590 São Carlos, São Paulo, Brazil;  Orcidhttps://orcid.org/0000-0002-1658-9572
    • Jaime Abad-Arredondo - Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias, Universidad Autónoma de Madrid, E28049 Madrid, Spain;  Orcidhttps://orcid.org/0000-0003-3980-966X
    • Marylyn Setsuko Arai - São Carlos Institute of Physics, University of São Paulo (USP), 13566-590 São Carlos, São Paulo, Brazil;  Orcidhttps://orcid.org/0000-0003-1278-5274
    • Osvaldo N. Oliveira Jr. - São Carlos Institute of Physics, University of São Paulo (USP), 13566-590 São Carlos, São Paulo, Brazil;  Orcidhttps://orcid.org/0000-0002-5399-5860
  • Author Contributions

    The manuscript was written through 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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This work was supported by grant PID2019-106211RB-I00 (NANONERV) funded by MCIN/AEI/10.13039/501100011033, by grants TED2021-129937B-I00 and CNS2022-135495 funded by MCIN/AEI/10.13039/501100011033, and by the “European Union NextGenerationEU/PRTR”. Work was financed by the Comunidad Autónoma de Madrid (S2022/BMD-7403 RENIM-CM) and cofinanced by the European structural and investment fund. O.N.O. and P.R.A.O. acknowledge CNPq, FAPESP (2018/22214-6), and CAPES for Ph.D. Fellowships (finance code 001). A.I.F.D. and J.A.-A. acknowledge funding from the Spanish Ministry of Science, Innovation and Universities through Grant Nos. PID2021-126964OB-I00 and TED2021-130552B-C21, as well as the European Union’s Horizon Programme through grant 101070700 (MIRAQLS). F.Z. acknowledges the scholarship from China Scholarship Council (No. 202108440235). A.S.S.d.C. and M.S.A. acknowledge support from the São Paulo Research Foundation (FAPESP) through the research grant 2013/07793-6 and the Ph.D. fellowship 2019/12588-9.

Abbreviations

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UCNPs

upconverting nanoparticles

PNSs

plasmonic nanostructures

OTs

optical tweezers

PNPs

plasmonic nanoparticles

TEM

transmission electron microscope

CCD

charge-coupled device

SPR

surface plasmon resonance

References

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This article references 43 other publications.

  1. 1
    Zou, W.; Visser, C.; Maduro, J. A.; Pshenichnikov, M. S.; Hummelen, J. C. Broadband dye-sensitized upconversion of near-infrared light. Nat. Photonics 2012, 6 (8), 560– 564,  DOI: 10.1038/nphoton.2012.158
    Google Scholar
    1
    Broadband dye-sensitized upconversion of near-infrared light
    Zou, Wenqiang; Visser, Cindy; Maduro, Jeremio A.; Pshenichnikov, Maxim S.; Hummelen, Jan C.
    Nature Photonics (2012), 6 (8), 560-564CODEN: NPAHBY; ISSN:1749-4885. (Nature Publishing Group)
    Photon upconversion of near-IR photons is a promising way to overcome the Shockley-Queisser efficiency limit of 32% of a single-junction solar cell. However, the practical applicability of the most efficient known upconversion materials at moderate light intensities is limited by their extremely weak and narrowband near-IR absorption. Here, we introduce the concept of an upconversion material where an org. near-IR dye is used as an antenna for the β-NaYF4:Yb,Er nanoparticles in which the upconversion occurs. The overall upconversion by the dye-sensitized nanoparticles is dramatically enhanced (by a factor of ∼3,300) as a result of increased absorptivity and overall broadening of the absorption spectrum of the upconverter. The proposed concept can be extended to cover any part of the solar spectrum by using a set of dye mols. with overlapping absorption spectra acting as an extremely broadband antenna system, connected to suitable upconverters.
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    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhtVehsb%252FF&md5=f0e7c0a8e155622af74ee3e69fb1c1a0
  2. 2
    Roh, J.; Yu, H.; Jang, J. Hexagonal β-NaYF4:Yb3+, Er3+ Nanoprism-Incorporated Upconverting Layer in Perovskite Solar Cells for Near-Infrared Sunlight Harvesting. ACS Appl. Mater. Interfaces 2016, 8 (31), 19847– 19852,  DOI: 10.1021/acsami.6b04760
    Google Scholar
    2
    Hexagonal β-NaYF4:Yb3+, Er3+ Nanoprism-Incorporated Upconverting Layer in Perovskite Solar Cells for Near-Infrared Sunlight Harvesting
    Roh, Jongmin; Yu, Haejun; Jang, Jyongsik
    ACS Applied Materials & Interfaces (2016), 8 (31), 19847-19852CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
    Hexagonal β-NaYF4:Yb3+, Er3+ nanoprisms, successfully prepd. using a hydrothermal method, were incorporated into MeNH3PbI3 perovskite solar cells (PSCs) as an upconverting mesoporous layer. Due to their near-IR (NIR) sunlight harvesting, the PSCs based on the upconverting mesoporous layer exhibited a power conversion efficiency of 16.0%, an increase of 13.7% compared with conventional TiO2 nanoparticle-based PSCs (14.1%). Probably the hexagonal β-NaYF4:Yb3+, Er3+ nanoprisms expand the absorption range of the PSC via upconversion photoluminescence, leading to an enhancement of the photocurrent.
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  3. 3
    Liu, Y.; Zhang, C.; Liu, H.; Li, Y.; Xu, Z.; Li, L.; Whittaker, A. Controllable synthesis of up-conversion nanoparticles UCNPs@MIL-PEG for pH-responsive drug delivery and potential up-conversion luminescence/magnetic resonance dual-mode imaging. J. Alloys Compd. 2018, 749, 939– 947,  DOI: 10.1016/j.jallcom.2018.03.355
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    3
    Controllable synthesis of up-conversion nanoparticles UCNPs@MIL-PEG for pH-responsive drug delivery and potential up-conversion luminescence/magnetic resonance dual-mode imaging
    Liu, Yana; Zhang, Cheng; Liu, Hui; Li, Yuebin; Xu, Zushun; Li, Ling; Whittaker, Andrew
    Journal of Alloys and Compounds (2018), 749 (), 939-947CODEN: JALCEU; ISSN:0925-8388. (Elsevier B.V.)
    Rare-earth doped up-conversion nanoparticles (UCNPs) with high uniformity and dispersibility were synthesized by a facile solvothermal method. The conditions of synthesis for NaYF4:Yb/Tm were explored, and the NaYF4:Yb/Tm particles with the optimal size (about 300nm) were obtained. Blue emission was obsd. with the excitation 980nm near IR (NIR) laser, indicating that the UCNPs can be potentially used for up-conversion luminescence (UCL) imaging. On basis of the optimal UCNPs, further coated by poly (ethylene glycol) (PEG) functionalized metal-org. frameworks (MOFs), a multifunctional platform UCNPs@MIL-PEG for cancer diagnosis and treatment was established. The core-shell structure was confirmed by TEM images. Doxorubicin (DOX) was selected as drug model and the drug loading of UCNPs@MIL-PEG was found to be 60%. Cytotoxicity indicated that UCNPs@MIL-PEG were highly biocompatible. The DOX release in different pH value revealed an excellent pH-triggered drug release. In addn., the UCNPs@MIL-PEG nanoparticles can be tracked by magnetic resonance imaging (MRI). A clear dose-dependent contrast enhancement in T2-weighted MR images indicated the potential act as T2 MRI contrast agents. The UCNPs@MIL-PEG nanoparticles are expected to be simultaneously used for UCL/MR dual-mode imaging and pH-responsive drug release.
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  4. 4
    Chan, M.-H.; Pan, Y.-T.; Lee, I.-J.; Chen, C.-W.; Chan, Y.-C.; Hsiao, M.; Wang, F.; Sun, L.; Chen, X.; Liu, R.-S. Minimizing the Heat Effect of Photodynamic Therapy Based on Inorganic Nanocomposites Mediated by 808 nm Near-Infrared Light. Small 2017, 13 (21), 1700038,  DOI: 10.1002/smll.201700038
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  5. 5
    Xu, E. Z.; Lee, C.; Pritzl, S. D.; Chen, A. S.; Lohmueller, T.; Cohen, B. E.; Chan, E. M.; Schuck, P. J. Infrared-to-ultraviolet upconverting nanoparticles for COVID-19-related disinfection applications. Optical Materials: X 2021, 12, 100099,  DOI: 10.1016/j.omx.2021.100099
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    There is no corresponding record for this reference.
  6. 6
    Li, Y.; Tang, J.; He, L.; Liu, Y.; Liu, Y.; Chen, C.; Tang, Z. Core–Shell Upconversion Nanoparticle@Metal–Organic Framework Nanoprobes for Luminescent/Magnetic Dual-Mode Targeted Imaging. Adv. Mater. 2015, 27 (27), 4075– 4080,  DOI: 10.1002/adma.201501779
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    6
    Core-Shell Upconversion Nanoparticle@Metal-Organic Framework Nanoprobes for Luminescent/Magnetic Dual-Mode Targeted Imaging
    Li, Yantao; Tang, Jinglong; He, Liangcan; Liu, Yong; Liu, Yaling; Chen, Chunying; Tang, Zhiyong
    Advanced Materials (Weinheim, Germany) (2015), 27 (27), 4075-4080CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)
    Core-shell upconversion nanoparticle@metal-org. framework (UCNP@MOF) nanostructures were constructed by coating hexagonal NaYF4:Yb,Er nanoparticle (NP) cores with amino-functionalized iron carboxylate MOF shells. These nanostructures combine the near-IR optical property of UCNP cores and the T2-magnetic response (MR) imaging property of MOF shells. After surface modification, the core-shell nanostructures were demonstrated as high-resoln. nanoprobes for targeted luminescence/MR imaging both in vitro and in vivo.
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  7. 7
    Huang, G.; Liu, Y.; Wang, D.; Zhu, Y.; Wen, S.; Ruan, J.; Jin, D. Upconversion nanoparticles for super-resolution quantification of single small extracellular vesicles. eLight 2022, 2 (1), 20,  DOI: 10.1186/s43593-022-00031-1
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    There is no corresponding record for this reference.
  8. 8
    Lee, C.; Xu, E. Z.; Liu, Y.; Teitelboim, A.; Yao, K.; Fernandez-Bravo, A.; Kotulska, A. M.; Nam, S. H.; Suh, Y. D.; Bednarkiewicz, A.; Cohen, B. E.; Chan, E. M.; Schuck, P. J. Giant nonlinear optical responses from photon-avalanching nanoparticles. Nature 2021, 589 (7841), 230– 235,  DOI: 10.1038/s41586-020-03092-9
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    8
    Giant nonlinear optical responses from photon-avalanching nanoparticles
    Lee, Changhwan; Xu, Emma Z.; Liu, Yawei; Teitelboim, Ayelet; Yao, Kaiyuan; Fernandez-Bravo, Angel; Kotulska, Agata M.; Nam, Sang Hwan; Suh, Yung Doug; Bednarkiewicz, Artur; Cohen, Bruce E.; Chan, Emory M.; Schuck, P. James
    Nature (London, United Kingdom) (2021), 589 (7841), 230-235CODEN: NATUAS; ISSN:0028-0836. (Nature Research)
    Abstr.: Avalanche phenomena use steeply nonlinear dynamics to generate disproportionately large responses from small perturbations, and are found in a multitude of events and materials1. Photon avalanching enables technologies such as optical phase-conjugate imaging2, IR quantum counting3 and efficient upconverted lasing4-6. However, the photon-avalanching mechanism underlying these optical applications has been obsd. only in bulk materials and aggregates6,7, limiting its utility and impact. Here, we report the realization of photon avalanching at room temp. in single nanostructures-small, Tm3+-doped upconverting nanocrystals-and demonstrate their use in super-resoln. imaging in near-IR spectral windows of maximal biol. transparency. Avalanching nanoparticles (ANPs) can be pumped by continuous-wave lasers, and exhibit all of the defining features of photon avalanching, including clear excitation-power thresholds, exceptionally long rise time at threshold, and a dominant excited-state absorption that is more than 10,000 times larger than ground-state absorption. Beyond the avalanching threshold, ANP emission scales nonlinearly with the 26th power of the pump intensity, owing to induced pos. optical feedback in each nanocrystal. This enables the exptl. realization of photon-avalanche single-beam super-resoln. imaging7 with sub-70-nm spatial resoln., achieved by using only simple scanning confocal microscopy and without any computational anal. Pairing their steep nonlinearity with existing super-resoln. techniques and computational methods8-10, ANPs enable imaging with higher resoln. and at excitation intensities about 100 times lower than other probes. The low photon-avalanching threshold and excellent photostability of ANPs also suggest their utility in a diverse array of applications, including sub-wavelength imaging7,11,12 and optical and environmental sensing13-15.
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  9. 9
    Soares, A. C. C.; Sales, T. O.; Ximendes, E. C.; Jaque, D.; Jacinto, C. Lanthanide doped nanoparticles for reliable and precise luminescence nanothermometry in the third biological window. Nanoscale Advances 2023, 5 (14), 3664– 3670,  DOI: 10.1039/D2NA00941B
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  10. 10
    Lin, G.; Jin, D. Responsive Sensors of Upconversion Nanoparticles. ACS Sensors 2021, 6 (12), 4272– 4282,  DOI: 10.1021/acssensors.1c02101
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    There is no corresponding record for this reference.
  11. 11
    Arai, M. S.; de Camargo, A. S. S. Exploring the use of upconversion nanoparticles in chemical and biological sensors: from surface modifications to point-of-care devices. Nanoscale Advances 2021, 3 (18), 5135– 5165,  DOI: 10.1039/D1NA00327E
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    There is no corresponding record for this reference.
  12. 12
    Chen, X.; Peng, D.; Ju, Q.; Wang, F. Photon upconversion in core–shell nanoparticles. Chem. Soc. Rev. 2015, 44 (6), 1318– 1330,  DOI: 10.1039/C4CS00151F
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    12
    Photon upconversion in core-shell nanoparticles
    Chen, Xian; Peng, Denfeng; Ju, Qiang; Wang, Feng
    Chemical Society Reviews (2015), 44 (6), 1318-1330CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
    A review. Photon upconversion generally results from a series of successive electronic transitions within complex energy levels of lanthanide ions that are embedded in the lattice of a cryst. solid. In conventional lanthanide-doped upconversion nanoparticles, the dopant ions homogeneously distributed in the host lattice are readily accessible to surface quenchers and lose their excitation energy, giving rise to weak and susceptible emissions. Therefore, present studies on upconversion are mainly focused on core-shell nanoparticles comprising spatially confined dopant ions. By doping upconverting lanthanide ions in the interior of a core-shell nanoparticle, the upconversion emission can be substantially enhanced, and the optical integrity of the nanoparticles can be largely preserved. Optically active shells are also frequently employed to impart multiple functionalities to upconversion nanoparticles. Intriguingly, the core-shell design introduces the possibility of constructing novel upconversion nanoparticles by exploiting the energy exchange interactions across the core-shell interface. In this tutorial review, we highlight recent advances in the development of upconversion core-shell nanoparticles, with particular emphasis on the emerging strategies for regulating the interplay of dopant interactions through core-shell nanostructural engineering that leads to unprecedented upconversion properties. The improved control over photon energy conversion will open up new opportunities for biol. and energy applications.
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  13. 13
    Cheng, T.; Marin, R.; Skripka, A.; Vetrone, F. Small and Bright Lithium-Based Upconverting Nanoparticles. J. Am. Chem. Soc. 2018, 140 (40), 12890– 12899,  DOI: 10.1021/jacs.8b07086
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    13
    Small and Bright Lithium-Based Upconverting Nanoparticles
    Cheng, Ting; Marin, Riccardo; Skripka, Artiom; Vetrone, Fiorenzo
    Journal of the American Chemical Society (2018), 140 (40), 12890-12899CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    In the context of light-mediated tumor treatment, the application of UV radiation can initiate drug release and photodynamic therapy. However, its limited penetration depth in tissues impedes the s.c. applicability of such radiation. On the contrary, near-IR (NIR) light is not energetic enough to initiate secondary photochem. processes, but can pierce tissues at a significantly greater depth. Upconverting nanoparticles (UCNPs) unify the advantages of both extremes of the optical spectrum, they can be excited by NIR irradn. and emit UV light through the process of upconversion, effective NIR-to-UV generation being attained with UCNPs as large as 100 nm. However, in anticipation of biomedical applications, the size of UCNPs must be greatly minimized to favor their cellular internalization; yet straightforward size redn. neg. affects the NIR-to-UV upconversion efficiency. Herein, we propose a two-step strategy to obtain small yet bright lithium-based UCNPs. First, we synthesized UCNPs as small as 5 nm by controlling the relative amt. of coordinating ligands, namely oleylamine (OM) and oleic acid (OA). Although these UCNPs were chem. unstable, particle coarsening via an annealing process in the presence of fresh OA yielded structurally stable and highly monodisperse sub-10 nm crystals. Second, we grew a shell with controlled thickness on these stabilized cores of UCNPs, improving the NIR-to-UV upconversion by orders of magnitude. Particularly in the case of LiYbF4:Tm3+/LiYF4 UCNPs, their NIR-to-UV upconversion surpassed the gold std. 90 nm-sized LiYF4:Tm3+, Yb3+ UCNPs. All in all, these UCNPs show great potential within the biomedical framework as they successfully combine the requirements of small size, deep tissue NIR penetration and bright UV emission.
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  14. 14
    Back, M.; Trave, E.; Marin, R.; Mazzucco, N.; Cristofori, D.; Riello, P. Energy Transfer in Bi- and Er-Codoped Y2O3 Nanocrystals: An Effective System for Rare Earth Fluorescence Enhancement. J. Phys. Chem. C 2014, 118 (51), 30071– 30078,  DOI: 10.1021/jp5080016
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    14
    Energy Transfer in Bi- and Er-Codoped Y2O3 Nanocrystals: An Effective System for Rare Earth Fluorescence Enhancement
    Back, Michele; Trave, Enrico; Marin, Riccardo; Mazzucco, Nicolo; Cristofori, Davide; Riello, Pietro
    Journal of Physical Chemistry C (2014), 118 (51), 30071-30078CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
    The enhancement of the low absorption cross section and widening of the absorption range of the RE ions in the UV-blue region is still a challenge to develop optical systems with high performance. In this work we synthesized Bi- and Er-codoped Y2O3 nanocrystals by means of Pechini type sol-gel process. X-ray powder diffraction (XRPD) and transmission electron microscopy (TEM) were performed to evaluate the nanocryst. particle size and phase. Photoluminescence investigation in the UV-vis and IR regions showed that the presence of Bi3+ ions promotes the strengthening of Er3+ emitter properties. In particular, an Er3+ sensitization process based on a broadband energy transfer mediated by the Bi3+ ions in the C2 site was evaluated, resulting in a wavelength spread for the photostimulation of the rare earth emissions in the visible and NIR range. We pointed out a resonant type via a dipole-dipole interaction as the most probable mechanism of energy transfer. Moreover, the crit. distance between the Bi3+ and Er3+ ions was estd. to be of about 8.5 Å.
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  15. 15
    Zhang, Y.; Wen, R.; Hu, J.; Guan, D.; Qiu, X.; Zhang, Y.; Kohane, D. S.; Liu, Q. Enhancement of single upconversion nanoparticle imaging by topologically segregated core-shell structure with inward energy migration. Nat. Commun. 2022, 13 (1), 5927,  DOI: 10.1038/s41467-022-33660-8
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    15
    Enhancement of single upconversion nanoparticle imaging by topologically segregated core-shell structure with inward energy migration
    Zhang, Yanxin; Wen, Rongrong; Hu, Jialing; Guan, Daoming; Qiu, Xiaochen; Zhang, Yunxiang; Kohane, Daniel S.; Liu, Qian
    Nature Communications (2022), 13 (1), 5927CODEN: NCAOBW; ISSN:2041-1723. (Nature Portfolio)
    Abstr.: Manipulating topol. arrangement is a powerful tool for tuning energy migration in natural photosynthetic proteins and artificial polymers. Here, we report an inorg. optical nanosystem composed of NaErF4 and NaYbF4, in which topol. arrangement enhanced upconversion luminescence. Three architectures are designed for considerations pertaining to energy migration and energy transfer within nanoparticles: outside-in, inside-out, and local energy transfer. The outside-in architecture produces the max. upconversion luminescence, around 6-times brighter than that of the inside-out at the single-particle level. Monte Carlo simulation suggests a topol.-dependent energy migration favoring the upconversion luminescence of outside-in structure. The optimized outside-in structure shows more than an order of magnitude enhancement of upconversion brightness compared to the conventional core-shell structure at the single-particle level and is used for long-term single-particle tracking in living cells. Our findings enable rational nanoprobe engineering for single-mol. imaging and also reveal counter-intuitive relationships between upconversion nanoparticle structure and optical properties.
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  16. 16
    Gargas, D. J.; Chan, E. M.; Ostrowski, A. D.; Aloni, S.; Altoe, M. V. P.; Barnard, E. S.; Sanii, B.; Urban, J. J.; Milliron, D. J.; Cohen, B. E.; Schuck, P. J. Engineering bright sub-10-nm upconverting nanocrystals for single-molecule imaging. Nat. Nanotechnol. 2014, 9 (4), 300– 305,  DOI: 10.1038/nnano.2014.29
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    16
    Engineering bright sub-10-nm upconverting nanocrystals for single-molecule imaging
    Gargas, Daniel J.; Chan, Emory M.; Ostrowski, Alexis D.; Aloni, Shaul; Altoe, M. Virginia P.; Barnard, Edward S.; Sanii, Babak; Urban, Jeffrey J.; Milliron, Delia J.; Cohen, Bruce E.; Schuck, P. James
    Nature Nanotechnology (2014), 9 (4), 300-305CODEN: NNAABX; ISSN:1748-3387. (Nature Publishing Group)
    Imaging at the single-mol. level reveals heterogeneities that are lost in ensemble imaging expts., but an ongoing challenge is the development of luminescent probes with the photostability, brightness and continuous emission necessary for single-mol. microscopy. Lanthanide-doped upconverting nanoparticles overcome problems of photostability and continuous emission and their upconverted emission can be excited with near-IR light at powers orders of magnitude lower than those required for conventional multiphoton probes. However, the brightness of upconverting nanoparticles was limited by open questions about energy transfer and relaxation within individual nanocrystals and unavoidable tradeoffs between brightness and size. Here, the authors develop upconverting nanoparticles under 10 nm in diam. that are over an order of magnitude brighter under single-particle imaging conditions than existing compns., allowing one to visualize single upconverting nanoparticles as small (d = 4.8 nm) as fluorescent proteins. The authors use advanced single-particle characterization and theor. modeling to find that surface effects become crit. at diams. under 20 nm and that the fluences used in single-mol. imaging change the dominant determinants of nanocrystal brightness. Factors known to increase brightness in bulk expts. lose importance at higher excitation powers and paradoxically, the brightest probes under single-mol. excitation are barely luminescent at the ensemble level.
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  17. 17
    Wu, D. M.; García-Etxarri, A.; Salleo, A.; Dionne, J. A. Plasmon-Enhanced Upconversion. J. Phys. Chem. Lett. 2014, 5 (22), 4020– 4031,  DOI: 10.1021/jz5019042
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    17
    Plasmon-Enhanced Upconversion
    Wu, Di M.; Garcia-Etxarri, Aitzol; Salleo, Alberto; Dionne, Jennifer A.
    Journal of Physical Chemistry Letters (2014), 5 (22), 4020-4031CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)
    A review. Upconversion, the conversion of photons from lower to higher energies, is a process that promises applications ranging from high-efficiency photovoltaic and photocatalytic cells to background-free bioimaging and therapeutic probes. Existing upconverting materials, however, remain too inefficient for viable implementation. In this Perspective, the authors describe the significant improvements in upconversion efficiency that can be achieved using plasmon resonances. As collective oscillations of free electrons, plasmon resonances can be used to enhance both the incident electromagnetic field intensity and the radiative emission rates. To date, this approach showed upconversion enhancements up to 450×. Both theor. underpinnings and exptl. demonstrations of plasmon-enhanced upconversion, examg. the roles of upconverter quantum yield, plasmonic geometry, and plasmon spectral overlap are discussed. The authors also discuss nonoptical consequences of including metal nanostructures near upconverting emitters. The rapidly expanding field of plasmon-enhanced upconversion provides novel fundamental insight into nanoscale light-matter interactions while improving prospects for technol. relevance.
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  18. 18
    Qin, X.; Carneiro Neto, A. N.; Longo, R. L.; Wu, Y.; Malta, O. L.; Liu, X. Surface Plasmon–Photon Coupling in Lanthanide-Doped Nanoparticles. J. Phys. Chem. Lett. 2021, 12 (5), 1520– 1541,  DOI: 10.1021/acs.jpclett.0c03613
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    There is no corresponding record for this reference.
  19. 19
    Park, W.; Lu, D.; Ahn, S. Plasmon enhancement of luminescence upconversion. Chem. Soc. Rev. 2015, 44 (10), 2940– 2962,  DOI: 10.1039/C5CS00050E
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    19
    Plasmon enhancement of luminescence upconversion
    Park, Wounjhang; Lu, Dawei; Ahn, Sungmo
    Chemical Society Reviews (2015), 44 (10), 2940-2962CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
    Frequency conversion has always been an important topic in optics. Nonlinear optics has traditionally focused on frequency conversion based on nonlinear susceptibility but with the recent development of upconversion nanomaterials, luminescence upconversion has begun to receive renewed attention. While upconversion nanomaterials open doors to a wide range of new opportunities, they remain too inefficient for most applications. Incorporating plasmonic nanostructures provides a promising pathway to highly efficient upconversion. Naturally, a plethora of theor. and exptl. studies have been published in recent years, reporting enhancements up to several hundred. It is however difficult to make meaningful comparisons since the plasmonic fields are highly sensitive to the local geometry and excitation condition. Also, many luminescence upconversion processes involve multiple steps via different phys. mechanisms and the overall output is often detd. by a delicate interplay among them. This review is aimed at offering a comprehensive framework for plasmon enhanced luminescence upconversion. We first present quantum electrodynamics descriptions for all the processes involved in luminescence upconversion, which include absorption, emission, energy transfer and nonradiative transitions. We then present a bird's eye view of published works on plasmon enhanced upconversion, followed by more detailed discussion on comparable classes of nanostructures, the effects of spacer layers and local heating, and the dynamics of the plasmon enhanced upconversion process. Plasmon enhanced upconversion is a challenging and exciting field from the fundamental scientific perspective and also from technol. standpoints. It offers an excellent system to study how optical processes are affected by the local photonic environment. This type of research is particularly timely as the plasmonics is placing heavier emphasis on nonlinearity. At the same time, efficient upconversion could make a significant impact on many applications including solar energy conversion and biomedical imaging. The marriage of luminescent materials research with nanophotonics currently being initiated with plasmon enhanced upconversion research explores a new frontier in photonics that could potentially spawn many exciting new fields.
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  20. 20
    Carneiro Neto, A. N.; Couto dos Santos, M. A.; Malta, O. L.; Reisfeld, R. 2 - Effects of Spherical Metallic Nanoparticle Plasmon on 4f–4f Luminescence: A Theoretical Approach. In Metal Nanostructures for Photonics, Kassab, L. R. P., de Araujo, C. B., Eds.; Elsevier, 2019; pp 19– 36.
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  21. 21
    Das, A.; Mao, C.; Cho, S.; Kim, K.; Park, W. Over 1000-fold enhancement of upconversion luminescence using water-dispersible metal-insulator-metal nanostructures. Nat. Commun. 2018, 9 (1), 4828,  DOI: 10.1038/s41467-018-07284-w
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    21
    Over 1000-fold enhancement of upconversion luminescence using water-dispersible metal-insulator-metal nanostructures
    Das Ananda; Mao Chenchen; Cho Suehyun; Park Wounjhang; Kim Kyoungsik; Park Wounjhang
    Nature communications (2018), 9 (1), 4828 ISSN:.
    Rare-earth activated upconversion nanoparticles (UCNPs) are receiving renewed attention for use in bioimaging due to their exceptional photostability and low cytotoxicity. Often, these nanoparticles are attached to plasmonic nanostructures to enhance their photoluminescence (PL) emission. However, current wet-chemistry techniques suffer from large inhomogeneity and thus low enhancement is achieved. In this paper, we report lithographically fabricated metal-insulator-metal (MIM) nanostructures that show over 1000-fold enhancement of their PL. We demonstrate the potential for bioimaging applications by dispersing the MIMs into water and imaging bladder cancer cells with them. To our knowledge, our results represent one and two orders of magnitude improvement, respectively, over the best lithographically fabricated structures and colloidal systems in the literature. The large enhancement will allow for bioimaging and therapeutics using lower particle densities or lower excitation power densities, thus increasing the sensitivity and efficacy of such procedures while decreasing potential side effects.
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  22. 22
    Xu, J.; Dong, Z.; Asbahi, M.; Wu, Y.; Wang, H.; Liang, L.; Ng, R. J. H.; Liu, H.; Vallée, R. A. L.; Yang, J. K. W.; Liu, X. Multiphoton Upconversion Enhanced by Deep Subwavelength Near-Field Confinement. Nano Lett. 2021, 21 (7), 3044– 3051,  DOI: 10.1021/acs.nanolett.1c00232
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  23. 23
    Wu, Y.; Xu, J.; Poh, E. T.; Liang, L.; Liu, H.; Yang, J. K. W.; Qiu, C.-W.; Vallée, R. A. L.; Liu, X. Upconversion superburst with sub-2 μs lifetime. Nat. Nanotechnol. 2019, 14 (12), 1110– 1115,  DOI: 10.1038/s41565-019-0560-5
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    Upconversion superburst with sub-2 μs lifetime
    Wu, Yiming; Xu, Jiahui; Poh, Eng Tuan; Liang, Liangliang; Liu, Hailong; Yang, Joel K. W.; Qiu, Cheng-Wei; Vallee, Renaud A. L.; Liu, Xiaogang
    Nature Nanotechnology (2019), 14 (12), 1110-1115CODEN: NNAABX; ISSN:1748-3387. (Nature Research)
    The generation of anti-Stokes emission through lanthanide-doped upconversion nanoparticles is of great importance for technol. applications in energy harvesting, bioimaging and optical cryptog. However, the weak absorption and long radiative lifetimes of upconversion nanoparticles may significantly limit their use in imaging and labeling applications in which a fast spontaneous emission rate is essential. Here, we report the direct observation of upconversion superburst with directional, fast and ultrabright luminescence by coupling gap plasmon modes to nanoparticle emitters. Through precise control over the nanoparticle's local d. of state, we achieve emission amplification by four to five orders of magnitude and a 166-fold rate increase in spontaneous emission. We also demonstrate that tailoring the mode of the plasmonic cavity permits active control over the color output of upconversion emission. These findings may benefit the future development of rapid nonlinear image scanning nanoscopy and open up the possibility of constructing high-frequency, single-photon emitters driven by telecommunication wavelengths.
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  24. 24
    Zhang, W.; Ding, F.; Chou, S. Y. Large Enhancement of Upconversion Luminescence of NaYF4:Yb3+/Er3+ Nanocrystal by 3D Plasmonic Nano-Antennas. Advanced Materials 2012, 24 (35), OP236– OP241,  DOI: 10.1002/adma.201200220
    Google Scholar
    There is no corresponding record for this reference.
  25. 25
    Yin, Z.; Li, H.; Xu, W.; Cui, S.; Zhou, D.; Chen, X.; Zhu, Y.; Qin, G.; Song, H. Local Field Modulation Induced Three-Order Upconversion Enhancement: Combining Surface Plasmon Effect and Photonic Crystal Effect. Adv. Mater. 2016, 28, 2518– 2525,  DOI: 10.1002/adma.201502943
    Google Scholar
    25
    Local Field Modulation Induced Three-Order Upconversion Enhancement: Combining Surface Plasmon Effect and Photonic Crystal Effect
    Yin, Ze; Li, Hang; Xu, Wen; Cui, Shaobo; Zhou, Donglei; Chen, Xu; Zhu, Yongsheng; Qin, Guanshi; Song, Hongwei
    Advanced Materials (Weinheim, Germany) (2016), 28 (13), 2518-2525CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)
    The authors present a novel device and significant modulation of gold nanorods (AuNRs)/Polymethylmethacrylate (PMMA) opal photonic crystals (OPCs) surface plasmon photonic crystal (SPPC) on upconversion luminescence (UCL) of NaYF4:Yb3+, Er3+ NPs, which has perfectly combined surface plasmon effect of AuNRs and PC effects of 3D PMMA opals. In the hybrids, the UCL of NaYF4:Yb3+, Er3+ has been enhanced more than 103 folds, which is at least an order of magnitude higher than that reported by the previous literature.
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  26. 26
    Chen, X.; Xu, W.; Zhang, L.; Bai, X.; Cui, S.; Zhou, D.; Yin, Z.; Song, H.; Kim, J. Large Upconversion Enhancement in the “Islands” Au–Ag Alloy/NaYF4: Yb3+, Tm3+/Er3+ Composite Films, and Fingerprint Identification. Adv. Funct. Mater. 2015, 25, 5462– 5471,  DOI: 10.1002/adfm.201502419
    Google Scholar
    26
    Large Upconversion Enhancement in the "Islands" Au-Ag Alloy/NaYF4: Yb3+, Tm3+/Er3+ Composite Films, and Fingerprint Identification
    Chen, Xu; Xu, Wen; Zhang, Lihang; Bai, Xue; Cui, Shaobo; Zhou, Donglei; Yin, Ze; Song, Hongwei; Kim, Dong-Hwan
    Advanced Functional Materials (2015), 25 (34), 5462-5471CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)
    The surface plasmon (SP) modulation is a promised way to highly improve the strength of upconversion luminescence (UCL) and expand its applications. The islands Au-Ag alloy film is prepd. by an org. removal template method and explored to improve the UCL of NaYF4: Yb3+, Tm3+/Er3+. After the optimization of Au-Ag molar ratio (Au1.25-Ag0.625) and the size of NaYF4 nanoparticles (NPs, ≈7 nm), an optimum enhancement ≤180 folds is obtained (by reflection measurement) for the overall UCL intensity of Tm3+. Systematic studies indicate that the UCL enhancement factor (EF) increases with the increased size of metal NPs and the increase of diffuse reflection, with the decreased size of NaYF4 NPs, with the decreased power d. of excitation light and with improving order of multiphoton populating. The total decay rate varies only ranging of ∼20% while EF changes significantly. All the facts above indicate that the UCL enhancement mainly originates from coupling of SP with the excitation electromagnetic field. Also, the fingerprint identification based on SP-enhanced UCL is realized in the metal/UC system, which provides a novel insight for the application of the metal/UC device.
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  27. 27
    Shen, J.; Li, Z. Q.; Chen, Y. R.; Chen, X. H.; Chen, Y. W.; Sun, Z.; Huang, S. M. Influence of SiO2 layer thickness on plasmon enhanced upconversion in hybrid Ag/SiO2/NaYF4:Yb, Er, Gd structures. Appl. Surf. Sci. 2013, 270, 712– 717,  DOI: 10.1016/j.apsusc.2013.01.133
    Google Scholar
    There is no corresponding record for this reference.
  28. 28
    Feng, A. L.; You, M. L.; Tian, L.; Singamaneni, S.; Liu, M.; Duan, Z.; Lu, T. J.; Xu, F.; Lin, M. Distance-Dependent Plasmon-Enhanced Fluorescence of Upconversion Nanoparticles using Polyelectrolyte Multilayers as Tunable Spacers. Sci. Rep. 2015, 5 (1), 7779,  DOI: 10.1038/srep07779
    Google Scholar
    28
    Distance-Dependent Plasmon-Enhanced Fluorescence of Upconversion Nanoparticles using Polyelectrolyte Multilayers as Tunable Spacers
    Feng, Ai Ling; You, Min Li; Tian, Limei; Singamaneni, Srikanth; Liu, Ming; Duan, Zhenfeng; Lu, Tian Jian; Xu, Feng; Lin, Min
    Scientific Reports (2015), 5 (), 7779CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)
    Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted widespread interests in bioapplications due to their unique optical properties by converting near IR excitation to visible emission. However, relatively low quantum yield prompts a need for developing methods for fluorescence enhancement. Plasmon nanostructures are known to efficiently enhance fluorescence of the surrounding fluorophores by acting as nanoantennae to focus elec. field into nano-vol. Here, we reported a novel plasmon-enhanced fluorescence system in which the distance between UCNPs and nanoantennae (gold nanorods, AuNRs) was precisely tuned by using layer-by-layer assembled polyelectrolyte multilayers as spacers. By modulating the aspect ratio of AuNRs, localized surface plasmon resonance (LSPR) wavelength at 980 nm was obtained, matching the native excitation of UCNPs resulting in max. enhancement of 22.6-fold with 8 nm spacer thickness. These findings provide a unique platform for exploring hybrid nanostructures composed of UCNPs and plasmonic nanostructures in bioimaging applications.
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  29. 29
    Saboktakin, M.; Ye, X.; Oh, S. J.; Hong, S.-H.; Fafarman, A. T.; Chettiar, U. K.; Engheta, N.; Murray, C. B.; Kagan, C. R. Metal-Enhanced Upconversion Luminescence Tunable through Metal Nanoparticle–Nanophosphor Separation. ACS Nano 2012, 6 (10), 8758– 8766,  DOI: 10.1021/nn302466r
    Google Scholar
    29
    Metal-Enhanced Upconversion Luminescence Tunable through Metal Nanoparticle-Nanophosphor Separation
    Saboktakin, Marjan; Ye, Xingchen; Oh, Soong Ju; Hong, Sung-Hoon; Fafarman, Aaron T.; Chettiar, Uday K.; Engheta, Nader; Murray, Christopher B.; Kagan, Cherie R.
    ACS Nano (2012), 6 (10), 8758-8766CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    The authors demonstrated amplification of luminescence in upconversion nanophosphors (UCNPs) of hexagonal phase NaYF4 (β-NaYF4) doped with the lanthanide dopants Yb3+, Er3+ or Yb3+, Tm3+ by close proximity to metal nanoparticles (NPs). The authors present a configuration in which close-packed monolayers of UCNPs are sepd. from a dense multilayer of metal NPs (Au or Ag) by a nanometer-scale oxide grown by at. layer deposition. Luminescence enhancements are dependent on the thickness of the oxide spacer layer and the type of metal NP with enhancements of up to 5.2-fold proximal to Au NPs and of up to 45-fold proximal to Ag NPs. Concomitant shortening of the UCNP luminescence decay time and rise time is indicative of the enhancement of the UCNP luminescence induced by resonant plasmonic coupling and nonresonant near-field enhancement from the metal NP layer, resp.
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  30. 30
    Luo, Q.; Chen, Y.; Li, Z.; Zhu, F.; Chen, X.; Sun, Z.; Wei, Y.; Guo, H.; Bo Wang, Z.; Huang, S. Large enhancements of NaYF4:Yb/Er/Gd nanorod upconversion emissions via coupling with localized surface plasmon of Au film. Nanotechnology 2014, 25 (18), 185401,  DOI: 10.1088/0957-4484/25/18/185401
    Google Scholar
    There is no corresponding record for this reference.
  31. 31
    Yin, Z.; Zhou, D.; Xu, W.; Cui, S.; Chen, X.; Wang, H.; Xu, S.; Song, H. Plasmon-Enhanced Upconversion Luminescence on Vertically Aligned Gold Nanorod Monolayer Supercrystals. ACS Appl. Mater. Interfaces 2016, 8 (18), 11667– 11674,  DOI: 10.1021/acsami.5b12075
    Google Scholar
    There is no corresponding record for this reference.
  32. 32
    Schietinger, S.; Aichele, T.; Wang, H.-Q.; Nann, T.; Benson, O. Plasmon-Enhanced Upconversion in Single NaYF4:Yb3+/Er3+ Codoped Nanocrystals. Nano Lett. 2010, 10 (1), 134– 138,  DOI: 10.1021/nl903046r
    Google Scholar
    32
    Plasmon-Enhanced Upconversion in Single NaYF4:Yb3+/Er3+ Codoped Nanocrystals
    Schietinger, Stefan; Aichele, Thomas; Wang, Hai-Qiao; Nann, Thomas; Benson, Oliver
    Nano Letters (2010), 10 (1), 134-138CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    In this Letter the authors report the plasmon-enhanced upconversion in single NaYF4 nanocrystals codoped with Yb3+/Er3+. Single nanocrystals and Au nanospheres were studied and assembled in a combined confocal and at. force microscope setup. The nanocrystals show strong upconversion emission in the green and red under excitation with a continuous wave laser in the near-IR at 973 nm. Using the at. force microscope, the authors couple single nanocrystals with Au spheres (30 and 60 nm in diam.) to obtain enhanced upconversion emission. An overall enhancement factor of 3.8 is reached. A comparison of time-resolved measurements on the bare nanocrystal and the coupled nanocrystal-Au sphere systems unveil that faster excitation as well as faster emission occurs in the nanocrystals.
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  33. 33
    Alizadehkhaledi, A.; Frencken, A. L.; Dezfouli, M. K.; Hughes, S.; van Veggel, F. C. J. M.; Gordon, R. Cascaded Plasmon-Enhanced Emission from a Single Upconverting Nanocrystal. ACS Photonics 2019, 6 (5), 1125– 1131,  DOI: 10.1021/acsphotonics.9b00285
    Google Scholar
    33
    Cascaded Plasmon-Enhanced Emission from a Single Upconverting Nanocrystal
    Alizadehkhaledi, Amirhossein; Frencken, Adriaan L.; Dezfouli, Mohsen Kamandar; Hughes, Stephen; van Veggel, Frank C. J. M.; Gordon, Reuven
    ACS Photonics (2019), 6 (5), 1125-1131CODEN: APCHD5; ISSN:2330-4022. (American Chemical Society)
    Plasmonics was used to enhance light-matter interaction at the extreme subwavelength scale. Intriguingly, it is possible to achieve multiple plasmonic resonances from a single nanostructure, and these can be used in combination to provide cascaded enhanced interactions. Here, the authors demonstrate three distinct plasmon resonances for enhanced upconversion emission from a single upconverting nanocrystal trapped in a metal nanoaperture optical tweezer. For apertures where the plasmonic resonances occur at the emission wavelengths only, a moderate enhancement of a factor of 4 is seen. However, by tuning the aperture to enhance the excitation laser as well, an addnl. factor of 100 enhancement in the emission is achieved. Since lanthanide-doped nanocrystals are stable emitters, this approach of using multiple subwavelength resonances can improve applications including photovoltaics, photocatalysis, and imaging. The nanocrystals can also contain only single ions, allowing for studying quantum emitter properties and applications to single-photon sources.
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  34. 34
    Alizadehkhaledi, A.; Frencken, A. L.; van Veggel, F. C. J. M.; Gordon, R. Isolating Nanocrystals with an Individual Erbium Emitter: A Route to a Stable Single-Photon Source at 1550 nm Wavelength. Nano Lett. 2020, 20 (2), 1018– 1022,  DOI: 10.1021/acs.nanolett.9b04165
    Google Scholar
    34
    Isolating Nanocrystals with an Individual Erbium Emitter: A Route to a Stable Single-Photon Source at 1550 nm Wavelength
    Alizadehkhaledi, Amirhossein; Frencken, Adriaan L.; van Veggel, Frank C. J. M.; Gordon, Reuven
    Nano Letters (2020), 20 (2), 1018-1022CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    Single-photon emitters based on individual atoms or individual at.-like defects are highly sought-after components for future quantum technologies. A key challenge in this field is how to isolate just one such emitter; the best approaches still have an active emitter yield of only 50% so that deterministic integration of single active emitters is not yet possible. Here, we demonstrate the ability to isolate individual erbium emitters embedded in 20 nm nanocrystals of NaYF4 using plasmonic aperture optical tweezers. The optical tweezers capture the nanocrystal, whereas the plasmonic aperture enhances the emission of the Er and allows the measurement of discrete emission rate values corresponding to different nos. of erbium ions. Three sep. synthesis runs show near-Poissonian distribution in the discrete levels of emission yield that correspond to the expected ion concns., indicating that the yield of active emitters is approx. 80%. Fortunately, the trap allows for selecting the nanocrystals with only a single emitter, and so this gives a route to isolating and integrating single emitters in a deterministic way. This demonstration is a promising step toward single-photon quantum information technologies that utilize single ions in a solid-state medium, particularly because Er emits in the low-loss fiber-optic 1550 nm telecom band.
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  35. 35
    Rodriguez-Sevilla, P.; Rodriguez-Rodriguez, H.; Pedroni, M.; Speghini, A.; Bettinelli, M.; Sole, J. G.; Jaque, D.; Haro-Gonzalez, P. Assessing Single Upconverting Nanoparticle Luminescence by Optical Tweezers. Nano Lett. 2015, 15 (8), 5068– 5074,  DOI: 10.1021/acs.nanolett.5b01184
    Google Scholar
    35
    Assessing Single Upconverting Nanoparticle Luminescence by Optical Tweezers
    Rodriguez-Sevilla, P.; Rodriguez-Rodriguez, H.; Pedroni, M.; Speghini, A.; Bettinelli, M.; Sole, J. Garcia; Jaque, D.; Haro-Gonzalez, P.
    Nano Letters (2015), 15 (8), 5068-5074CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    Stable, long-term immobilization and localization are reported of a single colloidal Er3+/Yb3+-codoped SrF2 upconverting fluorescent nanoparticle (UCNP) by optical trapping with a single IR laser beam. Contrary to expectations, the single UCNP emission differs from that generated by an assembly of UCNPs. The differences can be explained in terms of modulations caused by radiation-trapping, a phenomenon not considered before but that is revealed to be of great relevance.
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  36. 36
    Rodriguez-Sevilla, P.; Zhang, Y.; de Sousa, N.; Marques, M. I.; Sanz-Rodriguez, F.; Jaque, D.; Liu, X.; Haro-Gonzalez, P. Optical Torques on Upconverting Particles for Intracellular Microrheometry. Nano Lett. 2016, 16 (12), 8005– 8014,  DOI: 10.1021/acs.nanolett.6b04583
    Google Scholar
    There is no corresponding record for this reference.
  37. 37
    Baffou, G.; Polleux, J.; Rigneault, H.; Monneret, S. Super-Heating and Micro-Bubble Generation around Plasmonic Nanoparticles under cw Illumination. J. Phys. Chem. C 2014, 118 (9), 4890– 4898,  DOI: 10.1021/jp411519k
    Google Scholar
    37
    Super-Heating and Micro-Bubble Generation around Plasmonic Nanoparticles under cw Illumination
    Baffou, Guillaume; Polleux, Julien; Rigneault, Herve; Monneret, Serge
    Journal of Physical Chemistry C (2014), 118 (9), 4890-4898CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
    Under illumination, metal nanoparticles can turn into ideal nanosources of heat due to enhanced light absorption at the plasmonic resonance wavelength. In this article, we aim at providing a comprehensive description of the generation of microbubbles in a liq. occurring around plasmonic nanoparticles under continuous illumination. We focus on a common situation where the nanoparticles are located on a solid substrate and immersed in water. Exptl., we evidenced a series of singular phenomena: (i) the bubble lifetime after heating can reach several minutes, (ii) the bubbles are not made of water steam but of air, and (iii) the local temp. required to trigger bubble generation is much larger than 100 °C: This last observation evidences that superheated liq. water, up to 220 °C, is easy to achieve in plasmonics, under ambient pressure conditions and even over arbitrary large areas. This could lead to new chem. synthesis approaches in solvothermal chem.
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  38. 38
    Baffou, G.; Quidant, R.; García de Abajo, F. J. Nanoscale Control of Optical Heating in Complex Plasmonic Systems. ACS Nano 2010, 4 (2), 709– 716,  DOI: 10.1021/nn901144d
    Google Scholar
    38
    Nanoscale Control of Optical Heating in Complex Plasmonic Systems
    Baffou, Guillaume; Quidant, Romain; Garcia de Abajo, F. Javier
    ACS Nano (2010), 4 (2), 709-716CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    The authors introduce a numerical technique to study the temp. distribution in arbitrarily complex plasmonic systems subject to external illumination. The authors perform both electromagnetic and thermodn. calcns. based upon a time-efficient boundary element method. Two kinds of plasmonic systems are studied to illustrate the potential of such a technique. First, the authors focus on individual particles with various morphologies. In analogy with electrostatics, the authors introduce the concept of thermal capacitance. This geometry-dependent quantity allows one to assess the temp. increase inside a plasmonic particle from the sole knowledge of its absorption cross section. The authors present universal thermal-capacitance curves for ellipsoids, rods, disks, and rings. Addnl., the authors study assemblies of nanoparticles in close proximity and show that, despite its diffusive nature, the temp. distribution can be made highly nonuniform even at the nanoscale using plasmonic systems. A significant degree of nanoscale control over the individual temps. of neighboring particles is demonstrated, depending on the external light wavelength and direction of incidence. The authors illustrate this concept with simulations of Au sphere dimers and chains in H2O. Work opens new possibilities for selectively controlling processes such as local melting for dynamic patterning of textured materials, chem. and metabolic thermal activation, and heat delivery for producing mech. motion with spatial precision in the nanoscale.
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  39. 39
    Domínguez-García, P. Brownian Disks Lab: Simulating time-lapse microscopy experiments for exploring microrheology techniques and colloidal interactions. Comput. Phys. Commun. 2020, 252, 107123,  DOI: 10.1016/j.cpc.2019.107123
    Google Scholar
    There is no corresponding record for this reference.
  40. 40
    Qi, P.; Dai, Y.; Luo, Y.; Tao, G.; Zheng, L.; Liu, D.; Zhang, T.; Zhou, J.; Shen, B.; Lin, F.; Liu, Z.; Fang, Z. Giant excitonic upconverted emission from two-dimensional semiconductor in doubly resonant plasmonic nanocavity. Light: Science & Applications 2022, 11 (1), 176,  DOI: 10.1038/s41377-022-00860-2
    Google Scholar
    There is no corresponding record for this reference.
  41. 41
    Feng, Z.; Hu, D.; Liang, L.; Xu, J.; Cao, Y.; Zhan, Q.; Guan, B.-O.; Liu, X.; Li, X. Laser-Splashed Plasmonic Nanocrater for Ratiometric Upconversion Regulation and Encryption. Advanced Optical Materials 2019, 7 (19), 1900610,  DOI: 10.1002/adom.201900610
    Google Scholar
    There is no corresponding record for this reference.
  42. 42
    Li, X.; Cheng, Y.; Xu, J.; Lin, H.; Wang, Y. Utilizing Au–CuS heterodimer to intensify upconversion emission of NaGdF4:Yb/Er nanocrystals. J. Mater. Sci. 2020, 55 (16), 6891– 6902,  DOI: 10.1007/s10853-020-04512-x
    Google Scholar
    There is no corresponding record for this reference.
  43. 43
    Pan, C.; Ma, Q.; Liu, S.; Xue, Y.; Fang, Z.; Zhang, S.; Qin, M.; Wu, E.; Wu, B. Angularly anisotropic tunability of upconversion luminescence by tuning plasmonic local-field responses in gold nanorods antennae with different configurations. Nanophotonics 2022, 11 (10), 2349– 2359,  DOI: 10.1515/nanoph-2022-0037
    Google Scholar
    There is no corresponding record for this reference.

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  • Abstract

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    Figure 1

    Figure 1. (a) Experimental setup used for optical tweezing of a single, colloidal UCNP in the presence of PNPs. (b) Transmission electron microscopy (TEM) image of the UCNPs. (c) Histogram of the size distribution of UCNPs as obtained from the analysis of TEM images. (d) Emission spectrum of the UCNPs under 980 nm excitation.

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    Figure 2

    Figure 2. Scanning electron microscope images of the PNPs used in this work, with plasmon resonances at 980 and 574 nm (a and e, respectively). Histogram of the size distribution of Au PNPs with plasmon resonances at 980 and 574 nm (b and f, respectively). Extinction spectra of the PNPs showed the plasmon resonances at 980 and 574 nm (c and g, respectively). The gray dashed line indicates the wavelength of the trapping laser (980 nm). (d) Increase in local temperature induced by the PNPs under 980 nm irradiation as a function of the laser power density (red and yellow lines for the Au PNPs with plasmon resonances at 980 and 574 nm, respectively). (h) Fluorescence image of a single optically trapped UCNP on top of the substrate with PNPs with λSPR ≅ 574 nm under 980 nm excitation.

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    Figure 3

    Figure 3. (a) Schematic representation of the horizontal scan of an optically tweezed UCNP along a substrate partially covered with Au PNPs. (b) Schematic representation of the vertical scan of an optically tweezed UCNP with respect to the substrate with PNPs. (c) Periodic change in the upconversion luminescence intensity during the horizontal scan of a single UCNP along a substrate partially covered with PNPs. (d) Upconversion intensity generated by a tweezed UCNP during a vertical scan. Data obtained in the presence and absence of PNPs are included for comparison. All of the data included in this figure were obtained for a laser power intensity of 4.3 MW cm–2 and for the PNPs with λSPR ≅ 574 nm.

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    Figure 4

    Figure 4. (a) Sketch of the position of the UCNP within the optical trap. Δx sets the horizontal position of the laser focus, referenced to the position on top of the Au PNP. (b) Dependence of the Purcell factor at 580 nm on the vertical direction. Different colors correspond to the vertical scans performed at different positions (different Δx distances) with respect to the Au PNP. (c) Experimentally determined, laser-power-dependent force for optical trapping of a single UCNP on a substrate with PNPs. Solid lines plot linear fits to the experimental data. (d) Brownian motion trajectory of a single optically trapped UCNP within the transverse section of the laser focus (indicated by the black dashed circle). (e) Dependence of the in-plane spatially averaged Purcell effect at 580 nm along the vertical direction. (f) Upconversion luminescence decay curves recorded for an emission wavelength of 650 nm for UCNPs deposited on a glass substrate (gray) and on a glass substrate containing PNPs (orange) under 980 nm excitation. All of the data included were obtained with the PNPs with plasmon resonance at 574 nm.

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    Figure 5

    Figure 5. (a) Spatial profile of the laser intensity on top of a PNP and along the vertical distance (z, measured from the substrate on which PNPs are deposited) as obtained for different values of zUCNP. The profiles for laser position, zL ranging between 0 and 2000 nm, overlap almost completely. Inset: schematic of the UCNP on top of a Au PNP. (b) Position distribution of a single optically tweezed UCNP caused by Brownian motion within a longitudinal section of the laser beam axis. The black dashed ellipse indicates the Rayleigh range (long axis) and the size of the laser focus (short axis). (c) Dependence of the effective intensity (experienced by the Brownian UCNP) as a function of the OT vertical position, zL, and for half position distribution widths, w, ranging from 450 nm (black) to 1000 nm (orange). Inset: sketch of the UCNP at the on-top position of the Au nanoparticle. (d) Effective 980 nm laser intensity for zL = 0 nm as a function of the width of the UCNP position distribution.

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  • References

    This article references 43 other publications.

    1. 1
      Zou, W.; Visser, C.; Maduro, J. A.; Pshenichnikov, M. S.; Hummelen, J. C. Broadband dye-sensitized upconversion of near-infrared light. Nat. Photonics 2012, 6 (8), 560– 564,  DOI: 10.1038/nphoton.2012.158
      1
      Broadband dye-sensitized upconversion of near-infrared light
      Zou, Wenqiang; Visser, Cindy; Maduro, Jeremio A.; Pshenichnikov, Maxim S.; Hummelen, Jan C.
      Nature Photonics (2012), 6 (8), 560-564CODEN: NPAHBY; ISSN:1749-4885. (Nature Publishing Group)
      Photon upconversion of near-IR photons is a promising way to overcome the Shockley-Queisser efficiency limit of 32% of a single-junction solar cell. However, the practical applicability of the most efficient known upconversion materials at moderate light intensities is limited by their extremely weak and narrowband near-IR absorption. Here, we introduce the concept of an upconversion material where an org. near-IR dye is used as an antenna for the β-NaYF4:Yb,Er nanoparticles in which the upconversion occurs. The overall upconversion by the dye-sensitized nanoparticles is dramatically enhanced (by a factor of ∼3,300) as a result of increased absorptivity and overall broadening of the absorption spectrum of the upconverter. The proposed concept can be extended to cover any part of the solar spectrum by using a set of dye mols. with overlapping absorption spectra acting as an extremely broadband antenna system, connected to suitable upconverters.
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    2. 2
      Roh, J.; Yu, H.; Jang, J. Hexagonal β-NaYF4:Yb3+, Er3+ Nanoprism-Incorporated Upconverting Layer in Perovskite Solar Cells for Near-Infrared Sunlight Harvesting. ACS Appl. Mater. Interfaces 2016, 8 (31), 19847– 19852,  DOI: 10.1021/acsami.6b04760
      2
      Hexagonal β-NaYF4:Yb3+, Er3+ Nanoprism-Incorporated Upconverting Layer in Perovskite Solar Cells for Near-Infrared Sunlight Harvesting
      Roh, Jongmin; Yu, Haejun; Jang, Jyongsik
      ACS Applied Materials & Interfaces (2016), 8 (31), 19847-19852CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
      Hexagonal β-NaYF4:Yb3+, Er3+ nanoprisms, successfully prepd. using a hydrothermal method, were incorporated into MeNH3PbI3 perovskite solar cells (PSCs) as an upconverting mesoporous layer. Due to their near-IR (NIR) sunlight harvesting, the PSCs based on the upconverting mesoporous layer exhibited a power conversion efficiency of 16.0%, an increase of 13.7% compared with conventional TiO2 nanoparticle-based PSCs (14.1%). Probably the hexagonal β-NaYF4:Yb3+, Er3+ nanoprisms expand the absorption range of the PSC via upconversion photoluminescence, leading to an enhancement of the photocurrent.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xht1Gjt73L&md5=41260040efc39b60bd2caae7eda24b02
    3. 3
      Liu, Y.; Zhang, C.; Liu, H.; Li, Y.; Xu, Z.; Li, L.; Whittaker, A. Controllable synthesis of up-conversion nanoparticles UCNPs@MIL-PEG for pH-responsive drug delivery and potential up-conversion luminescence/magnetic resonance dual-mode imaging. J. Alloys Compd. 2018, 749, 939– 947,  DOI: 10.1016/j.jallcom.2018.03.355
      3
      Controllable synthesis of up-conversion nanoparticles UCNPs@MIL-PEG for pH-responsive drug delivery and potential up-conversion luminescence/magnetic resonance dual-mode imaging
      Liu, Yana; Zhang, Cheng; Liu, Hui; Li, Yuebin; Xu, Zushun; Li, Ling; Whittaker, Andrew
      Journal of Alloys and Compounds (2018), 749 (), 939-947CODEN: JALCEU; ISSN:0925-8388. (Elsevier B.V.)
      Rare-earth doped up-conversion nanoparticles (UCNPs) with high uniformity and dispersibility were synthesized by a facile solvothermal method. The conditions of synthesis for NaYF4:Yb/Tm were explored, and the NaYF4:Yb/Tm particles with the optimal size (about 300nm) were obtained. Blue emission was obsd. with the excitation 980nm near IR (NIR) laser, indicating that the UCNPs can be potentially used for up-conversion luminescence (UCL) imaging. On basis of the optimal UCNPs, further coated by poly (ethylene glycol) (PEG) functionalized metal-org. frameworks (MOFs), a multifunctional platform UCNPs@MIL-PEG for cancer diagnosis and treatment was established. The core-shell structure was confirmed by TEM images. Doxorubicin (DOX) was selected as drug model and the drug loading of UCNPs@MIL-PEG was found to be 60%. Cytotoxicity indicated that UCNPs@MIL-PEG were highly biocompatible. The DOX release in different pH value revealed an excellent pH-triggered drug release. In addn., the UCNPs@MIL-PEG nanoparticles can be tracked by magnetic resonance imaging (MRI). A clear dose-dependent contrast enhancement in T2-weighted MR images indicated the potential act as T2 MRI contrast agents. The UCNPs@MIL-PEG nanoparticles are expected to be simultaneously used for UCL/MR dual-mode imaging and pH-responsive drug release.
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    4. 4
      Chan, M.-H.; Pan, Y.-T.; Lee, I.-J.; Chen, C.-W.; Chan, Y.-C.; Hsiao, M.; Wang, F.; Sun, L.; Chen, X.; Liu, R.-S. Minimizing the Heat Effect of Photodynamic Therapy Based on Inorganic Nanocomposites Mediated by 808 nm Near-Infrared Light. Small 2017, 13 (21), 1700038,  DOI: 10.1002/smll.201700038
      There is no corresponding record for this reference.
    5. 5
      Xu, E. Z.; Lee, C.; Pritzl, S. D.; Chen, A. S.; Lohmueller, T.; Cohen, B. E.; Chan, E. M.; Schuck, P. J. Infrared-to-ultraviolet upconverting nanoparticles for COVID-19-related disinfection applications. Optical Materials: X 2021, 12, 100099,  DOI: 10.1016/j.omx.2021.100099
      There is no corresponding record for this reference.
    6. 6
      Li, Y.; Tang, J.; He, L.; Liu, Y.; Liu, Y.; Chen, C.; Tang, Z. Core–Shell Upconversion Nanoparticle@Metal–Organic Framework Nanoprobes for Luminescent/Magnetic Dual-Mode Targeted Imaging. Adv. Mater. 2015, 27 (27), 4075– 4080,  DOI: 10.1002/adma.201501779
      6
      Core-Shell Upconversion Nanoparticle@Metal-Organic Framework Nanoprobes for Luminescent/Magnetic Dual-Mode Targeted Imaging
      Li, Yantao; Tang, Jinglong; He, Liangcan; Liu, Yong; Liu, Yaling; Chen, Chunying; Tang, Zhiyong
      Advanced Materials (Weinheim, Germany) (2015), 27 (27), 4075-4080CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)
      Core-shell upconversion nanoparticle@metal-org. framework (UCNP@MOF) nanostructures were constructed by coating hexagonal NaYF4:Yb,Er nanoparticle (NP) cores with amino-functionalized iron carboxylate MOF shells. These nanostructures combine the near-IR optical property of UCNP cores and the T2-magnetic response (MR) imaging property of MOF shells. After surface modification, the core-shell nanostructures were demonstrated as high-resoln. nanoprobes for targeted luminescence/MR imaging both in vitro and in vivo.
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    7. 7
      Huang, G.; Liu, Y.; Wang, D.; Zhu, Y.; Wen, S.; Ruan, J.; Jin, D. Upconversion nanoparticles for super-resolution quantification of single small extracellular vesicles. eLight 2022, 2 (1), 20,  DOI: 10.1186/s43593-022-00031-1
      There is no corresponding record for this reference.
    8. 8
      Lee, C.; Xu, E. Z.; Liu, Y.; Teitelboim, A.; Yao, K.; Fernandez-Bravo, A.; Kotulska, A. M.; Nam, S. H.; Suh, Y. D.; Bednarkiewicz, A.; Cohen, B. E.; Chan, E. M.; Schuck, P. J. Giant nonlinear optical responses from photon-avalanching nanoparticles. Nature 2021, 589 (7841), 230– 235,  DOI: 10.1038/s41586-020-03092-9
      8
      Giant nonlinear optical responses from photon-avalanching nanoparticles
      Lee, Changhwan; Xu, Emma Z.; Liu, Yawei; Teitelboim, Ayelet; Yao, Kaiyuan; Fernandez-Bravo, Angel; Kotulska, Agata M.; Nam, Sang Hwan; Suh, Yung Doug; Bednarkiewicz, Artur; Cohen, Bruce E.; Chan, Emory M.; Schuck, P. James
      Nature (London, United Kingdom) (2021), 589 (7841), 230-235CODEN: NATUAS; ISSN:0028-0836. (Nature Research)
      Abstr.: Avalanche phenomena use steeply nonlinear dynamics to generate disproportionately large responses from small perturbations, and are found in a multitude of events and materials1. Photon avalanching enables technologies such as optical phase-conjugate imaging2, IR quantum counting3 and efficient upconverted lasing4-6. However, the photon-avalanching mechanism underlying these optical applications has been obsd. only in bulk materials and aggregates6,7, limiting its utility and impact. Here, we report the realization of photon avalanching at room temp. in single nanostructures-small, Tm3+-doped upconverting nanocrystals-and demonstrate their use in super-resoln. imaging in near-IR spectral windows of maximal biol. transparency. Avalanching nanoparticles (ANPs) can be pumped by continuous-wave lasers, and exhibit all of the defining features of photon avalanching, including clear excitation-power thresholds, exceptionally long rise time at threshold, and a dominant excited-state absorption that is more than 10,000 times larger than ground-state absorption. Beyond the avalanching threshold, ANP emission scales nonlinearly with the 26th power of the pump intensity, owing to induced pos. optical feedback in each nanocrystal. This enables the exptl. realization of photon-avalanche single-beam super-resoln. imaging7 with sub-70-nm spatial resoln., achieved by using only simple scanning confocal microscopy and without any computational anal. Pairing their steep nonlinearity with existing super-resoln. techniques and computational methods8-10, ANPs enable imaging with higher resoln. and at excitation intensities about 100 times lower than other probes. The low photon-avalanching threshold and excellent photostability of ANPs also suggest their utility in a diverse array of applications, including sub-wavelength imaging7,11,12 and optical and environmental sensing13-15.
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    9. 9
      Soares, A. C. C.; Sales, T. O.; Ximendes, E. C.; Jaque, D.; Jacinto, C. Lanthanide doped nanoparticles for reliable and precise luminescence nanothermometry in the third biological window. Nanoscale Advances 2023, 5 (14), 3664– 3670,  DOI: 10.1039/D2NA00941B
      There is no corresponding record for this reference.
    10. 10
      Lin, G.; Jin, D. Responsive Sensors of Upconversion Nanoparticles. ACS Sensors 2021, 6 (12), 4272– 4282,  DOI: 10.1021/acssensors.1c02101
      There is no corresponding record for this reference.
    11. 11
      Arai, M. S.; de Camargo, A. S. S. Exploring the use of upconversion nanoparticles in chemical and biological sensors: from surface modifications to point-of-care devices. Nanoscale Advances 2021, 3 (18), 5135– 5165,  DOI: 10.1039/D1NA00327E
      There is no corresponding record for this reference.
    12. 12
      Chen, X.; Peng, D.; Ju, Q.; Wang, F. Photon upconversion in core–shell nanoparticles. Chem. Soc. Rev. 2015, 44 (6), 1318– 1330,  DOI: 10.1039/C4CS00151F
      12
      Photon upconversion in core-shell nanoparticles
      Chen, Xian; Peng, Denfeng; Ju, Qiang; Wang, Feng
      Chemical Society Reviews (2015), 44 (6), 1318-1330CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
      A review. Photon upconversion generally results from a series of successive electronic transitions within complex energy levels of lanthanide ions that are embedded in the lattice of a cryst. solid. In conventional lanthanide-doped upconversion nanoparticles, the dopant ions homogeneously distributed in the host lattice are readily accessible to surface quenchers and lose their excitation energy, giving rise to weak and susceptible emissions. Therefore, present studies on upconversion are mainly focused on core-shell nanoparticles comprising spatially confined dopant ions. By doping upconverting lanthanide ions in the interior of a core-shell nanoparticle, the upconversion emission can be substantially enhanced, and the optical integrity of the nanoparticles can be largely preserved. Optically active shells are also frequently employed to impart multiple functionalities to upconversion nanoparticles. Intriguingly, the core-shell design introduces the possibility of constructing novel upconversion nanoparticles by exploiting the energy exchange interactions across the core-shell interface. In this tutorial review, we highlight recent advances in the development of upconversion core-shell nanoparticles, with particular emphasis on the emerging strategies for regulating the interplay of dopant interactions through core-shell nanostructural engineering that leads to unprecedented upconversion properties. The improved control over photon energy conversion will open up new opportunities for biol. and energy applications.
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      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1SksLjP&md5=e030bbb3b9d6ebdad4ad6257701d1985
    13. 13
      Cheng, T.; Marin, R.; Skripka, A.; Vetrone, F. Small and Bright Lithium-Based Upconverting Nanoparticles. J. Am. Chem. Soc. 2018, 140 (40), 12890– 12899,  DOI: 10.1021/jacs.8b07086
      13
      Small and Bright Lithium-Based Upconverting Nanoparticles
      Cheng, Ting; Marin, Riccardo; Skripka, Artiom; Vetrone, Fiorenzo
      Journal of the American Chemical Society (2018), 140 (40), 12890-12899CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      In the context of light-mediated tumor treatment, the application of UV radiation can initiate drug release and photodynamic therapy. However, its limited penetration depth in tissues impedes the s.c. applicability of such radiation. On the contrary, near-IR (NIR) light is not energetic enough to initiate secondary photochem. processes, but can pierce tissues at a significantly greater depth. Upconverting nanoparticles (UCNPs) unify the advantages of both extremes of the optical spectrum, they can be excited by NIR irradn. and emit UV light through the process of upconversion, effective NIR-to-UV generation being attained with UCNPs as large as 100 nm. However, in anticipation of biomedical applications, the size of UCNPs must be greatly minimized to favor their cellular internalization; yet straightforward size redn. neg. affects the NIR-to-UV upconversion efficiency. Herein, we propose a two-step strategy to obtain small yet bright lithium-based UCNPs. First, we synthesized UCNPs as small as 5 nm by controlling the relative amt. of coordinating ligands, namely oleylamine (OM) and oleic acid (OA). Although these UCNPs were chem. unstable, particle coarsening via an annealing process in the presence of fresh OA yielded structurally stable and highly monodisperse sub-10 nm crystals. Second, we grew a shell with controlled thickness on these stabilized cores of UCNPs, improving the NIR-to-UV upconversion by orders of magnitude. Particularly in the case of LiYbF4:Tm3+/LiYF4 UCNPs, their NIR-to-UV upconversion surpassed the gold std. 90 nm-sized LiYF4:Tm3+, Yb3+ UCNPs. All in all, these UCNPs show great potential within the biomedical framework as they successfully combine the requirements of small size, deep tissue NIR penetration and bright UV emission.
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    14. 14
      Back, M.; Trave, E.; Marin, R.; Mazzucco, N.; Cristofori, D.; Riello, P. Energy Transfer in Bi- and Er-Codoped Y2O3 Nanocrystals: An Effective System for Rare Earth Fluorescence Enhancement. J. Phys. Chem. C 2014, 118 (51), 30071– 30078,  DOI: 10.1021/jp5080016
      14
      Energy Transfer in Bi- and Er-Codoped Y2O3 Nanocrystals: An Effective System for Rare Earth Fluorescence Enhancement
      Back, Michele; Trave, Enrico; Marin, Riccardo; Mazzucco, Nicolo; Cristofori, Davide; Riello, Pietro
      Journal of Physical Chemistry C (2014), 118 (51), 30071-30078CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
      The enhancement of the low absorption cross section and widening of the absorption range of the RE ions in the UV-blue region is still a challenge to develop optical systems with high performance. In this work we synthesized Bi- and Er-codoped Y2O3 nanocrystals by means of Pechini type sol-gel process. X-ray powder diffraction (XRPD) and transmission electron microscopy (TEM) were performed to evaluate the nanocryst. particle size and phase. Photoluminescence investigation in the UV-vis and IR regions showed that the presence of Bi3+ ions promotes the strengthening of Er3+ emitter properties. In particular, an Er3+ sensitization process based on a broadband energy transfer mediated by the Bi3+ ions in the C2 site was evaluated, resulting in a wavelength spread for the photostimulation of the rare earth emissions in the visible and NIR range. We pointed out a resonant type via a dipole-dipole interaction as the most probable mechanism of energy transfer. Moreover, the crit. distance between the Bi3+ and Er3+ ions was estd. to be of about 8.5 Å.
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    15. 15
      Zhang, Y.; Wen, R.; Hu, J.; Guan, D.; Qiu, X.; Zhang, Y.; Kohane, D. S.; Liu, Q. Enhancement of single upconversion nanoparticle imaging by topologically segregated core-shell structure with inward energy migration. Nat. Commun. 2022, 13 (1), 5927,  DOI: 10.1038/s41467-022-33660-8
      15
      Enhancement of single upconversion nanoparticle imaging by topologically segregated core-shell structure with inward energy migration
      Zhang, Yanxin; Wen, Rongrong; Hu, Jialing; Guan, Daoming; Qiu, Xiaochen; Zhang, Yunxiang; Kohane, Daniel S.; Liu, Qian
      Nature Communications (2022), 13 (1), 5927CODEN: NCAOBW; ISSN:2041-1723. (Nature Portfolio)
      Abstr.: Manipulating topol. arrangement is a powerful tool for tuning energy migration in natural photosynthetic proteins and artificial polymers. Here, we report an inorg. optical nanosystem composed of NaErF4 and NaYbF4, in which topol. arrangement enhanced upconversion luminescence. Three architectures are designed for considerations pertaining to energy migration and energy transfer within nanoparticles: outside-in, inside-out, and local energy transfer. The outside-in architecture produces the max. upconversion luminescence, around 6-times brighter than that of the inside-out at the single-particle level. Monte Carlo simulation suggests a topol.-dependent energy migration favoring the upconversion luminescence of outside-in structure. The optimized outside-in structure shows more than an order of magnitude enhancement of upconversion brightness compared to the conventional core-shell structure at the single-particle level and is used for long-term single-particle tracking in living cells. Our findings enable rational nanoprobe engineering for single-mol. imaging and also reveal counter-intuitive relationships between upconversion nanoparticle structure and optical properties.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XisF2mu7rJ&md5=4afcc3d0ea6e2fd71911be621268ec7a
    16. 16
      Gargas, D. J.; Chan, E. M.; Ostrowski, A. D.; Aloni, S.; Altoe, M. V. P.; Barnard, E. S.; Sanii, B.; Urban, J. J.; Milliron, D. J.; Cohen, B. E.; Schuck, P. J. Engineering bright sub-10-nm upconverting nanocrystals for single-molecule imaging. Nat. Nanotechnol. 2014, 9 (4), 300– 305,  DOI: 10.1038/nnano.2014.29
      16
      Engineering bright sub-10-nm upconverting nanocrystals for single-molecule imaging
      Gargas, Daniel J.; Chan, Emory M.; Ostrowski, Alexis D.; Aloni, Shaul; Altoe, M. Virginia P.; Barnard, Edward S.; Sanii, Babak; Urban, Jeffrey J.; Milliron, Delia J.; Cohen, Bruce E.; Schuck, P. James
      Nature Nanotechnology (2014), 9 (4), 300-305CODEN: NNAABX; ISSN:1748-3387. (Nature Publishing Group)
      Imaging at the single-mol. level reveals heterogeneities that are lost in ensemble imaging expts., but an ongoing challenge is the development of luminescent probes with the photostability, brightness and continuous emission necessary for single-mol. microscopy. Lanthanide-doped upconverting nanoparticles overcome problems of photostability and continuous emission and their upconverted emission can be excited with near-IR light at powers orders of magnitude lower than those required for conventional multiphoton probes. However, the brightness of upconverting nanoparticles was limited by open questions about energy transfer and relaxation within individual nanocrystals and unavoidable tradeoffs between brightness and size. Here, the authors develop upconverting nanoparticles under 10 nm in diam. that are over an order of magnitude brighter under single-particle imaging conditions than existing compns., allowing one to visualize single upconverting nanoparticles as small (d = 4.8 nm) as fluorescent proteins. The authors use advanced single-particle characterization and theor. modeling to find that surface effects become crit. at diams. under 20 nm and that the fluences used in single-mol. imaging change the dominant determinants of nanocrystal brightness. Factors known to increase brightness in bulk expts. lose importance at higher excitation powers and paradoxically, the brightest probes under single-mol. excitation are barely luminescent at the ensemble level.
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    17. 17
      Wu, D. M.; García-Etxarri, A.; Salleo, A.; Dionne, J. A. Plasmon-Enhanced Upconversion. J. Phys. Chem. Lett. 2014, 5 (22), 4020– 4031,  DOI: 10.1021/jz5019042
      17
      Plasmon-Enhanced Upconversion
      Wu, Di M.; Garcia-Etxarri, Aitzol; Salleo, Alberto; Dionne, Jennifer A.
      Journal of Physical Chemistry Letters (2014), 5 (22), 4020-4031CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)
      A review. Upconversion, the conversion of photons from lower to higher energies, is a process that promises applications ranging from high-efficiency photovoltaic and photocatalytic cells to background-free bioimaging and therapeutic probes. Existing upconverting materials, however, remain too inefficient for viable implementation. In this Perspective, the authors describe the significant improvements in upconversion efficiency that can be achieved using plasmon resonances. As collective oscillations of free electrons, plasmon resonances can be used to enhance both the incident electromagnetic field intensity and the radiative emission rates. To date, this approach showed upconversion enhancements up to 450×. Both theor. underpinnings and exptl. demonstrations of plasmon-enhanced upconversion, examg. the roles of upconverter quantum yield, plasmonic geometry, and plasmon spectral overlap are discussed. The authors also discuss nonoptical consequences of including metal nanostructures near upconverting emitters. The rapidly expanding field of plasmon-enhanced upconversion provides novel fundamental insight into nanoscale light-matter interactions while improving prospects for technol. relevance.
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    18. 18
      Qin, X.; Carneiro Neto, A. N.; Longo, R. L.; Wu, Y.; Malta, O. L.; Liu, X. Surface Plasmon–Photon Coupling in Lanthanide-Doped Nanoparticles. J. Phys. Chem. Lett. 2021, 12 (5), 1520– 1541,  DOI: 10.1021/acs.jpclett.0c03613
      There is no corresponding record for this reference.
    19. 19
      Park, W.; Lu, D.; Ahn, S. Plasmon enhancement of luminescence upconversion. Chem. Soc. Rev. 2015, 44 (10), 2940– 2962,  DOI: 10.1039/C5CS00050E
      19
      Plasmon enhancement of luminescence upconversion
      Park, Wounjhang; Lu, Dawei; Ahn, Sungmo
      Chemical Society Reviews (2015), 44 (10), 2940-2962CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
      Frequency conversion has always been an important topic in optics. Nonlinear optics has traditionally focused on frequency conversion based on nonlinear susceptibility but with the recent development of upconversion nanomaterials, luminescence upconversion has begun to receive renewed attention. While upconversion nanomaterials open doors to a wide range of new opportunities, they remain too inefficient for most applications. Incorporating plasmonic nanostructures provides a promising pathway to highly efficient upconversion. Naturally, a plethora of theor. and exptl. studies have been published in recent years, reporting enhancements up to several hundred. It is however difficult to make meaningful comparisons since the plasmonic fields are highly sensitive to the local geometry and excitation condition. Also, many luminescence upconversion processes involve multiple steps via different phys. mechanisms and the overall output is often detd. by a delicate interplay among them. This review is aimed at offering a comprehensive framework for plasmon enhanced luminescence upconversion. We first present quantum electrodynamics descriptions for all the processes involved in luminescence upconversion, which include absorption, emission, energy transfer and nonradiative transitions. We then present a bird's eye view of published works on plasmon enhanced upconversion, followed by more detailed discussion on comparable classes of nanostructures, the effects of spacer layers and local heating, and the dynamics of the plasmon enhanced upconversion process. Plasmon enhanced upconversion is a challenging and exciting field from the fundamental scientific perspective and also from technol. standpoints. It offers an excellent system to study how optical processes are affected by the local photonic environment. This type of research is particularly timely as the plasmonics is placing heavier emphasis on nonlinearity. At the same time, efficient upconversion could make a significant impact on many applications including solar energy conversion and biomedical imaging. The marriage of luminescent materials research with nanophotonics currently being initiated with plasmon enhanced upconversion research explores a new frontier in photonics that could potentially spawn many exciting new fields.
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      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXmtVeisbk%253D&md5=cfa8098ae6035bef1336adeb5662c26d
    20. 20
      Carneiro Neto, A. N.; Couto dos Santos, M. A.; Malta, O. L.; Reisfeld, R. 2 - Effects of Spherical Metallic Nanoparticle Plasmon on 4f–4f Luminescence: A Theoretical Approach. In Metal Nanostructures for Photonics, Kassab, L. R. P., de Araujo, C. B., Eds.; Elsevier, 2019; pp 19– 36.
      There is no corresponding record for this reference.
    21. 21
      Das, A.; Mao, C.; Cho, S.; Kim, K.; Park, W. Over 1000-fold enhancement of upconversion luminescence using water-dispersible metal-insulator-metal nanostructures. Nat. Commun. 2018, 9 (1), 4828,  DOI: 10.1038/s41467-018-07284-w
      21
      Over 1000-fold enhancement of upconversion luminescence using water-dispersible metal-insulator-metal nanostructures
      Das Ananda; Mao Chenchen; Cho Suehyun; Park Wounjhang; Kim Kyoungsik; Park Wounjhang
      Nature communications (2018), 9 (1), 4828 ISSN:.
      Rare-earth activated upconversion nanoparticles (UCNPs) are receiving renewed attention for use in bioimaging due to their exceptional photostability and low cytotoxicity. Often, these nanoparticles are attached to plasmonic nanostructures to enhance their photoluminescence (PL) emission. However, current wet-chemistry techniques suffer from large inhomogeneity and thus low enhancement is achieved. In this paper, we report lithographically fabricated metal-insulator-metal (MIM) nanostructures that show over 1000-fold enhancement of their PL. We demonstrate the potential for bioimaging applications by dispersing the MIMs into water and imaging bladder cancer cells with them. To our knowledge, our results represent one and two orders of magnitude improvement, respectively, over the best lithographically fabricated structures and colloidal systems in the literature. The large enhancement will allow for bioimaging and therapeutics using lower particle densities or lower excitation power densities, thus increasing the sensitivity and efficacy of such procedures while decreasing potential side effects.
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    22. 22
      Xu, J.; Dong, Z.; Asbahi, M.; Wu, Y.; Wang, H.; Liang, L.; Ng, R. J. H.; Liu, H.; Vallée, R. A. L.; Yang, J. K. W.; Liu, X. Multiphoton Upconversion Enhanced by Deep Subwavelength Near-Field Confinement. Nano Lett. 2021, 21 (7), 3044– 3051,  DOI: 10.1021/acs.nanolett.1c00232
      There is no corresponding record for this reference.
    23. 23
      Wu, Y.; Xu, J.; Poh, E. T.; Liang, L.; Liu, H.; Yang, J. K. W.; Qiu, C.-W.; Vallée, R. A. L.; Liu, X. Upconversion superburst with sub-2 μs lifetime. Nat. Nanotechnol. 2019, 14 (12), 1110– 1115,  DOI: 10.1038/s41565-019-0560-5
      23
      Upconversion superburst with sub-2 μs lifetime
      Wu, Yiming; Xu, Jiahui; Poh, Eng Tuan; Liang, Liangliang; Liu, Hailong; Yang, Joel K. W.; Qiu, Cheng-Wei; Vallee, Renaud A. L.; Liu, Xiaogang
      Nature Nanotechnology (2019), 14 (12), 1110-1115CODEN: NNAABX; ISSN:1748-3387. (Nature Research)
      The generation of anti-Stokes emission through lanthanide-doped upconversion nanoparticles is of great importance for technol. applications in energy harvesting, bioimaging and optical cryptog. However, the weak absorption and long radiative lifetimes of upconversion nanoparticles may significantly limit their use in imaging and labeling applications in which a fast spontaneous emission rate is essential. Here, we report the direct observation of upconversion superburst with directional, fast and ultrabright luminescence by coupling gap plasmon modes to nanoparticle emitters. Through precise control over the nanoparticle's local d. of state, we achieve emission amplification by four to five orders of magnitude and a 166-fold rate increase in spontaneous emission. We also demonstrate that tailoring the mode of the plasmonic cavity permits active control over the color output of upconversion emission. These findings may benefit the future development of rapid nonlinear image scanning nanoscopy and open up the possibility of constructing high-frequency, single-photon emitters driven by telecommunication wavelengths.
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      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitVCksLrK&md5=b3a9ecd285bf6a8c21d21a9c137206f2
    24. 24
      Zhang, W.; Ding, F.; Chou, S. Y. Large Enhancement of Upconversion Luminescence of NaYF4:Yb3+/Er3+ Nanocrystal by 3D Plasmonic Nano-Antennas. Advanced Materials 2012, 24 (35), OP236– OP241,  DOI: 10.1002/adma.201200220
      There is no corresponding record for this reference.
    25. 25
      Yin, Z.; Li, H.; Xu, W.; Cui, S.; Zhou, D.; Chen, X.; Zhu, Y.; Qin, G.; Song, H. Local Field Modulation Induced Three-Order Upconversion Enhancement: Combining Surface Plasmon Effect and Photonic Crystal Effect. Adv. Mater. 2016, 28, 2518– 2525,  DOI: 10.1002/adma.201502943
      25
      Local Field Modulation Induced Three-Order Upconversion Enhancement: Combining Surface Plasmon Effect and Photonic Crystal Effect
      Yin, Ze; Li, Hang; Xu, Wen; Cui, Shaobo; Zhou, Donglei; Chen, Xu; Zhu, Yongsheng; Qin, Guanshi; Song, Hongwei
      Advanced Materials (Weinheim, Germany) (2016), 28 (13), 2518-2525CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)
      The authors present a novel device and significant modulation of gold nanorods (AuNRs)/Polymethylmethacrylate (PMMA) opal photonic crystals (OPCs) surface plasmon photonic crystal (SPPC) on upconversion luminescence (UCL) of NaYF4:Yb3+, Er3+ NPs, which has perfectly combined surface plasmon effect of AuNRs and PC effects of 3D PMMA opals. In the hybrids, the UCL of NaYF4:Yb3+, Er3+ has been enhanced more than 103 folds, which is at least an order of magnitude higher than that reported by the previous literature.
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      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhslWmtbo%253D&md5=07d0b8799ca9e810b43b8bca15c439ff
    26. 26
      Chen, X.; Xu, W.; Zhang, L.; Bai, X.; Cui, S.; Zhou, D.; Yin, Z.; Song, H.; Kim, J. Large Upconversion Enhancement in the “Islands” Au–Ag Alloy/NaYF4: Yb3+, Tm3+/Er3+ Composite Films, and Fingerprint Identification. Adv. Funct. Mater. 2015, 25, 5462– 5471,  DOI: 10.1002/adfm.201502419
      26
      Large Upconversion Enhancement in the "Islands" Au-Ag Alloy/NaYF4: Yb3+, Tm3+/Er3+ Composite Films, and Fingerprint Identification
      Chen, Xu; Xu, Wen; Zhang, Lihang; Bai, Xue; Cui, Shaobo; Zhou, Donglei; Yin, Ze; Song, Hongwei; Kim, Dong-Hwan
      Advanced Functional Materials (2015), 25 (34), 5462-5471CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)
      The surface plasmon (SP) modulation is a promised way to highly improve the strength of upconversion luminescence (UCL) and expand its applications. The islands Au-Ag alloy film is prepd. by an org. removal template method and explored to improve the UCL of NaYF4: Yb3+, Tm3+/Er3+. After the optimization of Au-Ag molar ratio (Au1.25-Ag0.625) and the size of NaYF4 nanoparticles (NPs, ≈7 nm), an optimum enhancement ≤180 folds is obtained (by reflection measurement) for the overall UCL intensity of Tm3+. Systematic studies indicate that the UCL enhancement factor (EF) increases with the increased size of metal NPs and the increase of diffuse reflection, with the decreased size of NaYF4 NPs, with the decreased power d. of excitation light and with improving order of multiphoton populating. The total decay rate varies only ranging of ∼20% while EF changes significantly. All the facts above indicate that the UCL enhancement mainly originates from coupling of SP with the excitation electromagnetic field. Also, the fingerprint identification based on SP-enhanced UCL is realized in the metal/UC system, which provides a novel insight for the application of the metal/UC device.
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    27. 27
      Shen, J.; Li, Z. Q.; Chen, Y. R.; Chen, X. H.; Chen, Y. W.; Sun, Z.; Huang, S. M. Influence of SiO2 layer thickness on plasmon enhanced upconversion in hybrid Ag/SiO2/NaYF4:Yb, Er, Gd structures. Appl. Surf. Sci. 2013, 270, 712– 717,  DOI: 10.1016/j.apsusc.2013.01.133
      There is no corresponding record for this reference.
    28. 28
      Feng, A. L.; You, M. L.; Tian, L.; Singamaneni, S.; Liu, M.; Duan, Z.; Lu, T. J.; Xu, F.; Lin, M. Distance-Dependent Plasmon-Enhanced Fluorescence of Upconversion Nanoparticles using Polyelectrolyte Multilayers as Tunable Spacers. Sci. Rep. 2015, 5 (1), 7779,  DOI: 10.1038/srep07779
      28
      Distance-Dependent Plasmon-Enhanced Fluorescence of Upconversion Nanoparticles using Polyelectrolyte Multilayers as Tunable Spacers
      Feng, Ai Ling; You, Min Li; Tian, Limei; Singamaneni, Srikanth; Liu, Ming; Duan, Zhenfeng; Lu, Tian Jian; Xu, Feng; Lin, Min
      Scientific Reports (2015), 5 (), 7779CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)
      Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted widespread interests in bioapplications due to their unique optical properties by converting near IR excitation to visible emission. However, relatively low quantum yield prompts a need for developing methods for fluorescence enhancement. Plasmon nanostructures are known to efficiently enhance fluorescence of the surrounding fluorophores by acting as nanoantennae to focus elec. field into nano-vol. Here, we reported a novel plasmon-enhanced fluorescence system in which the distance between UCNPs and nanoantennae (gold nanorods, AuNRs) was precisely tuned by using layer-by-layer assembled polyelectrolyte multilayers as spacers. By modulating the aspect ratio of AuNRs, localized surface plasmon resonance (LSPR) wavelength at 980 nm was obtained, matching the native excitation of UCNPs resulting in max. enhancement of 22.6-fold with 8 nm spacer thickness. These findings provide a unique platform for exploring hybrid nanostructures composed of UCNPs and plasmonic nanostructures in bioimaging applications.
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    29. 29
      Saboktakin, M.; Ye, X.; Oh, S. J.; Hong, S.-H.; Fafarman, A. T.; Chettiar, U. K.; Engheta, N.; Murray, C. B.; Kagan, C. R. Metal-Enhanced Upconversion Luminescence Tunable through Metal Nanoparticle–Nanophosphor Separation. ACS Nano 2012, 6 (10), 8758– 8766,  DOI: 10.1021/nn302466r
      29
      Metal-Enhanced Upconversion Luminescence Tunable through Metal Nanoparticle-Nanophosphor Separation
      Saboktakin, Marjan; Ye, Xingchen; Oh, Soong Ju; Hong, Sung-Hoon; Fafarman, Aaron T.; Chettiar, Uday K.; Engheta, Nader; Murray, Christopher B.; Kagan, Cherie R.
      ACS Nano (2012), 6 (10), 8758-8766CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      The authors demonstrated amplification of luminescence in upconversion nanophosphors (UCNPs) of hexagonal phase NaYF4 (β-NaYF4) doped with the lanthanide dopants Yb3+, Er3+ or Yb3+, Tm3+ by close proximity to metal nanoparticles (NPs). The authors present a configuration in which close-packed monolayers of UCNPs are sepd. from a dense multilayer of metal NPs (Au or Ag) by a nanometer-scale oxide grown by at. layer deposition. Luminescence enhancements are dependent on the thickness of the oxide spacer layer and the type of metal NP with enhancements of up to 5.2-fold proximal to Au NPs and of up to 45-fold proximal to Ag NPs. Concomitant shortening of the UCNP luminescence decay time and rise time is indicative of the enhancement of the UCNP luminescence induced by resonant plasmonic coupling and nonresonant near-field enhancement from the metal NP layer, resp.
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    30. 30
      Luo, Q.; Chen, Y.; Li, Z.; Zhu, F.; Chen, X.; Sun, Z.; Wei, Y.; Guo, H.; Bo Wang, Z.; Huang, S. Large enhancements of NaYF4:Yb/Er/Gd nanorod upconversion emissions via coupling with localized surface plasmon of Au film. Nanotechnology 2014, 25 (18), 185401,  DOI: 10.1088/0957-4484/25/18/185401
      There is no corresponding record for this reference.
    31. 31
      Yin, Z.; Zhou, D.; Xu, W.; Cui, S.; Chen, X.; Wang, H.; Xu, S.; Song, H. Plasmon-Enhanced Upconversion Luminescence on Vertically Aligned Gold Nanorod Monolayer Supercrystals. ACS Appl. Mater. Interfaces 2016, 8 (18), 11667– 11674,  DOI: 10.1021/acsami.5b12075
      There is no corresponding record for this reference.
    32. 32
      Schietinger, S.; Aichele, T.; Wang, H.-Q.; Nann, T.; Benson, O. Plasmon-Enhanced Upconversion in Single NaYF4:Yb3+/Er3+ Codoped Nanocrystals. Nano Lett. 2010, 10 (1), 134– 138,  DOI: 10.1021/nl903046r
      32
      Plasmon-Enhanced Upconversion in Single NaYF4:Yb3+/Er3+ Codoped Nanocrystals
      Schietinger, Stefan; Aichele, Thomas; Wang, Hai-Qiao; Nann, Thomas; Benson, Oliver
      Nano Letters (2010), 10 (1), 134-138CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      In this Letter the authors report the plasmon-enhanced upconversion in single NaYF4 nanocrystals codoped with Yb3+/Er3+. Single nanocrystals and Au nanospheres were studied and assembled in a combined confocal and at. force microscope setup. The nanocrystals show strong upconversion emission in the green and red under excitation with a continuous wave laser in the near-IR at 973 nm. Using the at. force microscope, the authors couple single nanocrystals with Au spheres (30 and 60 nm in diam.) to obtain enhanced upconversion emission. An overall enhancement factor of 3.8 is reached. A comparison of time-resolved measurements on the bare nanocrystal and the coupled nanocrystal-Au sphere systems unveil that faster excitation as well as faster emission occurs in the nanocrystals.
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    33. 33
      Alizadehkhaledi, A.; Frencken, A. L.; Dezfouli, M. K.; Hughes, S.; van Veggel, F. C. J. M.; Gordon, R. Cascaded Plasmon-Enhanced Emission from a Single Upconverting Nanocrystal. ACS Photonics 2019, 6 (5), 1125– 1131,  DOI: 10.1021/acsphotonics.9b00285
      33
      Cascaded Plasmon-Enhanced Emission from a Single Upconverting Nanocrystal
      Alizadehkhaledi, Amirhossein; Frencken, Adriaan L.; Dezfouli, Mohsen Kamandar; Hughes, Stephen; van Veggel, Frank C. J. M.; Gordon, Reuven
      ACS Photonics (2019), 6 (5), 1125-1131CODEN: APCHD5; ISSN:2330-4022. (American Chemical Society)
      Plasmonics was used to enhance light-matter interaction at the extreme subwavelength scale. Intriguingly, it is possible to achieve multiple plasmonic resonances from a single nanostructure, and these can be used in combination to provide cascaded enhanced interactions. Here, the authors demonstrate three distinct plasmon resonances for enhanced upconversion emission from a single upconverting nanocrystal trapped in a metal nanoaperture optical tweezer. For apertures where the plasmonic resonances occur at the emission wavelengths only, a moderate enhancement of a factor of 4 is seen. However, by tuning the aperture to enhance the excitation laser as well, an addnl. factor of 100 enhancement in the emission is achieved. Since lanthanide-doped nanocrystals are stable emitters, this approach of using multiple subwavelength resonances can improve applications including photovoltaics, photocatalysis, and imaging. The nanocrystals can also contain only single ions, allowing for studying quantum emitter properties and applications to single-photon sources.
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      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXmvFSjtL4%253D&md5=f66bdacb6a8ea84438e43e404febef5c
    34. 34
      Alizadehkhaledi, A.; Frencken, A. L.; van Veggel, F. C. J. M.; Gordon, R. Isolating Nanocrystals with an Individual Erbium Emitter: A Route to a Stable Single-Photon Source at 1550 nm Wavelength. Nano Lett. 2020, 20 (2), 1018– 1022,  DOI: 10.1021/acs.nanolett.9b04165
      34
      Isolating Nanocrystals with an Individual Erbium Emitter: A Route to a Stable Single-Photon Source at 1550 nm Wavelength
      Alizadehkhaledi, Amirhossein; Frencken, Adriaan L.; van Veggel, Frank C. J. M.; Gordon, Reuven
      Nano Letters (2020), 20 (2), 1018-1022CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      Single-photon emitters based on individual atoms or individual at.-like defects are highly sought-after components for future quantum technologies. A key challenge in this field is how to isolate just one such emitter; the best approaches still have an active emitter yield of only 50% so that deterministic integration of single active emitters is not yet possible. Here, we demonstrate the ability to isolate individual erbium emitters embedded in 20 nm nanocrystals of NaYF4 using plasmonic aperture optical tweezers. The optical tweezers capture the nanocrystal, whereas the plasmonic aperture enhances the emission of the Er and allows the measurement of discrete emission rate values corresponding to different nos. of erbium ions. Three sep. synthesis runs show near-Poissonian distribution in the discrete levels of emission yield that correspond to the expected ion concns., indicating that the yield of active emitters is approx. 80%. Fortunately, the trap allows for selecting the nanocrystals with only a single emitter, and so this gives a route to isolating and integrating single emitters in a deterministic way. This demonstration is a promising step toward single-photon quantum information technologies that utilize single ions in a solid-state medium, particularly because Er emits in the low-loss fiber-optic 1550 nm telecom band.
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    35. 35
      Rodriguez-Sevilla, P.; Rodriguez-Rodriguez, H.; Pedroni, M.; Speghini, A.; Bettinelli, M.; Sole, J. G.; Jaque, D.; Haro-Gonzalez, P. Assessing Single Upconverting Nanoparticle Luminescence by Optical Tweezers. Nano Lett. 2015, 15 (8), 5068– 5074,  DOI: 10.1021/acs.nanolett.5b01184
      35
      Assessing Single Upconverting Nanoparticle Luminescence by Optical Tweezers
      Rodriguez-Sevilla, P.; Rodriguez-Rodriguez, H.; Pedroni, M.; Speghini, A.; Bettinelli, M.; Sole, J. Garcia; Jaque, D.; Haro-Gonzalez, P.
      Nano Letters (2015), 15 (8), 5068-5074CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      Stable, long-term immobilization and localization are reported of a single colloidal Er3+/Yb3+-codoped SrF2 upconverting fluorescent nanoparticle (UCNP) by optical trapping with a single IR laser beam. Contrary to expectations, the single UCNP emission differs from that generated by an assembly of UCNPs. The differences can be explained in terms of modulations caused by radiation-trapping, a phenomenon not considered before but that is revealed to be of great relevance.
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      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtVOnt7%252FN&md5=460cc876f33a3f7585c5717b0daa0b90
    36. 36
      Rodriguez-Sevilla, P.; Zhang, Y.; de Sousa, N.; Marques, M. I.; Sanz-Rodriguez, F.; Jaque, D.; Liu, X.; Haro-Gonzalez, P. Optical Torques on Upconverting Particles for Intracellular Microrheometry. Nano Lett. 2016, 16 (12), 8005– 8014,  DOI: 10.1021/acs.nanolett.6b04583
      There is no corresponding record for this reference.
    37. 37
      Baffou, G.; Polleux, J.; Rigneault, H.; Monneret, S. Super-Heating and Micro-Bubble Generation around Plasmonic Nanoparticles under cw Illumination. J. Phys. Chem. C 2014, 118 (9), 4890– 4898,  DOI: 10.1021/jp411519k
      37
      Super-Heating and Micro-Bubble Generation around Plasmonic Nanoparticles under cw Illumination
      Baffou, Guillaume; Polleux, Julien; Rigneault, Herve; Monneret, Serge
      Journal of Physical Chemistry C (2014), 118 (9), 4890-4898CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
      Under illumination, metal nanoparticles can turn into ideal nanosources of heat due to enhanced light absorption at the plasmonic resonance wavelength. In this article, we aim at providing a comprehensive description of the generation of microbubbles in a liq. occurring around plasmonic nanoparticles under continuous illumination. We focus on a common situation where the nanoparticles are located on a solid substrate and immersed in water. Exptl., we evidenced a series of singular phenomena: (i) the bubble lifetime after heating can reach several minutes, (ii) the bubbles are not made of water steam but of air, and (iii) the local temp. required to trigger bubble generation is much larger than 100 °C: This last observation evidences that superheated liq. water, up to 220 °C, is easy to achieve in plasmonics, under ambient pressure conditions and even over arbitrary large areas. This could lead to new chem. synthesis approaches in solvothermal chem.
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    38. 38
      Baffou, G.; Quidant, R.; García de Abajo, F. J. Nanoscale Control of Optical Heating in Complex Plasmonic Systems. ACS Nano 2010, 4 (2), 709– 716,  DOI: 10.1021/nn901144d
      38
      Nanoscale Control of Optical Heating in Complex Plasmonic Systems
      Baffou, Guillaume; Quidant, Romain; Garcia de Abajo, F. Javier
      ACS Nano (2010), 4 (2), 709-716CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      The authors introduce a numerical technique to study the temp. distribution in arbitrarily complex plasmonic systems subject to external illumination. The authors perform both electromagnetic and thermodn. calcns. based upon a time-efficient boundary element method. Two kinds of plasmonic systems are studied to illustrate the potential of such a technique. First, the authors focus on individual particles with various morphologies. In analogy with electrostatics, the authors introduce the concept of thermal capacitance. This geometry-dependent quantity allows one to assess the temp. increase inside a plasmonic particle from the sole knowledge of its absorption cross section. The authors present universal thermal-capacitance curves for ellipsoids, rods, disks, and rings. Addnl., the authors study assemblies of nanoparticles in close proximity and show that, despite its diffusive nature, the temp. distribution can be made highly nonuniform even at the nanoscale using plasmonic systems. A significant degree of nanoscale control over the individual temps. of neighboring particles is demonstrated, depending on the external light wavelength and direction of incidence. The authors illustrate this concept with simulations of Au sphere dimers and chains in H2O. Work opens new possibilities for selectively controlling processes such as local melting for dynamic patterning of textured materials, chem. and metabolic thermal activation, and heat delivery for producing mech. motion with spatial precision in the nanoscale.
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      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXivFOhug%253D%253D&md5=e3e740a7473be2c9df86549d01f68324
    39. 39
      Domínguez-García, P. Brownian Disks Lab: Simulating time-lapse microscopy experiments for exploring microrheology techniques and colloidal interactions. Comput. Phys. Commun. 2020, 252, 107123,  DOI: 10.1016/j.cpc.2019.107123
      There is no corresponding record for this reference.
    40. 40
      Qi, P.; Dai, Y.; Luo, Y.; Tao, G.; Zheng, L.; Liu, D.; Zhang, T.; Zhou, J.; Shen, B.; Lin, F.; Liu, Z.; Fang, Z. Giant excitonic upconverted emission from two-dimensional semiconductor in doubly resonant plasmonic nanocavity. Light: Science & Applications 2022, 11 (1), 176,  DOI: 10.1038/s41377-022-00860-2
      There is no corresponding record for this reference.
    41. 41
      Feng, Z.; Hu, D.; Liang, L.; Xu, J.; Cao, Y.; Zhan, Q.; Guan, B.-O.; Liu, X.; Li, X. Laser-Splashed Plasmonic Nanocrater for Ratiometric Upconversion Regulation and Encryption. Advanced Optical Materials 2019, 7 (19), 1900610,  DOI: 10.1002/adom.201900610
      There is no corresponding record for this reference.
    42. 42
      Li, X.; Cheng, Y.; Xu, J.; Lin, H.; Wang, Y. Utilizing Au–CuS heterodimer to intensify upconversion emission of NaGdF4:Yb/Er nanocrystals. J. Mater. Sci. 2020, 55 (16), 6891– 6902,  DOI: 10.1007/s10853-020-04512-x
      There is no corresponding record for this reference.
    43. 43
      Pan, C.; Ma, Q.; Liu, S.; Xue, Y.; Fang, Z.; Zhang, S.; Qin, M.; Wu, E.; Wu, B. Angularly anisotropic tunability of upconversion luminescence by tuning plasmonic local-field responses in gold nanorods antennae with different configurations. Nanophotonics 2022, 11 (10), 2349– 2359,  DOI: 10.1515/nanoph-2022-0037
      There is no corresponding record for this reference.

  • Supporting Information

    Supporting Information

    The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.nanolett.4c00379.

    • Synthesis of the UCNPs, fabrication of the plasmonic substrate, experimental details, simulation of Brownian motion, numerical simulation models, and methods (PDF)

    • Bubble formation due to excessive heating (video)


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