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Enhanced upconversion luminescence intensity of core-shell NaYF4 nanocrystals guided by morphological control
摘要： How to further increase the upconversion luminescence (UCL) efficiency of core-shell upconversion nanoparticles (UCNPs) is highly desirable for their photoelectric and biological applications. Herein, a novel but facile strategy is proposed to substantially enhance the UCL intensity of NaYF4 based core-shell UCNPs by morphological control. The morphologies of core-shell UCNPs can be optimized from rod-like to spherical like by changing the ratio of oleic acid (OA) to 1-octadecene (ODE) during the shell growth process with other reaction conditions constant. The mechanism of shape control is further investigated based on the competitive absorption between OA molecules and lanthanide ions (Y3+, Yb3+, Er3+ or Tm3+) onto the different crystal axes (a, b and c) to guide their shell growth speed. The absolute quantum yields were up to 2.7 % and 1.8 % for spherical and rod like core-shell UCNPs under excitation of 980 nm laser (power density of 1.6 W/cm2), respectively. Moreover, the UCL intensity and effective lifetime (τeff) of Er3+ emission at 541 nm of spherical like core-shell UCNPs increased by 11.7 and 1.82 folds than rod like core-shell UCNPs. Therefore, our designed novel strategy can greatly improve the UCL efficiency of core-shell UCNPs and promote their development in diverse applications.
关键词： upconversion nanoparticles,upconversion luminescence,core-shell structure,morphological control
更新于2025-09-23 15:23:52
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Oligo(ethylene glycol)/alkyl-modified chromophore assemblies for photon upconversion in water
摘要： Molecular self-assembly is a powerful means to construct nanoscale materials with advanced photophysical properties. Although the protection of the photo-excited states from oxygen quenching is a critical issue, it still has been in an early phase of development. In this work, we demonstrate that a simple and typical molecular design for aqueous supramolecular assembly, modification of chromophoric unit with hydrophilic oligo(ethylene glycol) chains and hydrophobic alkyl chains, is effective to avoid oxygen quenching of triplet-triplet annihilation-based photon upconversion (TTA-UC). While a TTA-UC emission is completely quenched when the donor and acceptor are molecularly dispersed in chloroform, their aqueous co-assemblies exhibit a clear upconverted emission in air-saturated water even under extremely low chromophore concentrations down to 40 μM. The generalization of this nano-encapsulation approach offers new functions and applications using oxygen-sensitive species for supramolecular chemistry.
关键词： photon upconversion,photochemistry,oxygen quenching,self-assembly,triplet-triplet annihilation
更新于2025-09-23 15:23:52
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Inorganic Protection of Polymer Nanocapsules: A Strategy to Improve the Efficiency of Encapsulated Optically Active Molecules
摘要： We demonstrate that the efficiency under ambient conditions of optically active molecules encapsulated in polymer nanocapsules can be significantly improved by depositing an inorganic layer onto the polymeric shell. A triplet-triplet annihilation upconversion (TTA-UC) system consisting of a porphyrin derivative and perylene is used as a representative case. Different inorganic materials are deposited on the surface of functionalized polymer nanocapsules synthesized by free-radical polymerization in miniemulsion. First, a silicate clay with formula [Si8(Mg5.45Li0.4)O20(OH)4]Na0.7 is deposited on the surface of positively charged polystyrene nanocapsules via layer-by-layer deposition. Second, controlled in situ mineralization of hydroxyapatite and cerium(IV) oxide are carried out on the surface of negatively charged polystyrene nanocapsules. In both cases the inorganic materials on the nanocapsule surface act as a scavenger and avoid the entry of oxygen from the external environment. By avoiding the entry of oxygen, the photo-oxidation process of perylene molecules is avoided within the system, and an increase in the TTA-UC properties occurs.
关键词： upconversion,nanocapsule,crystallization,layer-by-layer,miniemulsion polymerization
更新于2025-09-23 15:23:52
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High Quantum Yield Single-Band Green Upconversion in La <sub/>2</sub> O <sub/>3</sub> :Yb <sup>3+</sup> , Ho <sup>3+</sup> Microcrystals for Anticounterfeiting and Plastic Recycling
摘要： Single-band green upconversion (UC) with high green purity and color stability is urgently required for plastic recycling and anticounterfeiting. However, it is very difficult to obtain single-band green emission for benchmark Yb3+/Er3+ activated UC materials (such as NaYF4:Yb3+,Er3+) due to the strong accompanying red UC. Herein, highly efficient and stable single-band green UC is reported in La2O3:Yb3+/Ho3+ (LYH) microcrystals with record high absolute UC quantum yield (UCQY) of 2.6% for single-band green UC. LYH yields pure green UC with large and stable intensity ratio, IGreen/IRed ≈ 18. LYH presents not only higher UCQY for a single-band green UC but also much more pure and stable green UC than the benchmark UC materials such as NaYF4:Yb3+,Er3+ and Gd2O2S:Yb3+,Er3+. These results suggest that the newly developed LYH can, in principle, be promising for anticounterfeiting and plastic recycling. Its proof-of-concept is demonstrated as a security label based on a transparent institute logo.
关键词： anticounterfeiting,high UC quantum yield,plastic recycling,upconversion materials,pure green UC
更新于2025-09-23 15:23:52
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Smartphone-based apparatus for measuring upconversion luminescence lifetimes
摘要： Luminescence lifetime detection plays an important role in time-resolved detection and research. However, the traditional instruments always require expensive detectors such as time-correlated single photon counter or streak camera. Herein, a low-cost and miniaturized apparatus for measuring upconversion luminescence lifetimes was developed by using a smartphone equipped with a 980 nm CW laser and a motor. When the motor was driving the sample circling at a high linear velocity, the excited sample would emit a luminescence arc, which could be photographed by the phone camera. The rotating rate could be measured by a tuner APP and then used for transferring arc length to delay times. By analyzing the grayscale distribution of the luminescence arc, the luminescence decay curve was obtained, which was then used for exponential fit and calculating lifetimes. The whole system was not only remarkably cheaper but also more miniaturized than traditional instruments for measuring luminescence lifetimes, indicating the promising applications in point of care testing for time-resolved luminescence detection for bioanalysis and disease diagnosis.
关键词： Lanthanide upconversion,Luminescence lifetime,Time-resolved,Motor,Smartphone
更新于2025-09-23 15:23:52
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Multifunctional nanoclusters of NaYF4:Yb3+,Er3+ upconversion nanoparticle and gold nanorod for simultaneous imaging and targeted chemotherapy of bladder cancer
摘要： This paper reports successful synthesis of multifunctional nanoclusters of upconversion nanoparticle (UCNP) and gold nanorod (AuNR) through a PEGylation process. UCNPs emit visible luminescence under near-infrared excitation, producing high-contrast images with no background fluorescence. When coupled with AuNRs, the resulting UCNP-AuNR multifunctional nanoclusters are capable of simultaneous detection and treatment of bladder cancer. These UCNP-AuNR nanoclusters are further functionalized with antibodies to epidermal growth factor receptor (EGFR) to target bladder cancer cells known to overexpress EGFRs. This paper demonstrates, for the first time, efficient targeting of bladder cancer cells with UCNP-AuNR nanoclusters. In addition to high-contrast imaging and consequently high sensitivity detection of bladder cancer cells, highly selective optoporation-assisted chemotherapy was accomplished using a dosage of chemotherapy agent significantly lower than any previous reports, within a clinically relevant incubation time window. These results are highly relevant to the eventual human application in which the nanoclusters and chemotherapy drugs will be directly instilled in bladder via urinary catheter.
关键词： Luminescence upconversion,Surface Plasmon,Bladder Cancer,Gold Nanorod,Optoporation
更新于2025-09-23 15:23:52
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Efficient near-infrared photocatalysts based on NaYF4:Yb3+,Tm3+@NaYF4:Yb3+,Nd3+@TiO2 core@shell nanoparticles
摘要： In this work, we fabricated NaYF4:Yb3+,Tm3+@NaYF4:Yb3+,Nd3+@TiO2 (Tm@Nd@TiO2) core@shell nanoparticles and investigated their near-infrared (NIR) photocatalytic activities. Comparing to traditional TiO2 based upconversion (UC) photocatalysts (i.e., NaYF4:Yb3+,Tm3+@TiO2, named Tm@TiO2), Tm@Nd@TiO2 exhibits enhanced photocatalytic activity under NIR light irradiation. The photocatalytic activity of Tm@Nd@TiO2 under 980, 808, and 980+808 nm laser irradiation is 4.40, 5.84, and 9.83 times as high as that of Tm@TiO2 under only 980 nm irradiation, respectively. The ethylene degradation rate of Tm@Nd@TiO2 under 980+808 nm laser irradiation is 6.4 times as that of Tm@TiO2. The photocatalytic activity of Tm@Nd@TiO2 under visible+NIR irradiation is even comparable with (~2/3) that under UV light irradiation during Rhodamine B (RhB) degradation. The enhanced photocatalytic activity of Tm@Nd@TiO2 can be attributed to the stronger light absorption in NIR region ascribed to Nd3+, lower water absorption and the enhanced UC emission of Tm@Nd with unique core@shell nanostructures. This work can provide a possible route to improve the NIR photocatalytic activity and stimulate the applications in many other fields.
关键词： upconversion,near-infrared irradiation,photocatalyst,core@shell structure
更新于2025-09-23 15:23:52
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Wide Spectrum Photocatalytic Activity in Lanthanide-doped Upconversion Nanophosphors Coated with Porous TiO2 and Ag-Cu Bimetallic Nanoparticles
摘要： Approaches towards maximum utilization of solar light spectrum for photocatalysis have currently attracted great interest. The combination of profoundly different properties, such as, upconversion, semiconducting and plasmonic properties can produce a favorable path in efficient utilization of the different regions of solar light reaching to earth. In this regard, design and fabrication of microstructures consisting of upconverting lanthanide doped nanophosphors coated with porous semiconducting material, TiO2 and decorated with plasmonic Ag-Cu bimetallic nanoparticles is presented in this work. These microstructures display great stability and exceptional photocatalytic activity by absorbing wide spectrum from ultraviolet to near infrared. The photocatalytic activity could be attributed to the synergistic effects between the different components and the efficient energy transfer between them. The development of such sort of hybrid microstructures could pave way for the development of new materials for the efficient utilization of the wide spectrum of sunlight.
关键词： bimetallic plasmonic nanoparticles,titania,wide spectrum utilization,photocatalysis,Upconversion nanophosphors
更新于2025-09-23 15:23:52
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Multicolour tuning and perfect white emission from novel PbWO4:Yb3+:Ho3+:Tm3+ nanophosphor
摘要： Upconverting (UC) nanoparticles have been an eye-candy for the people of optical world in the past decade because of their stupendous luminescence properties, photostability, effective quantum efficiency and most of all for its voluminous power of converting Infra-red (IR) waves into visible radiation. In this article, we have successfully synthesized novel Yb3+, Ho3+, Tm3+ doped lead tungstate nanophosphor by facile hydrothermal technique, where the product can also be scaled up in a large quantity. The phase purity and structure of the samples were characterized using X-Ray diffractometer and the structural morphology was studied using FEG TEM which shows formation of nano sphere of about 30-40 nm. Photoluminescence studies of the nanophosphor were carried out using spectroflurophotometer which shows red, green and blue emission due to the energy level transitions viz 5F5 → 5I8 and 5S2/5F4 → 5I8 of Ho3+,1G4 → 3H6, of Tm3+ respectively. The pumping power variation data was recorded using variable power which implies that the UC mechanism is a mixture of two and three photon process. The biexponential decay kinetics experiment was also done using the pulse mood laser source which shows the mean lifetime of 21.09 μs, 12.03 μs and 29.43 μs for blue, green and red emission respectively. Due to the perfect intermixing of the red, green and blue emission in the optimum sample a bright white light is obtained with CIE coordinates indexed as (0.34573,0.3449). The correlated colour temperature (CCT) values of the bright white light was calculated using McCamy’s approximations and it was found to be 4960 K which is almost equivalent to the colour “Horizon Daylight”. The colour temperature found after calculation, must be eye-friendly and hence perfect for using in optoelectronics applications.
关键词： Luminescence,White Light,Upconversion,Hydrothermal,Nanophosphor
更新于2025-09-23 15:23:52
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Near-Infrared-Light Activatable Nanoparticles for Deep-Tissue-Penetrating Wireless Optogenetics
摘要： Optogenetics has been developed to control the activities and functions of cells with high spatiotemporal resolution, cell-type specificity, and flexibility. However, current optogenetic tools generally rely on visible light (e.g., blue or yellow) with shallow tissue penetration ability that does require invasive fiber-optic probes to deliver visible light into organs and animal tissues. This often results in a series of side effects, such as tissue damage and unwanted inflammation. Fortunately, the emerging wireless optogenetic tools that can respond to deep-tissue-penetrating near-infrared (NIR) light have attracted increasing attention due to their much-reduced damage to living organisms. There are mainly two types of NIR-activatable optogenetic tools: one uses lanthanide-doped upconversion nanoparticles to transduce NIR light to visible light to modulate classical opsin-expressing neurons; the other type couples with an NIR absorber to convert NIR light to heat to activate thermosensitive proteins. These NIR-activatable optogenetic tools enable low-invasive 'remote control' activation and inhibition of cellular signaling pathways. This approach has great potential to help create more innovative therapies for diseases like cancer, diabetes, and neuronal disorders in the near future. Therefore, this review article summarizes the recent advances on design strategies and synthetic methods of NIR-activatable nanomaterials for wireless optogenetic applications.
关键词： nanomaterials,near infrared,optogenetics,photothermal,upconversion
更新于2025-09-23 15:23:52