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oe1(光电查) - 科学论文

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出版时间
  • 2019
  • 2018
  • 2017
  • 2016
研究主题
  • Optical pattern
  • Phase diagram
  • Surfactants
  • Optical properties
  • TB-MBJ
  • FP-LAPW
  • Electronic structure
  • GGA
  • DFT
  • Infrared Radiation
应用领域
  • Optoelectronic Information Science and Engineering
  • Chemistry
  • Materials Science and Engineering
机构单位
  • University of Texas at Arlington
  • Macquarie University
  • Universiti Malaysia Terengganu
  • Devi Ahilya University
  • National Institute of Information and Communications Technologies (NICT)
  • Povolzhskiy State University of Telecommunications and Informatics (PSUTI)
  • University of Sa?da Dr Tahar Moulay
  • University of Djillali Liabes
  • Assumption University
  • National Institute of Advanced Industrial Science and Technology
4497 条数据
?? 中文（中国） ▾

  • Coordination geometry-induced optical imaging of <scp>l</scp> -cysteine in cancer cells using imidazopyridine-based copper( <scp>ii</scp> ) complexes

    摘要： Overexpression of cysteine cathepsins proteases has been documented in a wide variety of cancers, and enhances the L-cysteine concentration in tumor cells. We report the synthesis and characterization of copper(II) complexes [Cu(L1)2(H2O)](SO3CF3)2, 1, L1 = 3-phenyl-1-(pyridin-2-yl)imidazo[1,5-a]pyridine, [Cu(L2)2(SO3CF3)]SO3CF3, 2, L2 = 3-(4-methoxyphenyl)-1-pyridin-2-yl-imidazo[1,5-a]pyridine, [Cu(L3)2(H2O)](SO3CF3)2, 3, L3 = 3-(3,4-dimethoxy-phenyl)-1-pyridin-2-yl-imidazo[1,5-a]pyridine and [Cu(L4)2(H2O)](SO3CF3)2, 4, L4 = dimethyl-[4-(1-pyridin-2-yl-imidazo[1,5-a]pyridin-3-yl)phenyl]amine as 'turn-on' optical imaging probes for L-cysteine in cancer cells. The molecular structure of complexes adopted distorted trigonal pyramidal geometry (τ, 0.68–0.87). Cu–Npy bonds (1.964–1.989 ?) were shorter than Cu–Nimi bonds (2.024–2.074 ?) for all complexes. Geometrical distortion was strongly revealed in EPR spectra, showing gk (2.26–2.28) and Ak values (139–163 × 10?4 cm?1) at 70 K. The d–d transitions appeared around 680–741 and 882–932 nm in HEPES, which supported the existence of five-coordinate geometry in solution. The Cu(II)/Cu(I) redox potential of 1 (0.221 V vs. NHE) was almost identical to that of 2 and 3 but lower than that of 4 (0.525 V vs. NHE) in HEPES buffer. The complexes were almost non-emissive in nature, but became emissive by the interaction of L-cysteine in 100% HEPES at pH 7.34 via reduction of Cu(II) to Cu(I). Among the probes, probe 2 showed selective and efficient turn-on fluorescence behavior towards L-cysteine over natural amino acids with a limit of detection of 9.9 × 10?8 M and binding constant of 2.3 × 105 M?1. The selectivity of 2 may have originated from a nearly perfect trigonal plane adopted around a copper(II) center (～120.70°), which required minimum structural change during the reduction of Cu(II) to Cu(I) while imaging Cys. The other complexes, with their distorted trigonal planes, required more reorganizational energy, which resulted in poor selectivity. Probe 2 was employed for optical imaging of L-cysteine in HeLa cells and macrophages. It exhibited brighter fluorescent images by visualizing Cys at pH 7.34 and 37 °C. It showed relatively less toxicity for these cell lines as ascertained by the MTT assay.

    关键词： optical imaging,cancer cells,turn-on fluorescence,imidazopyridine,L-cysteine,Copper(II) complexes

    更新于2025-11-21 11:08:12

  • From colloidal CdSe quantum dots to microscale optically anisotropic supercrystals through bottom-up self-assembly

    摘要： The development of fabrication techniques for novel nanostructured materials is one of the key tasks of modern materials science. One pathway to successfully complete this task is the bottom-up assembly of colloidal nanoparticles into ordered superstructures, possessing both the properties of individual nanoparticles and further novel properties resulting from their interactions. However, nanoparticle self-assembly depends on a variety of parameters, which makes the precise control of this process a complicated problem. Here, the time course of quantum dot (QD) self-assembly into ordered superstructures has been analyzed, along with the evolution of their morphological and optical properties. QD self-assembly occurs through two distinct stages (homo- and hetero-geneous), leading to the formation of supercrystals with a layered morphology. Analysis of the optical properties throughout the superstructures’ growth has shown that the absorption and photoluminescence (PL) bands are blue shifted, retaining almost the same PL lifetimes as in the initial QD solution. The supercrystals formed possess a further unique optical property caused by their layered morphology; namely, a four-fold symmetry characterized by strong birefringence. Such supercrystals may be used for the fabrication of microscale optical paths with high extinction coefficients and specific polarization properties for novel optoelectronic devices.

    关键词： optical anisotropy,nanostructured materials,birefringence,self-assembly,quantum dots,supercrystals

    更新于2025-11-21 11:08:12

  • Spectrophotometric Characterization of Thin Copper and Gold Films Prepared by Electron Beam Evaporation: Thickness Dependence of the Drude Damping Parameter

    摘要： Copper and gold films with thicknesses between approximately 10 and 60 nm have been prepared by electron beam evaporation and characterized by spectrophotometry from the near infrared up to the near ultraviolet spectral regions. From near normal incidence transmission and reflection spectra, dispersion of optical constants have been determined by means of spectra fits utilizing a merger of the Drude model and the beta-distributed oscillator model. All spectra could be fitted in the full spectral region with a total of seven dispersion parameters. The obtained Drude damping parameters shows a clear trend to increase with decreasing film thickness. This behavior is discussed in the context of additional non-optical characterization results and turned out to be consistent with a simple mean-free path theory.

    关键词： optical constants,gold,copper,ultrathin metal films,thickness dependence

    更新于2025-11-21 11:01:37

  • Preserved two-photon optical properties of hydrophilic proteins-conjugated quantum dots

    摘要： Nonlinear optical properties of colloidal CdSe quantum dots conjugated with proteins were investigated in a wide spectral range with the two-photon excited emission technique using a tunable femtosecond laser system in the range from 700 to 1000 nm. The most signi?cant value of the two-photon absorption cross section σ2 for 2.9 nm size hydrophilic CdSe quantum dot was equal to 4 505 GM, while the two-photon excitation action cross section σ2·QY was found to be 0.101 GM at 900 nm. The nonlinear absorption properties are present as appropriate cross sections normalized per molecular weight which allows comparison of the nonlinear properties of the studied quantum dots with various nanosystems or organic dyes. The properties of these proteins covering hydrophilic colloidal quantum dots can be potentially useful for nonlinear bioimaging.

    关键词： Hydrophilization,Semiconducting quantum dots,Nonlinear optical properties,Nanophotonics,Proteins

    更新于2025-11-20 15:33:11

  • Near-Infrared-Laser-Driven Robust Glass-Ceramic-Based Upconverted Solid-State-Lighting

    摘要： Laser lighting, generally consisting of blue laser and downconversion phosphors, is considered to be the next promising illumination to replace traditional LED lighting. However, the irradiation of high-power blue laser will inevitably cause significant thermal attack, which puts forward high demand on phosphor converters as well as device architecture. In this work, a proof-of-concept prototype of near-infrared laser-driven upconversion solid-state-lighting is proposed. Robust lanthanide doped α/β-NaYF4 embedded glass ceramics are developed as upconverted color converters and routine 980 nm laser is used as pumping source for its relatively low thermal effect and a perfect resonance with Yb3+ sensitizers. Stable and bright upconversion white light is indeed produced by coupling Yb/Tm/Er doped α-NaYF4 glass ceramic with 980 nm laser but the luminous efficiency and energy efficiency are only 0.3 lm/W and 0.12%, respectively, owing to low Er doping concentration. As an alternative, a stacking structure of Yb/Tm doped glass ceramics and Yb/Er doped one is designed as color converter to improve luminous efficiency up to 1.0 lm/W and energy efficiency of 0.5% under a laser power density of 275 W/cm2. It is believed that this research will provide a new idea for laser lighting and open the application field of glass ceramics.

    关键词： upconversion,lanthanide ions,optical materials,glass ceramics,laser lighting

    更新于2025-11-20 15:33:11

  • Dual-mode luminescent core-shell nanoarchitectures for highly sensitive optical nanothermometry

    摘要： Currently, FIR-based luminescent nanothermometry has aroused wide concern for its promising applications in fast-moving objects, harsh environments and microscopic temperature. Synchronously promoting the absolute and relative sensitivities of optical thermometers is one of the significant issues at present. In this work, a new nanothermometry strategy to possess both high absolute and relative sensitivities have been proposed by coupling of thermally-coupled-levels-based technique with non-thermally-coupled-levels method in the core-shell designed nanomaterials. Following this strategy, the core-shell-structured NaGdF4:Yb,Er@ NaYF4:Ce,Tb,Eu nanocrystals have been successfully prepared. Remarkably, the adverse cross-relaxation among different activators is extremely suppressed owing to the spatial separation of Er3+ and Eu3+/Tb3+ activators, being conducive to the realization of both intense green upconverting emissions and yellow downshifting luminescence. Moreover, the temperature-sensitive dual-mode luminescent behaviors of core-shell nanomaterials are systematically studied to probe the possible application in FIR-related luminescent thermometry. Specially, the thermally-coupled-levels-based FIR of Er3+ : 2H11/2 / 4I15/2 to Er3+ : 4S3/2 / 4I15/2 and non-thermally-coupled-levels-based FIR of Eu3+ : 5D0 / 7F2 to Tb3+ : 5D4 / 7F6 are proved to be applicable as temperature probes, leading to the achievement of dual-mode temperature sensing. Using the pre-designed core@shell nanoarchitectures, the absolute sensitivity can reach up to 1.02% K-1 based on Eu3+/Tb3+ Stokes emissions and the relative sensitivity could reach as high as 1.12% K-1 based on Er3+ anti-Stokes luminescence. We believe that this study provides a valid approach for developing high-performance optical nanothermometers.

    关键词： Optical nanothermometry,Rare-earth luminescent materials,Dual-mode emission,Core-shell nanoarchitectures

    更新于2025-11-20 15:33:11

  • Grinding Synthesis of APbX3 (A=MA, FA, Cs; X=Cl, Br, I) Perovskite Nanocrystals

    摘要： Currently, metal halide perovskite nanocrystals have been extensively explored due to their unique optoelectronic properties and wide application prospects. In the present work, a facile grinding method is developed to prepare whole-family APbX3 (A=MA, FA and Cs; X=Cl, Br and I) perovskite nanocrystals. This strategy alleviates the harsh synthesis conditions of precursor dissolution, atmosphere protection and high temperature. Impressively, the as-prepared perovskite nanocrystals are evidenced to have halogen-rich surfaces and yield visible full-spectral emissions with maximal photoluminescence quantum yield up to 92% and excellent stability. Additionally, the grinding method can be extended to synthesize widely concerned Mn2+-doped CsPbCl3 nanocrystals with dual-modal emissions of both excitons and dopants. As a proof-of-concept experiment, the present perovskite nanocrystals are demonstrated to be applicable as blue/green/red color converters in UV-excitable white-light-emitting diode.

    关键词： perovskite,CsPbBr3,optical materials,luminescence,LED

    更新于2025-11-20 15:33:11

  • Up-conversion luminescence and highly sensing characteristics of Er3+/Yb3+ co-doped borophosphate glass-ceramics

    摘要： Er3+/Yb3+ co-doped phosphate glass ceramics (GC) with a cubic KAlSi2O6 type structure were successfully fabricated by traditional melt-quenching technique and subsequent heat treatment. Structural characterization of the GC was achieved by X-ray powder diffractometer (XRD) combined with transmission electron microscope (TEM). The up-conversion (UC) optical properties were systemically investigated through absorption spectra, photoluminescence spectra, pump power dependent UC emission spectra, and UC decay curves. The possible energy transfer process and the transition channels were analyzed by using energy level diagram. Results show that the UC luminescence performance of the GC was enhanced compared to precursor glass (PG). Moreover, the temperature dependent UC emission spectra of the GC were measured in the temperature range of 298–798K under 980 nm laser excitation. Combined with the fluorescence intensity ratio (FIR) technique, the UC emissions of Er3+/Yb3+ co-doped GC with two thermally coupled energy levels (TCELs) of 525 nm (Er3+:2H11∕2→4I15∕2) and 549 nm (Er3+:4S3∕2→4I15∕2) were studied as a function of temperature in the range of 298–798K. For optimized Er3+/Yb3+ co-doped GC, the theoretical maximum value of relative sensitivity Sr?max is 1.67 % K?1 at 298 K, and absolute sensitivity Sa?max is 4.59 ×10?3 K?1 at 570 K, which indicates that the Er3+/Yb3+ co-doped phosphate GC is a very promising candidate for optical temperature sensors with higher sensitivity.

    关键词： Glass ceramic,Optical thermometric,Up-conversion

    更新于2025-11-20 15:33:11

  • Laser-driven structural transformations in dextran- <i>graft</i> -PNIPAM copolymer/Au nanoparticles hybrid nanosystem: the role of plasmon heating and attractive optical forces

    摘要： Laser induced structural transformations in a dextran grafted-poly(N-isopropylacrylamide) copolymer/Au nanoparticles (D-g-PNIPAM/AuNPs) hybrid nanosystem in water have been observed. The laser induced local plasmonic heating of Au NPs leads to Lower Critical Solution Temperature (LCST) phase transition in D-g-PNIPAM/AuNPs macromolecules accompanied by their shrinking and aggregation. The hysteresis non-reversible character of the structural transformation in D-g-PNIPAM/AuNPs system has been observed at the decrease of laser intensity, i.e. the aggregates remains in solution after the turn-off the laser illumination. This is an essential difference comparing to the case of usual heating–cooling cycles when there is no formation of aggregates and structural transformations are reversible. Such a fundamental difference has been rationalized as the result of action of attractive optical forces arising due to the excitation of surface plasmons in Au NPs. The attractive plasmonic forces facilitate the formation of the aggregates and counteract their destruction. The laser induced structural transformations have been found to be very sensitive to matching conditions of the resonance of the laser light with surface plasmon resonance proving the plasmonic nature of observed phenomena.

    关键词： Plasmon heating,Attractive optical forces,LCST phase transition,Au nanoparticles,Laser induced structural transformations,Dextran-graft-PNIPAM copolymer

    更新于2025-11-19 16:56:42

  • Nitrogen-doped graphene quantum dots: Optical properties modification and photovoltaic applications

    摘要： In this work, we utilize a bottom-up approach to synthesize nitrogen self-doped graphene quantum dots (NGQDs) from a single glucosamine precursor via an eco-friendly microwave-assisted hydrothermal method. Structural and optical properties of as-produced NGQDs are further modified using controlled ozone treatment. Ozone-treated NGQDs (Oz-NGQDs) are reduced in size to 5.5 nm with clear changes in the lattice structure and ID/IG Raman ratios due to the introduction/alteration of oxygen-containing functional groups detected by Fourier-transform infrared (FTIR) spectrometer and further verified by energy dispersive X-ray spectroscopy (EDX) showing increased atomic/weight percentage of oxygen atoms. Along with structural modifications, GQDs experience decrease in ultraviolet–visible (UV–vis) absorption coupled with progressive enhancement of visible (up to 16 min treatment) and near-infrared (NIR) (up to 45 min treatment) fluorescence. This allows fine-tuning optical properties of NGQDs for solar cell applications yielding controlled emission increase, while controlled emission quenching was achieved by either blue laser or thermal treatment. Optimized Oz-NGQDs were further used to form a photoactive layer of solar cells with a maximum efficiency of 2.64% providing a 6-fold enhancement over untreated NGQD devices and a 3-fold increase in fill factor/current density. This study suggests simple routes to alter and optimize optical properties of scalably produced NGQDs to boost the photovoltaic performance of solar cells.

    关键词： photovoltaics,optical properties,ozone treatment,nitrogen-doped graphene quantum dots,solar cells

    更新于2025-11-19 16:56:42