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Hybrid fluorescent liquid crystalline composites: directed assembly of quantum dots in liquid crystalline block copolymer matrices
摘要： Hybrid ?uorescent liquid crystalline (LC) composites containing inorganic quantum dots (QDs) are promising materials for many applications in optics, nanophotonics and display technology, combining the superior emission capability of QDs with the externally controllable optical properties of LCs. In this work, we propose the hybrid LC composites that were obtained by embedding CdSe/ZnS QDs into a series of host LC block copolymers of di?erent architectures by means of a two-stage ligand exchange procedure. The ABA/BAB triblock copolymers and AB diblock copolymers with di?erent polymerization degrees are composed of nematogenic phenyl benzoate acrylic monomer units and poly(4-vinylpyridine) blocks, which are capable of binding to the QD surface. Our results clearly show that the spatial distribution of QDs within composite ?lms as well as the formation of QD aggregates can be programed by varying the structure of the host block copolymer. The obtained composites form a nematic LC phase, with isotropization temperatures being close to those of the initial host block copolymers. In addition, the in?uence of the molecular architecture of the host block copolymers on ?uorescence properties of the obtained composites is considered. The described strategy for the QD assembly should provide a robust and conventional route for the design of highly ordered hierarchical hybrid materials for many practical applications.
关键词： liquid crystalline block copolymer matrices,ligand exchange procedure,fluorescence properties,CdSe/ZnS QDs,nematic LC phase,Hybrid ?uorescent liquid crystalline composites,quantum dots
更新于2025-09-23 15:19:57
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Aqueous synthesis of L-cysteine-modified cobalt-doped zinc selenide/zinc sulfide quantum dots with enhanced fluorescence
摘要： Cobalt-doped zinc selenide/zinc sulfide quantum dots have been successfully synthesized directly in aqueous solution by using L-cysteine as the modifier. The optical properties and structures of the as-prepared quantum dots have been characterized through transmission electron microscopy, X-ray powder diffraction, infrared spectrum, energy dispersive X-ray spectrum, ultraviolet-visible spectrum, and fluorescence spectrum. The results show that cobalt-doped zinc selenide/zinc sulfide quantum dots are spherical particles with a diameter around 2.8 nm, have good dispersity and have a cubic zinc blende structure. The effects of several synthesis conditions on the fluorescence properties of the as-prepared quantum dots are surveyed and the optimum synthesis conditions are found to be as follows: reaction solution pH of 10.0; molar ratio of L-cysteine to hydrogen selenide ions to zinc ions of 1.6:0.15:1; doping content of cobalt ions of 2%; molar ratio of shell (zinc sulfide) to core (cobalt-doped zinc selenide) of 1.5:1. The fluorescence quantum yield of the as-prepared quantum dots increases from 6.4% to 19% via doping with cobalt ions and the epitaxial growth of zinc sulfide shell. The L-cysteine modified on the surface of cobalt-doped zinc selenide/zinc sulfide quantum dots renders the quantum dots water-soluble and bioconjugation capable. The L-cysteine-modified cobalt-doped zinc selenide/zinc sulfide quantum dots will have potential applications in biological fluorescence analysis.
关键词： ZnSe:Co/ZnS,L-cysteine,Fluorescence,synthesis
更新于2025-09-23 15:19:57
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Mn-Doped ZnS Quantum dotsa?? An EffectiveNanoscale Sensor
摘要： Quantum dots (QDs), due inter alia to their colourtunable symmetry, narrow emission, broad absorption, stability, and solution processibility have received an upsurge of interest in the last decade as potential materials for diverse applications. Doped QDs, in particular, have gained significant attention as a new class of luminescent materials since dopants influence the optical behaviour of QDs. Therefore, doped ZnS QDs possess conspicuous properties like longer dopant emission lifetime and lower toxicity. The dopant emission lifetimes of transition-metal ions are longer than the energy-gap and defect-related luminescence of the host as well as the biological background fluorescence to offer immense prospect for removal of background fluorescence for sensing applications. Probes based on phosphorescence or fluorescence enhancement of QDs is crucial for the development of the detection capability. This current review highlights the optical property and various sensing strategies of Mn-doped ZnS QDs that make them exceptional probes for applications in sensing. The review not only intends to present an all-encompassing study of the well-documented usages of QDs, but is also rather addressing the current promising improvements, concepts, and excellent applications in research of doped QDs for chemo- and biosensing. Over 200 publications are overviewed and considered here in the perspective of leading applications in sensing dealing with for instance, fluorescence, phosphorescence, chemiluminescence, electrochemiluminescence and biosensing features.
关键词： Quantum dots,chemosensing,Mn-doped ZnS quantum dots,biosensing
更新于2025-09-23 15:19:57
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Synthesis of Water Soluble CuGaS2/ZnS Quantum Dots for Ultrasensitive Fluorescent Detection of Alkaline Phosphatase Based on Inner Filter Effect
摘要： Developing monitoring technique for alkaline phosphatase (ALP) is crucial due to the important role it plays in living cells. Here, a kind of biocompatible glutathione-modified CuGaS2/ZnS quantum dots (GSH-CGS/ZnS QDs) was used as a fluorescent substance and then fabricated “turn-off” fluorescent biosensor for detection of ALP by help of inner filter effect (IFE). Firstly, we prepared CuGaS2/ZnS (CGS/ZnS) QDs using solvothermal method and explored the efficient ligand (GSH) exchanges strategy for transferring oil-soluble CGS/ZnS QDs to aqueous phase. More importantly, we also explored the potential biological applications of the nanohybrid QDs. The obtained GSH-CGS/ZnS QDs emitted strong yellow fluorescence with the maximum excitation (400 nm) and emission (601 nm). Then, GSH-CGS/ZnS QDs were mixed with p-nitrophenylphosphate (PNPP) and ALP. PNPP could be hydrolyzed to p-nitrophenol (PNP) by help of catalysis of ALP, and the excitation spectrum of the GSH-CGS/ZnS QDs overlapped well with the absorption spectrum of PNP, so the fluorescence of GSH-CGS/ZnS QDs was initially quenched via the so-called “IFE”. Finally, a novel “turn-off” biosensor for sensitive detection of ALP in the range of 0.05-10 U L -1(R2 = 0.98) with a detection limit of 0.01 U L-1 was successfully obtained. Results indicated that I-III-VI2 nanocrystals have great potential for their promising biomedical application.
关键词： Inner filter effect,Alkaline phosphatase,GSH-CuGaS2/ZnS QDs,Fluorescent detection,Water solubility and biocompatibility
更新于2025-09-23 15:19:57
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<p>In vivo Comparison of the Biodistribution and Toxicity of InP/ZnS Quantum Dots with Different Surface Modifications</p>
摘要： In vivo Comparison of the Biodistribution and Toxicity of InP/ZnS Quantum Dots with Different Surface Modifications
关键词： in vivo,surface chemistry,nanotoxicology,biodistribution,InP/ZnS quantum dots
更新于2025-09-23 15:19:57
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Photophysical Properties of Multilayer Graphenea??Quantum Dots Hybrid Structures
摘要： Photoelectrical and photoluminescent properties of multilayer graphene (MLG)–quantum dots (QD) hybrid structures have been studied. It has been shown that the average rate of transfer from QDs to the MLG can be estimated via photoinduced processes on the QDs’ surfaces. A monolayer of CdSe QDs can double the photoresponse amplitude of multilayer graphene, without influencing its characteristic photoresponse time. It has been found that efficient charge or energy transfer from QDs to MLG with a rate higher than 3 × 108 s?1 strongly inhibits photoinduced processes on the QD surfaces and provides photostability for QD-based structures.
关键词： photophysical properties,CdSe–ZnS quantum dots,hybrid structures,photoelectrical properties,multilayered graphene,photoactivation
更新于2025-09-23 15:19:57
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Excess Random Laser Action in Memories for Hybrid Optical/Electric Logic
摘要： To surmount the scalability limitations of the nano-electronics industry, the invention of resistance random access memory (RRAM) has drawn considerable attention in recent years for being a new-era memory. Nevertheless, the data transmission speed of RRAM is confined by virtue of its sequential reading nature. To improve upon this weakness, a hybrid optical/electric memory with ION/IOFF ratio up to 105 and laser-level optical signal is proposed. The device was engineered through an adroit design of integrating a random laser (RL) into the conducting bridge random access memory (CBRAM). According to the electrochemical metallization (ECM) effect of CBRAM, agglomerative silver nanoparticles form in the insulating layer during the ON/OFF switching process, which can serve as scattering centers. By adding CdSe/ZnS quantum dots (QDs) as gain medium, a random laser system is obtained. Due to the quantum confinement effect, the device also features spectral tunable signal feedback by modulating the size of the QDs. In this study, devices with two different sizes of QDs are demonstrated such that a multiple-bits AND gate logic can be achieved. The innovation behind this RL-ECM memory might facilitate a key step toward the development of ultrahigh speed information technology.
关键词： RRAM,AND gate logic,random laser,electrochemical metallization effect,CdSe/ZnS colloidal quantum dots
更新于2025-09-23 15:19:57
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Alleviating the toxicity of quantum dots to Phanerochaete chrysosporium by sodium hydrosulfide and cysteine
摘要： Quantum dots (QDs) have caused large challenges in clinical tests and biomedical applications due to their potential toxicity from nanosize effects and heavy metal components. In this study, the physiological responses of Phanerochaete chrysosporium (P. chrysosporium) to CdSe/ZnS QDs with either an inorganic sulfide NaHS or an organic sulfide cysteine as antidote have been investigated. Scanning electron microscope analysis showed that the hyphal structure and morphology of P. chrysosporium have obviously changed after exposure to 100 nM of COOH CdSe/ZnS 505, NH2 CdSe/ZnS 505, NH2 CdSe/ZnS 565, or NH2 CdSe/ZnS 625. Fourier transform infrared spectroscopy analysis indicated that the existence of hydroxyl, amino, and carboxyl groups on cell surface could possibly conduct the stabilization of QDs in an aqueous medium. However, after NaHS or cysteine treatment, the cell viability of P. chrysosporium exposed to CdSe/ZnS QDs increased as compared to control group, since NaHS and cysteine have assisted P. chrysosporium to alleviate oxidative damage by regulating lipid peroxidation and superoxide production. Meanwhile, NaHS and cysteine have also stimulated P. chrysosporium to produce more antioxidant enzymes (superoxide dismutase and catalase), which played significant roles in the defense system. In addition, NaHS and cysteine were used by P. chrysosporium as sulfide sources to promote the glutathione biosynthesis to relieve CdSe/ZnS QDs-induced oxidative stress. This work revealed that sulfide sources (NaHS and cysteine) exerted a strong positive effect in P. chrysosporium against the toxicity induced by CdSe/ZnS QDs.
关键词： Detoxification,Cysteine,CdSe/ZnS quantum dots,Sodium hydrosulfide,Antioxidant enzymes,Oxidative stress
更新于2025-09-23 15:19:57
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Efficient quantum-dot light-emitting diodes using ZnSa??AgInS <sub/>2</sub> solid-solution quantum dots in combination with organic charge-transport materials
摘要： Colloidal quantum dots (QDs), which exhibit highly saturated color emission, are expected to be used as emitting materials in wide-color-gamut displays. However, the development of low-toxicity alternatives is necessary because QDs with high color purity and highly efficient emission contain toxic materials such as Cd and Pb. In this study, QD light-emitting diodes (QD-LEDs) with ZnS–AgInS2 solid-solution nanoparticles [(AgIn)xZn2(1?x)S2, ZAIS] as low-toxicity QDs were fabricated and their electroluminescence properties were investigated. The ZAIS QDs exhibited red photoluminescence, with a peak wavelength of ca. 700 nm. Because the charge-injection barrier of ZAIS QDs without a wide-bandgap shell is relatively low, the QD-LEDs with red ZAIS QDs in combination with organic charge-transport materials induce electron injection from an organic electron-transport layer. These QD-LEDs exhibit an external quantum efficiency of 2.2%, a turn-on voltage of 2.4 V, and red emission with chromaticity coordinates (0.66, 0.33).
关键词： quantum dots,electroluminescence,low-toxicity,light-emitting diodes,ZnS–AgInS2
更新于2025-09-23 15:19:57
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Efficient Perovskite Solar Cells Based on CdSe/ZnS Quantum Dots Electron Transporting Layer with Superior UV Stability
摘要： Stability is the main challenge in the field of perovskite solar cells (PSCs). Finding new strategies is required to protect the PSCs from deteriorated agents such as humidity, heating, and illumination. In this study, we propose a new electron transporting layer (ETL), i.e., CdSe/ZnS quantum dots (QDs) for the fabrication of efficient and stable PSCs. CdSe/ZnS QDs layer not only works as an ETL but also has down-shifting property, which can improve both efficiency and stability of the PSCs. Using CdSe/ZnS QDs ETL with green emission, a PSC with maximum power conversion efficiency (PCE) of 18% is achieved. More importantly, our device shows great UV stability much better than the device with TiO2 ETL, where it retains 90% of its initial PCE value after 75 h under continuous UV illumination.
关键词： down-shifting layer,perovskite,solar cell,CdSe/ZnS QDs,stability,UV stability
更新于2025-09-23 15:19:57