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Nanoparticles for Bioapplications: Study of the Cytotoxicity of Water Dispersible CdSe(S) and CdSe(S)/ZnO Quantum Dots
摘要： Semiconductor nanocrystals or quantum dots (QDs) have unique optical and physical properties that make them potential imaging tools in biological and medical applications. However, concerns over the aqueous dispersivity, toxicity to cells, and stability in biological environments may limit the use of QDs in such applications. Here, we report an investigation into the cytotoxicity of aqueous dispersed CdSe(S) and CdSe(S)/ZnO core/shell QDs in the presence of human colorectal carcinoma cells (HCT-116) and a human skin fibroblast cell line (WS1). The cytotoxicity of the precursor solutions used in the synthesis of the CdSe(S) QDs was also determined in the presence of HCT-116 cells. CdSe(S) QDs were found to have a low toxicity at concentrations up to 100 μg/mL, with a decreased cell viability at higher concentrations, indicating a highly dose-dependent response. Meanwhile, CdSe(S)/ZnO core/shell QDs exhibited lower toxicity than uncoated QDs at higher concentrations. Confocal microscopy images of HCT-116 cells after incubation with CdSe(S) and CdSe(S)/ZnO QDs showed that the cells were stable in aqueous concentrations of 100 μg of QDs per mL, with no sign of cell necrosis, confirming the cytotoxicity data.
关键词： core/shell QDs,HCT-116,water dispersive QDs,WS1,bioapplications of QDs,aqueous synthesis,in vitro cytotoxicity of QDs
更新于2025-11-21 11:08:12
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A “turn off-on” fluorescent nanoprobe consisting of CuInS2 quantum dots for determination of the activity of β-glucosidase and for inhibitor screening
摘要： A fluorescent “turn off-on” nanoprobe is described for highly sensitive and selective determination of the activity of the enzyme β-glucosidase (β-Glu). Firstly, cysteine modified CuInS2 quantum dots (Cys-CuInS2 QDs) were prepared from indium(III) and copper(II) salts and the presence of thiourea. The red fluorescence of the Cys-CuInS2 QDs, with excitation/emission maxima at 590/656 nm, is quenched by Cu(II). However, in the presence of β-Glu and the cyanogenic glycoside, enzymatic hydrolysis leads to the formation of cyanide. The latter competitively binds to Cu(II) owing to its high affinity for cyanide. This restores the fluorescence of the Cys-CuInS2 QDs. Under the optimum conditions, fluorescence increases linearly in the 0.5–700 U·L?1 β-Glu activity range. The detection limit is 0.2 U·L?1. The nanoprobe was applied to analyze spiked soil samples, and satisfactory results were obtained. The average recoveries of β-Glu were in the range of 96–103%, and the RSD was lower than 4.0%. The fluorescent probe can also be used to screen for β-Glu inhibitors as demonstrated for castanospermine as an example.
关键词： Cys-CuInS2 QDs,Cu(II),Cyanide,Competitively binds,Cyanogenic glycoside,Soil,Enzyme activity,Fluorescence,Amygdalin,Castanospermine
更新于2025-11-19 16:46:39
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Kidney toxicity and response of selenium containing protein-glutathione peroxidase (Gpx3) to CdTe QDs on different levels
摘要： The toxic mechanism of cadmium-quantum dot (Cd-QDs) to organisms is still debating. In this paper, it was found that Cd-QDs could induce adverse effects to kidney by entering into cells in a time and dose manner and disturbing the redox balance in vivo. As a selenium containing protein, glutathione peroxidase3 (Gpx3) plays a crucial role in maintaining the balance of redox system. The decrease of Gpx3 activity might be related to the imbalance of redox system. Similar to the animal results, it was demonstrated that Gpx3 activity is also inhibited by Cd-QDs in vitro. To investigate the underlying mechanism of Cd-QDs on conformational and functional changes of Gpx3, systematical measurements including calorimetric, multi-spectroscopic studies and molecular model studies were carried out on molecular level. Results showed that Cd-QDs binds to Gpx3 via Van der Waals' force and hydrogen bonds, resulting in structural changes with increasing contents of α-helix. By interacting with Glu136 in the cavity of Gpx3 as well as Phe132, Pro130 and Van129 surrounded, Cd-QDs changes the micro-environment of fluorophore and further reduce the activity of Gpx3.
关键词： glutathione peroxidase3,redox balance,molecular mechanism,kidney toxicity,Cd-QDs
更新于2025-11-19 16:46:39
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A high-performance room temperature methanol gas sensor based on alpha-iron oxide/polyaniline/PbS quantum dots nanofilm
摘要： A high-performance room temperature methanol gas sensor based on alpha-iron oxide/polyaniline/lead sulfide quantum dots (α-Fe2O3/PANI/PbS QDs) nanofilm was demonstrated in this paper, among which the α-Fe2O3 was an urchin-shaped hollow microsphere. The sensing film was fabricated on an epoxy substrate with interdigital electrodes via successive ionic layer adsorption and reaction technique. The prepared α-Fe2O3/PANI/PbS QDs nanocomposite was examined by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, scanning election microscopy and Fourier transform infrared spectrum. The methanol sensing performances of the α-Fe2O3/PANI/PbS QDs film sensor were investigated against methanol from 10 to 100 ppm at room temperature. The experimental results indicated that the methanol sensor in this work had an excellent response, outstanding selectivity and good repeatability at room temperature. The underlying sensing mechanism of the α-Fe2O3/PANI/PbS QDs film toward methanol was ascribed to a series of interactions and changes on the surface of thin films, which make their resistance change greatly. Larger surface area and much more active adsorption sites also played an important role.
关键词： Methanol gas sensor,Room temperature,Successive ionic layer adsorption and reaction,Hydrothermal method,α-Fe2O3/PANI/PbS QDs
更新于2025-11-14 17:15:25
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Room temperature synthesis of stable single silica-coated CsPbBr3 quantum dots combining tunable red emission of Ag–In–Zn–S for High-CRI white light-emitting diodes
摘要： White light emitting diodes (WLEDs) based on all-inorganic halide (CsPbX3, X ? Cl, Br and I) perovskite quantum dots (QDs) have attracted broad attention due to their high brightness. However, their poor stability and anion-exchange reaction when utilized together are still the main challenges that impede their applications. Herein, a one-step in situ method under room temperature in air is proposed to synthesize CsPbBr3 QDs coated with SiO2 (CsPbBr3@SiO2), where the whole process takes only 20 s. The as-prepared CsPbBr3@SiO2 QDs samples present an enhanced stability in the thermal and polar-solvent environment, maintaining its high photoluminescence quantum yield (PLQY~75%). Thereby WLEDs are constructed by combining CsPbBr3@SiO2 with red Ag–In–Zn–S QDs on InGaN blue chip, achieving a high color rendering index (CRI) of 91, a correlated color temperature (CCT) of 3689 K and a power efficiency of 40.6 lm W?1.
关键词： WLEDs,Ag–In–Zn–S QDs,Stability,CsPbBr3 QDs
更新于2025-11-14 15:32:45
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Acetylene black quantum dots as a bridge for few-layer g-C3N4/MoS2 nanosheet architecture: 0D–2D heterojunction as an efficient visible-light-driven photocatalyst
摘要： Great progress has been made based on photocatalytic theory research in the past few years. There is, however, still a long way to go to popularize the application of photocatalytic materials. Here, we introduce a simple synthetic 0D–2D (D: dimensional) heterogeneous material with more efficient photocatalytic degradation. We construct acetylene black (AB) as a bridge to connect a graphitic carbon nitride (g-C3N4) nano-layer and two-dimensional MoS2 sandwich structure based on a simple hydrothermal synthesis and ultrasonic chemical loading. Loading 1% AB onto 2D g-C3N4/(x%)MoS2 not only accelerates the transfer of charge, but also reduces electron–hole recombination, which increases the photocatalytic efficiency per unit time. Studies have shown that the degradation rate of the ternary g-C3N4/AB/3.1%MoS2 catalytic materials can reach 94.29%, which is obviously higher than that of the pure g-C3N4 (80%) or MoS2 (51.74%) in degradation of methyl blue within 130 min. In this work, the ternary heterogeneous catalyst realizes the complementary characteristics between materials, broadens the photocatalytic properties and accelerates the degradation rate of pollutants, and provides a feasible solution to environmental friendliness.
关键词： Graphitic carbon nitride,Ternary photocatalyst,Photocatalytic degradation,QDs/g-C3N4/MoS2
更新于2025-11-14 15:32:45
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Peptide-Functionalized Quantum Dots for Rapid Label-Free Sensing of 2,4,6-Trinitrotoluene
摘要： Explosive compounds, such as 2,4,6-trinitrotoluene (TNT), pose a great concern in terms of both global public security and environmental protection. There are estimated to be hundreds of TNT contaminated sites all over the world, which will affect the health of humans, wildlife, and the ecosystem. Clearly, the ability to detect TNT in soils, water supplies, and wastewater is important for environmental studies but also important for security, such as in ports and boarders. However, conventional spectroscopic detection is not practical for on-site sensing because it requires sophisticated equipment and trained personnel. We report a rapid and simple chemical sensor for TNT by using TNT binding peptides which are conjugated to fluorescent CdTe/CdS quantum dots (QDs). QDs were synthesized in the aqueous phase, and the peptide was attached directly to the surface of the QDs by using thiol groups. The fluorescent emission from the QDs was quenched in response to the addition of TNT. The response could even be observed by the naked eye. The limit of detection from fluorescence spectroscopic measurement was estimated to be approximately 375 nM. In addition to the rapid response (within a few seconds), selective detection was demonstrated. We believe this label-free chemical sensor contributes to progress for the on-site explosive sensing.
关键词： quantum dots (QDs),explosive detection,2,4,6-trinitrotoluene (TNT),label-free sensing,peptide-functionalized
更新于2025-11-14 15:23:50
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Engineering Charge Transfer Characteristics in Hierarchical Cu2S QDs @ ZnO Nanoneedles with p–n Heterojunctions: Towards Highly Efficient and Recyclable Photocatalysts
摘要： Equipped with staggered gap p-n heterojunctions, a new paradigm of photocatalysts based on hierarchically structured nano-match-shaped heterojunctions (NMSHs) Cu2S quantum dots (QDs)@ZnO nanoneedles (NNs) are successfully developed via engineering the successive ionic layer adsorption and reaction (SILAR). Under UV and visible light illumination, the photocatalytic characteristics of Cu2S@ZnO heterojunctions with different loading amounts of Cu2S QDs are evaluated by the corresponding photocatalytic degradation of rhodamine B (RhB) aqueous solution. The results elaborate that the optimized samples (S3 serial specimens with six cycles of SILAR reaction) by means of tailored the band diagram exhibit appreciable improvement of photocatalytic activities among all synthesized samples, attributing to the sensitization of a proper amount of Cu2S QDs. Such developed architecture not only could form p–n junctions with ZnO nanoneedles to facilitate the separation of photo-generated carries but also interact with the surface defects of ZnO NNs to reduce the electron and hole recombination probability. Moreover, the existence of Cu2S QDs could also extend the light absorption to improve the utilization rate of sunlight. Importantly, under UV light S3 samples demonstrate the remarkably enhanced RhB degradation efficiency, which is clearly testified upon the charge transfer mechanism discussions and evaluations in the present work. Further supplementary investigations illustrate that the developed nanoscale Cu2S@ZnO heterostructures also possess an excellent photo-stability during our extensive recycling photocatalytic experiments, promising for a wide range of highly efficient and sustainably recyclable photocatalysts applications.
关键词： Photocatalysis,QDs,ZnO@Cu2S hierarchical structure,Photostability,p-n heterojunctions
更新于2025-09-23 15:23:52
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Spectral-optical-tweezer-assisted fluorescence multiplexing system for QDs-encoded bead-array bioassay
摘要： As an efficient tool in the multiplexed detection of biomolecules, bead-array could achieve separation-free detection to multiple targets, making it suitable to analyze valuable and scarce samples like antigen and antibody from living organism. Herein, we propose a spectral-optical-tweezer-assisted fluorescence multiplexing system to analyze biomolecule-conjugated bead-array. Using optical tweezer, we trapped and locked beads at the focus to accept stimulation, offering a stable and optimized analysis condition. Moving the system focus and scanning the sample slide, we achieved emissions collection to QDs-encoded bead-array after the multiplexed detection. The emission spectra of fluorescence were collected and recorded by the spectrometer. By recognizing locations of decoding peaks and counting the intensities of label signals of emission spectra, we achieved qualitative and quantitative detection to targets. As proof-of-concept studies, we use this system to carry out multiplexed detection to various types of anti-IgG in the single sample and the detection limit reaches 1.52 pM with a linear range from 0.31 to 10 nM. Through further optimization of experimental conditions, we achieved specific detection to target IgG with sandwich method in human serum and the detection limit reaches as low as 0.23 pM with a linear range from 0.88 to 28 pM, validating the practical application of this method in real samples.
关键词： bead-array,QDs encoding,optical tweezers,multiplexed biodetection
更新于2025-09-23 15:23:52
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Room temperature synthesis of Au NR@Ag2S and Au NR@Ag2S/CdS core-shells using a facile photochemical approach
摘要： In this work, Au nanorods with tunable longitudinal plasmon resonance were synthesized using hydroquinone as complimentary surfactant. Ag2S quantum dots (QDs) were grown directly on Au nanorods using the replacement of cetyltrimethylammonium bromide (CTAB) with 3-Mercaptopropionic acid (MPA) via a novel photochemical approach. X-ray diffraction revealed the presence of Au cubic structure as well as Ag2S monoclinic phase. Fourier-transform infrared spectroscopy, electrochemical impedance spectroscopy and cyclic voltamettery confirmed the successful substitution of CTAB with MPA as an appropriate capping agent for the growth of Ag2S and CdS quantum dots. UV-Vis spectroscopy demonstrated a red shift of plasmon resonance peak from 750 nm up to 835 nm indicating the increase of dielectric constant of surrounded Au nanorods due to the formation of Ag2S QDs as shell. Photoluminescence spectroscopy revealed near Infrared (NIR) emission of Au@Ag2S core-shells as an indication of controllable size of Ag2S during the growth time. Transmission electron microscopy (TEM) images clearly showed the formation of Ag2S QDs as shell around Au nanorods. To indicate the flexibility of current growth method, CdS QDs were also grown on Au@Ag2S core-shells only by addition of Cd precursor to as prepared Au@Ag2S colloidal solution and continuation of UV illumination. The clear and intense visible light emission of the sample together with the NIR emission of Ag2S and gradual red shift of plasmon resonance of Au nanorods with elapsing photochemical treatment time were the indication of successful growth of Ag2S/CdS on Au nanorods. TEM images clearly showed Au@Ag2S/CdS almond shape core-shells. This method has the simplest chemistry and the procedure is very simple, rapid (less than 2 h), energy efficient and scalable for large production of such core-shells.
关键词： Au nanorods,Metal-semiconductor core-shells,Ag2S QDs,Photoluminescence,Electroimpedance spectroscopy
更新于2025-09-23 15:22:29