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68Ga CdTe/CdS fluorescent quantum dots for detection of tumors: investigation on the effect of nanoparticle size on stability and in vivo pharmacokinetics
摘要： Background: Quantum dots (QDs)-based theranostics offer exciting new approaches to diagnose and therapy of cancer. To take advantage of the unique properties of these fluorescent QDs for different biomedical applications, their structures, size and/or surface chemistry need to be optimized, allowing their stability and functionalities to be tailored for different biomedical applications. Methodology: Cadmium telluride/Cadmium sulfide QDs (CdTe/CdS QDs) were synthesized and their structure, size, photostability and functionalities as a bioprobe for detection of Fibrosarcoma tumors were studied and compared with Cadmium telluride (CdTe) QDs. Hence, CdTe/CdS QDs were labeled with 68Ga radionuclide for fast in vivo biological nuclear imaging. Using gamma paper chromatography (γ-PC), the physicochemical properties of the prepared labeled QDs were assessed. In vivo biodistribution and positron emission tomography (PET) imaging of the 68Ga@ CdTe/CdS QDs nanocrystals were investigated in Sprague Dawley? rats bearing Fibrosarcoma tumor. Results: CdS shell on the surface of CdTe core increases the size and photostability against high energy radiations; therefore, CdTe/CdS QDs show prolonged fluorescence as compared to CdTe QDs. Conclusion: Excellent accumulation in tumor was observed for core/shell quantum dots, but this study showed that small changes in the size of the QDs (+1 nm), after adding the CdS shell around CdTe core, greatly change their biodistribution (especially the liver uptake).
关键词： core/shell quantum dots,PET,tumor imaging,68Ga,Cadmium telluride/Cadmium sulfide
更新于2025-09-23 15:19:57
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Aqueous Synthesis for Highly Emissive 3-Mercaptopropionic Acid-Capped AIZS Quantum Dots
摘要： Highly ?uorescent and color tunable AgInS2 (AIS) and (AgInS2)x(ZnS)1?x (AIZS) quantum dots (QDs) were prepared via a facile aqueous-phase synthesis using AgNO3, In(NO3)3, Zn(OAc)2, and Na2S as precursors and 3-mercaptopropionic acid (3-MPA) as ligand. Produced AIZS QDs exhibit a small diameter (ca. 2.1 nm) and a cubic structure. Ag-3-MPA and In-3-MPA complexes formed during the preparation of AIS cores were found to play a key role on the fate of the reaction, and an atypical blue-shift of the photoluminescence emission was observed with the increase of the Ag/In ratio. The photoluminescence quantum yield (PL QY) of AIS QDs is modest but increased markedly after the alloying and shelling with ZnS (up to 65%). Size and composition-selective precipitations allowed to separate up to 13 fractions of AIZS QDs with exceptionally high PL QYs (up to 78%), which is the highest value reported for AIZS QDs prepared in the aqueous phase. These high PL QYs combined with their good colloidal stability and photostability make AIZS QDs of high potential as cadmium-free ?uorescent probes for various applications like bioimaging or sensing.
关键词： AgInS2,photoluminescence,bioimaging,cadmium-free,sensing,aqueous synthesis,AIZS,quantum dots
更新于2025-09-23 15:19:57
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Dielectric Measurements of Polymer Composite Based on CdS Quantum Dots in Low Density Polyethylene at Microwave Frequencies
摘要： CdS nanoparticles (NPs) as quantum dots (QDs) added into low density polyethylene (LDPE) can significantly change the MW dielectric properties of the composites. Introducing into the matrix of low density polyethylene CdS QDs increase the dielectric constant of more than twice. CdS QDs with concentration of 5 wt % to 20 wt % were prepared by the method of high-speed thermal decomposition. The size of CdS nanoparticles ranged from 2 nm to 7 nm. Experimental samples based on polymer-based nanocomposite in the form of thick films with a thickness of 80 to 100 microns were prepared by thermocompression. Complex dielectric permittivity of thick film samples was measured by T/R method from 2 to 8 GHz at room temperature (25°C). For samples with 20 wt % CdS NPs size effect was found. The change of dielectric properties of polymer composite materials is associated with the size of QDs. The dielectric constant and dielectric loss increases with decreasing size of the quantum dots. It is shown that the highest mean value of the dielectric constant and dielectric loss at a frequency range of 5 GHz to 8 GHz for cadmium sulfide nanoparticles with size of 4 nm were 12 and 189 dB/m, respectively. For QDs with ones of 6 nm average dielectric constant and dielectric loss were 5.8 and 134 dB/m, respectively. The effective dielectric constant and dielectric losses in the microwave range can be changed by CdS QDs of different sizes what consequently increases the possibility of using polymer nanocomposites as core elements of the microwave band-pass filters for various purposes.
关键词： quantum dot,cadmium sulfide,polymer composite,filled polymer,MW dielectric properties,low density polyethylene,composites
更新于2025-09-23 15:19:57
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Improved efficiency and photo-stability of methylamine-free perovskite solar cells via cadmium doping
摘要： Although perovskite solar cells containing methylamine cation can show high power conversion efficiency, stability is a concern. Here, methylamine-free perovskite material CsxFA1–xPbI3 was synthesized by a one-step method. In addition, we incorporated smaller cadmium ions into mixed perovskite lattice to partially replace Pb ions to address the excessive internal strain in perovskite structure. We have found that the introduction of Cd can improve the crystallinity and the charge carrier lifetime of perovskite films. Consequently, a power conversion efficiency as high as 20.59% was achieved. More importantly, the devices retained 94% of their initial efficiency under 1200 h of continuous illumination.
关键词： cadmium doping,methylamine-free,lattice strain,photo-stability
更新于2025-09-23 15:19:57
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Detail investigation of toxicity, bioaccumulation, and translocation of Cd-based quantum dots and Cd salt in white mustard
摘要： In this study, a model crop plant white mustard (Sinapis alba L.) was treated with an aqueous dispersion of silica-coated CdTe quantum dots (CdTe/SiO2 QDs) in a 72-hours short-term toxicity test. The toxicity was established via measurements of (i) the root length and (ii) the chlorophyll fluorescence. These results were compared to two other sources of cadmium, free Cd ions (CdCl2) and prime un-shell nanoparticles CdTe QDs. Tested compounds were applied in concentrations representing 20 and 200 μM Cd. The uptake and translocation of Cd were investigated using inductively coupled plasma optical emission spectrometry (ICP-OES) and the spatial Cd distribution was investigated in detail applying laser induced breakdown spectroscopy (LIBS). The LIBS maps with a lateral resolution of 100 μm were constructed for the whole plants, and maps with a lateral resolution of 25 μm (micro-LIBS arrangement) were used to analyse only the most interesting parts of plants with Cd presence (e.g. root tips or a part crossing the root into the above-ground part). Our results show that the bioaccumulation patterns and spatial distribution of Cd in CdTe/SiO2 QDs-treated plants differ from the plants of positive control and CdTe QDs. Fluorescence microscopy photographs revealed that CdTe/SiO2 became adsorbed onto the plant surface in comparison to CdTe QDs. Further, a physico-chemical characterization of QDs before and after the test exposure showed only minor changes in the nanoparticle diameters and no tendencies of QDs for agglomeration or aggregation during the exposure.
关键词： nanoparticles,cadmium,laser-induced breakdown spectroscopy,Sinapis alba L.,uptake,translocation
更新于2025-09-23 15:19:57
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Impact of Bi doping on CdTe thin films: Thermal annealing evolution of physical properties for solar cell absorber layer applications
摘要： To mitigate probability of instability and device degradation associated with traditional Cu doping and to tune required band gap as well as to reduce open circuit voltage loss to solar cell device, a study on evolution to the physical properties of Bi-doped CdTe films is reported. Thin films of CdTe:Bi 2% alloy are developed employing electron-beam deposition followed by air annealing. Structural studies reveal that films have preferred crystal growth along (111) plane and with annealing, films turned out to be polycrystalline. Absorbance of films is found to be affected with annealing where 450 °C annealed films show maximum absorbance. The current-voltage measurements show linear relationship reveal to ohmic contacts between the films and transparent conducting oxide substrate and conductivity is observed to be varied with annealing. The atomic force microscopy study indicates an increase in surface roughness with annealing (except for 300 °C). Our findings warrant that the optimized physical properties of CdTe:Bi 2% films annealed at 450 °C may play important role to enhance the solar cell device performance concerned.
关键词： Bismuth doping,Absorber layer,Air-annealing,Thin films,Cadmium telluride,Electron beam evaporation
更新于2025-09-23 15:19:57
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Laser-induced graphene hybrid photoelectrode for enhanced photoelectrochemical detection of glucose
摘要： The combination of electrocatalyst with semiconductor light-absorber is of great importance to increase the efficiency of photoelectrochemical (PEC) glucose detection. Here, in-situ and synchronous fabrication of Ni-based electrocatalyst (NiEC) and CdS semiconductor in laser-induced graphene (LIG) on indium?tin oxide glass is demonstrated via a one-step laser-induced solid phase transition. A series of component and structural characterizations suggest that the laser-induced NiEC uniformly disperses in the hybrid nanocomposite and exists mainly in the form of Ni0 and NiO state. Moreover, both electrochemical and PEC investigations confirm that the as-prepared hybrid photoelectrode exhibits excellent photoelectrocatalytic ability towards glucose, which is not only attributed to the strong synergistic interaction between CdS and NiEC, but also benefited from the high conductivity as well as 3D macroporous configuration of the simultaneously formed LIG, providing the key factor to achieve sensitive non-enzymatic PEC glucose sensors. Therefore, the laser-induced hybrid photoelectrode is then applied to the PEC detection of glucose, and a low detection limit of 0.4 μM is obtained with good stability, reproducibility, and selectivity. This study provides a promising paradigm for the facile and binder-free fabrication of electrocatalyst?semiconductor?graphene hybrid photoelectrode, which will find potential applications in sensitive PEC biosensing for a broad range of analytes.
关键词： nickel electrocatalyst,hybrid nanocomposite,cadmium sulfide,photoelectrochemical sensing,laser-induced graphene,glucose
更新于2025-09-23 15:19:57
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Impedimetric detection of Banana bunchy top virus using CdSe quantum dots for signal amplification
摘要： Banana bunchy top virus is considered to be the most economically destructive pathogens of banana that causes severe economic loss in banana plantations worldwide, including India. In this present study we have developed an improved electrochemical ELISA for detection of Banana bunchy top virus (BBTV). For enhanced and accurate detection we have used cadmium selenide (CdSe) quantum dots (QDs) as signal amplifiers. Experiments in this study were performed using primary antibody raised from recombinant coat protein of BBTV. CdSe QDs could significantly amplify the electrical signals in this assay and make the method appropriate for lab use. The result of electrical conduction showed the difference of impedance between the healthy and diseased sample of the order of ~ 100 Ω. The electrochemical ELISA could detect the virus in plant sap up to dilution of 1:25 as compared to 1:10 of conventional ELISA.
关键词： Faradic impedance spectroscopy,Cadmium selenide quantum dots (CdSe QDs),Banana bunchy top virus
更新于2025-09-23 15:19:57
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Photoinduced charge carrier dynamics in a ZnSe quantum dot-attached CdTe system
摘要： A new nanohybrid material is prepared by attaching CdTe nanoneedles (NNs) to surface-modified ZnSe quantum dots (QDs). The NNs and QDs are prepared by a colloidal synthesis method in an aqueous alkaline medium. The surface modification and the attachment of nanostructures are achieved by a bifunctional ligand 3-mercaptopropionic acid (3-MPA). The band gap of the ZnSe QDs is varied by controlling the size of the QDs in order to get the maximum overlap between the absorption band of the CdTe NNs and the emission band of the ZnSe QDs, which is a prerequisite for effective charge/energy transfer. The possibility of photoinduced charge transfer (PCT) and F?rster resonance energy transfer (FRET) from the donor (QDs) to the acceptor (NNs) has been assessed. Very fast (less than 800 ps) PCT and FRET from QDs to NNs occur because the emission band of QDs overlaps with the absorption band of NNs. The calculated large value of the overlapping integral, J(λ) ～4.5 × 1019 M?1 cm?1 nm4, of the donor and the acceptor bands proves the feasibility of energy transfer. These findings suggest that the ZnSe QDs can exchange photoinduced energy with the CdTe NNs effectively over a wide distance in a CdTe–ZnSe nanohybrid.
关键词： quantum dots,zinc selenide,F?rster resonance energy transfer,cadmium telluride,nanohybrid,charge transfer
更新于2025-09-23 15:19:57
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Colorimetric and dark-field microscopic determination of cadmium(II) using unmodified gold nanoparticles and?based on the formation of glutathione-cadmium(II) complexes
摘要： A colorimetric approach is presented for the determinaton of cadmium(II) using unmodified gold nanoparticles (AuNPs) as a colorimetric probe. The assay is based on AuNP aggregation that is induced by the complexes formed between Cd(II) and glutathione (GSH) in a concentrated solution of NaCl. Unmodified AuNPs are known to aggregate in high-salt medium, but GSH can prevent aggregation. In the presence of Cd(II), it will bind GSH, and this will cause the AuNPs to aggregate as indicated by yellow and red dots under dark-field microscopy observation and the formation of a blue coloration. By monitoring the intensity change of AuNPs (as a ratio of absorbances at 600 and 520 nm), Cd(II) can be quantified with a linear response in the 17 pM to 16.7 nM concentration range and a detection limit of 4.3 pM. The method was successfully applied to the determination of Cd(II) in spiked lake water by the standard addition mode, and the detection limit is 4.5 pM.
关键词： Microscopy,Yellow and red dots,Lake water,Glutathione,Ratiometric detection,Cadmium ion,Gold nanoparticle aggregation
更新于2025-09-23 15:19:57