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Ag2S-Glutathione Quantum Dots for NIR Image Guided Photothermal Therapy
摘要： Aqueous synthesis of glutathione (GSH) coated Ag2S quantum dots (QD) with strong emission in the medical imaging window (700-900 nm) were prepared from AgNO3. Variations in temperature, time, pH and sulfur source (Na2S and thioacetamide) were studied to tune the emission wavelength and intensity of QDs. The optimum synthesis condition to produce the smallest QDs (ca 7 nm) with the highest quantum yield (70 %) and excellent stability was determined as 50 ℃ and pH 10 where Na2S was used in 2 h reactions. Cytotoxicity was evaluated with MTT assay on HT29 and MCF7 cancer cell lines and indicated no significant toxicity of QDs up to 200 μg/mL. Photothermal Therapy (PTT) potential was first investigated by 795 nm, continuous-wave fiber coupled diode laser using aqueous solutions of QDs and then on HT29 and MCF7 cells. QD (150 μg/mL) treated MCF7 cells almost quantitatively died after 10 min irradiation at 795 nm (700 mW, 1.82 W/cm2) and the viability of HT29 cells dropped to 40%. Most cell death was late apoptotic/necrotic. This study indicates that such laser irradiation procedure and the QDs are safe yet, their combination provides a dramatic cell death upon short laser treatment. PTT coupled with strong intracellular optical signal promotes Ag2S-GSH QDs as potential theranostic nanoparticles.
关键词： glutathione coating,NIR imaging,Ag2S quantum dots,theranostic nanoparticles,photothermal therapy
更新于2025-09-23 15:19:57
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Thioglycolic Acid FTIR Spectra on Ag2S Quantum Dots Interfaces
摘要： The mechanism features of colloidal quantum dots (QDs) passivation with thioglycolic acid molecules (TGA) for cases of different luminescent properties is considered using FTIR. This problem is considered based on FTIR spectra analysis for various ionic forms of TGA. Experimental TGA molecules FTIR spectra is interpreted, basing on the data on modeling of TGA vibrational modes, realized in the framework of density functional method (DFT /B3LYP/6-31+G(d)) taking into account the vibrations anharmonicity of every functional group. This approach provides a significant improvement in the agreement between the experimental and calculated data. FTIR spectra of Ag2S/TGA QDs with exciton and recombination luminescence are differ from each other and B “freeB” TGA molecules. The ν(S ? H) TGA peak (2559 cm?1) disappears in FTIR spectra of Ag2S/TGA QD samples. This fact indicates the interactions between TGA thiol group and dangling bonds of Ag2S nanocrystals. Ag2S QDs passivation with TGA molecules leads to emergence νas(COO?) (1584 cm?1) and νs(COO?) (1387 cm?1) peaks. It indicates TGA adsorption in ionic form. For Ag2S/TGA QDs with exciton luminescence we observed (a) significant low-frequency shift of νs(COO?) peak from 1388 cm?1 to 1359 cm?1 and high-frequency shift of νas(COO?) peak from 1567 cm?1 to 1581 cm?1; (b) change in the ratio of intensities of νas(COO?) and νs(COO?) vibrations. This feature is caused by the change in the symmetry of TGA molecules due to passivation of Ag2S quantum dots.For Ag2S/TGA QDs with recombination luminescence, the insignificant high-frequency shift of 7–10 cm?1 for νas (COO?) at 1567 cm?1 and low-frequency shift of 3–5 cm?1 for νs (COO?) at 1388 cm?1, probably caused by the interaction of thiol with Ag2S surface is observed. Using FTIR spectra, it was found that IR luminescence photodegradation is also accompanied by changes in the thioglycolic acid molecules, which capped Ag2S QDs. In the case of Ag2S QDs with exciton luminescence, the degradation process is non-reversible. It is accompanied by TGA photodegradation with the formation of α-thiol-substituted acyl radical (S-CH2-CO?) TGA.
关键词： photodegradation,FTIR spectra,thioglycolic acid (TGA),dimer,luminescence,Ag2S quantum dots,ionic form
更新于2025-09-23 15:19:57
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A solid-state integrated photo-supercapacitor based on ZnO nanorod arrays decorated with Ag <sub/>2</sub> S quantum dots as the photoanode and a PEDOT charge storage counter-electrode
摘要： A planar solid-state photocapacitor with two electrodes has been prepared for the first time using a passivated film of ZnS with Ag2S quantum dots deposited on ZnO nanorods, which were electrochemically grown on ZnO seed layers, as the photoanode. The supercapacitor part is composed of a electrodeposited poly(3,4-ethylene-dioxythiophene) PEDOT film as the counter-electrode and an ionic liquid-based electrolyte between them deposited by the dip coating method. The different nanostructures and electrodes were morphologically and structurally characterized, and the device was electrochemically characterized and could reach a potential of 0.33 V during photocharge and a storage efficiency of 6.83%.
关键词： solid-state,ZnO nanorod arrays,electrochemical characterization,PEDOT,photo-supercapacitor,Ag2S quantum dots
更新于2025-09-19 17:13:59
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Photostimulated control of luminescence quantum yield for colloidal Ag <sub/>2</sub> S/2-MPA quantum dots
摘要： In this paper, we present the results on photoinduced formation of colloidal Ag2S quantum dots with sizes of 1.5–3 nm passivated by 2-mercaptopropionic acid (Ag2S/2-MPA) in the presence of ethylene glycol. The synthetized colloidal Ag2S/2-MPA QDs have NIR recombination luminescence with its maximum near 800 nm. The control of absorption and luminescence properties of the QDs is achieved by photoactivation. It is shown that photoexposure of colloidal solution of Ag2S/2-MPA QDs leads to an increase in the QD size and monodispersity along side with the growth of the luminescence quantum yield from 1% to 7.9%. Enhancement of the luminescence quantum yield is accompanied by an increase in the average luminescence lifetime up to 190 ns, which is due to the blocking of the nonradiative recombination channel with the radiative recombination rate being (3–5.5) × 105 s?1. It is shown that the purification of the Ag2S/2-MPA solution by a dialysis membrane from regenerated cellulose leads to an increase in the sample monodispersity, as well as stops the photoinduced growth of QDs, and also reduces the degradation of their photoluminescence.
关键词： Ag2S quantum dots,NIR luminescence,2-mercaptopropionic acid,luminescence quantum yield,photoactivation
更新于2025-09-16 10:30:52
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Bypassing pro-survival and resistance mechanisms of autophagy in EGFR-positive lung cancer cells by targeted delivery of 5FU using theranostic Ag <sub/>2</sub> S quantum dots
摘要： Targeted drug delivery systems that combine imaging and therapeutic functions in a single structure have become very popular in nanomedicine. Near-infrared (NIR) emitting Ag2S quantum dots (QDs) are excellent candidates for this task. Here, we have developed PEGylated Ag2S QDs functionalized with Cetuximab (Cet) antibody and loaded with an anticancer drug, 5-fluorouracil (5FU). These theranostic QDs were used for targeted NIR imaging and treatment of lung cancer using low (H1299) and high (A549) Epidermal Growth Factor Receptor (EGFR) overexpressing cell lines. The Cet conjugated QDs effectively and selectively delivered 5FU to A549 cells and provided significantly enhanced cell death associated with apoptosis. Interestingly, while treatment of cells with free 5FU activated autophagy, a cellular mechanism conferring resistance to cell death, these EGFR targeting multimodal QDs significantly overcame drug resistance compared to 5FU treatment alone. The improved therapeutic outcome of 5FU delivered to A549 cells by Cet conjugated Ag2S QDs is suggested as the synergistic outcome of enhanced receptor mediated uptake of nanoparticles, and hence the drug, coupled with suppressed autophagy even in the absence of addition of an autophagy suppressor.
关键词： lung cancer,EGFR,theranostic,Ag2S quantum dots,autophagy,targeted drug delivery,5-fluorouracil
更新于2025-09-16 10:30:52
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Synthesis of Silver Sulfide Quantum Dots Via the Liquid–Liquid Interface Reaction in a Rotating Packed Bed Reactor
摘要： We developed the high-gravity coupled liquid–liquid interface reaction technique on the basis of the rotating packed bed (RPB) reactor for the continuous and ultrafast synthesis of silver sulfide (Ag2S) quantum dots (QDs) with near-infrared (NIR) luminescence. The formation of Ag2S QDs occurs at the interface of microdroplets, and the average size of Ag2S QDs was 4.5 nm with a narrow size distribution. Ag2S QDs can disperse well in various organic solvents and exhibit NIR luminescence with a peak wavelength at 1270 nm under 980-nm laser excitation. The mechanism of the process intensification was revealed by both the computational fluid dynamics simulation and fluorescence imaging, and the mechanism is attributed to the small and uniform droplet formation in the RPB reactor. This study provides a novel approach for the continuous and ultrafast synthesis of NIR Ag2S QDs for potential scale-up.
关键词： Liquid–liquid interface reaction,Rotating packed bed,Ag2S quantum dots,Near-infrared luminescence,Process intensification
更新于2025-09-12 10:27:22
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Ag-Ag2S quantum-dots modified TiO2 nanorod arrays with enhanced photoelectrochemical and photocatalytic properties
摘要： In this paper, highly ordered titanium dioxide nanorod (TNR) arrays decorated with Ag-Ag2S quantum-dots (QDs) were synthesized on FTO substrate through hydrothermal treatment and in-situ vulcanization. The content of Ag2S QDs on Ag/TNR was controlled by changing the immersion time of Ag/TNR in the N-N-dimethyl formamide (DMF) solution containing dissolved sulfur element. The morphology, structure, composition and optical, photoelectric and photocatalytic properties of QDs/TNR arrays were studied in detail. In the visible range, the QDs/TNR array with a soaking time of 12 h exhibits the maximal photocurrent density (0.082 mA/cm2) and photodegradation rate (62.2%), which is 5.5 and 1.85 times higher than that of pure TNR. The improvement of these properties could be attributed to synergy effect between Ag and Ag2S materials. That is, Ag QDs can stably capture and transmit photo-generated electrons from the TNR surface, whereas the Ag2S promoter is regarded as the interface active sites to enhance photocatalytic reactions. Therefore, the synergistic effect of Ag-Ag2S can significantly enhance the photoelectrochemical and photocatalytic propertise of the TNR arrays.
关键词： Ag-Ag2S quantum-dots,photoelectrochemical and photocatalytic properties,synergistic effect,TiO2 nanorod arrays
更新于2025-09-10 09:29:36