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Cell Imaging Using Two-Photon Excited CdS Fluorescent Quantum Dots Working within the Biological Window
摘要： In recent years, two-photon excited semiconductor quantum dots (QDs) have been the subject of intense investigation due to their long excitation wavelength which helps to achieve deeper penetration and higher image resolution in optical bioimaging. In this paper, water-soluble CdS QDs were synthesized using a hydrothermal method and applied to human liver hepatocellular carcinoma (HepG2) cells. The first-principles calculation suggested that the S-rich defected structure contributes to a narrower band gap compared to the pristine structure. The resulting fluorescence wavelength was significantly red shifted, which was attributed to the deep defect states emission. The large Stokes shifts (> 200 nm) of the QDs can eliminate the possible cross-talk between the excitation light and the emission light. Two-photon induced red fluorescence emission can avoid overlapping with the autofluorescence emission of biological samples. The uptake and cell viability measurements of the HepG2 cells showed a good biocompatibility and a low toxicity of CdS QDs. Two-photon excited scanning microscopy images revealed that the HepG2 cells incubated with CdS QDs emitted bright red upconversion fluorescence and the fluorescence brightness was 38.2 times of that of the control group. These results support CdS QDs as a good candidate for application in cellular imaging.
关键词： two-photon absorption,CdS quantum dots,deep defect states,HePG2 cells,biological imaging
更新于2025-11-21 11:24:58
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Highly flexible self-powered photodetectors based on core–shell Sb/CdS nanowires
摘要： Flexible photodetectors have great applications in flexible image sensors, wearable electronics and smart robots. In this work, we reported the fabrication of highly flexible self-powered photodetectors with core-shell Sb/CdS nanowires as the sensing materials. The fabricated device exhibited high Ion/Ioff ratio of 3.54×103 under zero bias, fast speed of photoresponse and great stability. An open-circuit voltage of 0.35 V was generated due to the presence of CdS and CdSb interfaces within the core-shell nanowires. Besides, the photocurrent of the flexible device is nearly invariable at various bending angles and even after thousands of bending cycles, demonstrating the excellent flexibility and bending stability. The results indicated that the self-powered photodetectors are promising candidates for future passive optoelectronic devices.
关键词： core-shell Sb/CdS nanowires,optoelectronic devices,self-powered,flexible photodetectors
更新于2025-11-21 11:03:13
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LED visible-light driven label-free photoelectrochemical immunosensor based on WO3/Au/CdS photocatalyst for the sensitive detection of carcinoembryonic antigen
摘要： A ternary WO3/Au/CdS photocatalyst was prepared by reversible redox and ionic adsorption for the first time. The photocatalyst exhibited high photocatalytic activity and good photoelectrochemical (PEC) property in comparison with WO3, CdS, WO3/Au and WO3/CdS, because the localized surface plasmon resonance (LSPR) effect of Au nanoparticles (Au NPs) and the sensitization of CdS benefited the spatial separation of photogenerated electron-hole pairs and the absorption of visible light. Thus, its photocurrent response intensity was quite high, up to about 218-fold of WO3 and 87-fold of CdS under 430 nm LED light irradiation. Based on the large anodic photocurrent and the specific recognition between carcinoembryonic antigen (CEA) and anti-CEA, a novel PEC immunosensor was constructed for the sensitive and selective detection of CEA. Under the selected conditions, the change of photocurrent intensity was linear to the logarithm of CEA concentration over the range from 0.01 to 10 ng/mL, and the detection limit was down to 1 pg/mL. The immunosensor also showed good stability, reproducibility and repeatability. It was successfully applied to the detection of CEA in serum samples.
关键词： Au nanoparticles,WO3,Photoelectrochemical immunosensor,Carcinoembryonic antigen,CdS
更新于2025-11-21 11:01:37
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Valorization of tire wastes to carbon quantum dots (P-CDs) and photocatalytic degradation enhancement of organic wastes using ZnO-CDs nanocomposites
摘要： Valorization of solid wastes for the production of valuable materials is of great importance for sustainable development. In this paper, removal for solid and liquid wastes via hydrothermal and catalytic degradation was reported. The first removal process is the hydrothermal conversion of solid waste, here solid wastes of tire, to phosphorous and nitrogen doped carbon nanodots (P-CDs). The second removal is the visible-NIR light driven photocatalytic degradation of liquid waste, here methylene blue (MB) solution, using P-CDs loaded on ZnO nanoparticles. Energy-efficient light emitting diode (LED) was used as a weak sufficient irradiation source. Photodegradation rate constants for ZnO-P-CDs were almost 10 times higher (0.08 h?1 for ZnO-P-CDs) comparing to pure ZnO (0.008 h?1), such enhancement is significant for a weak light source. Cyclic voltammetry and optical properties were used to find HOMO and LUMO of P-CDs. Based on the energy levels of ZnO and P-CDs, the catalytic enhancement was attributed to increasing the separation rate of photogenerated electrons and hole due to the transfer of electrons from the conduction bands of P-CDs to the conduction band of ZnO. Up-conversion photoluminescence of P-CDs is another reason for increasing the separation of excitons and harvesting the longer wavelength light. The proposed approach, solid and liquid waste removal via hydrothermal and catalytic degradation combined with weak LED light, would be a powerful approach in solid waste treatment and water purification technology, simultaneously.
关键词： Valorization,Tire wastes,Carbon quantum dots,Photocatalytic degradation,ZnO-P-CDs nanocomposites
更新于2025-11-19 16:56:42
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Coordination between Surface Lattice Resonances of Poly(glycidyl Methacrylate) Line Array and Surface Plasmon Resonances of CdS Quantum on Silicon Surface
摘要： In this work, a unique hybrid system is proposed for one-dimensional gratings comprising of poly(glycidyl methacrylate) (PGMA) brushes and CdS quantum dots (CQDs). Generally, the emission of QDs is too weak to be observed in a dry state. Plasmonic resonances of the grating structures can be used to enhance the light emission or absorption of CQDs. The interaction between PGMA plasmonic nanostructures and inorganic CQDs plays a crucial role in engineering the light harvest, notably for optoelectronic applications. Extinction measurements of the hybrid system consisting of a PGMA grating and CQDs are reported. We designed one-dimensional gratings with various resolutions to tune the absorptance peaks of grating. PGMA grating grafted from a 1.5 μm resolution of trench arrays of photoresist exhibited absorptance peak at 395 nm, close to the absorption peak of CQDs, resulting in the photoluminescence enhancement of CQDs on the grating due to high charge carriers’ recombination rate. Generally, the emission of quantum dots occurs under irradiation at characteristic wavelengths. Immobilizing QDs on the grating facilitates the emission of QDs under irradiation of full-wavelength light. Furthermore, the PGMA gratings with CQDs were immersed in various solvents to change the geometries resulting the shift of absorptance peak of grating. The proposed method could be applied for sensing the nature of the surrounding media and vice versa, as well as for various media of solvents.
关键词： one-dimensional grating,CdS quantum dots,PGMA brush
更新于2025-11-14 17:03:37
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Improved H2-generation performance of Pt/CdS photocatalyst by a dual-function TiO2 mediator for effective electron transfer and hole blocking
摘要： Surface modification with noble metal cocatalysts was proved to be a useful route for boosting photocatalytic efficiency of various photocatalysts. Nevertheless, considering the random dispersion of metallic cocatalysts on the photocatalyst surface, the noble metal-loaded photocatalyst generally shows a limited enhancement of its activity because the noble metals can also work as the recombination sites of photoinduced charges. In this paper, TiO2 as a dual-function mediator (for effective electron transport and hole block) is successfully introduced into the interface of Pt and CdS to form Pt-TiO2/CdS photocatalyst, with an aim of suppressing the high recombination rate of electron-hole pairs on the Pt active sites. Under visible light, all the prepared Pt-TiO2/CdS displayed distinctly enhanced photocatalytic hydrogen-generation performance and the Pt-TiO2/CdS(8%) attains the highest photocatalytic H2-production rate (294.2 μmol/h), a value significantly higher than that of Pt/CdS about 3.2 time. A dual-function TiO2-mediated mechanism was put forward to account for the superior hydrogen production of Pt-TiO2/CdS photocatalyst, namely, the TiO2 layer in the Pt-TiO2/CdS not only works as electron-transport layers to effectively transfer photogenerated electrons to promote the H2-production reaction on Pt cocatalysts, but also acts as hole-block layer to prevent the possible recombination of photogenerated charges on the Pt active sites, resulting in a distinct improvement of final H2-generation activity.
关键词： Photocatalysis,Pt,H2 generation,CdS,TiO2
更新于2025-11-14 15:27:09
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Quenched Sandwich-type Photoelectrochemical Aptasensor forProtein Detection based on Exciton Energy Transfer
摘要： This work proposes a quenched photoelectrochemical sensing method for highly selective and sensitive detection of protein via Energy Transfer (ET) effect between the AuNPs and CdS:Mn quantum dots. This detection was performed on a sandwich-type aptamer sensing interface. Chitosan modified CdS:Mn/TiO2/ITO electrode was used to immobilize capture DNA (S1) via -CONH- bond. In the presence of target protein, AuNPs labeled DNA (AuNPs-S2) was further bonded to the protein to fabricate sandwich sensing platform, which forced the AuNPs away from the electrode surface. In this state, the photocurrent was greatly depressed, mainly due to two factors: (a) the ET effect produced by interparticle distance between CdS:Mn and AuNPs; (b) the steric hindrance of AuNPs-S2 partly obstructs the diffusion of the electron donor. The photocurrent decreased with the increasing concentration of the target protein. Using thrombin as a target, this sensitized method showed a detectable range of 0.1 pM to 8 nM and a detection limit of 30 fM. It possessed high selectivity and good stability for detection of thrombin. This method is extremely flexible and can be extended to varieties of protein targets.
关键词： CdS:Mn,Photoelectrochemical aptasensor,Thrombin,Energy transfer,AuNPs
更新于2025-11-14 15:15:56
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Efficient photocatalytic debromination of 2,2?,4,4?-tetrabromodiphenyl ether by Ag-loaded CdS particles under visible light
摘要： Highly active and visible light-driven Ag-loaded CdS photocatalysts were prepared via a hydrothermal synthesis and photodeposition method. The removal and debromination of 2,2?,4,4?-tetrabromodiphenyl ether was achieved efficiently using this Ag-loaded CdS under visible light, with a removal efficiency of 100% and a debromination ratio of 44.3% being achieved within 30 min. Both the reaction solvent and the water content were found to have a strong influence on the removal efficiency and the debromination ratio. In addition, the stepwise debromination preference was ortho > para, thereby indicating that the main debromination pathway was electron reduction. The stability and efficiency of these Ag-loaded CdS photocatalysts for the removal of BDE47 were satisfactory, and so our results confirmed the development of a promising visible light-driven catalyst for the removal of polybrominated diphenyl ethers.
关键词： Debromination ratio,Visible light-driven,Ag-loaded CdS,Photocatalyst,Removal efficiency
更新于2025-09-23 15:23:52
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Review on metal sulphide-based Z-scheme photocatalysts
摘要： Semiconductor-based heterojunction photocatalysts have received considerable attention for solar energy conversion and environmental purification due to their spatially separated reduction and oxidation sites, effective separation and transportation of photo-excited charge carriers and strong redox ability. With their wide visible-light responsive range and high photocatalytic activity, metal sulphide is an important material in developing photocatalysts. This review summarizes and highlights recent research progress in sulphide-based direct Z-scheme photocatalysts, followed by analysis on the limitations over all-solid-state Z-scheme photocatalyst. Furthermore, the applications and characterization methods of sulphide-based direct Z-scheme photocatalyst are summarized. Finally, the challenges and perspectives of sulphide-based Z-scheme photocatalyst are discussed.
关键词： CdS,direct Z-scheme,All-solid-state Z-scheme,S-scheme,metal sulphide
更新于2025-09-23 15:23:52
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Core-shell type Tourmaline@ZnO composites equipped with carbon dots for high efficiency photocatalyst
摘要： Here we report that a novel type of Tourmaline@ZnO core-shell composite equipped with carbon dots (CDs) as multi-band light active sensitizer has been successfully designed and efficiently utilized as the superior photocatalyst towards the degradation of methyl orange (MO) under Xenon lamp at room temperature. The bare ZnO, CDs/ZnO, Tourmaline@ZnO and CDs/Tourmaline@ZnO were systemically synthesized following the facile homogeneous precipitation process and characterized in detail by XRD, FTIR, FESEM, HRTEM, UV-Vis, PL, PC and EIS investigations in succession. Bare ZnO displays as 3-dimensional hierarchical nano-flowers with large specific surface area reaching up to 62.049 m2/g by BET measurement, while the other composite products confirm the core-shell structures with CDs inlaying on ZnO layer surfaces. The photocatalytic activities of the polynary hybridations obtain effective enhancements compared to pure ZnO, the ternary system (CDs/Tourmaline@ZnO) deserves more attention for achieving the maximum (91.25%). It should been the synergistic effect on the highly efficient catalysis performances exerting by the presence of CDs modifier and the Tourmaline core, which make ZnO matrix receive more photo-generated electrons and broaden the visible light response originated from CDs, and synchronously hinder the recombination of electrons-hole pairs by the spontaneous polarization and surface electric field of Tourmaline.
关键词： Tourmaline,photocatalysis,ZnO,core-shell,CDs
更新于2025-09-23 15:23:52