Toxicities of CdSe and CdSe/CdS quantum dots （QDs） synthesized by ultrasound-assisted methods were investigated in vitro and in vivo. Five human cell lines were used to assess the cytotoxicity of as-prepared CdSe an...Toxicities of CdSe and CdSe/CdS quantum dots （QDs） synthesized by ultrasound-assisted methods were investigated in vitro and in vivo. Five human cell lines were used to assess the cytotoxicity of as-prepared CdSe and CdSe/CdS by assays of MTT viability, red blood cell hemolysis, flow cytometry, and fluorescence imaging. The results show that these QDs may be cytotoxic by their influence in S and G2 phases in cell cycles. The cytotoxicity of QDs depends on both the physicochemical properties and related to target cells.展开更多
A new and convenient route is developed to synthesize CdSe and core-shell CdSe/CdS quantum dots（QDs） in aqueous solution.The gaseous precursors,H2Se and H2S,generated on-line by reducing SeO 3 2à with NaBH 4 an...A new and convenient route is developed to synthesize CdSe and core-shell CdSe/CdS quantum dots（QDs） in aqueous solution.The gaseous precursors,H2Se and H2S,generated on-line by reducing SeO 3 2à with NaBH 4 and the reaction between Na 2 S and diluted H2SO 4,are used to form high-quality CdSe and CdSe/CdS QDs,respectively.The synthesized water-soluble CdSe and CdSe/CdS QDs possess high quantum yield（3% and 20%） and narrow full-width-at-half-maximum（43 nm and 38 nm）.The synthesis process is easily reproducible with simple apparatus and low-toxic chemicals,and can be readily extended to the large-scale aqueous synthesis of QDs.展开更多
Water-soluble CdS quantum dots（CdS-QDs） capped with thioglycohc acid were easily prepared, and a detection method of adriamycin was presented based on the fluorescence quenching of CdS-QDs. It was found that a compl...Water-soluble CdS quantum dots（CdS-QDs） capped with thioglycohc acid were easily prepared, and a detection method of adriamycin was presented based on the fluorescence quenching of CdS-QDs. It was found that a complex could be formed between cetyhrimethyl ammonium bromide（CTAB） and CdS-QDs by using electrostatic interaction in Britton-Robinson（BR） buffer at pH = 7.00, and the strong fluorescence emission of the complex was observed at 500 nm when the complex was excited at 378 run. The presence of adriamycin, however, could strongly quench the fluorescence through hydrophobic interaction. The overall quenching percentage as a function of adriamycin concentration matches the Stern-Volmer equation very well. These properties make CdS-QDs a potential fluorescence probe for the detection of adriamycin. The detection hmit（3σ） of adriamycin is approximately 10^-9 mol/L.展开更多
The influence of surface S^2- dangling bonds and surface doped ions（Se^2-, Cu^2＋, and Hg^2＋） on the photoluminescence of Cd^2＋-rich CdS QDs was investigated. A quantitative model was proposed to understand the co...The influence of surface S^2- dangling bonds and surface doped ions（Se^2-, Cu^2＋, and Hg^2＋） on the photoluminescence of Cd^2＋-rich CdS QDs was investigated. A quantitative model was proposed to understand the complex transfer processes of excited electrons in CdS QDs. The transfer of excited electrons from either the conduction band or the Cd^2＋-related trap-state to the surface S^2-related shallow hole trap-state is effective. However, the trap of excited electrons by surface doped ion trap-states from the Cd^2＋-related trap-state is more effective than that from the conduction band. The efficiency of trapping electrons from both the conduction band and the Cd^2＋-related trap-state can be quantitatively understood with the help of the proposed model. The results show that the transfer efficiency of excited electrons is dependent on the location of the energy-level of the relevant surface-related trap-state. The trap of excited electrons by the surface trap-state with energy-level closer to that of the conduction band is more effective, especially for the trap of excited electrons from Cd^2＋-related trap-state.展开更多
In the study, we observed the strong adsorption of CdTe/CdS QDs to antibodies and the formation of QDs-antibodies conjugates. Capillary electrophoresis with laser-induced fluorescence detection （CE-LIF）, fluorescenc...In the study, we observed the strong adsorption of CdTe/CdS QDs to antibodies and the formation of QDs-antibodies conjugates. Capillary electrophoresis with laser-induced fluorescence detection （CE-LIF）, fluorescence spectrometry and fluorescence correlation spectroscopy （FCS） were used to characterize the QDs conjugates with antibody. We found that the QDs-antibody conjugates possessed high fluorescence, small hydrodynamic radii and good stability in aqueous solution. 2009 Ji Cun Ren. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
A novel chemiluminescence（CL） performance of CdTe/CdS/ZnS quantum dots（QDs） with periodate（KIO_4） was studied.Effects of concentration and pH on the CL system were investigated.Electron spin resonance（ESR） and...A novel chemiluminescence（CL） performance of CdTe/CdS/ZnS quantum dots（QDs） with periodate（KIO_4） was studied.Effects of concentration and pH on the CL system were investigated.Electron spin resonance（ESR） and the effects of radical scavenger analysis were employed for identification of intermediate species.The CL spectra for this system showed only one maximum emission peak centered around 620 nm,which was similar with photoluminescence（PL） spectra of CdTe/CdS/ZnS QDs.The CL of CdTe/CdS/ZnS QDs was induced by direct chemical oxidation and the possible mechanism could be explained by radiative recombination of injected holes and electrons.This investigation not only provided new sight into the optical characteristics of CdTe/CdS/ZnS QDs,but also broadened their potential optical utilizations.展开更多
In this paper, CdS quantum dots sensitized TiO2 composite powders （QD-CdS/TiO2） were synthesized by impregnating TiO2 powder into CdS sol with different concentrations. X-ray diffraction pattern （XRD） shows the cr...In this paper, CdS quantum dots sensitized TiO2 composite powders （QD-CdS/TiO2） were synthesized by impregnating TiO2 powder into CdS sol with different concentrations. X-ray diffraction pattern （XRD） shows the crystal structures of CdS and TiO2 are cubic phase and anatase phase separately in QD- CdS/TiO2 powder samples; the crystal size of CdS in QD- CdS/TiO2 is about 3-7 nm, while TiO2 crystal size is about 20 nm. With increasing CdS content in QD-CdS/TiO2 composite, the UV-Vis absorption spectrum shifted to the longer wavelength lines, exhibiting obvious quantum size effect. The fluorescence intensity of QD-CdS/TiO2 irradiated by blue light is weaker than that of pure CdS. When the molar ratio of CdS and TiO2 is about 1∶2, the QD-CdS/TiO2 powder has the best catalytic properties under visible-light irradiation, and the degradation rate of rhodamine B （RhB） is up to 92.2% within 60 min.展开更多
Novel CdTe/CdS quantum dots(QDs)coated with a hybrid of SiO_2 and ZnS were fabricated through a simple two-step approach.The hybrid SiO_2/ZnS coated CdTe/CdS quantum dots was characterized by transmission electron mic...Novel CdTe/CdS quantum dots(QDs)coated with a hybrid of SiO_2 and ZnS were fabricated through a simple two-step approach.The hybrid SiO_2/ZnS coated CdTe/CdS quantum dots was characterized by transmission electron microscopy(TEM),UV and fluorescence spectrometer.Results indicated that the core-shell structure gave the QDs outstanding photoluminescence properties,includinganarrowphotoluminescencespectrum,high photoluminescence(PL)quantum yield and long emission lifetime(average PL lifetime of increased from 26.4 ns to 49.1 ns).Cellular studies showed the QDs had good cytocompatibility with Hela cells as determined by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide(MTT)assay after coating SiO_2/ZnS,and also proved the feasibility of using the hybrid SiO_2/ZnS coated QDs as optical probes for in vitro cell imaging.The synthesis method of QDs is highly promising for the production of robust and functional optical probes for bio-imaging and sensing applications.展开更多
The thioglycollic acid（TGA） as a capping agent, CdTe/TGA quantum dots（QDs） with excellent properties were synthesized under microwave irradiation. The TGA/Cd/Te molar ratios, reaction time, temperature and p H are...The thioglycollic acid（TGA） as a capping agent, CdTe/TGA quantum dots（QDs） with excellent properties were synthesized under microwave irradiation. The TGA/Cd/Te molar ratios, reaction time, temperature and p H are the crucial factors for properties of QDs. The QDs were characterized by UVvis absorption and fluorescence spectra, transmission electron microscopy and Fourier transform infrared spectroscopy. The experimental results show that when the p H value is 11.5 and molar ratio of TGA：Cd：Te is 1.2：1：0.4 at 100 ℃ heating for 15 min, the resulted QDs exhibit a high fluorescence quantum yield of 78%. The fluorescence full width at half maximum（FHMW） of QDs is around 23 nm. The products are spherical with average size of 3-5 nm. There is a strong coordination effect between TGA and Cd2＋. Moreover, the results of interaction between as-made QDs and bovine serum albumin（BSA） suggest that the QDs-BSA binding reaction is a static quenching. The negative values of free energy（△G〈0） suggest that the binding process is spontaneous, △H〈0 and △S〈0 show that hydrogen bonds and van der Waals interactions play a major role in the binding reaction between QDs and BSA.展开更多
The photon-current conversion properties of nanostructured TiO2/Q-CdS film electrode were studied by using the photocurrent action spectra and the photocurrent dependence of potential.Because of quantum size effect,th...The photon-current conversion properties of nanostructured TiO2/Q-CdS film electrode were studied by using the photocurrent action spectra and the photocurrent dependence of potential.Because of quantum size effect,the bandgap of Q-CdS particles was widened to 2.51eV which were prepared when they were immersed in Cd(NO3)2 and Na2S solution respectively for 60s and then dried at 80℃.The diagram of energy level of Q-CdS film was determined with the photocurrent-potential curves and photoelectrochemical method.The valence band of Q-CdS film was-6.168eV(vs Vaccum).The nanostructured TiO2/Q-CdS film electrode could enlarge absorption region and obviously increase the photocurrent.The photon-electron conversion efficiency could be improved.展开更多
Well-dispersed CdS quantum dots (QDs) with narrow size-distribution were prepared using generation 4.5 ester-terminated PAMAM dendrimers as inner-templates. The average diameter of CdS QDs was 1.5 nm and the photolumi...Well-dispersed CdS quantum dots (QDs) with narrow size-distribution were prepared using generation 4.5 ester-terminated PAMAM dendrimers as inner-templates. The average diameter of CdS QDs was 1.5 nm and the photoluminescence was purple. The room temperature photoluminescence quantum yield (RT-PQY) was 0.015. The diameter of CdS QDs increased with the increase of n / nPAMAM, also the color of photoluminescence was tunable and could be changed from purple to blue.展开更多
基金supported by National Natural Science Foundation of China(No.60976004)Shanghai Municipal Commission for Science and Technology(No.09JC1405300)
文摘Toxicities of CdSe and CdSe/CdS quantum dots （QDs） synthesized by ultrasound-assisted methods were investigated in vitro and in vivo. Five human cell lines were used to assess the cytotoxicity of as-prepared CdSe and CdSe/CdS by assays of MTT viability, red blood cell hemolysis, flow cytometry, and fluorescence imaging. The results show that these QDs may be cytotoxic by their influence in S and G2 phases in cell cycles. The cytotoxicity of QDs depends on both the physicochemical properties and related to target cells.
文摘A new and convenient route is developed to synthesize CdSe and core-shell CdSe/CdS quantum dots（QDs） in aqueous solution.The gaseous precursors,H2Se and H2S,generated on-line by reducing SeO 3 2à with NaBH 4 and the reaction between Na 2 S and diluted H2SO 4,are used to form high-quality CdSe and CdSe/CdS QDs,respectively.The synthesized water-soluble CdSe and CdSe/CdS QDs possess high quantum yield（3% and 20%） and narrow full-width-at-half-maximum（43 nm and 38 nm）.The synthesis process is easily reproducible with simple apparatus and low-toxic chemicals,and can be readily extended to the large-scale aqueous synthesis of QDs.
基金the National Natural Science Foundation of China(No 30570465) the Municipal Science and Technology Committee of Chongqing
文摘Water-soluble CdS quantum dots（CdS-QDs） capped with thioglycohc acid were easily prepared, and a detection method of adriamycin was presented based on the fluorescence quenching of CdS-QDs. It was found that a complex could be formed between cetyhrimethyl ammonium bromide（CTAB） and CdS-QDs by using electrostatic interaction in Britton-Robinson（BR） buffer at pH = 7.00, and the strong fluorescence emission of the complex was observed at 500 nm when the complex was excited at 378 run. The presence of adriamycin, however, could strongly quench the fluorescence through hydrophobic interaction. The overall quenching percentage as a function of adriamycin concentration matches the Stern-Volmer equation very well. These properties make CdS-QDs a potential fluorescence probe for the detection of adriamycin. The detection hmit（3σ） of adriamycin is approximately 10^-9 mol/L.
基金Supported by the Measurement and Testing Center of Zhejiang Province, China(No.02079).
文摘The influence of surface S^2- dangling bonds and surface doped ions（Se^2-, Cu^2＋, and Hg^2＋） on the photoluminescence of Cd^2＋-rich CdS QDs was investigated. A quantitative model was proposed to understand the complex transfer processes of excited electrons in CdS QDs. The transfer of excited electrons from either the conduction band or the Cd^2＋-related trap-state to the surface S^2-related shallow hole trap-state is effective. However, the trap of excited electrons by surface doped ion trap-states from the Cd^2＋-related trap-state is more effective than that from the conduction band. The efficiency of trapping electrons from both the conduction band and the Cd^2＋-related trap-state can be quantitatively understood with the help of the proposed model. The results show that the transfer efficiency of excited electrons is dependent on the location of the energy-level of the relevant surface-related trap-state. The trap of excited electrons by the surface trap-state with energy-level closer to that of the conduction band is more effective, especially for the trap of excited electrons from Cd^2＋-related trap-state.
基金supported by the National Natural Science Foundation of China(No.20705019)National High-Tech R&D Program(No.2006AA03Z324)
文摘In the study, we observed the strong adsorption of CdTe/CdS QDs to antibodies and the formation of QDs-antibodies conjugates. Capillary electrophoresis with laser-induced fluorescence detection （CE-LIF）, fluorescence spectrometry and fluorescence correlation spectroscopy （FCS） were used to characterize the QDs conjugates with antibody. We found that the QDs-antibody conjugates possessed high fluorescence, small hydrodynamic radii and good stability in aqueous solution. 2009 Ji Cun Ren. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
基金supported by the National Natural Science Foundation of China(Nos.81373373,21435002,21227006)
文摘A novel chemiluminescence（CL） performance of CdTe/CdS/ZnS quantum dots（QDs） with periodate（KIO_4） was studied.Effects of concentration and pH on the CL system were investigated.Electron spin resonance（ESR） and the effects of radical scavenger analysis were employed for identification of intermediate species.The CL spectra for this system showed only one maximum emission peak centered around 620 nm,which was similar with photoluminescence（PL） spectra of CdTe/CdS/ZnS QDs.The CL of CdTe/CdS/ZnS QDs was induced by direct chemical oxidation and the possible mechanism could be explained by radiative recombination of injected holes and electrons.This investigation not only provided new sight into the optical characteristics of CdTe/CdS/ZnS QDs,but also broadened their potential optical utilizations.
基金Supported by the National Science Fund for Talent Training in Basic Science (J0830310)the Fundamental Research Funds for the Central Universities (017)
文摘In this paper, CdS quantum dots sensitized TiO2 composite powders （QD-CdS/TiO2） were synthesized by impregnating TiO2 powder into CdS sol with different concentrations. X-ray diffraction pattern （XRD） shows the crystal structures of CdS and TiO2 are cubic phase and anatase phase separately in QD- CdS/TiO2 powder samples; the crystal size of CdS in QD- CdS/TiO2 is about 3-7 nm, while TiO2 crystal size is about 20 nm. With increasing CdS content in QD-CdS/TiO2 composite, the UV-Vis absorption spectrum shifted to the longer wavelength lines, exhibiting obvious quantum size effect. The fluorescence intensity of QD-CdS/TiO2 irradiated by blue light is weaker than that of pure CdS. When the molar ratio of CdS and TiO2 is about 1∶2, the QD-CdS/TiO2 powder has the best catalytic properties under visible-light irradiation, and the degradation rate of rhodamine B （RhB） is up to 92.2% within 60 min.
基金The Fundamental Research Funds for the Central Universities,China(No.2232015D3-15)Shanghai Natural Science Foundation,China(No.14ZR1401300)“111 Project”Biomedical Textile Materials Science and Technology,China(No.B07024)
文摘Novel CdTe/CdS quantum dots(QDs)coated with a hybrid of SiO_2 and ZnS were fabricated through a simple two-step approach.The hybrid SiO_2/ZnS coated CdTe/CdS quantum dots was characterized by transmission electron microscopy(TEM),UV and fluorescence spectrometer.Results indicated that the core-shell structure gave the QDs outstanding photoluminescence properties,includinganarrowphotoluminescencespectrum,high photoluminescence(PL)quantum yield and long emission lifetime(average PL lifetime of increased from 26.4 ns to 49.1 ns).Cellular studies showed the QDs had good cytocompatibility with Hela cells as determined by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide(MTT)assay after coating SiO_2/ZnS,and also proved the feasibility of using the hybrid SiO_2/ZnS coated QDs as optical probes for in vitro cell imaging.The synthesis method of QDs is highly promising for the production of robust and functional optical probes for bio-imaging and sensing applications.
基金Funded by the China Scholarship Council and Hubei Provincial Department of Education of China(201308420539)the Science and Technology Research Program of Hubei Provincial Department of Education of China(Q20131105,B2016008)+1 种基金the Coal Conversion and New Carbon Materials Hubei Key Laboratory(Wuhan University of Science and Technology(WKDM201505,WKDM201507)the Wuhan University of Science and Technology Foundation of China(z00980,2014XG006)
文摘The thioglycollic acid（TGA） as a capping agent, CdTe/TGA quantum dots（QDs） with excellent properties were synthesized under microwave irradiation. The TGA/Cd/Te molar ratios, reaction time, temperature and p H are the crucial factors for properties of QDs. The QDs were characterized by UVvis absorption and fluorescence spectra, transmission electron microscopy and Fourier transform infrared spectroscopy. The experimental results show that when the p H value is 11.5 and molar ratio of TGA：Cd：Te is 1.2：1：0.4 at 100 ℃ heating for 15 min, the resulted QDs exhibit a high fluorescence quantum yield of 78%. The fluorescence full width at half maximum（FHMW） of QDs is around 23 nm. The products are spherical with average size of 3-5 nm. There is a strong coordination effect between TGA and Cd2＋. Moreover, the results of interaction between as-made QDs and bovine serum albumin（BSA） suggest that the QDs-BSA binding reaction is a static quenching. The negative values of free energy（△G〈0） suggest that the binding process is spontaneous, △H〈0 and △S〈0 show that hydrogen bonds and van der Waals interactions play a major role in the binding reaction between QDs and BSA.
文摘The photon-current conversion properties of nanostructured TiO2/Q-CdS film electrode were studied by using the photocurrent action spectra and the photocurrent dependence of potential.Because of quantum size effect,the bandgap of Q-CdS particles was widened to 2.51eV which were prepared when they were immersed in Cd(NO3)2 and Na2S solution respectively for 60s and then dried at 80℃.The diagram of energy level of Q-CdS film was determined with the photocurrent-potential curves and photoelectrochemical method.The valence band of Q-CdS film was-6.168eV(vs Vaccum).The nanostructured TiO2/Q-CdS film electrode could enlarge absorption region and obviously increase the photocurrent.The photon-electron conversion efficiency could be improved.
文摘Well-dispersed CdS quantum dots (QDs) with narrow size-distribution were prepared using generation 4.5 ester-terminated PAMAM dendrimers as inner-templates. The average diameter of CdS QDs was 1.5 nm and the photoluminescence was purple. The room temperature photoluminescence quantum yield (RT-PQY) was 0.015. The diameter of CdS QDs increased with the increase of n / nPAMAM, also the color of photoluminescence was tunable and could be changed from purple to blue.
