The ultrafast carrier relaxation processes in CdTe quantum dots are investigated by femtosecond fluorescence upconversion spectroscopy.Photo-excited hole relaxing to the edge of the forbidden gap takes a maximal time ...The ultrafast carrier relaxation processes in CdTe quantum dots are investigated by femtosecond fluorescence upconversion spectroscopy.Photo-excited hole relaxing to the edge of the forbidden gap takes a maximal time of ～ 1.6 ps with exciting at 400 nm,depending on the state of the photo-excited hole.The shallow trapped states and deep trap states in the forbidden gap are confirmed for CdTe quantum dots.In addition,Auger relaxation of trapped carriers is observed to occur with a time constant of ～ 5 ps.A schematic model of photodynamics is established based on the results of the spectroscopy studies.Our work demonstrates that femtosecond fluorescence up-conversion spectroscopy is a suitable and effective tool in studying the transportation and conversion dynamics of photon energy in a nanosystem.展开更多
In this work, the capillary electrophoresis mobility shift assay （CEMSA） was first adopted to study the interaction of protein with quantum dots （QDs）. In this study, bovine serum albumin （BSA） and CdTe QDs were...In this work, the capillary electrophoresis mobility shift assay （CEMSA） was first adopted to study the interaction of protein with quantum dots （QDs）. In this study, bovine serum albumin （BSA） and CdTe QDs were used as model samples. We observed that BSA was facilely adsorbed to CdTe QDs surface, and the QD-BSA complex was formed by a 1：1 stoichiometric ratio. A value of 2.17 4-0.27 × 10^6 mol^-1 L^-1 （at 25 ℃） for the association constant was obtained by CEMSA.展开更多
The cytotoxicity and DNA damage caused by thioglycolic acid（TGA）-capped cadmium telluride（CdTe） quantum dots（QDs） to hepatocyte line HL-7702 were investigated.Cell viability was measured by 3-（4,5-dimethylthiaz...The cytotoxicity and DNA damage caused by thioglycolic acid（TGA）-capped cadmium telluride（CdTe） quantum dots（QDs） to hepatocyte line HL-7702 were investigated.Cell viability was measured by 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide（MTT） assay;DNA damage was detected by single cell gel electrophoresis（SCGE）;the change of cell cycle progression was examined by propidium iodide（PI）-flow cytometry（FCM）;apoptosis was measured by acridine orange/ethidium bromide（AO/EB） assay and Annexin V-FITC/PI-FCM（FITC：fluorescein isothiocyanate）.The results show that the cytotoxicity induced by CdTe QDs was increased in a dose-dependent and time-dependent manner;after exposure to QDs for 24 h,as the exposure dose increased,the rate of DNA damage was significantly increased（P0.05）,and the degree of DNA damage was elevated.As the dose of CdTe QDs increased,the percentage of G 0 /G 1 phase cells was significantly decreased（P0.001）,while the percenttages of S and G 2 /M phases cells were significantly increased（P0.001）.In AO/EB assay,apoptotic cells could be observed under a fluorescence microscope,and apoptotic rate was increased as exposure dose increased.In Annexin V-FITC/PI-FCM assay,the apoptotic rates of CdTe QDs treated groups were significantly increased compared with that of control group（P0.05）.Our studies indicate that CdTe QDs could influence cell viability,and induce DNA damage,the S and G2 /M phases arrest and apoptosis of HL-7702.展开更多
This paper explored the feasibility for the application of luminescent CdTe quantum dots prepared in aqueous phase to live cell imaging. The highly luminescent CdTe quantum dots （QDs） were first prepared in aqueous ...This paper explored the feasibility for the application of luminescent CdTe quantum dots prepared in aqueous phase to live cell imaging. The highly luminescent CdTe quantum dots （QDs） were first prepared in aqueous phase, and then were covalentiy coupled to a plant lectin （UEA-1）, as a fluorescent probe. After incubating with of human umbilical vein endothelial cells （HUVECs）, the QD probe with UEA-1 was able to specifically bind the corresponding cell receptor. The good cell images were obtained in live cells using laser confocal scanning microscopy. We predict that QDs prepared in water phase will probably become an attractive alternative probe in cellular imaging and bio-labeling.展开更多
The influence of stabilizing agents and reaction time on the luminescent properties of water-soluble CdTe quantum dots(QDs) was discussed.The thioglycolic acid(TGA)-CdTe ODs were characterized by TEM,XRD and FTIR.It i...The influence of stabilizing agents and reaction time on the luminescent properties of water-soluble CdTe quantum dots(QDs) was discussed.The thioglycolic acid(TGA)-CdTe ODs were characterized by TEM,XRD and FTIR.It is found that larger-size QDs can be synthesized more easily when L-cysteine(Cys) or golutathione(GSH) is chosen as stabilizing agent and TGA is proper to prepare highly luminescent QDs because of the effect between Cd2+ and sulfhydryl group.Furthermore,the absorption wavelength,full width at half maximum(FWHM),stokes shift,photoluminescence(PL) quantum yield and PL stability of TGA-CdTe are strongly dependent on reaction time,in which the absorption wavelength changes against reaction time with an exponential function.The TGA-CdTe QDs prepared at 2 h possess more excellent luminescent properties.展开更多
<strong>Objective: </strong>The quantum dots are the useful materials in microelectronics and biomedical research. However its toxicity has to be considered. We studied the effect of cell inhibition with Z...<strong>Objective: </strong>The quantum dots are the useful materials in microelectronics and biomedical research. However its toxicity has to be considered. We studied the effect of cell inhibition with ZnS core quantum dots and CdTe quantum dots modified with Thioglycolic acid or Cysteine functional group (TGA-CdTe, TGA-CdTe/ZnS, Cys-CdTe, Cys-CdTe/ZnS) on Caco-2 cell proliferation. <strong>Methods</strong>: We studied the effect of cell inhibition with ZnS core QDs and CdTe QDs modified with functional group on Caco-2 cell proliferation by MTT assay at 0, 12.5, 25, 50, 100 μg/ml and 6, 24, 48 h. <strong>Result:</strong> Our results showed that all QDs have inhibited cell proliferation and reached maximum 79.21%. The inhibition rate of Cys-modified QDs increased with the increase of concentration and reached maximum 66.72%. The inhibition rate of TGA-modified QDs increased with the increase of time. The ratios of Cys-modified to TGA-modified were less than 1 at all concentrations and three exposure times (P ≤ 0.01). The average ratios of Cys-CdTe/ZnS to Cys-CdTe reached 1.11 only for 48 h (P ≤ 0.05). The ratios of TGA-CdTe/ZnS to TGA-CdTe were closed to 1 at all concentrations and exposure times. <strong>Conclusion:</strong> The regularity of QDs modified with functional group is that inhibition of TGA-modified higher than Cys-modified. Inhibition exhibited dose-dependent for Cys-modified while exhibited time-dependent for TGA-modified. The regularity of CdTe-QDs with ZnS or not is that the inhibition of Cys-CdTe/ZnS was higher than Cys-CdTe while TGA-CdTe/ZnS and TGA-CdTe were consistent.展开更多
This study aims at preparing water soluble aspartic acid （ASP） modified CdTe quantum dots with tunable fluorescence emission controlled by reaction time. The size of the synthesized CdTe quantum dots was evaluated u...This study aims at preparing water soluble aspartic acid （ASP） modified CdTe quantum dots with tunable fluorescence emission controlled by reaction time. The size of the synthesized CdTe quantum dots was evaluated using transmission electron microscope （TEM） and also calculated based on their UV-vis spectra. The optical properties of TGA-CdTe quantum dots were characterized by UV-vis and fluorescence （FL） spectroscopy. The red-shift in the UV-vis absorption and FL emission with the increase of reaction time was observed. The biocompatibility examination indicated that the ASP modified CdTe QDs had low cytotoxicity.展开更多
We have developed a simple method for the preparation of highly fluorescent and stable, water-soluble CdTe quantum dots in sol-gel-derived composite silica spheres which were coated with calix[6]arene. The resulting n...We have developed a simple method for the preparation of highly fluorescent and stable, water-soluble CdTe quantum dots in sol-gel-derived composite silica spheres which were coated with calix[6]arene. The resulting nanoparticles (NPs) were characterized in terms of UV, fluorescence and FT-IR spectroscopy and TEM. The results show that the new NPs display more intense fluorescence intensity and are more stable than its precursors of the type SiO2/CdTe. Under the optimum, the novel NPs exhibit a higher selectivity and ultrasensitive fluorescence probes for the determination of gly-phosate over other pesticides, the fluorescence intensity increase with the concentration of glyphosate in the range from 1.0 to 25.0 nmol/L and the detection limit is low to 0.0725 nmol/L. A mechanism is suggested to explain the inclusion process by a Langmuir binding isotherm.展开更多
In this study, we report an efficient CdTe-SnOquantum dot（QD） solar cell fabricated by heat-assisted drop-casting of hydrothermally synthesized CdTe QDs on electrospun SnOnanofibers. The as-prepared QDs and SnOnanof...In this study, we report an efficient CdTe-SnOquantum dot（QD） solar cell fabricated by heat-assisted drop-casting of hydrothermally synthesized CdTe QDs on electrospun SnOnanofibers. The as-prepared QDs and SnOnanofibers were characterized by dynamic light scattering（DLS）, UV–Vis spectroscopy,photoluminescence（PL） spectra, X-ray diffraction（XRD） and transmission electron microscopy（TEM）. The SnOnanofibers deposited on fluorine-doped tin oxide（SnO） and sensitized with the CdTe QDs were assembled into a solar cell by sandwiching against a platinum（Pt） counter electrode in presence of cobalt electrolyte. The efficiency of cells was investigated by anchoring QDs of varying sizes on SnO. The best photovoltaic performance of an overall power conversion efficiency of 1.10%, an open-circuit voltage（Voc）of 0.80 V, and a photocurrent density（JSC） of 3.70 m A/cmwere obtained for cells with SnOthickness of5–6 μm and cell area of 0.25 cmunder standard 1 Sun illumination（100 m W/cm）. The efficiency was investigated for the same systems under polysulfide electrolyte as well for a comparison.展开更多
<div style="text-align:justify;"> <span style="font-family:Verdana;">Positively and negatively charged polyelectrolytes, namely, Poly(diallyldimethylammonium chloride) and Poly(styrene ...<div style="text-align:justify;"> <span style="font-family:Verdana;">Positively and negatively charged polyelectrolytes, namely, Poly(diallyldimethylammonium chloride) and Poly(styrene sulfonate), respectively, were employed to disperse and deploy negatively charged quantum dots on an otherwise passive metamaterial structure with a resonant frequency of 0.62 THz, by employing a layer-by-layer, self-assembly scheme. Upon exposure to a UV source with a wavelength of 365 nm the amplitude modulation was observed to increase with increases in the number of deposited bi-layers, until a modulation maximum of 2.68% was recorded enabling an all-optical, dynamically reconfigurable metamaterial geometry. Furthermore, amplitude modulation was subsequently observed to decrease with further increases in the number of layers employed due to quenching and shadowing effects. The experimental observations reported herein will enable the utilization of all-optical reconfigurable THz devices for communication and data transmission applications.展开更多
Quantum dots(QDs)luminescent films are extensively applied to optoelectronics and optical devices.However,QDs aggregation results in the quenching of their fluorescence property which limits their practical applicatio...Quantum dots(QDs)luminescent films are extensively applied to optoelectronics and optical devices.However,QDs aggregation results in the quenching of their fluorescence property which limits their practical applications to a greater extent.In order to resolve this issue,3-mercaptopropionic acid(3-MPA)functionalized Cadmium Tellurium(CdTe)QDs were stabilized by silk fibroin(SB)and coassembled with layered doubled hydroxide(LDH)to form(QDs@SF/LDH)_(n)ultrathin films(UTFs)via the layer-by-layer(LBL)technique.UV-Vis absorption and fluorescence spectroscopy showed a stepwise and normal growth of the films upon increasing the number of deposition cycles.XRD and AFM studies confirmed the formation of a periodic layered structure and regular surface morphology of the thin films.As compared to(CdTe QDs/LDH)_(n)UTFs,the(CdTe QDs@SF/LDH)_(n)UTFs displayed fluorescence enhancement and longer fluorescent lifetime,both in solid states and aqueous solutions.Furthermore compared with the solution state,the fluorescence enhancement of SF-RC and SF-β are,respectively,7 times and 17 times in the(CdTe QDs@SF/LDH)_(n)UTFs,indicating that the LDH nanosheets favor the fluorescence enhancement effect on the CdTe QDs@SF.The fabricated materials displayed fluorescence response to a biological molecule such as immune globulin,lgG.Thus,the(CdTe QDs@SF/LDH)_(n)UTFs has a potential to be used as biosensor.展开更多
A ultra-sensitive,highly specific,real-time polymerase chain reaction system based on mercaptoacetic acid-modified CdTe nanocrystals(mQDs)is reported.With the addition of 3 nm mQDs into the PCR reagent,the photolumine...A ultra-sensitive,highly specific,real-time polymerase chain reaction system based on mercaptoacetic acid-modified CdTe nanocrystals(mQDs)is reported.With the addition of 3 nm mQDs into the PCR reagent,the photoluminescent(PL)intensities of mQDs decreased gradually as the DNA templates and PCR cycles increased,in an approximate negative linear relation to the DNA concentration logarithm or cycles,the PL peaks exhibited red-shifts synchronously.Mg2+ions decreased the PL intensity of mQDs in a dose-dependent means,and Taq DNA polymerase enhanced the PL intensity of mQDs in a dose-dependent means.Real-time PCR based on mQDs showed an increased sensitivity at least 103 fold higher than that based on SYBR Green I.The specificity of PCR was enhanced in the PCR reagent with less than 1.33mg/mL mQDs.The potential mechanism is also discussed.This novel PCR system based on mQDs has great potential in applications such as ultra-sensitive specific DNA or RNA detection,dynamic molecular imaging,and photoelectric biosensors.展开更多
In this paper,dual-stabilizer-capped CdTe quantum dots were used as modulated photoluminescence(PL)sensors for the subpicomolar level detection of copper(II)(Cu^(2+))and mercury(II)(Hg^(2+))ions in aqueous solution fo...In this paper,dual-stabilizer-capped CdTe quantum dots were used as modulated photoluminescence(PL)sensors for the subpicomolar level detection of copper(II)(Cu^(2+))and mercury(II)(Hg^(2+))ions in aqueous solution for the first time.The dual-stabilizer-capped CdTe quantum dots were synthesized using mercaptopropionic acid(MPA)and sodium hexametaphosphate(SHMP)as surface-modified ligands via a convenient hydrothermal process.The researches showed a low interference response of the MPASHMP-capped CdTe quantum dots towards other metal ions.The highly efficient PL quenching ability in the presence of Hg^(2+)or Cu^(2+)ions due to the formed nonfluorescent metal complexes via robust Hg^(2+)–O interaction with the carboxy oxygen elements of surface ligands of MPA,and on the basis of the competitive binding of the mercapto groups of the MPA between the CdTe quantum dots and the Cu^(2+)ions,respectively,which allowed the analysis of Hg^(2+)or Cu^(2+)ions down to the picomolar levels.Under optimal conditions,the response of the MPA-SHMP-capped CdTe quantum dot PL intensity is linearly proportional to the Cu^(2+)and Hg^(2+)ion concentration ranging from 0.1 to 1000 and 0.3 to 1000 nM with a detection limit of 41.6 and 97.0 pM,respectively.The diagnostic capability and potential in practical applications of this method have been demonstrated by detecting Cu^(2+)and Hg^(2+)ions in environmental water samples.展开更多
Most luminescent glucose sensors based on the interaction of glucose with organic boric acids or borates.Herein,a new luminescent glucose sensor is designed using thioglycolic acid-capped CdTe quantum dots in the pres...Most luminescent glucose sensors based on the interaction of glucose with organic boric acids or borates.Herein,a new luminescent glucose sensor is designed using thioglycolic acid-capped CdTe quantum dots in the presence of cheap inorganic boric acid.Both peak position and intensities change upon the addition of glucose because of the interaction of boric acid with glucose and thioglycolic acid-capped CdTe quantum dots,which enables glucose detection by either color change or intensity change.The luminescent intensities change linearly with glucose concentrations in the ranges from 0.03 to 1 mM and 1–25 mM with a detection limit of 10μM(S/N=3).Moreover,glucose concentrations can be conveniently detected by color change in the range from 1 mM–25 mM.It displays a highly selective response to glucose over other interfering but biologically important saccharides,amino acids,and common ions.Graphical Abstract A thioglycolic acid-capped CdTe QD-based sensor can detect glucose with wide linear range by change in intensity or color in the presence of cheap inorganic boric acid.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
CdTe/CdS quantum dots（QDs） are fabricated on Si nanowires（NWs） substrates with and without Au nanoparticles（NPs）. The formation of Au NPs on Si NWs can be certified as shown in scanning electron microscopy image...CdTe/CdS quantum dots（QDs） are fabricated on Si nanowires（NWs） substrates with and without Au nanoparticles（NPs）. The formation of Au NPs on Si NWs can be certified as shown in scanning electron microscopy images. The optical properties of samples are also investigated. It is interesting to find that the photoluminescence（PL） intensity of Cd Te/Cd S QD films on Si nanowire substrates with Au NPs is significantly increased,which can reach 8-fold higher than that of samples on planar Si without Au NPs. The results of finite-difference time-domain simulation indicate that Au NPs induce stronger localization of electric field and then boost the PL intensity of QDs nearby. Furthermore, the time-resolved luminescence decay curve shows the PL lifetime, which is about 5.5 ns at the emission peaks of QD films on planar, increasing from 1.8 ns of QD films on Si NWs to4.7 ns after introducing Au NPs into Si NWs.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
A simple one-bath strategy has been developed to synthesize a novel CdTe@SiO_2@MIP（molecularly imprinted and silica-functionalized CdTe quantum dots,MISFQDs）,in which a silica shell was coated on the surface of CdTe...A simple one-bath strategy has been developed to synthesize a novel CdTe@SiO_2@MIP（molecularly imprinted and silica-functionalized CdTe quantum dots,MISFQDs）,in which a silica shell was coated on the surface of CdTe quantum dots （CdTe@SiO_2 QDs） and then a polymer for selective recognition of 4-chlorophenol（4-CP） was constructed on the surface of CdTe@SiO_2 QDs using mercaptoacetic acid as stabilizer,3-aminopropyl-trimethoxysilane（APTES） as functional monomers and tetraethoxysilane（TEOS） as crosslink agent.The structures of CdTe@SiO_2@MIP were analyzed by ultraviolet-visible absorption. Fluorescence,FT-IR spectrum and powder X-ray diffraction.The application and characterization of the CdTe@SiO_2@MIP were investigated by experiments.All results indicated that the CdTe@SiO_2@MIP can selectively recognize 4-chlorophenol.展开更多
The nanocomposites of poly-diallyldimethylammonium chloride (PDADMAC) and CdTe quantum dots (QDs) (i.e. QDs-PDADMAC nanocomposites) have been prepared based on electrostatic interaction and their fluorescence stabilit...The nanocomposites of poly-diallyldimethylammonium chloride (PDADMAC) and CdTe quantum dots (QDs) (i.e. QDs-PDADMAC nanocomposites) have been prepared based on electrostatic interaction and their fluorescence stability in aqueous solution has been investigated. MTT method (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide method) was used to study their cytotoxicity and A549 lung cancer cell as a model cell was also used to evaluate their cellular imaging. It was shown that the fluorescence stability of QDsPDADMAC nanocomposites was much better than that of bare QDs both in aqueous solution and cell. Meanwhile, QDs-PDADMAC nanocomposites display very low cytotoxicity in the low concentrations and better staining ability compared with QDs. QDs-PDADMAC nanocomposites will have great advantage on the cell analysis detection and imaging.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11074003 and 20973001)the Key Program of Educational Commission of Anhui Province of China (Grant No. KJ2010A132)
文摘The ultrafast carrier relaxation processes in CdTe quantum dots are investigated by femtosecond fluorescence upconversion spectroscopy.Photo-excited hole relaxing to the edge of the forbidden gap takes a maximal time of ～ 1.6 ps with exciting at 400 nm,depending on the state of the photo-excited hole.The shallow trapped states and deep trap states in the forbidden gap are confirmed for CdTe quantum dots.In addition,Auger relaxation of trapped carriers is observed to occur with a time constant of ～ 5 ps.A schematic model of photodynamics is established based on the results of the spectroscopy studies.Our work demonstrates that femtosecond fluorescence up-conversion spectroscopy is a suitable and effective tool in studying the transportation and conversion dynamics of photon energy in a nanosystem.
基金This work was financially supported by the National Natural Science Foundation of China （No.20675052, 20727005）；National High-Tech R＆D Program （No.2006AA03Z324）.
文摘In this work, the capillary electrophoresis mobility shift assay （CEMSA） was first adopted to study the interaction of protein with quantum dots （QDs）. In this study, bovine serum albumin （BSA） and CdTe QDs were used as model samples. We observed that BSA was facilely adsorbed to CdTe QDs surface, and the QD-BSA complex was formed by a 1：1 stoichiometric ratio. A value of 2.17 4-0.27 × 10^6 mol^-1 L^-1 （at 25 ℃） for the association constant was obtained by CEMSA.
基金Supported by the Funding Project for Academic Human Resources Development in Higher Learning Institution Under the Jurisdiction of Beijing Municipality,China(No.PHR201006110)the Innovative Team Project of Beijing Education Committee,China(No.PHR201107116)
文摘The cytotoxicity and DNA damage caused by thioglycolic acid（TGA）-capped cadmium telluride（CdTe） quantum dots（QDs） to hepatocyte line HL-7702 were investigated.Cell viability was measured by 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide（MTT） assay;DNA damage was detected by single cell gel electrophoresis（SCGE）;the change of cell cycle progression was examined by propidium iodide（PI）-flow cytometry（FCM）;apoptosis was measured by acridine orange/ethidium bromide（AO/EB） assay and Annexin V-FITC/PI-FCM（FITC：fluorescein isothiocyanate）.The results show that the cytotoxicity induced by CdTe QDs was increased in a dose-dependent and time-dependent manner;after exposure to QDs for 24 h,as the exposure dose increased,the rate of DNA damage was significantly increased（P0.05）,and the degree of DNA damage was elevated.As the dose of CdTe QDs increased,the percentage of G 0 /G 1 phase cells was significantly decreased（P0.001）,while the percenttages of S and G 2 /M phases cells were significantly increased（P0.001）.In AO/EB assay,apoptotic cells could be observed under a fluorescence microscope,and apoptotic rate was increased as exposure dose increased.In Annexin V-FITC/PI-FCM assay,the apoptotic rates of CdTe QDs treated groups were significantly increased compared with that of control group（P0.05）.Our studies indicate that CdTe QDs could influence cell viability,and induce DNA damage,the S and G2 /M phases arrest and apoptosis of HL-7702.
基金This work was financially supported by the National Natural Science Foundation of China （No. 20335020, 90408014） and the Nano-Science Foundation of Shanghai （0452NM052, 05NM0500 -2）.
文摘This paper explored the feasibility for the application of luminescent CdTe quantum dots prepared in aqueous phase to live cell imaging. The highly luminescent CdTe quantum dots （QDs） were first prepared in aqueous phase, and then were covalentiy coupled to a plant lectin （UEA-1）, as a fluorescent probe. After incubating with of human umbilical vein endothelial cells （HUVECs）, the QD probe with UEA-1 was able to specifically bind the corresponding cell receptor. The good cell images were obtained in live cells using laser confocal scanning microscopy. We predict that QDs prepared in water phase will probably become an attractive alternative probe in cellular imaging and bio-labeling.
基金Projects(10805069,10405034) supported by the National Natural Science Foundation of China
文摘The influence of stabilizing agents and reaction time on the luminescent properties of water-soluble CdTe quantum dots(QDs) was discussed.The thioglycolic acid(TGA)-CdTe ODs were characterized by TEM,XRD and FTIR.It is found that larger-size QDs can be synthesized more easily when L-cysteine(Cys) or golutathione(GSH) is chosen as stabilizing agent and TGA is proper to prepare highly luminescent QDs because of the effect between Cd2+ and sulfhydryl group.Furthermore,the absorption wavelength,full width at half maximum(FWHM),stokes shift,photoluminescence(PL) quantum yield and PL stability of TGA-CdTe are strongly dependent on reaction time,in which the absorption wavelength changes against reaction time with an exponential function.The TGA-CdTe QDs prepared at 2 h possess more excellent luminescent properties.
文摘<strong>Objective: </strong>The quantum dots are the useful materials in microelectronics and biomedical research. However its toxicity has to be considered. We studied the effect of cell inhibition with ZnS core quantum dots and CdTe quantum dots modified with Thioglycolic acid or Cysteine functional group (TGA-CdTe, TGA-CdTe/ZnS, Cys-CdTe, Cys-CdTe/ZnS) on Caco-2 cell proliferation. <strong>Methods</strong>: We studied the effect of cell inhibition with ZnS core QDs and CdTe QDs modified with functional group on Caco-2 cell proliferation by MTT assay at 0, 12.5, 25, 50, 100 μg/ml and 6, 24, 48 h. <strong>Result:</strong> Our results showed that all QDs have inhibited cell proliferation and reached maximum 79.21%. The inhibition rate of Cys-modified QDs increased with the increase of concentration and reached maximum 66.72%. The inhibition rate of TGA-modified QDs increased with the increase of time. The ratios of Cys-modified to TGA-modified were less than 1 at all concentrations and three exposure times (P ≤ 0.01). The average ratios of Cys-CdTe/ZnS to Cys-CdTe reached 1.11 only for 48 h (P ≤ 0.05). The ratios of TGA-CdTe/ZnS to TGA-CdTe were closed to 1 at all concentrations and exposure times. <strong>Conclusion:</strong> The regularity of QDs modified with functional group is that inhibition of TGA-modified higher than Cys-modified. Inhibition exhibited dose-dependent for Cys-modified while exhibited time-dependent for TGA-modified. The regularity of CdTe-QDs with ZnS or not is that the inhibition of Cys-CdTe/ZnS was higher than Cys-CdTe while TGA-CdTe/ZnS and TGA-CdTe were consistent.
基金funded by the Danish Strategic Research Council(No.DSF-10-93456,FENAMI Project)the Fundamental Research Funds for the Central Universities(No.JUSRP1042)+2 种基金the Open Project Program of Key Laboratory of Eco-textiles,Ministry of Education,Jiangnan University(No.KLET1202)the National Natural Science Foundation of China under Grant No.31201134National High-tech R&D Program of China(863 Program,No. 2012AA030313)
文摘This study aims at preparing water soluble aspartic acid （ASP） modified CdTe quantum dots with tunable fluorescence emission controlled by reaction time. The size of the synthesized CdTe quantum dots was evaluated using transmission electron microscope （TEM） and also calculated based on their UV-vis spectra. The optical properties of TGA-CdTe quantum dots were characterized by UV-vis and fluorescence （FL） spectroscopy. The red-shift in the UV-vis absorption and FL emission with the increase of reaction time was observed. The biocompatibility examination indicated that the ASP modified CdTe QDs had low cytotoxicity.
文摘We have developed a simple method for the preparation of highly fluorescent and stable, water-soluble CdTe quantum dots in sol-gel-derived composite silica spheres which were coated with calix[6]arene. The resulting nanoparticles (NPs) were characterized in terms of UV, fluorescence and FT-IR spectroscopy and TEM. The results show that the new NPs display more intense fluorescence intensity and are more stable than its precursors of the type SiO2/CdTe. Under the optimum, the novel NPs exhibit a higher selectivity and ultrasensitive fluorescence probes for the determination of gly-phosate over other pesticides, the fluorescence intensity increase with the concentration of glyphosate in the range from 1.0 to 25.0 nmol/L and the detection limit is low to 0.0725 nmol/L. A mechanism is suggested to explain the inclusion process by a Langmuir binding isotherm.
基金supported by Solar Energy Research Initiative(SERI)of Department of Science and Technology(DST),Govt.of India
文摘In this study, we report an efficient CdTe-SnOquantum dot（QD） solar cell fabricated by heat-assisted drop-casting of hydrothermally synthesized CdTe QDs on electrospun SnOnanofibers. The as-prepared QDs and SnOnanofibers were characterized by dynamic light scattering（DLS）, UV–Vis spectroscopy,photoluminescence（PL） spectra, X-ray diffraction（XRD） and transmission electron microscopy（TEM）. The SnOnanofibers deposited on fluorine-doped tin oxide（SnO） and sensitized with the CdTe QDs were assembled into a solar cell by sandwiching against a platinum（Pt） counter electrode in presence of cobalt electrolyte. The efficiency of cells was investigated by anchoring QDs of varying sizes on SnO. The best photovoltaic performance of an overall power conversion efficiency of 1.10%, an open-circuit voltage（Voc）of 0.80 V, and a photocurrent density（JSC） of 3.70 m A/cmwere obtained for cells with SnOthickness of5–6 μm and cell area of 0.25 cmunder standard 1 Sun illumination（100 m W/cm）. The efficiency was investigated for the same systems under polysulfide electrolyte as well for a comparison.
文摘<div style="text-align:justify;"> <span style="font-family:Verdana;">Positively and negatively charged polyelectrolytes, namely, Poly(diallyldimethylammonium chloride) and Poly(styrene sulfonate), respectively, were employed to disperse and deploy negatively charged quantum dots on an otherwise passive metamaterial structure with a resonant frequency of 0.62 THz, by employing a layer-by-layer, self-assembly scheme. Upon exposure to a UV source with a wavelength of 365 nm the amplitude modulation was observed to increase with increases in the number of deposited bi-layers, until a modulation maximum of 2.68% was recorded enabling an all-optical, dynamically reconfigurable metamaterial geometry. Furthermore, amplitude modulation was subsequently observed to decrease with further increases in the number of layers employed due to quenching and shadowing effects. The experimental observations reported herein will enable the utilization of all-optical reconfigurable THz devices for communication and data transmission applications.
基金This work was supported by the 973 Program(Grant2014CB932101)the National Natural Science Foundation of China,111 Project(Grant no.B07004)Innovation Research Team in University and Central University Research Funds of China(buctrc201527).
文摘Quantum dots(QDs)luminescent films are extensively applied to optoelectronics and optical devices.However,QDs aggregation results in the quenching of their fluorescence property which limits their practical applications to a greater extent.In order to resolve this issue,3-mercaptopropionic acid(3-MPA)functionalized Cadmium Tellurium(CdTe)QDs were stabilized by silk fibroin(SB)and coassembled with layered doubled hydroxide(LDH)to form(QDs@SF/LDH)_(n)ultrathin films(UTFs)via the layer-by-layer(LBL)technique.UV-Vis absorption and fluorescence spectroscopy showed a stepwise and normal growth of the films upon increasing the number of deposition cycles.XRD and AFM studies confirmed the formation of a periodic layered structure and regular surface morphology of the thin films.As compared to(CdTe QDs/LDH)_(n)UTFs,the(CdTe QDs@SF/LDH)_(n)UTFs displayed fluorescence enhancement and longer fluorescent lifetime,both in solid states and aqueous solutions.Furthermore compared with the solution state,the fluorescence enhancement of SF-RC and SF-β are,respectively,7 times and 17 times in the(CdTe QDs@SF/LDH)_(n)UTFs,indicating that the LDH nanosheets favor the fluorescence enhancement effect on the CdTe QDs@SF.The fabricated materials displayed fluorescence response to a biological molecule such as immune globulin,lgG.Thus,the(CdTe QDs@SF/LDH)_(n)UTFs has a potential to be used as biosensor.
基金supported by the National Natural Science Foundation of China(No.20803040 and No.20471599)Chinese 973 Project(2010CB933901),863 Key Project(2007AA022004)+2 种基金New Century Excellent Talent of Ministry of Education of China(NCET-08-0350)Special Infection Diseases Key Project of China(2009ZX10004-311)Shanghai Science and Technology Fund(10XD1406100).
文摘A ultra-sensitive,highly specific,real-time polymerase chain reaction system based on mercaptoacetic acid-modified CdTe nanocrystals(mQDs)is reported.With the addition of 3 nm mQDs into the PCR reagent,the photoluminescent(PL)intensities of mQDs decreased gradually as the DNA templates and PCR cycles increased,in an approximate negative linear relation to the DNA concentration logarithm or cycles,the PL peaks exhibited red-shifts synchronously.Mg2+ions decreased the PL intensity of mQDs in a dose-dependent means,and Taq DNA polymerase enhanced the PL intensity of mQDs in a dose-dependent means.Real-time PCR based on mQDs showed an increased sensitivity at least 103 fold higher than that based on SYBR Green I.The specificity of PCR was enhanced in the PCR reagent with less than 1.33mg/mL mQDs.The potential mechanism is also discussed.This novel PCR system based on mQDs has great potential in applications such as ultra-sensitive specific DNA or RNA detection,dynamic molecular imaging,and photoelectric biosensors.
基金the National Natural Science Foundation of China(21575022,21535003),the National High Technology Research and Development Program(“863”Program)of China(2015AA020502)the Fundamental Research Funds for the Central Universities,Qing Lan Project and A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.And we greatly appreciate the support of the National Natural Science Foundation of China(21575123,21675139,21705140)+1 种基金the Natural Science Foundation of Jiangsu Province(BK20170474)the Industry-University-Research Cooperative Innovation Foundation of Jiangsu Province(BY2015057-17).
文摘In this paper,dual-stabilizer-capped CdTe quantum dots were used as modulated photoluminescence(PL)sensors for the subpicomolar level detection of copper(II)(Cu^(2+))and mercury(II)(Hg^(2+))ions in aqueous solution for the first time.The dual-stabilizer-capped CdTe quantum dots were synthesized using mercaptopropionic acid(MPA)and sodium hexametaphosphate(SHMP)as surface-modified ligands via a convenient hydrothermal process.The researches showed a low interference response of the MPASHMP-capped CdTe quantum dots towards other metal ions.The highly efficient PL quenching ability in the presence of Hg^(2+)or Cu^(2+)ions due to the formed nonfluorescent metal complexes via robust Hg^(2+)–O interaction with the carboxy oxygen elements of surface ligands of MPA,and on the basis of the competitive binding of the mercapto groups of the MPA between the CdTe quantum dots and the Cu^(2+)ions,respectively,which allowed the analysis of Hg^(2+)or Cu^(2+)ions down to the picomolar levels.Under optimal conditions,the response of the MPA-SHMP-capped CdTe quantum dot PL intensity is linearly proportional to the Cu^(2+)and Hg^(2+)ion concentration ranging from 0.1 to 1000 and 0.3 to 1000 nM with a detection limit of 41.6 and 97.0 pM,respectively.The diagnostic capability and potential in practical applications of this method have been demonstrated by detecting Cu^(2+)and Hg^(2+)ions in environmental water samples.
基金the National Natural Science Foundation of China(Nos.21475123 and 21505128)Chinese Academy of Sciences(CAS)and Faculty Development Program of the Bahauddin Zakaryia University,Multan,Pakistan(100 Foreign Scholarships)(No.PF/Cont./2-50/Admin/5398).
文摘Most luminescent glucose sensors based on the interaction of glucose with organic boric acids or borates.Herein,a new luminescent glucose sensor is designed using thioglycolic acid-capped CdTe quantum dots in the presence of cheap inorganic boric acid.Both peak position and intensities change upon the addition of glucose because of the interaction of boric acid with glucose and thioglycolic acid-capped CdTe quantum dots,which enables glucose detection by either color change or intensity change.The luminescent intensities change linearly with glucose concentrations in the ranges from 0.03 to 1 mM and 1–25 mM with a detection limit of 10μM(S/N=3).Moreover,glucose concentrations can be conveniently detected by color change in the range from 1 mM–25 mM.It displays a highly selective response to glucose over other interfering but biologically important saccharides,amino acids,and common ions.Graphical Abstract A thioglycolic acid-capped CdTe QD-based sensor can detect glucose with wide linear range by change in intensity or color in the presence of cheap inorganic boric acid.
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 Qing Lan Project of the Higher Education Institutions of Jiangsu Province,Qing Lan Project of Yangzhou Polytechnic Institute,the Natural Science Foundation of Yangzhou City under Grant No YZ2016123the National Natural Science Foundation of China under Grant No 61376004
文摘CdTe/CdS quantum dots（QDs） are fabricated on Si nanowires（NWs） substrates with and without Au nanoparticles（NPs）. The formation of Au NPs on Si NWs can be certified as shown in scanning electron microscopy images. The optical properties of samples are also investigated. It is interesting to find that the photoluminescence（PL） intensity of Cd Te/Cd S QD films on Si nanowire substrates with Au NPs is significantly increased,which can reach 8-fold higher than that of samples on planar Si without Au NPs. The results of finite-difference time-domain simulation indicate that Au NPs induce stronger localization of electric field and then boost the PL intensity of QDs nearby. Furthermore, the time-resolved luminescence decay curve shows the PL lifetime, which is about 5.5 ns at the emission peaks of QD films on planar, increasing from 1.8 ns of QD films on Si NWs to4.7 ns after introducing Au NPs into Si NWs.
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the financial support from the Hubei Science Foundation(No.2010CDA061)the Science Foundation of the Education Department of Hubei Province(No.D200922005)
文摘A simple one-bath strategy has been developed to synthesize a novel CdTe@SiO_2@MIP（molecularly imprinted and silica-functionalized CdTe quantum dots,MISFQDs）,in which a silica shell was coated on the surface of CdTe quantum dots （CdTe@SiO_2 QDs） and then a polymer for selective recognition of 4-chlorophenol（4-CP） was constructed on the surface of CdTe@SiO_2 QDs using mercaptoacetic acid as stabilizer,3-aminopropyl-trimethoxysilane（APTES） as functional monomers and tetraethoxysilane（TEOS） as crosslink agent.The structures of CdTe@SiO_2@MIP were analyzed by ultraviolet-visible absorption. Fluorescence,FT-IR spectrum and powder X-ray diffraction.The application and characterization of the CdTe@SiO_2@MIP were investigated by experiments.All results indicated that the CdTe@SiO_2@MIP can selectively recognize 4-chlorophenol.
基金supported by the grant from the National Natural Science Foundation of China (Grant No. 81001686)by the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions of China
文摘The nanocomposites of poly-diallyldimethylammonium chloride (PDADMAC) and CdTe quantum dots (QDs) (i.e. QDs-PDADMAC nanocomposites) have been prepared based on electrostatic interaction and their fluorescence stability in aqueous solution has been investigated. MTT method (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide method) was used to study their cytotoxicity and A549 lung cancer cell as a model cell was also used to evaluate their cellular imaging. It was shown that the fluorescence stability of QDsPDADMAC nanocomposites was much better than that of bare QDs both in aqueous solution and cell. Meanwhile, QDs-PDADMAC nanocomposites display very low cytotoxicity in the low concentrations and better staining ability compared with QDs. QDs-PDADMAC nanocomposites will have great advantage on the cell analysis detection and imaging.
