CdTe/Mn3 O4/SiO2荧光/磁共振双模成像纳米球的制备与表征

成功地制备了CdTe/Mn_3O_4/SiO_2核壳结构的荧光/磁共振成像双功能纳米球,并用透射电镜(TEM)、能谱分析(EDXA)、磁共振成像(MRI)、红外、荧光光谱等对其结构、磁共振成像和发光性能进行了表征。TEM照片显示所合成的纳米球具有明显的球形核壳结构。EDXA分析显示所制备的CdTe/Mn_3O_4/SiO_2纳米球表面只检测到Si和O元素,证明CdTe量子点和Mn_3O_4纳米立方体被成功地包被于二氧化硅纳米球之内。荧光发射光谱显示相对于CdTe量子点,CdTe/Mn_3O_4/SiO_2纳米球荧光发射光谱虽然发生了一定的蓝移,但是仍具有良好的荧光性能。MRI分析可知CdTe/Mn_3O_4/SiO_2纳米球的弛豫参数(r_1)为3.88 s~(-1)(mg·L~(-1))~(-1),说明所合成的CdTe/Mn_3O_4/SiO_2纳米球可用于T_1-加权磁共振成像。细胞毒性实验表明,当CdTe/Mn_3O_4/SiO_2溶液浓度达到300μg·mL~(-1)时,细胞活力仍可达到90%以上,表明此浓度对细胞的毒性作用较弱。     

碲化镉纳米晶的制备及应用

基于自身的量子限域效应、尺寸效应、介电限域效应、宏观量子隧道效应和表面效应,碲化镉(CdTe)纳米晶独特的性质在非线性光学、磁介质、催化、医药及功能材料等方面得到了广泛的应用,并且展现出极为广阔的应用前景,同时对生命科学和信息技术的持续发展以及物质领域的基础研究也产生了深刻的影响。本文以 CdTe 纳米晶为对象,详细介绍了其5种典型的制备方法和应用的最新进展。在制备方面,5种典型的制备方法各有利弊,如何在温和的条件下制备出形貌和尺寸可控的 CdTe 纳米晶仍是一个值得追求的目标。通过自组装技术可以制备形貌独特,性能优异的 CdTe 纳米材料,进而实现 CdTe 半导体纳米器件的研制,具有重要的科学意义,是今后研究的热门方向。在应用方面,CdTe纳米晶不但实现了其在光电器件、生物学等领域的应用,而且将会在这些领域继续深化和延伸,开发出新的应用领域。本文同时对 CdTe 纳米晶的发展趋势也进行了展望。     

通过静电相互作用制备CdTe/SiO2纳米复合物

以四乙氧基硅烷(TEOS)为原料,在乙醇相中制备了尺寸为80nmSiO₂纳米粒子,用3-氨基丙基三乙氧基硅烷对SiO₂纳米粒子进行了氨基化.以巯基乙酸为配体,在水相中合成了CdTe纳米晶.通过静电相互作用,CdTe纳米晶被吸附到氨基化的二氧化硅球的表面上.研究了两种粒子复合后引起的CdTe纳米晶发光光谱的变化.     

利用水相合成的CdTe纳米晶构建超晶格结构研究--纳米晶聚集体的调控

用巯基丙酸作稳定剂,在水溶液中制备了CdTe纳米晶.通过加入Cd2+、聚丙烯酸(PAA)以及长期放置分别得到了CdTe纳米晶的聚集体,改变Cd2+浓度或PAA加入量可以调控聚集体的尺寸.过量的Cd2+加速了聚集体的形成,通过与纳米晶表面羧酸根的静电相互作用,Cd2+成为连接不同CdTe纳米晶的“桥梁”.PAA链上大量的羧基与CdTe纳米晶有较强的配位相互作用,可以诱导纳米晶聚集.新制CdTe纳米晶在长期放置时,表面的羧基与Cd2+的相互作用导致纳米晶逐渐聚集.在聚集过程中纳米晶表面结构得到改善,并引起荧光增强.这些结果表明通过控制各种聚集条件,可以得到不同尺寸的聚集体.     

基于CdTe量子点-电纺纳米纤维组装体可视化、便携检测铜离子

采用静电纺丝技术制备得到抗湿性能良好的电纺纳米纤维,进一步与CdTe量子点(CdTe QDs)静电结合得到组装体.扫描电镜、透射电镜和共聚焦荧光显微成像表征结果表明,在pH 7.2、静电组装时间90 min的条件下,CdTe QDs均匀地组装在电纺纳米纤维表面,在365 nm紫外灯照射下,CdTe QDs-电纺纳米纤维...     

巯基乙胺稳定的水溶性CdTe纳米粒子的合成与表征

用巯基乙胺(cysteamine，CA)作为稳定剂，在水相中合成了发光可调的CdTe半导体纳米粒子。这些巯基乙胺稳定的CdTe纳米粒子表面带有大量的正电荷。实验结果表明，稳定剂与Cd的比例以及pH等实验条件对CdTe纳米粒子体系的荧光发射强度影响较大。在pH为6.1时，纳米粒子体系在橙红波段的荧光量子产率达到了9%左右。控制实验条件，合成了各种尺寸的CdTe纳米粒子，荧光发射光谱在520～600 nm范围连续可调。分别用X射线光电子能谱(XPS)，透射电子显微镜(TEM)，X射线衍射仪(XRD)，红外吸收     

用水溶液中合成的量子点作为生物荧光标记物的研究

以巯基丙酸(HS-CH₂CH₂COOH)为稳定剂,在水溶液中合成了具有窄而对称(FWHM=40nm)的荧光发射带且尺寸为3nm的CdTe半导体纳米粒子,并用此纳米粒子成功地标记了生物分子胰蛋白酶.与单独的CdTe纳米粒子的溶液相比较,CdTe-胰蛋白酶溶液的吸收光谱在400～600nm范围内较为平坦,其发射光谱蓝移8nm,但发射峰的半峰宽不变.实验证明,CdTe-胰蛋白酶溶液吸收和发射光谱的变化是由CdTe纳米粒子与胰蛋白酶之间的结合反应引起的,而不是由空气中的O₂所引起的,加热可促进CdTe纳米粒子与胰蛋白酶之间的结合反应.     

基于CdTe量子点自组装的超分支结构的制备及发光特性

提出了一种简单高效制备立体型纳米结构的方法.利用强偶极相互作用,CdTe量子点通过层级自组装形成超分支纳米结构.场发射高分辨透射电子显微(HRTEM)照片显示,制备的超分支纳米结构的构建单元即为原始的CdTe量子点,即组装后的结构保留了原始量子点的量子局限特性.该结构形态受熟化时间、环境pH值以及沉淀剂比例的影响.荧光实验发现,该结构良好地保持了原始量子点的线性光学特性.由于其超分支形态与量子局限效应同时存在,因此该种结构在光伏转换和传感等领域有着重要的潜在应用价值.     

电化学法合成强荧光CdTe量子点

采用电化学方法产生的H2Te为碲源(Te2-),快速合成了水溶性强荧光的CdTe量子点.该方法具有操作简单、安全、快速廉价和可大量制备等优点.合成过程中考察了合成温度,pH值和配体比例对制备CdTe量子点的影响.在最优化的实验条件下,电化学方法合成的巯基丙酸配位的CdTe荧光量子产率可达到55％;通过紫外可见光谱(UV...     

CdTe量子点DNA荧光纳米探针的合成及表征

采用水相合成法合成了巯基乙酸(TGA)修饰的水溶性CdTe量子点,通过反相微乳液法制备了二氧化硅及壳聚糖修饰的核壳型复合荧光纳米粒子,将其与DNA吸附连接,得到CdTe量子点DNA荧光纳米探针。用扫描电镜、透射电镜、荧光光谱、红外光谱、紫外光谱、ζ电位等测试方法对产物的理化性质进行了分析表征。结果表明制备了表面富含氨基的复合荧光纳米粒子,其对DNA具有良好的吸附作用。     

Factors governing the quality of aqueous CdTe nanocrystals: calculations and experiment

The aqueous synthesis of thiol-stabilized semiconductor CdTe colloidal nanocrystals has been revisited. We found optimal conditions for the synthesis of high-quality CdTe NCs through a study of the influence of the initial conditions (structure and concentration of Cd-thiol complexes) on the quality of the CdTe nanocrystals. A numerical calculation shows a clear correlation between the concentration of CdL (where L is (SCH(2)COO)(2-)) in the initial solution and the photoluminescence quantum efficiency of the CdTe nanocrystals.     

Dynamic distribution of growth rates within the ensembles of colloidal II-VI and III-V semiconductor nanocrystals as a factor governing their photoluminescence efficiency

The distribution of properties within ensembles of colloidally grown II-VI and III-V semiconductor nanocrystals was studied. A drastic difference in the photoluminescence efficiencies of size-selected fractions was observed for both organometallically prepared CdSe and InAs colloids and for CdTe nanocrystals synthesized in aqueous medium, indicating a general character of the phenomenon observed. The difference in the photoluminescence efficiencies is attributed to different averaged surface disorder of the nanocrystals originating from the Ostwald ripening growth mechanism when larger particles in the ensemble grow at the expense of dissolving smaller particles. At any stage of growth, only a fraction of particles within the ensemble of growing colloidal nanocrystals has the most perfect surface and, thus, shows the most efficient photoluminescence. This is explained by a theoretical model describing the evolution of an ensemble of nanocrystals in a colloidal solution. In an ensemble of growing nanocrystals, the fraction of particles with the highest photoluminescence corresponds to the particle size having nearly zero average growth rate. The small average growth rate leads to the lowest possible degree of surface disorder at any given reaction conditions.     

Synthesis and Surface Modification of CdTe Nanocrystals

IntroductionThe study on semiconductor nanocrystals has re-ceived considerable attention in the past decades[1—4].Because of the quantum confinement effect, smallnanocrystals show very special physical and chemicalproperties when their sizes are close to…     

CdTe纳米晶与蛋白相互作用研究

当半导体纳米晶的直径小于其电子的玻尔直径时 ,半导体纳米晶对电子具有量子限域效应 ,其发光波长与纳米晶的尺寸相关 .与有机荧光分子相比 ,荧光半导体纳米晶具有以下优点 :(1 )其激发谱在吸收阈值以上几乎是连续的 ,利于多波长激发 ;(2 )高强荧光发射 ,谱峰窄 ,峰形对称 ;(3 )发射波长随着粒径的增大而有规律地红移 ,只需改变粒径即可获得多色发光 ;(4)纳米晶的发光稳定性好 ,不易被光分解和漂白 .因此 ,半导体纳米晶作为新一代荧光生物标记物已有研究[1～ 6] .荧光生物标记要求使用水溶性的纳米粒子 ,水相合成半导体纳米晶操作简便、重复…     

Comparative examination of the stability of semiconductor quantum dots in various biochemical buffers

Due to their greater photostability compared to established organic fluorescence markers, semiconductor quantum dots provide an attractive alternative for the biolabeling of living cells. On the basis of a comparative investigation using differently sized thiol-stabilized CdTe nanocrystals in a variety of commonly used biological buffers, a method is developed to quantify the stability of such a multicomponent system. Above a certain critical size, the intensity of the photoluminescence of the nanocrystals is found to diminish with pseudo-zero-order kinetics, whereas for specific combinations of particle size, ligand, and buffer there appears to be no decay below this critical particle size, pointing out the necessity for thorough investigations of this kind in the view of prospect applications of semiconductor nanocrystals in the area of biolabeling.     

CdTe nanocrystals sensitized chemiluminescence and the analytical application

It was found that the mixing of CdTe semiconductor nanocrystals (NCs) with luminol in the presence of KMnO₄ can induce a great sensitized effect on chemiluminescence (CL) emission. When the concentration of luminol, KMnO₄ and NaOH were fixed at 1 μM, 1 μM and 0.05 M, respectively, the most excellent performance can be obtained for the CdTe NCs sensitized CL. By means of CL and photoluminescence spectra, we suppose the enhanced CL signals resulted from the accelerated luminol CL induced by the oxidized species of CdTe NCs. Based on the finding, using thioglycolic acid-capped CdTe NCs as label and immunoglobulin G (IgG) as a model analyte, a CL immunoassay protocol for IgG content detection was developed. The strong inhibition effect of phenol compounds on luminol-KMnO₄-CdTe NCs CL system was also observed. All these findings demonstrated the possibility of semiconductor nanocrystals induced chemiluminescence to be utilized for more practical applications.     

半导体CdTe纳米晶的合成及其光学性能

半导体CdTe纳米晶的合成及其光学性能;CdTe;纳米晶;光学性能     

Synthesis of Zinc Blende CdTe Nanocrystals and Facile Shape Conversion from Multipods to Dot-shaped Particles

Branched CdTe nanocrystals with zinc blende structure were directly synthesized in the early growth stage at a high initial concentration of cadmium precursor and a high molar ratio of Cd precursor to Te precuesor. Activation of the cadmium precursor by octadecylamine was found to be critical for the formation of branched CdTe nanocrystals. Furthermore, these as-prepared CdTe nanocrystals can evolve into nearly monodisperse dots through Ostwald ripening and still keep strong photoluminescence. These results manifest a new route to synthesize branch- and dot-shaped CdTe nanocrystals with zinc blende structure.     

Chemiluminescence of CdTe nanocrystals induced by direct chemical oxidation and its size-dependent and surfactant-sensitized effect

CdTe nanocrystals (NCs) capped with thioglycolic acid (TGA) were synthesized via a microwave-assisted method. The chemiluminescence (CL) of CdTe NCs induced by directly chemical oxidation and its size-depended and surfactant-sensitized effect in aqueous solution were then investigated. It was found that oxidants, especially hydrogen peroxide and potassium permanganate, could directly oxidize CdTe NCs to produce strong CL emission in basic conditions. The oxidized CL of CdTe NCs displayed size-dependent effect and its intensity increased along with increasing the sizes of the NCs. Moreover, the CL intensity could, if surfactants CTAB or beta-cyclodextrin were added to the above CL system, be sensitized to some degree. The sensitized CL induced by CTAB and beta-cyclodextrin is mainly contributing to the formation of aggregate nanostructure and the micellar micronanoenvironment, respectively. The possible oxidized CL mechanisms were further examined by means of photoluminescence spectra, CL spectra, and transmission electron microscopy studies. The CL properties of CdTe NCs not only will be helpful to study physical chemistry properties of semiconductor nanocrystals but also are expected to find use in many fields such as luminescence devices, bioanalysis, and multicolor labeling probes.     

Prototype of immunochromatographic assay strips using colloidal CdTe nanocrystals as biological luminescent label

Colloidal semiconductor nanocrystals have attracted considerable attention as a novel biological luminescent label. The bioinorganic conjugates of luminescent CdTe nanocrystals and protein, including CdTe/BSA (bovine serum albumin) and CdTe/MAB (mouse monoclonal antibody against hepatities B surface antigen), were formed via electrostatic/coordination self-assembly. Pure CdTe nanocrystals, CdTe/BSA and CdTe/MAB were used in the immunochromatographic assay experiments, respectively. And the results indicated that CdTe nanocrystals could be used and developed as a novel label with good stability, high sensitivity and facile determination of several analytes in immunochromatographic assay strips.