【作者】 王益林；

【导师】 王柯敏；

【作者基本信息】 湖南大学 ， 分析化学， 2005， 硕士

【摘要】 本文对量子点的结构特征和光致发光特点,量子点的合成及其应用研究进展作了概述; 采用水相合成法分别制备了以巯基乙酸和巯基乙胺为稳定剂的水溶性CdTe量子点,并以量子点作为荧光探针,建立了荧光猝灭测定Cu²⁺离子的新方法; 为进一步提高巯基乙胺修饰的水溶性CdTe量子点的稳定性,将单个颗粒分别包被于硅壳中,并以包壳后的量子点作为荧光探针,成功应用于细胞识别研究; 在此基础上,进一步简化量子点的合成与包壳步骤,发展了一种一釜法制备硅壳型水溶性CdTe量子点的新方法。（1）以巯基乙酸为稳定剂,在水溶液中合成了CdTe量子点,用紫外-可见吸收光谱、荧光光谱及原子力显微镜对合成样品进行了表征。以该量子点为荧光探针,基于荧光猝灭对Cu²⁺离子进行了定量检测。考察了缓冲体系、缓冲液浓度、缓冲液pH值、反应时间、量子点浓度等多种因素的影响。在最优实验条件下,该方法的线性区间为2～200μg·L^-1,检测下限为0.29μg·L^-1。用电荷转移机制解释了量子点荧光猝灭的原因,主要是由于价带电子激发到导带以后被表面结合的Cu²⁺离子捕获而产生的结果,在此基础上,用光解实验进行了进一步的验证。（2）在水相中合成了巯基乙胺修饰的CdTe量子点,用紫外-可见吸收光谱及荧光光谱对合成样品进行了表征。将单个CdTe量子点包被于硅壳内,且在颗粒表面同步修饰上氨基及磷酸基团,从而制得了既具有良好的稳定性与水溶性,又能与生物分子直接偶连的量子点。考察了配体交换时间、TEOS用量、回流温度等反应条件对包壳后量子点性质的影响; 采用荧光光谱、光漂白实验、AFM、粒度分布、Zeta电位、荧光胺实验等多种手段对包壳后的量子点进行了表征,并将包壳后的量子点与乳糖酸偶连,成功应用于肝细胞的识别。（3）在前一部分工作的基础上,进一步简化量子点的合成与包壳步骤,以MPS为稳定剂,制备了硅壳包被的CdTe量子点,并在硅壳外同步修饰氨基及磷酸基团,首次成功实现了量子点的合成与表面的功能化修饰在同一体系中进行,从而制得了水溶性的、表面带有氨基和磷酸基团的硅壳型CdTe量子点。考察了MPS浓度、反应温度及pH值等因素对产物的影响,并用荧光光谱、AFM、粒度分布、Zeta电位、光漂白实验等多种手段对合成的样品进行了表征。更多还原

【Abstract】 This thesis describes the unique optical properties of quantum dots （qdots）, current approaches for the synthesis of qdots and their applications on life science research. CdTe qdots were synthesized directly in aqueous solution by using thioglycolic acid （TGA） or cysteamine （MA） as the stabilizer. Based on TGA-modified qdots, a new approach was developed for sensitive and selective determination of copper ions. In order to improve the stability of MA-modified qdots, silica layer was added to each individual quantum dot. Furthermore, the silica-coated qdots were successfully used to the cells labelling. Meanwhile, a new one-pot approach was proposed for the first time to prepare silica-coated qdots. （1） CdTe qdots were synthesized in aqueous solution by using TGA as the stabilizer. They were characterized by UV-Vis, fluorescence spectroscopy and AFM, respectively. With this kind of water-soluble qdots as fluorescence probes, a novel approach was developed for sensitive and selective determination of copper ions. Different influence factors were studied, including the buffer concentration, qdots concentration, pH values and reaction time. Under the optimized conditions, the relative fluorescence intensity decreased linearly with the copper ions concentration in the range from 2 to 200μg·L^-1 and the detection limit could reach 0.29μg·L^-1. Based on the charge-transfer quenching mechanism, the copper ions bounding onto the surface of qdots could absorb electrons from valance band, which results in the quenching of fluorescence. This was proved by photolysis experiment. （2） The MA-capped CdTe qdots were prepared in aqueous solution, and then characterized by UV-Vis and fluorescence spectroscopy. In order to improve the stability of this kind of qdots, a thin silica layer was covalently bound to the surface of every particle to prepare silica-coated qdots. Amine and phosphonate groups were modified on their surface simultaneously. The qdots after coating was monodisperse and well separated. Various reaction conditions that affected the properties of silica-coated qdots were studied, including ligand-exchange time, the dosage of TEOS and the reaction temperature. Furthermore, the silica-coated qdots were characterized by a series of techniques, such as fluorescence spectra, AFM, size distributions, Zeta potential and photobleaching, etc. Moreover, it was successfully linked with lactobionic acid through amine groups on the surface of particles, and used to recognize living liver cells successfully. （3） In order to simplify the proceeding of preparation of silica-coated qdots, a novel one-pot method using 3-mercaptopropyl-trimethoxysilane （MPS） as a capping molecule was proposed for the first time. Furthermore, amine and phosphonate groups were also modified on the surface of silica-coated qdots simultaneously. This was the first time the synthesis and the surface modification of qdots were performed in the same system. The effects of MPS concentration, pH values and reaction temperature on emission properties were investigated. A series of techniques, including fluorescence spectra, AFM, size distributions, Zeta potential and photobleaching, were used to characterize this kind of products.更多还原