【作者】 张婷婷；

【导师】 邹炳锁；

【作者基本信息】 湖南大学 ， 生物化学与分子生物学， 2008， 硕士

【摘要】 纳米材料由于具有体相材料所不具备的新颖的光学、电学以及磁学等性质,引起了人们广泛的研究和关注。在本文中,我们对量子点的制备、表征及生物应用进行了系统的研究,主要的研究内容如下:(1)在开放体系的水溶液中,我们合成了发射光谱可调的CdTe量子点,考察了其反应时间,pH值等条件对量子点光学性质的影响,通过检测反应液的吸收光谱和发射光谱提供了粒子成核与生长情况,并用高分辨透射电镜和X-射线衍射仪对量子点进行表征。合成的CdTe量子点进一步考察了其光化学稳定性,结果表明,CdTe量子点随着光照时间的延长,荧光强度大幅度提高。分析其原因,辐射推动CdTe量子点表面巯基乙酸的光化学降解,巯基分子中的硫原子与溶液中的镉离子反应,在CdTe纳米颗粒表面形成CdS的壳层,钝化了CdTe纳米颗粒表面缺陷,从而使荧光效率大大提高。(2)在前一部分工作的基础上,用二氧化硅对CdTe量子点进行包覆,制备了CdTe/SiO2荧光微球,并对比了CdTe量子点和CdTe/SiO2荧光微球发光情况的变化。以多聚赖氨酸为模板,制备了含有CdSe/ZnS纳米粒子的量子点微球,利用激光共聚焦显微镜考察了量子点在微球中的分布情况,结果显示该微球在生理条件下十分稳定。(3)利用量子点的荧光特性合成了荧光探针,用于肿瘤靶向标记和细胞内成像的研究。该荧光探针是将亲水性的CdTe量子点连接叶酸分子。利用叶酸对多数肿瘤细胞膜表面叶酸受体的高度亲和性,将量子点靶向至肿瘤,并通过肿瘤细胞的内吞作用进入细胞内。用荧光显微镜对量子点荧光标记的细胞进行成像,图像显示有叶酸介导的量子点成功进入肿瘤细胞内部,发出明亮的荧光,没有叶酸介导的,荧光很微弱。这些现象说明合成的生物靶向性的量子点荧光探针能准确的识别出肿瘤细胞并且能够长时间对细胞进行标记。更多还原

【Abstract】 Nanomaterials, which are different from their corresponding bulk materials, have the novel optic, electric and magnetic properties. In this dissertation, the synthesis, characterization and biological labeling of some nanoscale semiconductor materials have been systematically studied. The main research results are shown as follows:(1)Emission-tunable CdTe quantum dots were synthesized Under open-air conditions。Various reaction conditions that affected the optical properties of CdTe nanoparticles were studied, including the time of reaction and the pH. Furthermore, these nanoparticles were characterized by High resolution electron microscopy, fluorescence spectra and UV-Vis spectroscopy, the UV-Vis spectroscopy provide information about the progress of nucleation and growth of the particles. The prepared CdTe quantum dots were further observed on their photochemical stability. The result shows that illumination can greatly increase the photoluminescence of CdTe quantum dots. Illumination-assisting photoluminescence enhancement effects were explained by the photochemical degradations of thioglycolic acid on the surface of quantum dots. Sulfide ions may react with cadmium ions on the CdTe particle surface and form a shell structure of CdS. The formation CdS shell on the CdTe will effectively passive the CdTe surface and give rise to a great increment in photoluminescence intensity. (2) Based on the above work, CdTe quantum dots were coated SiO2, CdTe/SiO2 fluorescence microspheres were synthesized,and fluorescence spectra of CdTe and CdTe/SiO2 fluorescence microspheres were studied. Polylysine was used as template and the CdSe/ZnS were incorporated into the microspheres. Under laser confocal microscopy, it’s clearly to see that the luminescent quantum dots was well-proportioned in the microsphere. The stability of the microsphere was also examined and results shows that the microspheres were very stable. (3) Fluorescent Probes based on semiconductor quantum dots (QDs) were successfully synthesized for tumors targeting and imaging in vivo. The structural of fluorescent probes design involves conjugating hydrophilic CdTe QDs to folic acid to target the folate-binding protein, this molecule is the folate receptor that is overexpressed on the surface of many tumoral cells. Folate targeting improved the specificity of QDs for labeling tumor. Intracellular distribution of QD staining was characterized with fluorescence microscopy. Derived images of tissues lableled with QDs-FA probes generally show bright fluorescence, whereas images of tumors only with QDs display little or no fluorescence. These findings suggest the use of QDs via folate as an effective probe for detecting tumors and long-term labeling of cells.更多还原