【作者】 王凌凌；

【导师】 郑鹄志；

【作者基本信息】 西南大学 ， 分析化学， 2010， 硕士

【摘要】 由于具有摩尔吸光系数高,荧光量子产率高,发射波长可调谐,耐光漂白等显著优点,量子点在科研、医疗、生产和生活中得到广泛应用,人们接触到的机会也逐渐增加。同时量子点的生物安全性和环境安全性研究也逐渐引起了人们的重视。与宏观材料相比,量子点的尺寸小,表面能量高,反应活性大,其毒性的评价研究也不能依照常规材料的方法。本文基于发光细菌发光抑制法系统检测了六种量子点的毒性,并初步探讨了新型荧光碳点的毒性。主要的研究工作归纳如下：1.量子点的合成。分别以巯基乙酸(MAA-)、L-半胱氨酸(Cys-)、二巯基辛酸(DHLA-)和牛血清白蛋白(BSA-)为稳定剂,水相合成了荧光性能良好的CdSe QDs,并用相似的方法合成了DHLA-CdTe QDs。油相中合成了银铟锌型(ZAIS)量子点,然后用二巯基辛酸(DHLA)做了水溶性修饰,得到具有生物兼容性的水溶性DHLA-ZAIS QDs.2.量子点的毒性检测。以发光细菌发光抑制法检测了各种量子点的毒性,得到了量子点的半数有效浓度(EC50),并得到了量子点的浓度、组成成分和表面修饰基团影响其毒性大小的结论。3.毒性机理的探讨。通过紫外照射实验、维生素C对毒性的影响实验和超薄切片结合透射电子显微镜技术,探讨量子点毒性机理。4.荧光碳点的合成与检测。普通回流方法合成荧光碳点,并用聚乙二醇(PEG1500)进行表面钝化,得到未钝化C-Dots和PEG-C-Dots两种荧光碳点。然后用发光细菌发光抑制法对未钝化C-Dots和PEG-C-Dots的毒性做了初步探讨。实验证实碳点存在一定的毒性,并且PEG钝化后碳点毒性降低。更多还原

【Abstract】 With the bright fluorescence, narrow emission, broad absorption coefficients,and high photostability, quantumdots (QDs) have received significant attention as potential alternatives to organic dyes during the last decades.However, with the extensive application of quantum dots in the biological fields, it was more accessible for people to contact them. So research concerning the potential toxicity of QDs had also gained a great amount of interest. It was critically important to select QDs with low toxicity in order to realize applications in cellular as well as in vivo labeling. In this paper, a novel method so-called bioluminescence inhibition assay with luminous bacteria (Photobacterium phosphoreum) was introduced to evaluate the toxicity of quantum dots.The main research works are summarized as follows:1.With the mercaptoacetic acid (MAA-), L-cysteine (Cys-),dihydrolipoic acid (DHLA-) and bovine serum albumin (BSA-) as the stabilizers, we prepared CdSe in aqueous phase. And DHLA-CdTe was synthesized under the same synthesis conditions (i.e. reaction temperature, pH, precursor concentration and ratio of Cd2+/Se or Te/ligand).Then the fresh products were dialyzed just before the experiments against ultrapure water to remove the excess ions.While ZAIS QDs were synthesized in organic solution, following water-solubilized with DHLA by a ligand exchange procedure.2.Using the luminous bacteria as a microbial sensing element, we carried out a systematic study on the toxicity of a series of QDs we prepared. Median effective concentration (EC50),the concentration of a compound that inhibits 50% of the bacterial bioluminescence, was chosen as the indication to estimate the toxicity of QDs. These results demonstrated that both composition and surface modification were responsible for the toxicity of QDs. 3.Through UV irradiation experiments,the influence of vitamin C on the toxicity and transmission electron microscopy, the mechanism of toxicity of quantum dots was investigated.4.Bare carbon dots (C-Dots) were prepared of by oxidation of carbon soot with nitric acid refluxing. After surface passivation with polyethylene glycol(PEG1500N), we got the PEG-C-Dots.The toxicity of the two C-Dots was studied based on the bioluminescence inhibition assay with luminous bacteria. Our results demonstrated that the C-Dots were toxic and the surface passivation with PEG reduced the toxicity effectively.更多还原