【作者】 伊魁宇；

【导师】 徐淑坤；

【作者基本信息】 东北大学 ， 分析化学， 2009， 硕士

【摘要】 量子点（quantum dots,QDs）又称半导体纳米晶（semiconductor nanocrystals）是一种高效的光致发光纳米晶体。近年来,量子点表面化学的快速发展,使它们得到了越来越广泛的应用,例如细胞及生物组织多色成像和生物大分子检测等。本项研究以水热法在水相中直接合成了四种不同粒径的巯基乙酸修饰的CdTe量子点,利用透射电子显微镜（TEM）、吸收光谱和荧光光谱对所合成的量子点进行了表征。结果表明,所合成的量子点具有粒径均匀、分散性好、尺寸分布较窄、发光性能良好的特点,可以用于定量检测。首次以合成的量子点作为pH敏感探针,实现了对抗坏血酸的定量检测。实验中观察到水溶液中抗坏血酸可以与量子点发生尺寸依赖的非线性淬灭现象。处于0.05mol·L^-1 PBS缓冲溶液中的巯基乙酸包覆的CdTe量子点,当pH从8.22下降到6.45时,体系发生荧光淬灭,其荧光强度与相应pH之间呈现良好的线性关系。由此提出了一种简单,快速,准确定量检测抗坏血酸的方法,并对反应机理进行了探讨。在最优条件下,量子点的淬灭程度（1g（F₀/F））与抗坏血酸在1.25×10^-5～1.00×10^-4 mol·L^-1的浓度范围内呈现良好的线性关系,相关系数为0.9981,检出限为3.6×10^-6 mol·L^-1。对浓度为3.75×10^-5 mol·L^-1的标准溶液平行测定11次,得到的相对标准偏差为2.1%。用本方法测定了维生素C药片和注射液中抗坏血酸的含量,结果与氧化还原滴定方法和标定值一致。首次以合成的CdTe量子点作为生物探针,基于荧光淬灭作用建立了一种灵敏,选择性好,操作简便的定量检测血红蛋白的方法,并对反应机理进行了探讨。在最佳条件下,量子点的淬灭程度（F₀-F）与血红蛋白的浓度在0.90～12μg·mL^-1范围内呈现良好的线性关系,相关系数为0.9982,检出限为0.3μg·mL^-1。对浓度为3.0μg·mL^-1的标准溶液平行测定11次,得到的相对标准偏差为1.4%。用该方法对牛血中的血红蛋白含量进行了定量检测,检测结果与常规标准方法测定值无显著性差异。更多还原

【Abstract】 Quantum dots （QDs） have attracted tremendous attentions in the past two decades because of their high emission quantum yields, good chemical and photo-stability, size-tunable emission profiles and narrow spectral bands in comparisons with conventional organic fluorophores. Recently, the great advances in the surface chemistry of QDs allow them to be effective in practical applications, such as biological imaging and biological macro molecular detection.In this work, four kinds of thioglycolic acid （TGA） capped water-soluble CdTe quantum dots （QDs） with different size were synthesized via a hydrothermal synthesis method. The as-prepared QDs were characterized by transmission electron microscopy （TEM） and UV-vis absorption and fluorescence spectra. The results indicated that the synthesized CdTe QDs have small size, good monodispersity and uniform size distribution, which is suitable for the demand of quantitative determination and biological analytical applications.The as prepared thiol-modified CdTe quantum dots were used as pH-sensitive probes for the determination of ascorbic acid in aqueous solutions for the first time and the quenching mechanism was also discussed. The fluorescence of the water-soluble QDs could be irreversibly quenched by H⁺ and the fluorescence intensity of the water-soluble QDs decreased linearly with the pH decrease in the range of 6.45-8.22. Based on this phenomenon, a simple, rapid and specific method to quick determination of ascorbic acid was proposed. Under optimum conditions, the relative fluorescence intensity was linearly proportional to the concentration of ascorbic acid in the range of 1.25×10^-5-1.00×10^-4 mol·L^-1 with a correlation coefficient of 0.9981. The limit of detection （3σ） of 3.6×10^-6 mol·L^-1 was obtained with the relative standard deviation （RSD） of 2.1% for a 3.75×10^-5 mol·L^-1 ascorbic acid （n=11）. As an application, the proposed method was successfully applied to the analysis of ascorbic acid in medical samples, and the results were consistent with those obtained from the oxidation-reduction titration method and the claimed value. This method also provided a new idea to determine acidic medicine and further to explore application of quantum dots in fluorescence sensor field.Based on the fluorescence quenching effect of the CdTe QDs caused by bovine hemoglobin, a sensitive, convenient and selective quantification method for the determination of bovine hemoglobin was proposed for the first time, and the reaction mechanism was also discussed. Under optimum conditions, a linear relationship was observed in the range of 0.90 - 12μg·mL^-1 with a correlation coefficient of 0.9982 forbovine hemoglobin. The detection limit （3σ） of 0.3μg·mL^-1 was obtained with the relative standard deviation （RSD） of 1.4% for a 3μg·mL^-1 BHb （n=11）. The proposed method was applied to the determination of BHb in bovine blood, and there were not significant difference between the content found by this method and routine standard method.更多还原