镉(Ⅱ)-半胱氨酸配合物对CdS量子点的荧光增强作用及其在离子检测中的应用

Enhanced Fluorescence of Cd S Quantum Dots by Cadmium( Ⅱ)-Cysteine and Its Application in Ion Detection

合成了弱配体柠檬酸三钠修饰的Cd S量子点（Cit-Cd S QDs）,透射电子显微镜表征结果表明,Cit-Cd S QDs的粒径分布均匀（4～6 nm）,分散性好。研究了金属离子（银（Ⅰ）离子、镉（Ⅱ）离子）、巯基化合物（巯基乙酸、半胱氨酸）以及金属离子（银（Ⅰ）离子、镉（Ⅱ）离子）与巯基化合物形成的配合物对Cit-Cd S QDs荧光的影响。发现金属离子（银离子、镉离子）与巯基化合物（巯基乙酸、半胱氨酸）形成的水溶性配合物可以显著增强Cit-Cd S QDs的荧光,配合物对Cit-Cd S QDs的增强程度比单独的金属离子或巯基化合物均要高,而且配合物修饰的Cd S QDs对铜（Ⅱ）离子的响应要高于单独用金属离子或巯基化合物修饰的量子点。建立了铜（Ⅱ）离子高灵敏度荧光检测方法,该方法检测范围宽（1.0×10^-8～1.0×10^-6mol/L）,检测限低（1.0×10^-9mol/L）且具有很好的选择性,拓展了配合物作为量子点修饰剂的应用。

CdS quantum dots capped by citrate （Cit-CdS QDs） were synthesized in aqueous solution. TEM analysis indicates that the Cit-CdS QDs are well-dispered with the diameter of 4 to 6 nm. The influence of silver（ Ⅰ）, cadmium （ Ⅱ）, thioglycolic acid, cysteine and the complexes formed by silver （ Ⅰ ）/cadmium （Ⅱ） with the thiol compounds（thioglycolic acid or cysteine） on the fluorescence of Cit-CdS QDs was investigated. All above modifiers can enhance the fluorescence intensity of Cit-CdS QDs. The complexes above have much greater fluorescence enhancement effect than that of the solely metal ions or thiol compounds. In addition, the CdS QDs modified by the complexes also have much higher sensitivity for copper（Ⅱ） sensing. Based on this phenomenon, a highly sensitive and selective fluorescence probe for Cu^2＋ was developed with a wide range of 1.0×10^-8～1.0×10^-6mol/L and a low detection limit of 1.0×10^-9mol/L. It may open up new opportunity for the synthesis and application of complex modified quantum dots in analytical chemistry.