基于L-半胱氨酸/CdTe量子点修饰电极的电化学传感器的制备及其对Pb~(2+)的检测

成功制备了由L-半胱氨酸和CdTe量子点作为修饰材料的电化学传感器并用于水体中Pb~(2+)的检测。巯基丙酸修饰的CdTe量子点通过水相合成,表面含有大量羧基,与L-半胱氨酸表面的氨基形成酰胺键,修饰于金电极表面。通过荧光分光光度计、透射电子显微镜、红外光谱、X射线衍射对L-Cys/CdTe QDs复合材料进行表征。采用循环伏安法(CV)研究了L-Cys/CdTe QDs修饰成分在金电极上的电化学性能及CdTe量子点的最佳自组装时间。采用差分脉冲溶出伏安法(DPSV)研究了铅离子在修饰电极上的电化学行为。在优化实验条件下,Pb~(2+)浓度在1.0×10~(-6)~1.0×10~(-2) mol/L范围内与其峰电流呈良好的线性关系,相关系数(r2)为0.993 8,检出限(3σ,n=5)为4.0×10~(-7) mol/L。该传感器具有良好的重现性和稳定性,有望用于实际水样中铅离子的检测。

Preparation of an Electrochemical Sensor Based on L-cysteine/CdTe Quantum Dots Modified Electrode and Its Detection of Lead Ions

A simple and sensitive electrochemical sensor was fabricated for the detection of Pb2+based on L-cysteine (L-Cys)/CdTe quantum dots (QDs) hybrid nanocomposites modified gold electrode (GE).CdTe QDs were synthesized in aqueous phase.Then,carboxyl labeled CdTe QDs were covalently bonded to L-cysteine on gold electrode,depending on connection between-COOH on MPA-CdTe surface and —NH2 in L-cysteine.The morphology and composition of CdTe QDs and hybrid nanocomposites were characterized by fourier transform infrared spectroscopy (FTIR),X-ray powder diffraction (XRD),transmission electron microscopy (TEM),UV-Vis and fluorescence spectrometry.The electrochemical performance of L-Cys/CdTe nanocomposite and the optimized selfassembly time of CdTe QDs on electrode were investigated by cyclic voltammetry(CV).The electrochemical behavior of lead ions at L-Cys/CdTe nanocomposite modified gold electrode was investigated by different pulse stripping voltammetry(DPSV).Under the optimal hybridization conditions,different pulse stripping voltammetric responses of L-Cys/CdTe/GE sensor were in linearity with Pb2+ in the concentration range of 1.0 × 10-6-1.0 × 10-2 mol/L with a detection limit of(3σ,n =5) 4.0 ×10-7 mol/L and a correlation coefficient(r2) of 0.993 8.Therefore,the electrochemical sensor modified with L-Cys/CdTe/GE nanocomposites exhibited the advantages of high sensitivity,good reproducibility and stability,providing a potential platform for the fabrication of other electrochemical sensors.