层层自组装纳米金与乙酰胆碱酯酶电化学生物传感器检测有机磷农药

采用层层自组装技术制备了快速检测有机磷农药的生物传感器,利用带正电荷的高分子聚电解质聚二烯丙基二甲基氯化铵(PDDA)将乙酰胆碱酯酶(AChE)和金纳米粒子(AuNPs)通过静电力逐层固定到玻碳电极(GCE)表面,并采用交流阻抗和微分脉冲伏安法研究了此生物传感器的电化学行为。由于金纳米粒子优异的电催化性能和良好的生物相容性,使固定化的乙酰胆碱酯酶对其底物具有更高的亲和力和更快的响应速度。实验结果表明:修饰金纳米粒子后,传感器的氧化电流明显增大,在4.6×10-5～5.3×10-3mol/L范围内,固定化酶的抑制率与甲基对硫磷浓度的对数成正比,检出限为7.6×10-6mol/L。该生物传感器具有制备方法简便、成本低、灵敏度高等优点,已成功用于蔬菜样品中甲基对硫磷含量的测定。

Detection of Organophosphate Pesticides with Electrochemical Biosensors Based on Layer-by-layer Self-assembly Acetylcholinesterase and Gold Nanoparticles

An amperometric biosensor for the detection of organophosphorus pesticide was developed based on layer-by-layer self-assembly both acetylcholinesterase(AChE) and gold nanoparticles(AuNPs) on glassy carbon electrodes(GCE) in the presence of poly(diallyldimethylammonium chloride)(PDDA).The electrochemical properties of the biosensor were investigated by electrochemical impedance spectroscopy and differential pulse voltammetry.The proposed biosensor exhibited a high affinity to the substrate of AChE and produced a detectable and fast response owing to its excellent electron transfer rate and satisfactory biocompatibility of AuNPs.Compared with that at the unmodified electrode,the peak current of thiocholine at the proposed biosensor obviously increased.Under the optimum conditions,the inhibition rate of methyl parathion to the immobilized AChE was proportional to the logarithm of concentration of methyl parathion over the range of 4.6×10-5-5.3×10-3 mol/L with a detection limit of 7.6×10-6 mol/L.The proposed biosensor was successfully applied in the determination of methyl parathion in vegetable sample,which means that the proposed biosensor provides a new promising tool for the pesticide analysis.