基于免标记电化学免疫传感的蔬菜中农药残留检测研究

Label-free Electrochemical Immunosensor for Sensitive Detection of Pesticide Residue in Vegetables

摘要:

本文利用层层自组装技术构建了一种用于农药残留高灵敏检测的免标记电化学免疫传感器。该免疫传感器首先通过在天然聚合物海藻酸钠修饰的玻碳电极上利用电化学方法原位聚合金纳米粒子，然后借助金纳米粒子与蛋白质抗体之间的较强吸附作用进一步原位组装农药抗体，从而成功构建了免标记电化学免疫传感器。实验中以呋喃丹农药为模型，呋喃丹分子通过特异性的免疫反应在抗体功能化电极表面生成免疫复合物，该复合物阻碍了电化学探针在电极表面的电子传递，从而减小了免疫传感器的电流响应，利用电流响应的变化与农药分子浓度的关系可以实现呋喃丹农药的快速、高灵敏检测。在优化的实验条件下，该传感器对呋喃丹农药的线性检测范围为1~105 μg/L，检测限为1 μg/L。同时，该免疫传感器还实现了多种蔬菜样品中呋喃丹农药残留的高灵敏检测。

Abstract:

This study describes the application of a label-free electrochemical immunosensor that was designed for highly sensitive detection of pesticide residue using a layer-by-layer self-assembly technique. This electrochemical immunosensor was first constructed by placing self-assembling gold nanoparticles on the sodium alginate functionalized glassy carbon electrode (GCE) using in situ electrodeposition. Subsequently, further in situ assembly of the pesticide antibody was conducted by utilizing the strong adsorption between the gold nanoparticles and protein molecules in order to successfully construct the label-free electrochemical immunosensor. In the experiment, carbofuran was used as the pesticide model. An immune complex was produced by the specific immune reaction between carbofuran and the antibody on the self-assembled GCE. This immune complex clearly blocked the electron transfer of electrochemical probes on the electrode surface and resulted in a significant reduction of current signal of the immunosensor. Rapid and highly sensitive detection of pesticide carbofuran was achieved, as inferred based on the relationship between the changes of current signal and the pesticide concentration. Under optimal conditions, the linear detection range of this electrochemical immunosensor to carbofuran was from 1 to 105 μg/L, with a low detection limit of 1 μg/L. Furthermore, the immunosensor could be employed for the detection of carbofuran pesticide residue in various vegetable samples with high sensitivity.