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