Impedance Immunsensor Based on Interdigitated Array Microelectrode and its Experiment Parameter Optimization

Abstract

This article accounts for a novel impedance immunosensor based on the specificity reaction of the antigen-antibody and the sensitivity of the interdigitated array microelectrode (IDAM) for the determination of chlorpyrifos residues. The basic knowledge of immunoassay was in relation to its IDAM electrode surface modification, antibody immobilization, bovine serum albumin (BSA) blocking and sample detection. The SPA was dropped onto the surface of IDAM electrode, used for binding antibody Fc fragments. Next, antibody was immobilized on the SPA modified electrode. Finally, BSA was employed to block the possible remaining active sites avoiding any nonspecific adsorption. Target chlorpyrifos was then captured by the immobilized antibody, resulting in a change in the impedance of the IDAM microelectrode surface. The fabrication procedure of the immunosensor and the sample detection were characterized by electrochemical impedance spectroscopy (EIS). The influences of the experiment parameters were investigated. Under optimized conditions, an excellent biosensor was fabricated. Many of the antibodies, enzymes and other reagents integral to immunoassays were very expensive, often hundreds of dollars per milligram, therefore miniaturization reduces reagent costs drastically. In this article the volume of the reagents was micro upgrade, the antibodies, SPA and BSA were 30 mL, the chlorpyrifos sample and detection solution were 50mL. The advantages of the immunosensor were exhibited in its better specificity, stability, selectivity and regeneration. The proposed method was proven to be a feasible quantitative method for chlorpyrifos analysis in vegetables and fruits.

Keywords

• Immunosensor
• Interdigitated array microelectrode
• Electrochemical impedance spectroscopy
• Parameter optimization
• Chlorpyrifos immunosensor.