Electrochemical impedimetric immunosensor for the detection of okadaic acid in mussel sample

A-label-free electrochemical impedimetric immunosensor for rapid detection of okadaic acid was developed. The sensor was based on the diazonium-coupling reaction mechanism for the immobilization of anti-okadaic acid monoclonal antibody (anti-OA-MAb) on screen printed carbon electrode. Following initial grafting of 4-carboxyphenyl film by electrochemical reduction of 4-carboxyphenyl diazonium salt, anti-OA-MAb was covalently bound by its primary amine groups to the activated carboxylic. The steps of the immunosensor fabrication were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). An equivalent electric circuit, including ohmic resistance (Rs), the electron transfer resistance (Ret), Warburg impedance (Zw) and the constant phase element (Qdl) was used for investigating the performance of impedimetric immunosensor. The increase in electron transfer resistance was linearly proportional to the OA concentration in the range of 0.195–12.5 μg/L, with a detection limit of 0.3 μg/L. The assays with mussel samples showed acceptable recovery percentages.