Electrochemical impedance immunosensor for the detection of cardiac biomarker Myogobin (Mb) in aqueous solution

A label-free, electrochemical impedance immunosensor based on surface modified thin flat gold wire electrode is reported for the quantitative detection of cardiac biomarker Myoglobin in aqueous solution. The protein antibody, ab-Mb, was covalently immobilized through a self assembled monolayer of 11-mercaptoundecanoic acid (MUA) and 3-mercapto propionic acid (MPA) via carbodiimide coupling reaction using N-(3-dimethylaminopropyl)-N′-ethyl carbodiimide hydrochloride (EDC) and N-Hydroxy Succinamide (NHS). The immunosensor (ab-Mb/MUA-MPA/Au) was characterized by electrochemical techniques. The electrochemical performance of the immunosensor was studied by electrochemical impedance spectroscopy. The immunosensor showed an increased electrontransfer resistance on coupling with biomarker protein antigen, ag-Mb, in the presence of a redox probe [Fe (CN)6]3−/4−. The modified Au electrode immunosensor exhibits an electrochemical impedance response to antigen, ag-Mb concentrations in a linear range from 10 ng to 650 ng mL−1 with a lowest detection limit of 5.2 ng mL−1.