Study on electrochemical detection of antibody-antigen interaction

Abstract

In this paper, a new electrochemical enzyme immunoassay technique for sensing antibody-antigen interaction has been developed. The gold electrode was covered with the mixed SAMs of mercaptododecanoic acid (MDA) and mercaptoundecanol (MUO) and then partially ferrocenyl-tethered dendrimer (Fc-D) was covalently immobilized to the electrode surface using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC)/N-hydroxy succinimide (NHS) coupling. The Fc-D acts not only as a building block but also as a electron transfer mediator. As a building block, the remaining amines of immobilized Fc-D are able to be modified with biotin groups, and its ferrocene part acts as an electrocatalyst to enhance the electrochemical signals. The biospecific recognition of alkaline phosphatase conjugated anti-biotin antibody to biotin-functionalized surface results in converting the electrochemical inactive substrates to electroactive products by enzymatic reaction. The electroactive enzymatic products lead to the electrocatalytic reaction of ferrocene. The electroactive enzymatic products are electrocatalytically oxidized by the electronic mediation of ferrocene. The relationship between this enhanced signal and concentration of anti-biotin antibody is investigated. To characterize this mechanism, we carried out cyclic voltammetry (CV) and surface plasmon resonance (SPR) experiments.