Electropolymerized biotinylated poly (pyrrole–viologen) film as platform for the development of reagentless impedimetric immunosensors

We describe herein the synthesis and electrochemical polymerization of a viologen monomer functionalized by a biotin group and the use of its redox properties for the impedimetric sensing of protein binding. The electrochemical oxidation of the pyrrole group at 0.85 V in CH3CN led to a biotinylated polypyrrole film allowing the successive anchoring of an avidin layer and a biotinylated cholera toxin layer. EIS performed at −0.45 V/SCE without redox probe in solution showed the specific immobilization of the anti-cholera toxin antibody.