Impedimetric immunosensor using avidin–biotin for antibody immobilization

The potentialities of an electrodeposited biotinylated polypyrrole film as an immobilisation matrix for the fabrication of impedimetric immunosensors are described. Biotinylated antibody (anti-human IgG), used as a model system, was attached to free biotin groups on the electrogenerated polypyrrole film using avidin as a coupling reagent. This immobilization method allows to obtain a highly reproducible and stable device. The resulting immunosensor has a linear dynamic range of 10–80 ng ml−1 of antigen and a detection limit of 10 pg ml−1. Furthermore, this immunosensor exhibited minor loss in response after two regeneration steps.