Development of an amperometric immunosensor for horseradish peroxidase (HRP) involving a non-diffusional osmium redox polymer co-immobilised with anti-HRP antibody

An amperometric immunosensor containing a non-diffusional redox polymer to transfer electrons between the electrode surface and the antigen (horseradish peroxidase; HRP) bound to its specific antibody on the sensing surface was developed. The redox polymer [Os(bpy)(2)(PVP)(10)Cl]Cl (bpy = bipyridyl, PVP = poly-4-vinylpyridine) was co-immobilised with the antibody on the electrode surface by crosslinking between the antibody with glutaraldehyde to form a combined sensing and electron transfer system. When the antigen (HRP) was bound to the antibody on the surface of the sensing film, an 'electrical wiring' occurred between the electrode and the redox centres in the bound HRP. The immunosensor showed greatly enhanced performance in terms of the magnitude of the response and the detection limit than that for a similar sensor employing a diffusional mediator.