DEVELOPMENT OF AN AMPEROMETRIC IMMUNOSENSOR FOR HORSERADISH-PEROXIDASE (HRP) INVOLVING A NON-DIFFUSIONAL OSMIUM REDOX POLYMER CO-IMMOBILIZED WITH ANTI-HRP ANTIBODY

An amperometric immunosensor containing a non-diffusional redox polyme r to transfer electrons between the electrode surface and the antigen (horseradish peroxidase; HRP) bound to its specific antibody on the se nsing surface was developed. The redox polymer [Os(bpy)(2)(PVP)(10)Cl] Cl (bpy = bipyridyl, PVP = poly-4-vinylpyridine) was co-immobilised wi th the antibody on the electrode surface by crosslinking between the a ntibody with glutaraldehyde to form a combined sensing and electron tr ansfer 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 employ ing a diffusional mediator.