Highly Sensitive Detection of N1,N12-Diacetylspermine Based on Electrochemical Charge Accumulation

A novel immunosensor is presented based on a charge accumulation system using an electrode modified with a polymer containing [osmium(4,4′-dimethyl-2,2′-bipyridine)2chloride]+/2+ and horseradish peroxidase (Os/HRP polymer) to detect N1,N12-diacetylspermine (DiAcSpm). Glucose oxidase (GOx)-labeled antibody captured with immunoreaction on Os/HRP polymer catalyzed the production of hydrogen peroxide, which oxidizes [Os(bpy)2Cl]+ in polymer with HRP. [Os(bpy)2Cl]2+ was gradually accumulated in the polymer and reduced back to [Os(bpy)2Cl]+ by applying −0.1 V. This accumulation system of redox species allows enhancement of the response.