Electrochemical Determination of Enzyme Based on the Solid Enzyme Catalytic Reaction

Based on the catalytic action of solid horseradish peroxidase (HRP) on oxidation of o-phenylenediamine by hydrogen peroxide,an electrochemical method for determination of HRP and its labelled enzyme HRP-IgG was proposed.The Au-Pt/PAN/GCE was used as working electrode,and its preparation was described in detail.A definite amount of HRP was immobilized on the modified electrode to give a modified electrode of HRP/Au-Pt/PAN/GCE,which was placed into a substrate solution of pH 5.0 PBS containing definite amounts of o-phenylenediamine and reacted for 10 min.The HRP/Au-Pt/PAN/GCE was taken out,and the square wave voltammetric peak of the product of catalytic reaction in the substrate solution was recorded by an electrochemical analyzer.As shown by the experimental results,a well-defined reduction peak at the potential of -0.488 V (vs.SCE) was obtained at the working electrode in the base solution before the enzyme catalytic reaction,and a much larger reduction peak at the potantial of -0.584 V (vs.SCE) was observed after the enzyme catalytic reaction,with remarkable enhancement of the peak current (Ip).It was found that linear relationship between the values of Ip and mass concentration of HRP on the modified GCE was kept in the range of 1.0×10-2~2.0×102μg·L-1.Detection limit (3S/N) of HRP by the method was found to be 3.0 ng·L-1.