Hydorgen peroxide biosensor based on direct electrochemistry of hemin in egg-phosphatidylcholine films

The mixture of egg-PC vesicles and hemin was casted onto indium-tin oxide glass (ITO) electrode. The hemin showed a direct electrochemical behavior on the modified electrode. A well-defined pair of redox peaks was obtained from the cyclic voltammograms at ITO electrode modified by the mixture of hemin and egg-phosphatidylcholine (egg-PC). The average value of the surface coverage of electroactive hemin, μ, was 3.25 × 10-12 mol cm-2. The formal potential (Eo') of hemin in the lipid film was linearly varied with the pH of phosphate buffer solution in the range from 4.0 to 9.0 with a slope of -43.7 mV/pH. The pH value of buffer solution for measuring hydrogen peroxide was decided to be 4.0. The linear range of the biosensor was from 10 μM to 200 μM with a detection limit of 5 μM. The modified electrode exhibited a good catalytic activity towards hydrogen peroxide. Therefore a third generation biosensor was developed.