Hydrogen Peroxide Biosensor Based on Direct Electrochemistry of Hemin in Egg-Phosphatidylcholine Films
The mixture of egg-phosphatidylcholine( 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 welldefined pair of redox peaks was obtained from the cyclic voltammograms at the mixture of hemin and egg-PC modified ITO electrode. The average value of the surface coverage of electroactive hemin,Γ,was equal to3. 25 × 10!12mol / cm2. 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 our biosensor was from10 μmol / L to 200 μmol / L with a detection limit of 5 μmol / L. The modified electrode exhibited a good catalytic activity towards hydrogen peroxide. Therefore a third generation biosensor was developed.