An Amperometric Hydrogen Peroxide Biosensor Based on a Hemoglobin‐Immobilized Dopamine‐Oxidation Polymer/Prussian Blue/Au Electrode

A novel method to immobilize hemoglobin (Hb) in a polymer grown from dopamine (DA) oxidation was proposed. The growth of the polymeric films during DA oxidation at the Prussian blue (PB) modified Au electrode in weak alkaline phosphate buffer (pH 9.18) and the immobilization of Hb into the polymeric films during their growth were traced by the electrochemical quartz crystal impedance analysis (EQCIA) method. A hydrogen peroxide (H₂O₂) biosensor was thus constructed, and effects of experimental parameters on the sensor performance, including the applied potential, solution pH and electroactive interferents, were examined. At an optimal potential of ?0.25 V vs. SCE, the current response of the biosensor in the selected phosphate buffer (pH 5.29) was linear with the concentration of H₂O₂ from 0.01 to 4.5 mM, with a lower limit of detection of 0.5 μM (S/N=3), short response time (within 10 s) and good anti‐interferent ability. The Michaelis constant (K_m^app) was estimated to be 3.80 mM. Compared with the separate film of PB or Hb, the composite film of Hb and PB exhibited a higher catalytic activity toward the reduction of H₂O₂, as a result of the additive effect of the chemical and biological catalyses.