A New Biosensor for Hydrogen Peroxide Based on Ag Colloid-modified Electrode and Azure C Mediation

Abstract

A procedure for fabricating an enzyme electrode has been described based on the effective immobilization of horseradish peroxidase (HRP) to a nano-scaled particulate silver (nano-Ag)-modified platinum electrode with polyvinyl butyral (PVB) as the matrix. The hydrogen peroxide concentration was determined in the presence of azure C as a mediator to transfer electrons between the electrode and HRP. The HRP immobilized on colloidal Ag was stable and retained its biological activity. The biosensor displayed excellent electrocatalytic activity to the reduction of H₂O₂. The characteristics of the biosensor were studied by cyclic voltammetry and chronoamperometry. The effects of experimental variables such as the operating potential of the working electrode, mediator concentration, pH and temperature of the measuring solution were investigated for optimum analytical performance by using an amperometric method. Linear calibration for H₂O₂ was obtained in the range 2.0 x 10^-6 to 6.0 x 10^-3 M under the optimized conditions. The sensor was highly sensitive to H₂O₂ with a detection limit of 1.0 x 10^-6 M and the sensor achieved 95% of the steady-state current within 5 s. The sensor exhibited high sensitivity and stability.


Keywords: Horseradish peroxidase; Ag colloid; Azure C; Hydrogen peroxide


South African Journal of Chemistry Vol.58 2005: 4-8