A new polyaniline-catalase-glutaraldehyde-modified biosensor for hydrogen peroxide detection

A new biosensor based on catalase enzyme immobilized on electrochemically constructed polyaniline (PANI) film modified with glutaraldehyde has been developed for the determination of hydrogen peroxide (H₂O₂) in milk samples. Assembly processes of polyaniline and immobilization of the enzyme were monitored with the help of electrochemical impedance spectroscopy. Amperometric measurements have been performed at cathodic peak (-0.3 V vs. Ag/AgCI) which was attributed to reduction of PANI. Hydrogen peroxide was determined by using amperometric method at -0.3 V. The biosensor responses were correlated linearly with the hydrogen peroxide concentrations between 5.0 × 10^-6 and 1.0 × 10^-4 M by amperometric method. Detection limit of the biosensor is 2.18 × 10^-6 M for H₂O₂. In the optimization studies of the biosensor, some parameters such as optimum pH, temperature, concentration of aniline, amount of enzyme, and number of scans during electropolymerization were investigated.