Electrocatalytic activity of horseradish peroxidase/chitosan/carbon microsphere microbiocomposites to hydrogen peroxide

Colloidal carbon microspheres (CMS) are dispersed in chitosan (CHIT) solution to form an organic–inorganic hybrid with excellent micro-environment for the immobilization of biomolecules. A novel amperometric biosensor for the determination of hydrogen peroxide (H2O2) has been constructed by entrapping horseradish peroxidase (HRP) in as-synthesized CMS/CHIT hybrid. The modification of glassy carbon electrode is made by a simple solution-evaporation method. The electrochemical properties of the biosensor are characterized in electrochemical methods. The proposed biosensor shows high sensitive determination and fast response to H2O2 at −0.15 V. The constructed HRP/CHIT/CMS/GC electrode also exhibits a fine linear correlation with H2O2 concentration. The calculated value of the apparent Michaelis–Menten constant, 2.33 mM, suggests that the HRP in CMS/CHIT hybrid keeps its native bioactivity and has high affinity for H2O2.