Direct electrochemistry and electrocatalysis of horseradish peroxidase immobilized in hybrid organic–inorganic film of chitosan/sol–gel/carbon nanotubes

A hybrid organic–inorganic nanocomposite film of chitosan/sol–gel/multi-walled carbon nanotubes was constructed for the immobilization of horseradish peroxidase (HRP). This film was characterized by scanning electron microscopy. Direct electron transfer (DET) and bioelectrocatalysis of HRP incorporated into the composite film were investigated. The results indicate that the film can provide a favorable microenvironment for HRP to perform DET on the surface of glassy carbon electrodes with a pair of quasi-reversible redox waves and to retain its bioelectrocatalytic activity toward H2O2.