Electrochemistry and electrocatalysis of a nanobiocomposite film containing hematin and carbon nanotubes–chitosan on a poly-(acridine red) modified glassy carbon electrode

Abstract

A novel nanocomposite material based on poly-acridine red (PAR), multi-walled carbon nanotubes (MWCNTs) and chitosan (CS) was used to incorporate hematin onto the surface of a glassy carbon electrode for studying the electron transfer and electrocatalytic activity of hematin. A pair of well defined and quasi-reversible redox peaks, corresponding to the hematin Fe(III)/Fe(II) redox couple, appeared at about −0.272 V (vs. Ag/AgCl). The electron transfer rate constant was estimated to be 5.06 s⁻¹. The results indicated that the MWCNT–CS and PAR composite film enhanced the electron transfer process of hematin. The hematin immobilized in the MWCNT–CS and PAR film exhibited bioelectrocatalytic activity for the reduction of H₂O₂. The peak current of the biosensor by cyclic voltammetry varied linearly with the concentration of H₂O₂ from 10.0 to 1000.0 μM and the detection limit was 1.75 μM. The amperometric response of the biosensor varied linearly with the concentration of H₂O₂ from 1.0 to 10.0 μM and the detection limit was 0.61 μM (S/N = 3). The results indicate that the composite film is a versatile platform for the fabrication of electrochemical biosensors.