Direct Electrochemistry and Electrocatalysis of Myoglobin Immobilized on a Novel Chitosan-Nickel Hydroxide Nanoparticles-Carbon Nanotubes Biocomposite Modified Glassy Carbon Electrode

A novel myoglobin-based electrochemical biosensor was developed. The fabricated biosensor is based on a nanobiocomposite prepared from multiwalled carbon nanotubes and Ni(OH)2 nanoparticles that were coated with myoglobin and chitosan. Cyclic voltammogram of the electrode showed a pair of well-defined and quasi-reversible redox peaks with a formal potential (E0 ) of –0.330 V in 0.1 M pH=7.5 phosphate buffer solution, which was the characteristic of the Mb heme Fe(III)/Fe(II) redox couple. Immobilized Mb exhibits excellent electrocatalytic activity toward the reduction of hydrogen peroxide. The linear range for the determination of hydrogen peroxide was from 0.4 to 702 ?M with a detection limit of 0.08 ?M using chronoamperometry method. The kinetic parameters such as the electron transfer coefficient and the heterogeneous electron transfer rate constant for H2O2 determination were determined using electrochemical approaches. The biosensor was used for determination of H2O2 in human blood serum and the oxidant with satisfactory results.