Direct electrochemistry and electrocatalysis of myoglobin immobilized on zirconia/multi-walled carbon nanotube nanocomposite

Zirconia/multi-walled carbon nanotube (ZrO2/MWCNT) nanocomposite was prepared by hydrothermal treatment of MWCNTs in ZrOCl2·8H2O aqueous solution. The morphology and structure of the synthesized ZrO2/MWCNT nanocomposite were characterized by transmission electron microscopy and X-ray diffraction analysis. It was found that ZrO2 nanoparticles homogeneously distributed on the sidewall of MWCNTs. Myoglobin (Mb), as a model protein to investigate the nanocomposite, was immobilized on ZrO2/MWCNT nanocomposite. Ultraviolet–visible spectroscopy and electrochemical measurements showed that the nanocomposite could retain the bioactivity of the immobilized Mb to a large extent. The Mb immobilized in the composite showed excellent direct electrochemistry and electrocatalytic activity to the reduction of hydrogen peroxide (H2O2). The linear response range of the biosensor to H2O2 concentration was from 1.0 to 116.0 μM with the limit of detection of 0.53 μM (S/N = 3). The ZrO2/MWCNT nanocomposite provided a good biocompatible matrix for protein immobilization and biosensors preparation.