Direct electrochemistry and electrocatalysis of heme proteins on SWCNTs-CTAB modified electrodes

Direct electrochemistry and electrocatalysis of heme proteins including hemoglobin (Hb), myoglobin (Mb) and horseradish peroxidase (HRP) were studied with the protein incorporated single walled carbon nanotubes (SWCNTs)-cetylramethylammonium bromide (CTAB) nanocomposite film modified glassy carbon electrodes (GCEs). The incorporated heme proteins were characterized with Fourier transform infrared spectroscopy (FTIR), ultraviolet visible (UV) spectroscopy, atomic force microscopy (AFM) and electrochemistry, indicating the heme proteins in SWCNTs-CTAB nanocomposite films keep their secondary structure similar to their native states. The direct electron transfer between the heme proteins in SWCNTs-CTAB films and GCE was investigated. The electrochemical parameters such as formal potentials and apparent heterogeneous electrontransfer rate constants (ks) were estimated by square wave voltammetry with nonlinear regression analysis. The heme protein-SWCNT-CTAB electrodes show excellent electrocatalytic activities for the reduction of H2O2 and NO2−, which have been utilized to determine the concentrations of H2O2 and NO2−.