Electrochemical biosensors utilising electron transfer in heme proteins immobilised on Fe3O4 nanoparticles

Fe3O4 nanoparticles cast on pyrolytic graphite (PG) electrodes were used to immobilize hemoglobin (Hb), myoglobin (Mb) and horseradish peroxidase (HRP). The Fe3O4 nanoparticles provided a favorable microenvironment for the proteins to directly transfer electrons with electrodes. The protein-Fe3O4 films were used to electrochemically catalyze the reduction of oxygen, trichloroacetic acid, nitrite and hydrogen peroxide, and showed a potential applicability in fabricating biosensors. Transmission electron microscopy (TEM), UV-visible absorption and reflectance absorption infrared (RAIR) spectroscopy, and cyclic and square wave voltammetry, were used to characterize the films.