Abstract

Direct electron transfer of hemoglobin, immobilized on a nickel oxide nanoparticles modified graphite electrode, was studied. Nickel oxide nanoparticles synthesized by electrochemical methods. The prepared nanoparticles were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). The resulting electrode displayed an excellent redox behavior for the hemoglobin. The hemoglobin showed a quasi-reversible electrochemical redox behavior with a formal potential of -48±5 mV (versus Ag/AgCl) in 50 mM potassium phosphate buffer solution at pH 7.0 and temperature 25°C. The cathodic transfer coefficient was 0.45 and electron transfer rate constant was evaluated to be 1.95 s⁻¹. Furthermore, the modified electrode was used as a biosensor and exhibited a satisfactory stability and sensitivity to H₂O₂. The linear range of this biosensor for H₂O₂ determination was from 15 to 650 µM while standard deviation in 40 µM H₂O₂ concentration was 2.8% for 4 repetitions.

Key words: Electron transfer, hemoglobin, nickel oxide, nanoparticles, biosensor.