Direct Electron Transfer of Hemoglobin on Cadmium Oxide Nanoparticles Modified Carbon paste Electrode

摘要

Direct electron transfer of hemoglobin, immobilized on a cadmium oxide nanoparticles modified carbon paste electrode, was investigated. Cadmium oxide nanoparticles synthesized by chemical methods. The prepared nanoparticles were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). The resulting electrode displayed a superior redox behavior for the hemoglobin. The hemoglobin showed a quasi-reversible electrochemical redox behavior with a formal potential of -50 mV (versus SCE) in 50 mM potassium phosphate buffer solution at pH 7.0 and temperature 25°C. The cathodic transfer coefficient was 0.40 and electron transfer rate constant was evaluated to be 1.47 s?1. Moreover, the modified electrode was used as a biosensor and exhibited a satisfactory stability and sensitivity to NO. In addition, NO induced a cathodic potential shift of the catalytic reduce peak of oxygen. This potential shift was proportional to the logarithm of NO concentration ranging from 5.0 × 10?8 to 5.0 × 10?6 mol/L. The detection limit has been estimated to be 50 nM. Thus the linear range of this biosensor for NO determination was from 0.05 to 5 μM while standard deviation in 5 μM NO concentration was 2.5% for 4 repetitions.