Characterization and electrochemical study of hemoglobin-carbon nanoparticles-polyvinyl alcohol nanoporous hybrid film

A hybrid film is fabricated by casting hemoglobin (Hb)-carbon nanoparticles (CNPs)-polyvinyl alcohol (PVA) suspension on glassy carbon electrode (GCE). The resulting film shows a three-dimensional nanoporous structure. In the hybrid film, the ultraviolet visible (UV-Vis) absorption spectra of Hb keep almost unchanged. The organic-inorganic hybrid material can promote the direct electron transfer of Hb. A pair of well-defined and quasireversible peaks with a formal potential of -0.348 V (vs saturated calomel electrode) is obtained, which is caused by the electrochemical reaction of the Fe(III)/Fe(II) couple of Hb. The electron transfer rate constant (k(s)) is estimated to be 3.9 s(-1). The immobilized Hb exhibits high stability and excellent electrochemical catalysis to the reduction of oxygen (O-2), hydrogen peroxide (H2O2), and nitrite (NO2-). The catalytic currents are linear to the concentrations of H2O2 and NO2- from 1.96 to 112 mu M and from 0.2 to 1.8 mM, respectively. Therefore, the hybrid film may be a good matrix for protein immobilization and biosensor fabrication.