Direct Electrochemistry of Hemoglobin Immobilized in Polyvinylalcohol and Clay Composite Film Modified Carbon Ionic Liquid Electrode

In this paper room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) was used as binder to fabricate a carbon ionic liquid electrode (CILE). Hemoglobin (Hb) was immobilized on the surface of CILE with clay and polyvinyl alcohol (PVA) composite film by layer to layer method. UV-Vis and FT-IR spectra showed that Hb in the film retained the essential features of its native structure. Electrochemical experiments indicated that a pair of well-defined quasi-reversible redox peak was obtained in pH 7.0 Britton-Robinson (B-R) buffer solution. The reduction and oxidation peak potentials were located at - 0.405 V and - 0.274 V (vs. SCE) with the formal potential as - 0.340 V, which was contributed to the electrochemical reaction of heme Fe(III)/Fe(II) redox couples. The results suggested that the direct electron transfer of Hb in the PVA/Clay film with the CILE was accomplished. The direct electrochemical behaviors of Hb were carefully studied with the electrochemical parameters calculated. The PVA/Clay/ Hb modified CILE gave excellent electrocatalytic ability to the reduction of H2O2 and the apparent Michaelis-Menten constant (K-M(app)) value of Hb in the PVA/Clay film was calculated as 56.26 mu mol L-1.