J. Iran. Chem. Soc., Vol. 7, No. 2 June 2010, pp.470~477.

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Direct Electrochemistry of Hemoglobin in a Nafion and CuS Microsphere Modified Carbon Ionic Liquid Electrode and its Electrocatalytic Behavior

W. Sun*, R.-F. Gao, R.-J. Zhao, H.-T. Zhu and K. Jiao

Key Laboratory of Eco-Chemical Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042,P.R.China

      Direct electrochemistry of hemoglobin (Hb) was realized on a Nafion and CuS microsphere composite film modified carbon ionic liquid electrode (CILE) with N-butylpyridinium hexafluorophosphate (BPPF6) as binder. Scanning electron microscopy (SEM), UV-Vis absorption spectroscopy and cyclic voltammetry were used to characterize the fabricated Nafion/CuS/Hb/CILE. Experimental results showed that a pair of well-defined quasi-reversible redox peaks appeared with the formal potential as -0.386 V (vs. SCE) in pH 7.0 Britton-Robinson (B-R) buffer solution, which was attributed to the Hb heme Fe(III)/Fe(II) redox couples. The electrochemical parameters of Hb in the composite film were carefully investigated with the charge transfer coefficient (α), the electron transfer number (n) and the electron transfer rate constant (ks) as 0.505, 1.196 and 0.610 s-1, respectively. The composite film provided a favorable microenvironment for retaining the native structure of Hb. The presence of CuS microspheres showed great improvement on the electron transfer rate of Hb with the CILE, which maybe due to the contribution of specific characteristics of CuS microspheres and the inherent advantages of ionic liquid on the modified electrode. The fabricated Hb modified electrode showed good electrocatalytic ability in the reduction of H2O2. The proposed bioelectrode can be used as a new third generation H2O2 biosensor.

Keywords: N-Butylpyridinium hexafluorophosphate, CuS microsphere, Carbon ionic liquid electrode, Hemoglobin, Hydrogen peroxide 

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