title: Self-assembled films of hemoglobin/laponite/chitosan: application for the direct electrochemistry and catalysis to hydrogen peroxide.
abstract: A highly stable biological film was formed on the functional glassy carbon electrode (GCE) via step-by-step self-assembly of chitosan (CHT), laponite, and hemoglobin (Hb). Cyclic voltammetry (CV) of the Hb/laponite/CHT/GCE showed a pair of stable and quasi-reversible peaks for the Hb-Fe(III)/Fe(II) redox couple at about -0.035 V versus a saturated calomel electrode in pH 6.0 phosphate buffer at a scan rate of 0.1 V s(-1). The electrochemical reaction of Hb entrapped on the laponite/CHT self-assembled film exhibited a surface-controlled electrode process. The formal potential of the Hb-heme-Fe(III)/Fe(II) couple varied linearly with the increase of pH over the range of 3.0-8.0 with a slope of -63 mV pH(-1), which implied that an electron transfer was accompanied by single-proton transfer in the electrochemical reaction. The position of the Soret absorption band of this self-assembled Hb/laponite/CHT film suggested that the entrapped Hb kept its secondary structure similar to its native state. The self-assembled film showed excellent long-term stability, the CV peak potentials kept in the same positions, and the cathodic peak currents retained 90% of their values after 60 days. The film was used as a biological catalyst to catalyze the reduction of hydrogen peroxide. The electrocatalytic response showed a linear dependence on the H2O2 concentration ranging widely from 6.2 x 10(-6) to 2.55 x 10(-3) M with a detection limit of 6.2 x 10(-6) M at 3 sigma.
authors.affiliation: Key Laboratory of Environmental Materials and Environmental Engineering of Jiangsu Province, Yangzhou, China. danshan@yzu.edu.cn
authors.forename: Dan
authors.initials: D
authors.lastname: Shan
authors.forename: En
authors.initials: E
authors.lastname: Han
authors.forename: Huaiguo
authors.initials: H
authors.lastname: Xue
authors.forename: Serge
authors.initials: S
authors.lastname: Cosnier
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D002384:Catalysis; D002417:Cattle; D048271:Chitosan / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods*; D004912:Erythrocytes / Q000378:metabolism; D006418:Heme / Q000737:chemistry; D006454:Hemoglobins / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D017640:Silicates / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods