Direct electrochemistry of hemoglobin in PHEA and its catalysis to H2O2

Hemoglobin (Hb) was immobilized on glassy carbon (GC) electrode by a kind of synthetic water-soluble polymer, poly-alpha,beta-[N-(2-hydroxyethyl)L-aspartamide] (PHEA). A pair of well-defined and quasi-reversible cyclic voltammetric peaks was achieved, which reflected the direct electron-transfer of the Fe(III)/Fe(II) couple of Hb. The formal potential (E degrees'), the apparent coverage (Gamma*) and the electron-transfer rate constant (k(s)) were calculated by integrating cyclic voltammograms experimental data. Scanning electron microscopy (SEM) demonstrated the morphology of Hb-PHEA film very different from the Hb and PHEA films. Ultraviolet visible (UV-vis) spectroscopy showed Hb in PHEA film remained its secondary structure similar to the native state. In respect that the immobilized protein remained its biocatalytic activity to the reduction of hydrogen peroxide (H2O2), a kind of mediator-free biosensor for H2O2 could be developed. The apparent Michaelis-Menten constant (K-m(app)) was estimated to be 18.05 mu M. The biosensor exhibited rapid electrochemical response and good stability. Furthermore, uric acid (UA), ascorbic acid (AA) and dopamine (DA) had little interferences with the amperometric signal of H2O2, which provide the perspective of this H2O2 sensor to be used in biological environments. (c) 2006 Elsevier B.V. All rights reserved.