A novel platform of hemoglobin on core-shell structurally Fe3O4@Au nanoparticles and its direct electrochemistry

A novel platform, which hemoglobin (Hb) was immobilized on core-shell structurally Fe3O4/Au nanoparticles (simplified as Fe3O4@Au NPs) modified glassy carbon electrode (GCE), has been developed for fabricating the third biosensors. Fe3O4@Au NPs, characterized using transmission electron microscope (TEM), scanning electron microscope (SEM) and energy dispersive spectra (EDS), were coated onto GCE mediated by chitosan so as to provide larger surface area for anchoring Hb. The thermodynamics, dynamics and catalysis properties of Hb immobilized on Fe3O4@Au NPs were discussed by UV-visible spectrum (UV-vis), electrochemical impedance spectroscopy (EIS), electrochemical quartz crystal microbalance technique (EQCM) and cyclic voltammetry (CV). The electrochemical parameters of Hb on Fe3O4@Au NPs modified GCE were further carefully calculated with the results of the effective working area as 3.61 cm(2), the surface coverage concentration (Gamma) as 1.07 x 10(-12) mol cm(-2), the electron-transfer rate constant (K-s) as 1.03s(-1), the number of electron transferred (n) as 1.20 and the standard entropy of the immobilized Hb (Delta S-0') as calculated to be -104.1 J mol(-1) K-1. The electrocatalytic behaviors of the immobilized Hb on Fe3O4@Au NPs were applied for the determination of hydrogen peroxide (H2O2), oxygen (O-2) and trichloroacetic acid (TCA). The possible functions of Fe3O4 core and Au shell as a novel platform for achieving Hb direct electrochemistry were discussed, respectively. (C) 2011 Elsevier Ltd. All rights reserved.