Novel Composite of Multiwalled Carbon Nanotubes and Gold Nanoparticles Stabilized by Chitosan and Hydrophilic Ionic Liquid for Direct Electron Transfer of Glucose Oxidase

A novel composite was fabricated through dispersing multiwalled carbon nanotubes (MWNTs) in gold nanoparticle (GPs) colloid stabilized by chitosan and ionic liquid (i.e., 1-butyl-3-methylimidazolium tetrafluoroborate. BMIMBF4). Transmission electron microscopy (TEM) experiment showed that the GPs highly dispersed on the MWNTs probably due to the electrostatic interaction among GPs. MWNTs and the imidazolium cation of BMIMBF4. X-ray photoelectron spectroscopy (XPS) indicated that thus-formed gold nanostructure was mediated by BMIMBF4, When glucose oxidase (GOD) was immobilized on the composite (MWNTs-GPs) its ultraviolet-visible absorption spectrum kept almost unchanged. The immobilized GOD coated glassy carbon electrode (GOD/MWNTs-GPs/GC) exhibited a pair of well-defined peaks in 0.10 M pH 7.0 phosphate buffer solution (PBS), with a formal potential of -0.463 V (vs. SCE). The electrochemical process involved two-electron transfer. The electron transfer coefficient was ca.0.56 and the electron transfer rate constant was 9.36 s(-1). Furthermore, the immobilized GOD presented good catalytic activity to the oxidation of glucose in air-saturated PBS. The K-m and I-m values were estimated to he 13.7 mu M and 0.619 mu A The GOD/MWNTs-GPs/GC electrode displayed good stability and reproducibility.