Abstract

Direct electron transferring of glucose oxidase (GOx) was investigated on different templates, i.e. goldcoated Fe3O4 nanoparticles (GNPs), carbon nanotubes (CNTs) and graphene (Gr). The direct electrochemistry GOx on GNPs, CNTs and Gr showed a cyclic voltammograms corresponding to the FAD/FADH(2) redox couple with a formal potential of -280, -489 and -443 mV, respectively in 0.1 M phosphate buffer solution and air saturated condition for similarity of in vivo usage. The cyclic voltamrnograms (CVs) of GOx on Gr is reversible, but on GNPs and CNTs are quasi-reversible. Also, the CVs results show, the current intensity of GOx on GNPs is higher than CNTs and Gr. The electrochemical parameters such as apparent charge transfer rate constant (k(s)) and electron transfer coefficient (a) for electron transfer between the electrode surface and GOx, were calculated as 0.53 and 0.5 s(-1) and 0.27 and 0.24 for GNPs and CNTs. These studies make useful insight into the enzyme immobilization on nanoparticles for biosensors and bio-fuel cell preparation.