Direct electrochemistry of glucose oxidase on screen-printed electrodes through one-step enzyme immobilization process with silica sol-gel/polyvinyl alcohol hybrid film

A one-step enzyme immobilization process with silica sol-gel/polyvinyl alcohol was described to achieve direct electrochemistry of glucose oxidase on screen-printed electrodes. The immobilized glucose oxidase displays a couple of stable and well-defined redox peaks with an electron transfer rate constant of 8.38 s(-1) and a formal potential of -460 mV (versus SCE) in phosphate buffer (0.05 M. pH 7.0) at a scan rate of 300 mV s-1. The results suggested that conformation and bioactivity of glucose oxidase could be retained efficiently using the proposed immobilization method and the porous structure of screen-printed electrode Surface was helpful for electron communication of glucose oxidase and the electrode. Furthermore, the modified electrode was used as a glucose biosensor, exhibiting a linear response to glucose concentration ranging from 0 to 4.13 mM and a sensitivity of 3.47 mu A mM(-1) cm(-2) at an applied potential of -0.5 V. The detection limit of the biosensor is 9.8 mu M, based on a signal-to-noise ratio of 3. The present work provided a promising strategy for fabricating a novel and disposable mediatorless glucose biosensor, which could be mass-produced through further development. (C) 2008 Elsevier B.V. All rights reserved.