Direct Electron Transfer of Glucose Oxidase Immobilized on a Mesoporous Silica KIT-6 Matrix to Screen-Printed Electrodes

Abstract

The direct electron transfer of glucose oxidase (GOx) immobilized on a large-pore mesoporous silica KIT-6 matrix fixed to a screen-printed electrode (SPE) and its application as a disposable biosensor were studied. KIT-6 plays a vital role in this method through immobilizing GOx and facilitating the electron communication between the active centers of GOx and the surface of the SPE. GOx immobilized on KIT-6 maintains its bioactivity and structure and displays stable and well-defined redox peaks with a formal potential of -428 mV (vs. Saturated Calomel Electrode), with a heterogeneous electron transfer rate constant of 4.15 s(-1) in phosphate buffer (0.05 M, pH 6.0). Upon the addition of glucose into air-saturated phosphate buffer solution, the reduction peak current decreases, which can be used analytically for glucose detection. The biosensor exhibits a linear response to glucose concentration ranging from 0 to 2.83 mM and a sensitivity of 7.29 microA (mM)(-1) cm(-2) at an applied potential of -0.5 V. The present work provides a promising strategy for fabricating a novel and disposable mediator-free glucose biosensor, which could be potentially mass-produced through further development.