A glucose biosensor based on direct electron transfer of glucose oxidase immobilized onto glassy carbon electrode modified with nitrophenyl diazonium salt

摘要

This study reports a novel, simple and fast approach for construction of a highly stable glucose biosensor based on the immobilization of glucose oxidase (GOx) onto a glassy carbon electrode (GCE) electrografted with 4-aminophenyl (AP) by diazonium chemistry. Aminophenyl was used as cross-linker for covalent attachment of glucose oxidase to the electrode surface. Cyclic voltammograms of the GOx-modified GCE in phosphate buffer solution exhibited a pair of well-defined redox peaks, attesting the direct electron transfer (DET) of GOx with the underlying electrode. The proposed biosensor could be used to detect glucose based on the consumption of O_2 with the oxidation of glucose catalyzed by GOx and exhibited a wide linear range of glucose from 0.05 mM to 4.5 mM and low detection limit of 10 μM. The surface coverage of active GOx, heterogeneous electron transfer rate constant (k_s) and Michaelis-Menten constant (K_M) of immobilized GOx were 1.23 × 10~(-12) mol cm~(-2), 4.25 s~(-1) and 2.95 mM, respectively. The great stability of this biosensor, technically simple and possibility of preparation at short period of time make this method suitable for fabrication of low-cost glucose biosensors.