One-step solvothermal preparation of silver-ZnO hybrid nanorods for use in enzymatic and direct electron-transfer based biosensing of glucose

This article describes an electrochemical glucose biosensor that is based on the immobilization of the enzyme glucose oxidase (GOx) on a glassy carbon electrode that was modified with silver-ZnO hybrid nanorods (HNRs). The HNRs containing different fractions of silver were synthesized by a one-step solvothermal method. Transmission electron microscopy, energy dispersive spectroscopy and X-ray diffraction confirmed the formation of these HNRs. FTIR spectroscopy and cyclic voltammetry demonstrated that the enzyme on the HNRs retained its native structure and bioactivity. The HNRs containing 11.26 wt% silver produced the best electrochemical response and direct electron transfer between enzyme and electrode surface. The sensor responds to glucose with two linear ranges (from 0.01 to 0.1 mM and from 0.1 to 1.5 mM). The sensitivity is 18.7 mAa (TM) M-1 a (TM) cm(-2), and the detection limit is 5 mu M (at an SNR of 3). The biosensor is selective, acceptably stable, and well reproducible. It was successfully applied to the quantitation of glucose in human serum, and results were within -8.1 % and +6.5 % of data obtained with a reference method.