Direct electrochemistry of glucose oxidase and its biosensing to glucose based on the Chit-MWCNTs-AuNRs modified gold electrode

A new glucose biosensor was constructed by immobilizing glucose oxidase (GOD) in the Chitosan (Chit)Multi-walled carbon nanotubes (MWCNTs)/Gold Nanorods (AuNRs) composite membrane. The Chit-MWCNTs/GOD/AuNRs/gold electrode (GE) displayed a pair of well-defined and reversible redox peaks with the formal potentials (E-theta') of -0.384 V in 0.1 mol L-1 pH 7.0 PBS. The apparent heterogeneous electron transfer rate constants (k(s)) of GOD confined to Chit-MWCNTs/AuNRs membrane was evaluated as 11.03 s(-1) to Laviron's equation. The surface concentration (Gamma*) of the electroactive GOD in the film was estimated to be (7.03 +/- 0.02) x 10(-11) mol cm(-2). The electrocatalytic oxidation to glucose of Chit-MWCNTs/GOD/AuNRs/GE was also studied. Its apparent Michaelis-Menten constant for glucose was 1.34 mmol L-1. The experiment results showed that the linear dependence of the electrocatalytic current of the biosensor was from 0.28 to 5.88 mmol L-1, the detection limit of the sensor was 2.06 x 10(-5) mol L-1 (S/N = 3), and the obtained sensitivity was 38.2 mu A mmol(-1) cm(-2). Moreover, the biosensor showed rapid response to glucose, good stability and reproducibility. (C) 2012 Elsevier B.V. All rights reserved.