Direct electrochemistry of glucose oxidase in a colloid Au-dihexadecylphosphate composite film and its application to develop a glucose biosensor

Colloid Au (Au-nano) with a diameter of about 10 nm was prepared and used in combination with dihexadecylphosphate (DHP) to immobilize glucose oxidase (GOD) onto the surface of a graphite electrode (GE). The direct electrochemistry of GOD confined in the composite film was investigated. The immobilized GOD displayed a pair of redox peaks with a formal potential of -0.475 mV in pH 7.0 O-2-free phosphate buffers at scan rate of 150 mV s(-1). The GOD in the composite film retained its bioactivity and could catalyze the reduction of dissolved oxygen. Upon the addition of glucose, the reduction peak current of dissolved oxygen decreased, which could be developed for glucose determination. A calibration linear range of glucose was 0.5-9.3 mM with a detection limit of 0.1 mM and a sensitivity of 1.14 mu A mM(-1). The glucose biosensor showed good reproducibility and stability. The general interferences that coexisted in human serum sample such as ascorbic acid and uric acid did not affect glucose determination. (C) 2006 Elsevier B.V. All rights reserved.