Amperometric Biosensor for Glucose Based on a Nanometer-Sized Microband Gold Electrode Coimmobilized with Glucose Oxidase and Poly(o-phenylenediamide)

A nanometer-sized (88 mm) microband gold electrode for glucose detection is described. These noble metal ultramicrosensors are prepared by electrochemical copolymerization of o-phenylenediamide (PDA) and glucose oxidase at the nanometer-sized electrodes. Electropolymerization conditions of PDA at the microband surface are optimized. The current can rapidly (3s) reach a steady value upon the potential step from 0 to +0.6 V without stirring the solution. The permselectivity characteristics of polymer can eliminate the interference of ascorbic acid. The amperometric response to glucose shows a linear relation in the range of 0.5 mM to about 10 mM with the correlation coefficient of 0.9993. With further increasing of glucose concentration an obvious Michaelis-Menten's response can be observed. The maximum steady current density is ca. 4.4 ± 0.2 mA/cm2 and the apparent Michaelis-Menten constant is 21.1 ± 0.2 mM.