Amperometric Glucose Sensors Based on Immobilized Glucose Oxidase-Polyquinone System

Non-cross-linked and also cross-linked poly(ether amine quinone)s were prepared and tested for their efficiency as electron-transfer relay systems in amperometric glucose biosensors. Cyclic voltammetry and constant applied potential measurements showed that poly(ether amine quinone) relay systems efficiently mediated electron transfer from reduced glucose oxidase to a conventional carbon paste electrode. Sensors containing these relay systems respond rapidly to low (< 0.1 mM) glucose concentrations and reach steady-state current responses in less than 1 min. Electrodes constructed with cross-linked polymer and glucose oxidase were stable, indicating that the glucose oxidase was trapped in the polymer matrix and did not freely diffuse away from the electrode surface into aqueous solutions. The cross-linked polymer is a large molecular system which facilitates a flow of electrons from enzyme to the electrode, acting as an electron-transfer relay system and not as a diffusional mediator.