Enzyme electrode based on gold-plated polyester cloth. I: Preparation of glucose oxidase electrode which exchanges electron with electrode

Summary Glucose oxidase is immobilized on gold-plated polyester cloth by entrapment method and coupled with an electron mediator, ferrocene derivative. Cyclic voltammogram depends on the existence of the substrate glucose and the flavo-enzyme was shown to donate electron(s) to the cloth electrode with mediation of the ferrocene derivative even in the immobilized state. The glucose-concentration dependence of the peak current was linear upto several tens of 35 mM, depending on the concentration of the mediator. Co-immobilization of polymer-anchored electron mediator is also studied. Many efforts have been made to utilize specific recognition and selective catalysis performed by enzymes in analytical or productive purposes; biosensors and bioreactors. One of the most important problems to obtain much more effective system for these purposes is how to communicate the direct exchange or transfer between the biology-origin materials and the energy supplying artificial systems. Taking the most popular enzyme electrode, glucose oxidase (GOD)electrode, as an example, conventional GOD electrodes measure the concentration of oxygen, consumed by GOD reaction with glucose, or of hydrogen peroxide, a product of the same reaction, with the electrolytic process on the platinum electrode. In such a system the high performance of the enzyme is utilized only indirectly and the principal detecting system is more or less non-specific and general. Therefore attempts of multifunctionalization by combining other bio-systems is found difficult and the supply of oxygen caused several problems in attempts of hioreactors. It has been getting understood that by immobilizing enzymes directly on proper electrode and coupling with some electron mediators the electron transfer on the electrode surface is controlled by the electric potential given on it and hence the reaction of oxido-reductase is controlled.(1) Mediators are required since the direct electron exchange between the electrode and the enzyme is hard to occur in most of the cases. Another important problem for the utilization of enzyme electrode in various purposes is in the materials of the electrode. Most usually platinum or gold is used but they are expensive and inflexible. Carbon fibers are better in these senses but they are still inconvenient to treat. In this connection we developed enzyme electrodes which use gold-plated polyester cloth.(2) It is advantageous in many points such as flexibility, wide-surface area, processability after enzyme immobilization and cheapness. In this study GOD was chosen since it is considered as a standard example in such a research of enzyme immobilization. The oxido-reductase