Electron transfer in amperometric biosensors

At present direct electron transfer between an electrode and protein ranks among promising areas of biosensor research. This review focuses on current trends and methods in the development of third-generation amperometric biosensors. It describes the construction of the biosensors of three generations and enzyme immobilization techniques. The design of the electrode interface and biosensor architecture are essential in bioelectrocatalysis, fast electron transfer and electrode construction. Differences in the architectures usually reflect specific electron transfer mechanisms. In the second-generation biosensors, the preferred design consists of biosensors with mediators tightly bound in the active layer of the electrode surface. Attempts at the direct electron transfer employ techniques like self-assembled monolayers, conducting polymers, reconstitution of the prosthetic group and apoenzyme in active holoenzyme and integration of nanotechnology. Despite considerable efforts, no commercially available biosensors based on the direct electron transfer have been developed so far. Modem approaches such as redox proteins and enzymes with engineered electron pathways can make this type of biosensors commercially attractive.