Graphite-methacrylate biocomposite material with renewable sensing surfacefor reagentless amperometric biosensors based on glucose dehydrogenase

A glucose biosensor based on a rigid conducting biocomposite has been prepa red. The biocomposite is made of graphite powder and poly(methacrylate) inc orporating the glucose dehydrogenase (GDH) and nicotinamide adenine dinucle otide phosphate (NADP(+)) coenzyme system. This material is prepared easily using dry-chemistry procedures allowing for the bulk immobilisation of the enzyme and the cofactor. Although the immobilisation is not very stable, t he biocomposite acts as a reservoir of the biological material with a sacri ficial sensing surface that may be renewed by polishing. This results in a bioelectrochemical response that is highly reproducible. The enzyme and coe nzyme system is stable within the biocomposite for more than 120 days. The technique presented is a practical alternative to more conventional procedu res for the fabrication of reagentless biosensors based on NAD(+)-dependent dehydrogenases, that imply the use of costly and sophisticated wet-chemist ry procedures not compatible with mass-fabrication techniques. (C) 2000 Els evier Science S.A. All rights reserved.