Graphite–methacrylate biocomposite material with renewable sensing surface for reagentless amperometric biosensors based on glucose dehydrogenase

A glucose biosensor based on a rigid conducting biocomposite has been prepared. The biocomposite is made of graphite powder and poly(methacrylate) incorporating the glucose dehydrogenase (GDH) and nicotinamide adenine dinucleotide 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, the biocomposite acts as a reservoir of the biological material with a sacrificial sensing surface that may be renewed by polishing. This results in a bioelectrochemical response that is highly reproducible. The enzyme and coenzyme system is stable within the biocomposite for more than 120 days. The technique presented is a practical alternative to more conventional procedures for the fabrication of reagentless biosensors based on NAD+-dependent dehydrogenases, that imply the use of costly and sophisticated wet-chemistry procedures not compatible with mass-fabrication techniques.