Electrical Contact of Redox Enzyme Layers Associated with Electrodes: Routes to Amperometric Biosensors

Tailoring of electrically contacted enzyme electrodes provides the grounds for bioelectronic and biosensor systems. Redox-enzymes organized onto electrodes as monolayer assemblies, and chemically functionalized by redox-relay groups, yield electrically contacted enzyme electrodes exhibiting bioelectrocatalytic features. The sensitivity of the enzyme electrode can be enhanced, or tuned, by the organization of multilayer enzyme electrodes and the application of rough metal supports. Enzyme electrodes of extremely efficient electrical communication with the electrode are generated by the reconstitution of apo-flavoenzymes onto relay-FAD monolayers associated with electrodes. The reconstitution process results in an aligned enzyme on the surface, and its effective electrical contact with the electrode yields selective enzyme electrodes of unprecedented high current responses. Integrated electrodes consisting of relay-NAD(P)⁺-cofactor and enzyme units are generated by the reconstitution of NAD(P)⁺-dependent enzymes onto a relay-NAD(P)⁺ monolayer assembly followed by lateral crosslinking of the enzyme network.