COFACTOR-CONTAINING BIOLUMINESCENT FIBEROPTIC SENSOR - NEW DEVELOPMENTS WITH POLY(VINYL ALCOHOL) MATRICES

A cofactor-containing bioluminescent fibre-optic sensor for nicotinamide adenine dinucleotide (NADH) is described. The oxidoreductase-luciferase membrane placed at the tip of the fibre-optic ensures the specific molecular recognition of NADH and, in the presence of both a flavin cofactor [flavin mononucleotide (FMN)] and an aldehydic substrate, light emission occurs. The combination of immobilized enzymes and entrapped co-reactants would allow the biosensor to operate in a reagentless way. In a first step to design a self-contained biosensor, the flavin cofactor was entrapped in poly(vinyl alcohol) matrices and was internally released in the vicinity of the bound enzymes, whereas the aldehyde was continuously supplied in the reaction medium. The non-covalent immobilization of the flavin in translucent matrices was performed by entrapment in either a photo-cross-linked poly(vinyl alcohol) (PVA) network or a PVA matrix reticulated with glutaraldehyde. The performance of the biosensor was evaluated with regard to sensitivity (detection limit), dynamic linear range and self-containment.