Fiber-optic biosensor for ethanol, based on an internal enzyme concept.

A new type of biosensor is introduced, based on a novel internal enzyme system which separates the sample solution from the analytical reaction. The bioanalyte diffuses through a gas-permeable membrane into the internal enzyme solution. A reaction that includes the bioanalyte is catalysed and the rate of this reaction is related to the bioanalyte concentration. The first example of this type of biosensor is illustrated by the development of a fiber-optic internal enzyme biosensor for ethanol. Alcohol dehydrogenase is the enzyme and the rate of production of reduced nicotinamide adenine dinucleotide is measured. Results that demonstrate the feasibility of the internal enzyme system are presented and the relative merits of this type of biosensor are discussed.