SOL-GEL-ENCAPSULATED ALCOHOL-DEHYDROGENASE AS A VERSATILE, ENVIRONMENTALLY STABILIZED SENSOR FOR ALCOHOLS AND ALDEHYDES

Silicate-encapsulated yeast alcohol dehydrogenase (ADH) can be employe d as a sensor for short-chained alcohols in standard aqueous, harsh no naqueous, and gas-phase environments. Specifically, the implementation of sensing schemes based on encapsulated ADH/NAD(+) or ADH/NADH, and utilization of changes in fluorescence from the soluble, reduced cofac tor nicotinamide adenine dinucleotide (NADH) upon exposure to alcohols or aldehydes, allows for semiquantitative determination of both subst rates. Additionally, by using fluorescence from NADH, we find that cyc ling of the enzymatic probe can be accomplished via successive exposur e to alcohol and aldehyde substrates, thus converting the system into a multiple-use sensor. Finally, we find that the gel matrix provides s ufficient enzyme stabilization to permit the assemblies to be used ana lytically in hostile and inherently denaturing sample environments, in cluding vapor-phase and nonpolar liquid (e.g., hexane) environments.