An organically modified silicate-based ethanol biosensor

A novel electrocatalytic ethanol biosensor using ferrocene-encapsulated pal ladium (Pd)-linked organically modified sol-gel glass (ormosil) is reported . The alkoxy precursors used to prepare the new ormosil-based electrocataly tic biosensor are Pd-linked glycidoxypropyltrimethoxysilane and trimethoxys ilane. Pd-glycidoxypropyltrimethoxysilane (black solution) is made by mixin g aqueous solutions of palladium chloride and glycidoxypropyltrimethoxysila ne. The new ormosil is made using a Pd-linked silane precursor, trimethoxys ilane, an aqueous solution of ferrocene monocarboxylic acid, and HCl. Alcoh ol dehydrogenase (ADH) is assembled over the ferrocene-ormosil layer using polyvinyl alcohol and then protecting the immobilized enzyme layer using Mi llipore filter membranes (pore size 1 mum). The electrocatalytic response o f immobilized ADH, soluble nicotinamide adenine dinucleotide, and Pd-linked ormosil-encapsulated ferrocene is then observed. The electrocatalytic oxid ation of NADH and the subsequent ADH-catalyzed formation of NADH are monito red electrochemically. Typical results recorded after the addition of varyi ng concentrations of ethanol are reported; however, the sensor is sensitive to other alcohol and known ADH-sensitive substrates, The stability and rep roducibility of the new ethanol biosensor are reported. (C) 2001 Academic P ress.