GLUCOSE AND ACETYLCHOLINE SENSING MULTILAYER ENZYME ELECTRODES OF CONTROLLED ENZYME LAYER THICKNESS

Multilayer enzyme networks assembled by a stepwise synthesis onto Au e lectrodes provide the basis for glucose, choline, and acetylcholine am perometric biosensors. Glucose oxidase is assembled as a multilayer ar ray on smooth and rough An electrodes. Electrical communication of the GOx layers with the electrode is established by the presence of ferro cenecarboxylic acid as diffusional electron mediator or by covalent li nkage of [(ferrocenylmethyl)amino]caproic acid to the enzyme component s, The resulting enzyme electrodes are applied as amperometric biosens ors for glucose. The sensitivity of the resulting enzyme electrode is controlled by the number of enzyme layers assembled onto the electrode and by the roughness factor of the electrode surface. A multilayer en zyme array of choline oxidase (ChO) immobilized onto ,a rough An elect rode provides an amperometric biosensor for the amperometric detection of choline in the presence of 2,6-dichloroindophenol (DIP) as diffusi onal electron mediator. Stepwise organization of a multilayer biocatal ytic array consisting of four layers of ChO and three layers of acetyl choline esterase (AChE) provides a bifunctional enzyme electrode for t he amperometric detection of acetylcholine, In this system, choline ge nerated by AChE hydrolysis of acetylcholine is amperometrically detect ed by the ChO layers in the presence of DIP acting as diffusional elec tron mediator, Here we report on novel means to enhance the sensitivit y of multilayer enzyme electrodes by the application of rough Au elect rodes as the surface for assembling the enzyme network.