GLUCOSE-OXIDASE POLYION COMPLEX-BILAYER MEMBRANE FOR ELIMINATION OF ELECTROACTIVE INTERFERENTS IN AMPEROMETRIC GLUCOSE SENSOR

An amperometric glucose-sensing electrode was prepared by immobilizing glucose oxidase (GOx) on a polyion complex membrane. First, a monolay er of 3-mercaptopropionic acid (MPA) was made on the surface of a gold electrode by immersing it in an ethanol solution containing MPA. Aque ous solutions of poly-L-lysine and poly-4-styrenesulfonate were succes sively placed on the electrode surface and allowed to dry. A GOx layer was then formed on the poly-L-lysine/poly-4-styrenesulfonate-complex layer by crosslinking the enzyme by the addition of a glutaraldehyde s olution. The polyion complex layer was effective for eliminating elect rochemical interferents such as L-ascorbic acid, uric acid and acetami nophen. whereas the hydrogen peroxide produced through the GOx-catalyz ed reaction permeated rapidly through the layer. This resulted in a ra pid response (100% response in <5 s) with a low interference level (e. g., the ratio of response for L-ascorbic acid to that for the same con centration of glucose was 0.07). The electrode was applied to the assa y of glucose in beverages and sera, and could be used for more than tw o months, (C) 1998 Elsevier Science :B.V.