THE EFFECT OF LIPID BILAYER MANIPULATION ON THE RESPONSE OF THE GLUCOSE-OXIDASE LIPOSOME ELECTRODE

The use of lipids in the construction of membranes for biosensors has been well documented. They have been used on electrode surfaces to red uce interferences from electroactive species such as ascorbate, while lipid bilayers have been used to immobilize enzymes. Recently, liposom es have been used to encapsulate glucose oxidase and these liposomes h ave been immobilized on a Rank electrode polarized to measure the prod uction of hydrogen peroxide. In this case liposomes were used as a dif fusion limiting membrane to reduce the exposure of the oxidase to gluc ose and therefore increase the linear range of the enzyme to a level o f clinical use (0-40 mM). The original method of liposome production ( reverse phase evaporation) was altered to a method of vesicle extrusio n to provide more reproducible results. Liposomal electrodes from this system showed an extended K-m of over 100 mM and a slow response time of 5 min. This paper describes research undertaken on the manipulatio n of the lipid bilayer of the liposome. By varying the composition of the lipids in the bilayer the response size, time and apparent K-m can all be altered. (C) 1997 Published by Elsevier Science Limited.