PLATINIZED CARBON ULTRAMICROELECTRODES AS GLUCOSE BIOSENSORS

Miniaturized glucose biosensors were constructed by all-chemical means from disk-shaped carbon ultramicroelectrodes (UMEs) (diameter = 8 mum ). These ultramicrobiosensors (UMBs) are capable of direct measurement of glucose in the presence of interfering species. Carbon UMEs were p artially platinized by the electrochemical reduction of a platinum (IV ) complex. Platinization of the carbon UMEs gave an increased current response to hydrogen peroxide and allowed the modified electrode to be operated at a lower oxidative potential. Glucose oxidase (E.C. 1.1.3. 4.) was immobilized either by glutaraldehyde cross-linking or by direc t covalent attachment to the electrode surface using carbodiimide. Res ponse time (100% response) was 15-45 seconds. Response was linear over the range of 3-7 mM glucose. An electropolymerized film of poly(1,3-d iaminobenzene) was used to prevent interfering species.