SANDWICH-TYPE AMPEROMETRIC ENZYME ELECTRODES FOR DETERMINATION OF GLUCOSE

Sandwich type amperometric enzyme electrodes for glucose based on oxidases were studied. Polyethersulphone (PES) and polycarbonate (PC) membranes were used as inner and outer membranes, respectively. Glucose oxidase was entrapped between these two membranes. The selectivity of the inner membrane against a group of electroactive compounds in blood were tested. The PES membrane fulfilled all the requirements of a permselective membrane. The outer surface of PC membranes were further modified by deposition of hexamethyldisiloxane (HMDS) in a glow-discharge reactor or by coating with polyvinylalcohol (PVAL) to increase the linear range of the electrode while keeping or improving the blood-compatible properties of membrane. Linearity of these enzyme electrodes were investigated in different media (i.e., buffer solutions, blood plasma and blood). Blood-compatibilities of the PC membrane and its modified forms were obtained in in-vitro experiments. HMDS treatment significantly increased the linearity of enzyme electrode but did not affect their blood-compatibilities or significantly change the selectively. Also, the PVAL coating, considerably, extended the linear range of the electrode, slightly improved blood-compatibility but did not change the selectivity.