POLYMERIC MERCAPTOSILANE-MODIFIED PLATINUM-ELECTRODES FOR ELIMINATIONOF INTERFERANTS IN GLUCOSE BIOSENSORS

An oxidase-based glucose sensor has been developed that uses a mercapt osilane-modified platinum electrode to achieve selectivity of electroc hemical interferants. A platinum-iridium (9:1) wire (0.178 mm o.d., se nsing area of 1.12 mm(2)) is modified with (3-mercaptopropyl)trimethox ysilane. The modified sensors show excellent operational stability for more than 5 days. Glucose oxidase is immobilized on the modified surf ace (i) by using 3-maleimidopropionic acid as a linker or (ii) by cros s-linking with bovine serum albumin using glutaraldehyde. Sensitivitie s in the range of 9.97 nA/mM glucose are observed when the enzyme is i mmobilized by method ii, Lower sensitivities (1.13 x 10(-1) nA/mM gluc ose) are observed when immobilization method i is employed. In terms o f linear response range, the sensor enzyme-immobilized by method i is superior to that immobilized by method ii. The linearity is improved u pon coating the enzyme layer with polyurethane, The sensor immobilized by method ii and coated with polyurethane exhibits a linear range to 15 mM glucose and excellent selectivity to glucose (0.47 nA/mM) agains t interferants such as ascorbic acid, uric acid, and acetaminophen.