Glucose biosensors based on the immobilization of glucose oxidase and polytyramine on rodhinized glassy carbon and screen printed electrodes

This work reports on a new amperometric glucose biosensor based on the modification of glassy carbon and screen printed electrodes with rhodium as catalyst, glucose oxidase (GOx) as biorecognition element, and in situ electrogenerated polytyramine as anti-interferents barrier. The excellent electrocatalytic activity of rhodium makes possible a huge enhancement in the oxidation currents of the hydrogen peroxide enzymatically generated from glucose. The polytyramine layer largely improves the selectivity of such response. No interference is observed even for large excess of ascorbic acid, uric acid and acetaminophen. A fast response (5 s) is obtained at the glassy carbon electrode modified with rhodium, glucose oxidase and polytyramine, with a linear realtionship between current and glucose concentration up to 1.50 x 10(-2) M (2.70 g/L) and a the detection limit of 2.5 x 10(-5) M (0.0045 g/L). In the case of screen printed-modified electrodes the response is linear up to 1.0 x 10(-2) M (1.80g/L) glucose. The effect of the experimental conditions for the preparation of the biosensor on the analytical performance of the resulting bioelectrodes is examined and optimized. (c) 2005 Elsevier B.V. All rights reserved.