A glucose biosensor based on modified-enzyme incorporated within electropolymerised poly(3,4-ethylenedioxythiophene) (PEDT) films

We have constructed and characterised a glucose sensor using glucose oxidas e (GOD) covalently attached to carboxylic acid polyethyleneglycol (PEG), ca lled (PEG-GOD). This modified enzyme was entrapped afterwards within poly(3 ,4-ethylenedioxythiophene) (PEDT) films electrogenerated on glassy carbon ( GC) electrodes. The composite (PEG-GOD/PEDT) film is more porous than the f ilm without enzyme (PEDT + PEG). Data from electrochemical quartz microbala nce (ECQM) and pH-stat experiments indicate a good relative activity of the modified enzyme, ca. 12-15%. Amperometric measurements, using ferrocenemet hanol as the redox mediator, confirms that the modified enzyme is catalytic ally active. The effect of film thickness was also investigated. The sensit ivities were quite similar for modified-GOD electrodes (ca. 3 mA cm (-2) M (-1)) and unmodified-GOD electrodes (ca. 2.7 mA cm -(2) M (-1)) but a bette r stability was obtained with modified PEG-GOD electrodes. (C) 2001 Elsevie r Science B.V. All rights reserved.