ELECTROSYNTHESIZED NONCONDUCTING POLYMERS AS PERMSELECTIVE MEMBRANES IN AMPEROMETRIC ENZYME ELECTRODES - A GLUCOSE BIOSENSOR BASED ON A CO-CROSS-LINKED GLUCOSE-OXIDASE OVEROXIDIZED POLYPYRROLE BILAYER

A glucose amperometric biosensor based on glucose oxidase immobilized on an overoxidized polypyrrole (PPyox) platinum modified electrode, by glutaraldehyde co-crosslinking with bovine serum albumine, is describ ed. The advantages of covalent immobilization techniques (e.g., high l oading and long-term stability of the enzyme) are coupled with the exc ellent interferent rejection of electrosynthesized non-conducting poly mers. The sensor showed an apparent Michaelis-Menten constant of 16 +/ - 0.8 mM, a maximum current density of 490 mu A/cm(2) and a shelf life time of at least 3 months. Ascorbate, urate, cysteine and acetaminophe n at their maximum physiological concentrations produced a glucose bia s in the low micromolar range. Flow-injection response was linear up t o 20 mM glucose with typical sensitivity of 84.0 +/- 1.5 nA/mM. The se nsor was tested for glucose determination of untreated serum samples f rom both normal and diabetic subjects; results of amperometric assay c ompared well with those obtained by a standard enzymatic-colorimetric method. (C) 1998 Published by Elsevier Science Limited.