DEVELOPMENT OF AMPEROMETRIC BIOSENSORS BASED ON THE IMMOBILIZATION OF ENZYMES IN POLYMER-FILMS ELECTROGENERATED FROM A SERIES OF AMPHIPHILIC PYRROLE DERIVATIVES

A series of amphiphilic pyrrolyl-alkylammonium ions differing in the size of their ammonium heads has been used for the immobilization at the electrode surface of horseradish peroxidase, galactose oxidase, polyphenol oxidase, glucose oxidase and xanthine oxidase in polypyrrolic films electrogenerated from adsorbed amphiphilic pyrrole-enzyme mixtures. The enzyme retention properties of the different polymers have been determined indicating that the less hydrophobic monomer has the best immobilization efficiency. The electrochemical assays performed for galactose, glucose and hypoxanthine detection show clearly that the bioelectrode sensitivity is related to the permeability of the host polymer. The selectivity of the glucose oxidase electrodes towards interfering agents like ascorbate, urate and acetaminophen has also been examined, these agents interfering to some extent when present at physiological concentrations.