Talanta 43 (1996) 1615-1619 Talanta Short communication Polyphenol oxidase-catechol: an electroenzymatic model system for characterizing the performance of matrices for biosensors J.-L. Besombes, S. Cosnier”, P. Labbit Received 18 October 1995; accepted 5 February 1996 Ktywm/ss: Biosensors; Enzyme electrodes; Matrices; Polyphenol oxidase-catechol 1. Introduction Enzyme electrodes are analytical devices based on the combination of the high specificity of biocatalytic reactions with the electrochemical (mainly amperometric) transduction of the recog- nition event [l]. Analysis of enzyme electrode kinetics is of importance for designing a sensor or for optimization of parameters [2-61. Since the overall sensor response depends on the enzymatic reaction and on the mass transfer processes, the enzyme layer permeability and the efficiency of the enzymatic reaction are two crucial biosensor parameters. Their determination can give valuable information for the optimization of the biosensor configuration as well as for the development of new strategies for enzyme immobilization [5,7]. For this purpose, we present in this paper the properties of an original electroenzymatic system * Corresponding author based on polyphenol oxidase (PPO) and catechol for evaluating the performance of host matrices used to fabricate enzyme electrodes. PPO and catechol constitute a versatile system since the substrate (catechol) and product (o&o-quinone) of the enzymatic reaction can be independently determined electrochemically. Furthermore, the thermal deactivation of immobilized PPO can give additional information about the substrate diffu- sion through the host matrix loaded with en- zymes. The utilization of this simple system to obtain criteria for optimization of sensor perfor- mance is exemplified here for enzyme electrodes fabricated by polymer entrapment [g-lo]. The model of the electrode material was a polypyrrole film obtained by electropolymerization of an am- phiphilic monomer, the 12-(pyrrol- 1 -yl)dodecyltri- ethylammonium tetrafluoroborate (1) [ 111. The in- fluence of the amount of enzyme immobilized within this model of electrode material on the characteristics of the resulting enzyme electrodes is investigated via the PPO-catechol system. 0039.9140/96~$15.00 0 1996 Elsevier Science B.V. All rights reserved PII SOO39-9 I40(96)0 1907-S