195 Bioelectrochemistry and Bioenergetics. 23 (1990) 195-202 A section of J. ElectroanaL Chem., and constituting VoL 298 (1990) Elsevier Sequoia S.A., Lausanne - Printed in The Neth~lands New enz3 me sensors for urea and creatinine analysis * L. Campanella **, F. Mazzei, M.P. Sammartino and M. Tomassetti Dipartimento di Chimica, Universitd "La Sapienza", p.le A. More, 5, 00185 Roma (Italy) (Received 29 September 1989; in revised form 28 December 1989) ABSTRACT New selective sensors sensitive to urea or creatinine have been developed and different geometries of the electrocnzymatie systems investigated. The sensors were characterised and used to analyse clinical matrices (urines and control sera). INTRODUCTION In the program presently running in our laboratory, aimed at the development of new electrochemical potentiometric sensors and ion-selective electrodes [1,2], we recently developed both a new assembly procedure for ion-selective polymeric electrodes [3] and an efficient immobilisation method for the entrapment of en- zymes [4]. The most recent results of the~se investigations concern the realisation of two new kinds of enzymatic sensor for the determination of urea and creatinine, respectively. By using an electrode selective to the ~mmonium ion, with a PVC-based membrane containing sebacate as plasticising agent and nonactine as ionophore, a probe sensitive to urea and an other one sensitive to creatinine were designed and built up, by immobifisafion respectively of urease and creatinine deiminase by polyazetidine prepol~0raer [1,5]. The entrapment of one of these two enzymes, in cellulose triacetate membranes, by a procedure developed by us [4,6], avoiding any possible denaturation of the enzyme, was also carried out. Thus, we obtained two new biosensors for urea and creatinine, characterised by a completely different geometry. In this case a cellulose triacetate membrane, containing one of the two * Presented at the 10th Bioelectrochemical Conference (BEC X), Pont-~-Mousson (France), 24-30 September 1~89. ** To whom correspondence should be addressed. 0302-4598/90/$03.50 © 1990 - Elsevier Sequoia S.A.