ENZYME ELECTRODES: FROM THE SELF-CONTAINED PROBE TO THE DESIGN OF AN AUTOMATIC ANALYZER

Abstract

Analytical potentialities of collagen films used in our group for enzyme immobilization werefirst tested for the design of a self-contained glucose electrode based on hydrogen peroxidedetection . For this purpose, an enzymic disc of the appropriate size was cutout of the bioactive membrane and tightly pressed against a platinum anode with a screwed cap . This biosensor wascharacterized by a very low detection limit , 10-8 M, a wide linear calibration range ‚107 to 2.103 M, and the possibility to perform several thousands of assays with the samedisc. One of the main bottlenecks for practical applications of enzyme electrodes in industry is the detection and subtraction of interferences. A differential two-electrode system has been set up and a microprocessor-based analyzer "Glucoprocesseur"® derived from the above mentioned work was designed and marketed by Solea-Tacussel, France. Results are displayed 30 seconds after injections which can be performed at 90-secondintervals using unpretreated samples. injection is manual but filling and emptying the measurementcell are automatic, Excellent results were obtained in foodstuffs with this analyzer. We proposed recently a very simple andfast procedure to prepare cheaply andreliably new enzymic membranes by using a commercially available preactivated membrane : the Pall Biodyne™ ImmunoAffinity membrane for biotechnological applications. Enzyme immobilization occurs spontaneously in a few minutes. Depending on the oxidase used , different analytes could be monitored with the analyzer equipped with such membranes . Anyone who needsto prepare his own enzymic membrane with non-commercially available enzymes maydo soeasily and in ouropinion, this may make such biosensors more widely used in industrial processes.