Uricase enzyme types immobilized in poly-N-methylpyrrole for biosensor applications

The suitability of three different enzymes (from porcine liver, from Candida Utilis, from Bacillus Fastidiosus) have been investigated and significant differences have been found. The results indicate, that beside specific activity also the molecular structure of the enzymes must be taken into account by a biosensor application. A new type of electronically-conducting-polymer based enzymatic uric acid biosensor has been investigated. The layout of the substrate, which consists of 4 electrode surfaces (Working1, Working2, Reference, Counter) was prepared by thick film technology on sintered alumina ceramic sheets. Dodecyl sulfate doped poly-N-methyl-pyrrole layer was used for enzyme immobilization. This polymer film can incorporate the enzyme in one step during the process of the electropolymerization. By the applied bipotentiostatic measurement method the two working electrodes (with and without the enzyme) are identically prepared and polarized and the currents in the two circuits are measured simultaneously. The concentration of the uric acid is calculated from the current difference.