A NEW METHOD FOR ENZYME MEMBRANE PREPARATION BASED ON POLYURETHANE TECHNOLOGY - ELECTRODE MODIFICATION FOR SENSOR DEVELOPMENT

The new method developed for enzyme membrane preparation is based on cross-linking poly(vinyl alcohol) (PVAL) with triisocyanate (TIC) in the presence of enzyme. Dimethylsulfoxide (DMSO) was the only solvent found to dissolve PVAL, TIC and enzyme at room temperature, without completely denaturing the latter. The rate of gelation to form the desired network membrane can be controlled by the amount of solvent used. All the enzymes tested (alkaline phosphatase and alcohol, cholesterol and glucose oxidases) dissolved in DMSO and retained sufficient activity for use in electrochemical sensors. Membranes were formed on both graphite and platinized graphite electrodes. The resulting prototype sensors were examined with regard to feasibility of preparation, adhesion of the gels to the electrode surfaces, swelling properties of the gels in DMSO and aqueous buffers, and their electrochemical properties.