DESIGN OF ENZYME ELECTRODES FOR EXTENDED USE AND STORAGE LIFE

A novel design for an extended-life amperometric enzyme electrode is p resented. The enzyme electrode is fabricated by arranging the three co mponents of a biosensor (an electrode material, an enzyme, and a stabi lizer) on a shapable electroconductive (SEC) film (a polyanion-doped p olypyrrole film) surface by a layer-after-layer approach. First, a thi n and compact Pt black layer is prepared onto the SEC film by the heat -press method. Then, an ultrathin layer of L-lactate oxidase (LOx) is cast on the platinized SEC film, and after drying, a thin gelatin laye r is prepared on the LOx-cast SEC film. Finally, the dried layer assem bly is cross-linked by exposing it to a diluted glutaraldehyde solutio n for a very short time. The performance of the developed sensor is ev aluated by a FIA system at 37 degrees C and under continuous polarizat ion at 0.4 V (vs Ag/AgCl). The developed sensor shows remarkably impro ved performance. The sensor produces a large response current with a w ide linear dynamic range. The sensor shows an extended working life of more than 2 months and a shelf life of about 2 years when it is store d dry in a freezer at -18 degrees C and about 1 year when it is stored at room temperature.