Polyelectrolyte stabilized oxidase based biosensors: effect of diethylaminoethyl-dextran on the stabilization of glucose and lactate oxidases into porous conductive carbon

The lifetime and the reproducibility of novel enzyme stabilizing techniques based on polyelectrolyte agents such as diethylamimoethyl-dextran have been studied. Glucose oxidase and lactate oxidase, used as the model enzymes, are stabilized with the cationic polyelectrolyte, and the resulting enzyme-polyelectrolyte complexes are physically adsorbed into a highly porous and conductive carbon electrode for the construction of the biosensors. The amounts of diethylaminoethyl-dextran and enzyme are optimized with respect to sensor's sensitivity and stability. Optimum results were obtained using soaking solutions of 2500 U/ml GOx and 1.0 w/v deae-dextran. Additionally, experiments with lactate oxidase sensors constructed using 200 U/ml LOx and 0.5% w/v deae-dextran solution showed improved operational, and storage stability. The sensor-to-sensor reproducibility was good, the relative standard deviation being less than 5.0%. (C)2000 Elsevier Science B.V. All rights reserved.