Activity and stability of glucose oxidase in molecular films assembled alternately with polyions

Anionic glucose oxidase (GOD) was assembled alternately with polycations poly(ethylenimine) and poly(dimethyldially-ammonium chloride) for molecular film preparation. The enzymatic activity of the films was investigated by sequential redox reaction with glucose, peroxidase and DA67 dye. The enzyme activity of the GOD film was maintained for 14 weeks when stored in buffer and in air at 4 °C. Activity measurement after incubation at elevated temperatures showed that significant deactivation was not observed up to 50 °C, showing that GOD in the film has higher thermostability than native GOD. The pH profile of the GOD activity in the film became broad and shifted towards higher pH than that of native GOD.