Activity of glucose oxidase immobilized onto Fe3+ attached hydroxypropyl methylcellulose films

Hydroxypropyl methylcellulose (HMPC) insoluble films were prepared by 60Co-γ irradiation of 10% (w/w) aqueous solutions of hydroxypropyl methylcellulose. The adsorption of Fe3+ onto HPMC films was studied in the range of pH 3.0–7.0. The effect of initial concentrations of Fe3+ solutions on adsorption capacity was studied in the range of 100–1000 ppm. Maximum adsorption capacity was found as 250 mg Fe3+/g dry HPMC film at pH 5.0. The structure and the morphology of Fe3+-attached HPMC film were evaluated by using FTIR/ATR and SEM–EDX methods. Glucose oxidase (GOX) immobilization on both pristine HPMC and maximum Fe3+-attached HPMC film was investigated in aqueous solutions containing different amount of GOX and at different pHs. Maximum GOX adsorption capacity was found as 500 mg/g Fe3+-attached HPMC film. Residual activity of GOX on pristine HPMC and Fe3+-attached HPMC films was investigated with changing pH. While maximum residual GOX activity was observed at pH 6.0 for free enzyme, it was obtained by HPMC and Fe3+-attached HPMC at pH 7.0. GOX desorption studies were achieved by using pH 6.0 buffer (I = 0.02 M) and 0.1 M EDTA solutions. The long-term stability and activity studies of GOX, which is immobilized onto Fe3+-attached HPMC films are still under our investigation.