Preparation and characterization of oxygen generating (OG) hydrogels using γ-ray irradiation crosslinking

Oxygen generating (OG) hydrogels immobilizing glucose oxidase (GOx, EC 1.1.3.4) and peroxidase (PO) (EC 1.11.1.7) were prepared using a ? -ray irradiation polymerization technique, and the properties were examined. In physiological tests of the OG hydrogels ranging from 15 to 70 kGy, GOx or PO showed higher gel contents at 87% for the poly(vinyl alcohol) (PVA) hydrogel and 90% for the poly(vinylpyrrolidone) (PVP) hydrogel. The optimal irradiation conditions affecting the entrapment ratio for preparing the OG hydrogel was 35 kGy for the PVP hydrogel, and both enzymes (GOx, 95% and PO, 89%). Optimal GOx and PO activity of the prepared OG hydrogel occurred at pH 6.0 and 35 oC, and both enzymes showed stable activity under acidic conditions. The optimal glucose condition was 4 mg, which resulted in a maximum oxygen generating yield by the OG hydrogels. When oxygen concentration was compared, the OG hydrogels showed higher oxygen pressure than that of control hydrogels without the GOx and PO enzymes. Moreover, the OG hydrogel continuously converted potassium iodide to iodine in a glucose dosage and time dependant manner for 15 h, producing approximately 0.1 M iodine in 5 h.