A new immobilized glucose oxidase using SiO2 nanoparticles as carrier

Using SiO2 nanoparticles as a carrier, a novel immobilized glucose oxidase (GOD) (EC1.1.3.4) was prepared via crosslinking with glutaraldehyde (GA). The optimal immobilization condition was achieved with 1% (v/v) GA, 2% (v/v)3-aminopropiltrietoxysilane (APTS), 2.5 mg GOD (in 34 mg carrier) and solution pH of 6.5. The immobilized GOD showed maximal catalytic activity at pH 7.0 and 60 degrees C, and more than 85% of initial activity at the temperature from 20 degrees C to 80 degrees C. After immobilization, the enzyme exhibited improved thermal, storage and operation stability. The immobilized GOD still maintained 85% of its initial activity after the incubation at 45 degrees C for 360 min, whereas free enzyme had only 23% of initial activity after the same incubation. After kept at 4 degrees C for 30 days, the immobilized and free enzyme retained 84% and 60% of initial activity, respectively. The immobilized GOD also preserved 87% of its initial activity after six consecutive operations. (C) 2011 Elsevier B.V. All rights reserved.