Co-immobilization of glucose oxidase and catalase in silica inverse opals for glucose removal from commercial isomaltooligosaccharide

In this work, glucose oxidase (GOD) and catalase (CAT) were co-immobilized on novel silica inverse opals (IO-SiO2) through sol-gel process. The immobilized bi-enzyme system named GOD/CAT@IO-SiO2 was successfully fabricated and characterized. Morphology characterization indicated that GOD/CAT@IO-SiO2 had hierarchical porous structure, and the pore diameter of macroporous and mesoporous were 500 ± 50 nm and 6.8 nm, respectively. The macrospores were connected through windows of 100 ± 30 nm. The results of stability tests indicated that both acid (or base) resistance and thermal tolerance of GOD/CAT@IO-SiO2 were improved. When GOD/CAT@IO-SiO2 was used to remove glucose from commercial isomaltooligosaccharide (IMO), the immobilized bi-enzyme system exhibited the good performance. The removal efficiency of glucose reached up to 98.97% under the conditions of GOD/CAT activity ratio of 1:30, the amount of enzyme of 68.8 mg, reaction time of 9.39 h, reaction temperature of 35.2 °C and pH of 7.05. After reused 6 times, 79.19% of removal efficiency could be still retained. The present work demonstrates that the immobilized bi-enzyme (GOD/CAT@IO-SiO2) is not only a very promising system for glucose removal but also has great potential for applications in production of gluconic acid, preparation of biosensors, enzyme bioreactors, etc.