The mesostructured cellular foams (MCFs) were synthesized in aqueous hydrochloric acid by using dilute Pluronic P123 solutions in the presence of 1,3,5-trimethylbenzene (TMB) as organic cosolvent. And the amino-functionalized MCFs (NH₂-MCFs) were prepared from primary MCFs by post-synthesis method using 3-aminopropyl-trimethoxysilane (APTMS) as the chemical modifier. The SEM and TEM observations showed the similar morphologies and pore structures of both MCFs and NH₂-MCFs, indicating that the surface modification had little effect on the morphologies and pore structures. Glucose oxidase (GOD) was physically adsorbed on MCFs and NH₂-MCFs at different pH. The maximum immobilized amount of GOD on NH₂-MCFs (487 mg g⁻¹) was much higher than that of MCFs (216 mg g⁻¹) at pH 5.0. The larger loading capacity of NH₂-MCFs suggested that the electrostatic interaction was the dominant force for GOD adsorption. Furthermore, the immobilized GOD exhibited improved thermal and storable stabilities. The GOD immobilized on NH₂-MCFs (NH₂-MCFs-GOD) still maintained 80% of initial activity after incubation at 60°C for 1 h, whereas the free GOD and the GOD immobilized on MCFs (MCFs-GOD) remained only 40% and 60%, respectively. Moreover, after stored at 4°C for 30 days, the free GOD, the MCFs-GOD and the NH₂-MCFs-GOD retained 37%, 52% and 73% of initial activities, respectively. Based on these results, possible mechanisms were also discussed.
Keywords: Amino-functionalization; Enzyme immobilization; Enzyme stability; Glucose oxidase; Mesostructured cellular foams.
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