Amino-functionalized mesostructured cellular foams as carriers of glucose oxidase

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.