alpha-Amylase immobilization capacities of mesoporous silicas with different morphologies and surface properties

作者：Hisamatsu Kanako; Shiomi Toru; Matsuura Shun ichi; Nara Takayuki Y; Tsunoda Tatsuo^*; Mizukami Fujio; Sakaguchi Kengo

来源：Journal of Porous Materials, 2012, 19(1): 95-102.

DOI：10.1007/s10934-011-9452-2

• Mesoporous silica
• Protein encapsulation
• Immobilized enzyme
• alpha-amylase

alpha-Amylase was encapsulated in several mesoporous materials (folded sheet mesoporous silica (FSM), cubic mesoporous silica (KIT-6), and two-dimensional hexagonal mesoporous silica (SBA-15)) that differed morphologically in terms of particle shape, pore size, and pore structure. The encapsulation capacity and thermal stability of encapsulated alpha-amylase were examined. The amount of alpha-amylase encapsulated increased with increasing pore size in the following order: SBA-15 %26lt; KIT-6 %26lt; FSM. Nitrogen adsorption experiments were performed before and after alpha-amylase encapsulation in mesoporous silicas with pore sizes larger than the size of a-amylase, confirming that alpha-amylase was encapsulated in the pores. Among mesoporous silicas with similar pore sizes, FSM was found to have the highest capacity for alpha-amylase encapsulation both per weight and per surface area of silica. Furthermore, alpha-amylase encapsulated in FSM demonstrated high thermal stability at 90 degrees C relative to the thermal stability of free alpha-amylase or free alpha-amylase encapsulated in other mesoporous silicas. Zeta potential measurements showed that the FSM surface had an isoelectric point that was lower than that of other mesoporous silicas, and hydrophilicity measurements showed that its surface was more hydrophilic. The surface properties of FSM contributed to the high thermal stability of the alpha-amylase encapsulated within the pores.

• 出版日期2012-2