Synthesis of Highly ordered Large Size Mesoporous Silica and Effect of Stabilization as Enzyme Supports in Organic Solvent

FSM 16, MCM 41 and SBA 15 types of hexagonal mesoporous silica with a highly ordered 2 dimensional structure were synthesized by using different silicon sources and surfactants. In the 2 dimensional silicate framework, pore size can be uniformly controlled by the combined use of the surfactants having different alkyl chain lengths and the swelling agents(triisopropyl benzene). The pore diameter of FSM 16 and MCM 41 can be expanded to be 10 nm, SBA 15 to be 15 nm. The crystal regularity was decreased with the increase of the pore diameter. In FSM 16 derived from kanemite(silicon source) and MCM 41 from water glass, their anionic characteristics on the pore wall may be stronger than those of SBA 15 derived from oligomeric tetramethoxysilane(TMOS). We have successfully used FSM 16 and MCM 41 to immobilize the enzyme having cationic residues below isoelectric point. The level of adsorption of enzymes in FSM 16 and MCM 41 was relatively high, but was low in SBA 15 support. The mechanism of enzyme to be adsorbed in mesoporous silica was suggested to be the ionic interactions. In aqueous solutions, horseradish peroxidase(HTP) was immobilized in FSM 16 with 8.9 nm mesopores and the highest loading amount(183 mg/mg FSM) was obtained, but for the FSM 16 of pore diameter 30 nm only an amount of 28 mg/mg FSM was obtained. The catalytic activity in the organic solvent was high when HRP was immobilized in FSM 16 and MCM 41, but it was low in case of SBA 15.