120th General Meeting of the KCS

Type Poster Presentation
Area Inorganic Chemistry
Room No. Exhibition Hall 2+3
Time 10월 19일 (목요일) 11:00~12:30
Code INOR.P-38
Subject Hollow Mesoporous Silica Capsule with Few Surface Holes: Efficient Immobilization of Enzymes
Authors Ki Jung Kim, In-Hwan Choi, SEONG HUH*
Department of Chemistry, Hankuk University of Foreign Studies, Korea
Abstract Hollow capsular materials with surface holes are attractive for noncovalent encapsulation of native enzymes or proteins for various applications. In this case, hollow capsular materials with few controllable surface holes are ideal for enzyme encapsulation. Once the enzymes are encapsulated into these materials, the enzymes cannot easily leach out from the capsular materials due to the limited number of surface holes. Contrarily, relatively small substrates freely enter through the surface holes and then converted into desired products inside of capsular materials. By this way, effective enzyme immobilization system with high recyclability can be realized. It is not easy to introduce few controllable surface holes for hollow capsular materials. We developed a new method of preparation of hollow mesoporous silica capsule (HMSC) with few controllable surface holes. Nanosized monodisperse polystyrene (PS) beads were coated with mesoporous silica layer by using CTAB and TEOS in basic condition. Calcination of the resulting material produced HMSC with high surface area. Then, thin nonporous silica layer was additionally coated to make the capsular materials completely nonporous. Mild etching of the HMSC with Ca(II) ions in methanolic solution successfully gave HMSC with few surface holes. The final HMSC was simply immersed into aqueous buffer solutions containing proteins or lipase PS for encapsulation of proteins or enzymes. In order to demonstrate the recyclability of encapsulated enzyme, lipase PS-encapsulated HMSC was subject to biocatalytic transesterification of the racemic 1-phenylethanol with isopropenyl acetate for the production of enantiomerically pure 1-phenylethanol. The catalytic reaction could be repeated multiple times without significant loss of activity.
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