Enzyme Immobilized in Mesoporous Silica Nanoparticles: Effect of Confinement on Orientation, Conformation, and Catalytic Activity
| Autor: | Kun-Che Kao, 高琨哲 |
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| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 In this dissertation, there are two topics mainly including the syntheses of pore-expanded mesoporous silica nanomaterials and the fundamental study of enzyme immobilized in mesoporous silica nanoparticles. In chapter 3, for the purposes of fast mass transport and high diffusion rate to immobilize large bio-molecules, mesoporous silica nanoparticles (MSNs) with particle size below 100 nm and pore size large than 6.0 nm were synthesized. We used alkanes as pore-expanded reagents to synthesize pore-expanded MSNs and several synthetic factors were systematically studied. Eventually, we can obtain pore-expanded MSNs with a pore size up to 6.0 nm and simultaneously maintained well-ordered mesostructures. In addition, in the same synthetic solution of pore expanded MSNs, mesoporous silica thin films (MSTFs) with vertical nanochannels could be synthesized on silicon wafers. MSTFs not only had well-ordered pore structures with pore size up to 5 – 6 nm, but the nanochannels were perpendicular to the silicon substrates. The synthetic mechanisms of vertical MSTF were investigated. Alkane molecules in the synthetic solution played an important role to construct the vertical nanochannels of MSTFs. Without the addition of alkane, the nanochannels of MSTFs were randomly oriented. Furthermore, concentration of ammonia solution could control the film thickness based on a nucleation and growth mechanism. Through a series of investigation, we finally could fabricate a MSTF with large scale and excellent mesostructure. In chapter 4, pore-expanded MSNs were used to adsorb lysozyme for studying its structural stability in comparison to that on Stӧber silica nanoparticle (SSN). To really study the structure of lysozyme in a confined space, a well-designed desorption strategy were performed. We found that the secondary structures of lysozyme confined in the nanochannels of MSNs were unchanged and the thermal stability was significantly improved. The MSN-lysozyme nano-composites can be reused at least five times. In chapter 5, to study the orientation effect of enzyme inside the nanochannels of mesoporous silica, we modified silica surfaces with different functional groups to attach the model enzyme (cytochrome c) with different binding sites through covalent bonds. From molecular modeling, enzyme showed different orientations in the nanochannels and finally resulted in different enzyme stability and catalytic activity. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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