| Summary: | 碩士 === 國立雲林科技大學 === 化學工程與材料工程系 === 103 === Application of immobilized enzymes in various biotechnological processes could not only promote catalytic efficiency, but also reduce production cost.Silica particle has been regarded as a promising carrier due toits easy preparation and high surface area with versatile surface functionalization. Inthisstudy, we firstly synthesized silica (SiO2) and amino-functionalized silica (SiO2-NH2) particles by sol-gel technique. Then three kinds of carboxyl-functionalized silica particles (SiO2-COOHs) were prepared by surface modification using N-(phosphonomethyl) iminodiacetic acid, succinic anhydride (SA) and polyacrylic acid.Finally, lipase was covalently immobilized onto the carriers via carbodiimide. SEM images show that allSiO2particles are uniformly spherical with about 70~250 nm in diameter.FTIR results confirm successful surface carboxyl functionalization. SiO2-SAwas selected as the support for covalently immobilized lipase, due to its higher immobilized efficiency.The optimum pH and temperature for both free and immobilized lipase activities were found to be 7.0 and 30oC, respectively. The immobilization of lipase onto SiO2 remarkably increases its stability at higher temperature and shows better pH tolerance. Moreover, the Michaelis constant (Km) of lipase after immobilization slightly increases from 0.048 (free) to 0.059 mg/mL (covalent immobilization).
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