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Immobilization Studies on Pepsin and Lipase by the Use of Nanosacale SBA-15

Author SunSiJia
Tutor DiQingZhou;MaYuQin
School Changchun University of Science and Technology
Course Condensed Matter Physics
Keywords mesoporous material SBA-15 pepsin lipase physical adsorption
Type Master's thesis
Year 2013
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In this study. mesoporous material SBA-15was prepared under the strong acidic condition by hydrothermal synthesis. Mesoporous molecular sieve SBA-15surface was separately methylated and phenylated by post-synthesis method. Phenylation mesoporous molecular sieve SBA-15and methylation mesoporous molecular sieve SBA-15were prepared. Then, pepsin and lipase were immobilized on host materials to form host-guest composite materials SBA-15-pepsin, SBA-15-lipase.(CH3-SBA-15)-pepsin and (Ph-SBA-15)-lipase. The effect experiments of ionic intensity for composite materials showed that as the ionic intensity of NaCl gradually increased, it made the amount of enzyme immobilization decreased. Immobilization efficiency of modified composite materials was improved a little. The prepared composite materials were characterized. The frameworks of the prepared materials were remained intact and ordered but the crystalline degrees were decreased by powder X-ray diffraction and Fourier transform infrared spectroscopy. The scanning electron microscopy studies indicated fiber shape characteristic and size dimension of mesoporous molecular sieve SBA-15and immobilized composite materials. The average particle diameter of nanocomposite material SBA-15-pepsin and SBA-15-lipase were338±10nm and337±10nm. respectively. The average particle diameter of nanocomposite material (CH3-SBA-15)-pepsin and (Ph-SBA-15)-lipase were343±10nm and339±10nm. respectively. The low-temperature nitrogen adsorption-desorption experiments showed that the pore size and specific surface area decreased compared with those of host material. This showed that the enzyme immobilization occupied the definite location of the host material, indicating that the enzyme went into the channels of the SBA-15. The studies of luminous spectra and the solid state diffuse reflection absorption spectra suggested that emission spectra of composite material and enzyme nearly consistent. The enzyme has been already successfully immobilized into host materials and the composite materials have the definite character of luminescence and the conformation of immobilized enzyme was not changed. The materials have the potential value in the field of luminescence materials. The catalytic activity test results of lipase showed that activity of immobilized lipase was upgraded compared with that of free lipase. The maximum catalytic activity is87.4U/g. The reusability ratio of the composite materials reached five times, improving the catalytic utilization ratio of enzyme and reducing the industrial cost.

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