| Summary: | 碩士 === 長庚大學 === 化工與材料工程研究所 === 91 === In this study, the macroporous temperature-sensitive hydrogel membrane was prepared by crosslinking N-isopropylacrylamide (NIPAAm) with N,N-methylene bisacrylamide (MBAAm) in the presence of N-acryloxysuccinimide (NAS) and 2-hydroxyethyl methacrylate (HEMA) on nonwoven support. The carboxyl groups of the membrane were modified by imminodiacetic acid (IDA). Copper ions were added to form Cu2+-IDA cheletes which can be utilized to adsorb histidine-containing proteins by immobilized metal affinity (IMA). In order to enhance the efficiency of protein desorption, temperature sensitivity of the hydrogel membranecan be used . The membrane’s volume can change with the surrounding temperature. It swells below lower critical solution temperature at about 33~34℃ and deswells above the temperature .
25μmole of IDA can be immobilized on 1cm2 membrane at 25℃ and pH 9. In the experiment, we found that the binding constant (Kd) decreased and the maximum capacity (Qmax) increased when the histidine numbers on the surface of proteins increased. This indicated that our support has strong interaction with proteins. However, the molecular weight of proteins also plays an important rule in influencing behavior due to the steric hindrance. At 40℃, the experimental data shows that Kd and Qmax were not influenced by the molecular weight and the number of exposed histidine residues. Judge from the Qmax, we found that the amount of protein adsorption at 4℃ is much greater than that at 40℃. This proves that hydrogel membranes swelling at low temperature can increasingly promote adsorption efficiency. Contrary to above, the high temperature enhances the ability of contraction of hydrogel membrane. The phenomenon increases the possibility of the protein desorption. Otherwise, the reusability of the macroporous temperature-sensitive hydrogel membrane is quite well.
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