| With the research development in field of biotechnology, the enzyme production and application also increasingly widespread, new technology of enzymes application, including immobilized enzyme technology which is an important research field. Enzyme immobilization offers advantages over free enzymes in choice of batch or stability, continuous processes, reusability of catalysts, controlled product purity and process effect, ease of enzyme survival in the reaction mixture and adaptability to various environment designs. One important factor for enzyme immobilization is the support material. Compared with other materials, porous materials possess the unique advantages such as high surface area, porous network, easy to carry out chemical modification to make porous materials in adsorption, separation, enzyme immobilization, which make porous materials have potential applications in biomedical field.In this paper, variety of macroporous materials designed for the purpose have been introduced and discussed which were synthesized by inverse suspension polymerization approach. Preparation of new kind of support materials through combining macroporous materials technology and bio-immobilized technology offer the immobilized enzyme a biofriendly microenvironment and improved activity. The relative experiments and results are summarized as follow:1. Macroporous Polyacrylamide (PAM) microspheres were synthesized by inverse suspension polymerization approach in the presence of toluene as porogenic agents. In which the continuous phase was cyclohexane, dispersing agent was N,N'-methylene-bis-acrylamide, iniator was ammonium persulfate, monomer wad acrylamide and N,N-dimethylformamide was porogen. The relationship with the particle size of the resin, stability of system and the amount of dispersing agent, iniator, porogen and stirring speed were studied. The optimum reaction conditions were determined. Various types of measurements, such as scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), Laser Particle Size Distribution Analyzer, N2 absorption analysis (BET) and mercury intrusion porosimetry were conducted in chanracterizing PAM-co-PNIPAM particles. The results indicated that the obtained PAM-co-PNIPAM microspheres are perfect microspheres with porous structures which make the PAM-co-PNIPAM microspheres possess large surface area and high water absorption.2. Pectinase was immobilized onto the thermo-responsive macroporous polyacrylamide (PAM) microspheres synthesized via an inverse suspension polymerization approach, resulting in 81.7% immobilization yield. The stability of the macroporous Poly (acrylamide-co-N-isopropylacrylamide) (PAM-co-PNIPAM) microspheres with certain lower critical solution temperature (LCST) were synthesized by inverse suspension polymerization approach in the presence of toluene/carbon tetrachloride as porogenic agents, which has a large surface area, is not impeded by the adsorbed proteins despite the fact that up to 296.3 mg of enzyme is immobilized per gram of the carrier particles. The immobilized enzyme retainedmore than 75% of its initial activity over 30 days, and the optimum temperature/pH also increased to the range of 50-60℃/3.0-5.0. The immobilized enzyme also exhibited great operational stability, and more than 75% residual activity was observed after 10 batch reactions.3. Pectinase was immobilized onto the thermo-responsive macroporous polyacrylamide (PAM) microspheres synthesized via an inverse suspension polymerization approach, resulting in 81.7% immobilization yield. The stability of the macroporous PAM support, which has a large surface area, is not impeded by the adsorbed proteins despite the fact that up to 322.6 mg of enzyme is immobilized per gram of the carrier particles. The optimum temperature/pH also increased to the range of 50-60℃/3.0-5.0 and the immobilized enzyme retained nearly 80% of its initial activity over 30 days. The immobilized enzyme also exhibited great operational stability, and more than 68% residual activity was observed after 20 batch reactions. Moreover, the LCST of the PAM-co-PNIPAM support can be switched on or off by a small change of solution temperature. By means of this, the immobilized pectinase could be recovered and shows durable activity at the process of recycle. |
PDF Full Text Request