Studies Of Macroporous Carriers For Immobilization Of Lipase

Macroporous poly-(glycidyl methacrylate-co-divinylbenzene) carrier(B) containing epoxide group was prepared by bulk polymerization using multiple porogens which consisted of nano-granules of calcium carbonate as solid porogen and the mixture of toluene and heptane as liquid porogen. Results revealed that the carrier, with the porosity of59.82%and specific surface area of29.60m2·g-1, mainly contained two kinds of pores, macro pores (150-400nm, approximately60%) and super pores (2000-8000nm, about14.9%). The preparation conditions were optimized. At the same time, comparisons with carrier A which didn’t contain solid porogen and carrier C which only contained solid porogen using the same method had been made. Because of the presence of the macro pores, immobilization of lipase on carrier B was better than on the other two carriers.The conditions of immobilization of lipase on carrier B were investigated. The best results were achieved with the mass ratio of lipase to carrier, immobilizing temperature and time were1:1,20-25℃and1.5h, respectively. The optimum pH and temperature of immobilized lipase were 8.5and40℃. Activity of immobilized lipase remained94%of the origin after storage at4℃for7days. All the results showed that the thermal stability and operational stability were improved in comparison to free lipase.After the above work, the carriers with different hydrophobic properties were prepared using the same polymerization method and pore-making mode as carrier B. In the water phase, effects of immobilization of lipase on the carriers with relative high hydrophobic properties were more excellent than on the carriers with low hydrophobic properties. Salinity affected the lipase’s adsorption on the carrier with high hydrophobic properties severely. The activity of immobilized lipase could be decreased by28.6%when the salinity was changed from0to1mol·L-1. The optimum effects could be obtained when the immobilizing time and the mass ratio of lipase to carrier were3h and0.8, respectively. While in the organic phase, effects of immobilization of lipase on the carrier with relative high hydrophobic properties were below those on the carrier with low hydrophobic properties.Finally, the synthesis of ball shape porous carrier was preliminary studied. The carrier was prepared by suspension polymerization using styrene as polymeric monomer, divinylbenzene as cross-linking agent, cyclohexanol and lauryl alcohol as porogens. Results showed that pore range in the carrier was below50nm. Under the same condition, activity of immobilized lipase on the carrier was100U·gcarrier-1,which only accounted for12.5%of that on carrier B.