The Preparation And Application Of Dye-attached Magnetic Microspheres Using Spacer Arms

Considerable attentions have been focused on magnetic polymer microspheres, due to their remarkable properties. Such as, small particle size, large specific surface, good dispersion, super paramagnetic, a simple and rapid magnetic separation and so forth. Thanks to the special nature of magnetic polymer microspheres, researchers had took advantage of it and greatly promote it to be used in cell separation, targeted drug delivery, enzyme immobilization, protein separation and other areas. The main contents of this paper are listed as below.(1) Using methyl methacrylate as monomer in the presence of oleic acid coated Fe3O4, poly(methyl methacrylate)(PMMA) magnetic microspheres in the size range of 10 to 25 ?m were successfully prepared by a suspension polymerization. Then the magnetic microspheres with plenty of carboxyl groups were successfully obtained via the hydrolysis of ester group into carboxyl group.(2) To avoid steric effects, ethylenediamine(EDA), poly(ethylene glycol) 400(PEG 400) and poly(vinyl alcohol)(PVA) were utilized as spacer arms to bind to the microspheres, the Cibacron Blue dye ligand was then covalently coupled with aminated or hydroxylated microspheres via a nucleophilic reaction. A series of CB-attached magnetic microspheres(CB-EDA-PMMA?CB-PVA-PMMA?CB-PEG 400-PMMA) were prepared.(3) The influence of BSA immobilized on the CB functional magnetic microspheres was investigated and the results indicated that the CB content, BSA concentration, medium pH, and ionic strength had significant effect on the adsorption of BSA on microspheres. The adsorption–elution cycle was repeated using the same microspheres; the results indicated that the CB functional magnetic microspheres could be reused without significant decreases in their adsorption capacities.(4) Furthermore, the CB functional magnetic microspheres were used to immobilize Candida rugosa lipase. It is found that the lipase activity was decreased with the increase of CB content. When the amounts of lipase is 3 mg, pH = 7.0, the highest specific activity and activity recovery were observed. Finally, the optimum temperature and pH stability of immobilized enzyme were also studied. Compared with the free lipase, the optimal temperature and pH stability of immobilized lipase were enhanced.