Synthesis Of Multi-shell Magnetic Polymer Microspheres And Their Surface Modification

Magnetic polymer microspheres, combined by inorganic magnetic particles andorganic polymer materials, are new type materials. We can obtain surface functionalizedmagnetic microspheres via surface modification reactions, these surface functionalizedmagnetic microspheres possess a great many important applications such as celldissociation, targeted drug delivery, immobilized enzyme and cell marking.In this study, we describe the synthesis of surface functionalized magneticmicrospheres with multi-shell structure. The specifics steps are: first, we preparedpolystyrene particles by dispersion polymerization and cladded a bed SiO₂on them, thenwe prepared Fe₃O₄by thermal decomposition process and modified them toethanol-soluble magnetofluid, at last, incorporated magnetite nanoparticles into a silicashell around preformed PSt/SiO₂core/shell microspheres, at this time the outermost silicashell had linked with amino group and for further applications, via the reaction between–NH2and–COOH, we used PEG diacid to obtain carboxyl functionalized microspheres.Optical microscope and scanning electron microscopy show that the microspheres aremonodisperse with the average diameter about2um; vibrating sample magnetometerindicates that the synthesized sample with amino-group on the surface exhibitssuperparamagnetism with the saturation magnetization7emu/g; thermogravimetry revealsthat the microspheres are thermally stable when temperature is below300℃and theFe₃O₄content is20.68%；last, fluorescence microscope shows that the microspheres weobtain can all link with fluorescence and the luminescent intensity do not have the certainrelationship with the concentration of streptavidin and antibody, it indicates that themicrospheres we obtain possess bioactivity, they can successfully conjugate withstreptavidin and antibody.