| The magnetic polymer microspheres with perfect sphericity, smooth surface,homogeneous particles size distribution and well magnetic properties were prepared byemulsion polymerization of styrene （St）, acrylic acid （AA） and starch in the presence of Fe3O4magnetic nano-particles. The drug release properties in vitro were investigated using themagnetic microspheres as drug carrier.Firstly, the superparamagnetic Fe3O4nano-particles were successfully prepared withoutinert gas protection by chemical co-precipitation, which were modified with oleic acid atlow-temperature and were hydrophobic. The effects of the molar ratio, reaction pH value,reaction temperature, curing temperature, oleic acid dosage and washing styles on themorphology, yield and magnetic property of Fe3O4nano-particles were discussed. Themorphology, structure and properties of magnetic nano-particles were characterized by TEM,XRD, FT-IR and VSM, respectively. The results showed that the Fe3O4nano-particles havehigh purity and the average diameter of10nm when the molar ratio of Fe2+and Fe3+was1:1,the pH11, the reaction temperature30℃and the curing temperature60℃.The magneticFe3O4nano-particles modified with oleic acid were lipophilic, superparamagnetic,monodisperse, and averaged size is1416nm.Secondly, the polystyrene composite microspheres were prepared by emulsionpolymerization of styrene, acrylic acid and soluble starch. The optimum system was obtainedthrough the single factor experiment and the following orthogonal experiments, which were0.2g of initiator, emulsifier of0.3g,20mL of styrene,1.5mL of acrylic acid,0.4g of starch,450r/min of mixing speed, and80℃of reaction temperature. The morphologies of theprepared polystyrene composite microspheres observed by scanning electron microscopy（SEM） are smooth surface and spherical particles with diameters of about0.25μm. Thepolystyrene composite microspheres with hydroxy groups and carboxyl groups wereconfirmed through infrared spectrum analysis.Finally, the Fe3O4/PS magnetic polymer microspheres were synthesized and optimizedaccording to the preparation factors of Fe3O4nano-particles and polystyrene compositemicrospheres. The optimum dosages of materials were of2mL of divinylbenzene,0.675g ofFe3O4magnetic particles,10mL of St,2mL of AA and0.4g of Starch. The morphology, structure and properties of magnetic polymer microspheres prepared were characterized viaTEM, FT-IR, XRD, TG-DTA, VSM and UV, respectively. The results showed that themagnetic polymer microspheres were even surface, perfect sphericity with obvious core-shellstructure and about188nm in size. The magnetic polymer microspheres prepared containactive hydroxy groups and carboxyl groups. Moreover, the magnetic polymer microspheresprepared exhibit superparamagnetism, excellent thermal stability, weak acids and strong alkaliresistance. The magnetic polymer microspheres loaded drug were prepared withacetylsalicylic acid as a model medicine and the magneic polymer microspheres as a carrier.The drug release properties in vitro of magnetic polymer microspheres loaded drug werepreliminarily investigated at different temperature, pH value and the applied magnetic field.The results showed that the drug release rate increase with improving system temperature, pHvalue and the action of applied magnetic field. However, the cumulative release amounts werelow and the drug release performances of magnetic polymer microspheres loaded drug need tobe improved. |
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