Silica Magnetic Composite Microspheres

Magnetic materiers as nanoscale or microscale, which have unique physical and chemical properties, have been extensively exploited of biomedicine such as drug delivery, cancer treatment, biosensor, magnetic resonance imaging. Silica magnetic composite microspheres have been demonstrated to have a wide application in biomedical because of its superparamagnetic, reliable chemical stability, biocompatibility, and reactivity with various coupling agents. Recently, scientists have been interested in the silica magnetic composite microspheres synthesize. Sol-gel process, reversed microemulsion, aerosol pyrolysis, ultrasonication and modeling methods have been reported. Herein three different methods was optimaized to synthesize silica magnetic composite microspheres:sol-gel process, modified Stober and reverse microemulsion.1:A sol-gel method was carried out to prepared core-shell silica magnetic composite microspheres in the alcohol-water solution at room temperature by hydrolysising TEOS under the alkaline conditions. The reaction condition was optimized to discuss the effects of the silica reaction conditions on magnetic composite microspheres. The morphology,microstructure and properties of the silica magnetic composite microspheres were characterized by TEM,FT-IR,LPSA,X-RD,VSM. The results show that the prepared spheres with core-shell structure, superparamagnetic at room temperature. And the size is in the rang of 30～60nm.2:Modified Stober method was used to obtain the silica magnetic composite microspheres in toluene/alcohol/water mixture, using the Fe3O4 as the cores with the hydrolysis of TEOS under the catalysis of ammonium. The morphology,microstructure and properties of the silica magnetic composite microspheres were characterized by TEM,FT-IR,X-RD VSM. The results show that the prepared spheres with core-shell structure, superparamagnetic at room temperature. And the size is 200 nm.3:The reverse microemulsion was applied as a microreactor to prepare the silica magnetic composite microspheres by using cyclohexane as the oil phase and Brij35 as surfactant. The morphology,microstructure and properties of the silica magnetic composite microspheres were characterized by TEM,FT-IR,X-RD,VSM. The results show that the prepared spheres with core-shell structure, superparamagnetic at room temperature. And the size is 50 nm.Silica magnetic composite microspheres were synthesized by three different methods. They have different morphology,microstructure and properties. The silica magnetic composite microspheres make up of magnetite and silica showing superparamagnetics at room temperature. The obtained silica magnetic composite microspheres have definite structure and good properties, which make them be applied in biomedical field.