Preparation And Characterization Of Fe₃O₄-based Magnetic-optical Nanocomposites

Magnetic nanocomposites with diversified structure and specific functionhave shown a broad space for development and bright application prospect in manyfields such as biomedicine and materials science. With the rapid development ofmedicine, functional biomaterials based on magnetic nanocomposites have infiltratedtargeted drug therapy, magnetic resonance imaging, cell separation and otherapplication areas. However, biomedical requirements for materials become more andmore strict, and functional magnetic nanocomposites with excellent performance andtraceability have been proved to be a hot topic. Due to fine magnetic responsibilityand biocompatibility, Fe3O4gets top priority among magnetic nanocomposites. ZnSpossesses excellent fluorescence effect and photoluminescence function, whichexhibits huge potential in the magnetism, optics, catalysis as well as other field. Thestudy took Fe3O4and ZnS as research objects, mainly investigated the preparation ofmagnetic Fe3O4with different morphologies, spherical Fe3O4@SiO2@ZnS andcubical Fe3O4@ZnS bifunctional magnetic-optical nanocomposites in synthesis andcharacterization.The results shown solid spherical Fe3O4nanoparticles were prepared by asolvothermal method. These nanoparticles were about200nm with excellentdispersibility and homogeneous morphology. Magnetism data revealed Fe3O4had finemagnetic responsibility without magnetic memory. Cubical Fe3O4nanoparticles weresynthetized by high temperature thermal decomposition method. However, thecrystalline structure of cubical Fe3O4was prone to be influenced by different coolingways. Magnetic responsibility of cubical Fe3O4was the same as the spherical, butsaturation magnetization influenced by size was lower. With spherical Fe3O4as thecore, core-shell structural Fe3O4@SiO2particles could be prepared by sol-gel method.Via the transition of amorphous SiO2layer, bifunctional magnetic-optical Fe3O4@SiO2@ZnS nanocomposites with ZnS layer on Fe3O4@SiO2were obtained bychemical deposit. The results of scanning electron microscopy and transmissionelectron microscopy shown the nanocomposites had a perfect crystal shape with threelayers of core-shell structure. At room temperature, the saturation magnetization ofFe3O4@SiO2@ZnS was22.41emu/g, which was lower than pure Fe3O4. TheFe3O4@SiO2@ZnS nanocomposites emitted obvious blue fluorescence underfluorescence microscope. Cubical Fe3O4could be a magnetic source and coated withZnS particles on its crystallographic plane by epitaxial growth method. Magnetismand crystallization properties of Fe3O4@ZnS were still nice without boad coat. Thenanocomposites had fine magnetic responsibility by vibrating sample magnetometerand strong blue fluorescence under ultraviolet ray. In conclusion, this study was basedon Fe3O4about synthesis and characterization of bifunctional magnetic-opticalnanocomposites, which were expected to provide a reference for application ofbifunctional or multifunctional nanocomposites on biomedicine and so on.