Preparation Of Polystyrene Nanospheres And Functional Composite Nanospheres

Magnetic polymer nanospheres and quantum dots were widely used in cancer treatment and fluorescent markers. When the magnetic polymer nanospheres implanted in animals, the stranded situation in different tissues is difficult to determine, it just can be detected by nuclear magnetic resonance（NMR）. Although NMR imaging has the advantages of high resolution, no tissue depth limit, but it also has the disadvantages of low sensitivity, high cost, long imaging time and others, if we can graft some fluorescent marker on nanospheres, the transfer processes in body of magnetic polymer nanospheres can be tested in vivo. It also can greatly avoide sacrificed animals, and reduce the number of experimental samples, so the study period can be shorted, the research costs can be reducing. In this paper, we do the following research for fluorescent-magnetic nanospheres.The nanospheres were prepared through miniemulsion polymerization, employing styrene as monomer, acrylic acid as functional monomer. Zeta potential and laser particle size instrument, TEM, FT-IR spectrophotometry, conductivity meter and thermogravimetric analyzer（TGA） were used to characterize the particle size, morphology and structure, contents of carboxyl, thermal properties of the nanospheres. The results showed that particle size ranged from 50⁷0 nm. With the increase of the addition amount of acrylic acid, the area of infrared characteristic peak increased, the particle size became smaller. The TGA curve also reflected the characteristics of the thermal decomposition of acrylic acid. These results indicated that carboxyl were successfully synthesized in polystyrene nanospheres, and the carboxyl content can be adjusted by controlling the monomer ratio.A coprecipitation method was used to prepare the Fe₃O₄ nanoparticles with less than 10 nm, and its surface was coated with oleic acid. FT-IR spectrophotometry, Transmission electron microscopy（TEM） and X-ray diffraction（XRD） were used to characterize the morphology and structure of the Fe₃O₄ nanoparticles. The magnetic properties and solubility of the Fe₃O₄ nanoparticles were investigated. And the effect of adding method of NH3·H2O on the yield and morphology of Fe₃O₄ nanocrystals was discussed. The results showed that the inverse spinel Fe₃O₄ nanocrystals were coated by oleic acid and could be dissolved in a variety of organic solvents. The magnetic hysteresis loop showed that the Fe₃O₄ nanocrystals were superparamagnetic material. The growth and yield of Fe₃O₄ nanocrystals were significantly influenced by modifying the adding method of NH3·H2O.The nanospheres which particle size in 50⁷0 nm were prepared through miniemulsion polymerization, employing styrene as monomer, acrylic acid as functional monomer and Fe₃O₄ magnetic fluids. Then the microspheres dispersed in Zn（NO3）2 solution, after sufficient adsorption of Zn2+, it dispersed into diethanolamine solutionin, the ZnO QDs were prepared on surface of the nanospheres in situ growth method.Through the analysis of the dispersion, natural sedimentation rate and magnetic response, PS-Fe₃O₄ dispersion in water is better than PS-Fe₃O₄-ZnO, magnetic response is good; TEM results reflected that Fe₃O₄ is coated by PS, and layers of particles formed on the surface, through fluorescence micrograph and fluorescence spectra analysis can determine the PS-Fe₃O₄ are coated by ZnO quantum dots.In summary, the biosafety fluorescent-magnetic nanospheres were successfully prepared in this paper, and the nanospheres have a good magnetic and fluorescence properties. This paper laid a solid foundation for prepared fluorescent magnetic nanospheres which have higher magnetic content and higher luminous intensity.