Synthesis,Assembly And Biomedical Applications Of Magnetic Core-Shell Nanoparticles

Controlled synthesis and assembly of nanometer magnetic materials is currently the subject of intense research work due to their novel properties, which could have promising applications, such as high-density magnetic recording media, sensors, catalysts, biotechnology, and magneto-optical devices and so on. In particular, it has been attracted much attentions in the fields of biotechnology and high-density magnetic recording media that the use of the nanometer magnetic materials. Therefore, scientists made abroad interests on the study of new nanometer magnetic materials and nanometer magnetic composite materials.In recent years there has been increased interest in coating surfaces of nanoparticles with a thin shell material for various electronic and biomedical applications. Methods of ATRP to coat a polymer shell with a controllable thickness on magnetic nanoparticles may aid in the development of ordered arrays of magnetic nanoparticles. The formation of polymeric shells is essential for biomedical applications of magnetic nanoparticles such as magnetic targeting drug delivery and magnetic resonance imaging (MRI) contrast enhancement.In this thesis, we prepared the core-shell magnetic nanoparticles, and fabrication of multifunctional nanoparticles assemblies on polystyrene particles. The core-shell magnetic nanoparticles also developed in biomedical applications films which is assembly with DNA.In Chapter Two, we prepared multifunctional magnetic composite particles. We describe the synthesis of bi-functional nanoparticles with super-paramagnetic Fe3O4 nanoparticle core and CdS nanoparticles shell by surface-initiated atom transfer radical polymerization. We imported two functional monomer---cadmium dimethacrylate Cd(MA)2 and methylmethacrylate, during the polymerization of surface-initiated ATRP from initiator modified Fe3O4 nanoparticle surface. The magnetic nanocomposites have both the properties of magnetic nanoparticles and the imported material, which extend the using fields of magnetic materials. These works would supply new methods for preparing functional magnetic nanocomposites.In Chapter Three, we prepared amphibious by surface-initiated atom transfer radical polymerization, the magnetic nanopaticles can be adsorbed with the carboxyl on the surface of PS latex microspheres by self-assembly approach, and the nanoparticles as a medium could adsorbed with other negative functional nanoparticles such as CdTe Au or Pd to form multifunctional composite core-shell particles.We also used the magnetic nanoparticles assembly with DNA, these magnetic nanomaterials have become increasingly important both technologically and for fundamental studies due to their extensive applications in the fields of biology, medicine and the tunable anisotropic interaction they exhibit.In summary, based on the different using of magnetic materials, we prepared we prepared the core-shell magnetic nanoparticles by ATRP, and fabrication of multifunctional nanoparticles assemblies on polystyrene particles, and achieved the self-assembly of magnetic nanoparticles with DNA. All of these works would establish the groundwork of the using of nanometer magnetic materials in the fields of bioscience and high density magnetic recording.