Hollow The Preparation Of Magnetic Nanoparticles And Their Sustained Release Behavior Research

At the moment, the hollow nanoparticles and microparticles have made attention over the world since they have potential application in coated, control release, catalysis, separation and many other aspects[1-5] because of their low density, high surfacearea,controllable structure and optical properties. On the other hand, functional composite is also causing people more and more attention because of their application in materials science and biological technology. Among that, magnetic materials as a common functional materials is more in a wide range of applications in biomedical and biotechnology, such as enzyme immobilization, protein and immune determination, the purification of RNA and DNA, cell separation and magnetic targeted drugs [6-9]. So, if magnetic and hollow structure can be combined it will have a better application in the biological. such as targeted drugs.The reason is that not only its magnetic can be used to targeted lacation, but also its hollow or porous structure can be used to drug coated.At present, the methods to prepare magnetic hollow nanocomposites are as follows:(1) template method. polystyrene or silica as templates, on which the magnetic particles were assembled by LBL, then removed the templates, and the hollow magnetic can be obtained. The advantage of this method is the coated layer thickness can be controlled more accurately. The defect is must have template and eventually need to be liminated through high temperature or chemical method, for this, the properties of magnetic microspheres can be influenced;(2) Hydrothermal technique. That is through reaction under high pressure and high temperature with a specific block polymer as templates, this method is simple but it is also need high temperature, high pressure, and selective block polymer;(3) composite emulsion method. That is to get magnetic hollow particles through the forming of double emulsion. The advantage of this method is that the method is simple, the disadvantage is monomer can be choosed very little.We prepared hollow magnetic nanaparticles with excellent magnetic properties through the magnetic material coated by silica, which made up the shortage of the template synthesis method. And we researched their properties and application. The works includes the following respects: 1. Synthesis and properties of micrometer hollow magnetic nanoparticlesPrepared method of polymer microsphere is a simple and controllable, which is a good substrate for preparation of hollow and core-shell composite particles. We prepared micrometer PSt microsphere with dispersion polymerization, synthesized composite particles with interface deposition method, and prepared microsphere with sol-gel method. Finally, hollow magnetic nanoparticles were prepared through calcination of PSt. The composite particles were characterized by SEM, TEM, FT-IR, and VSM, it can be confirmed we prepared hollow magnetic nanoparticles with good dispersion, large surface area and super-paramagnetic.2. Controlled release of pesticides using micrometer magnetic hollow particlesUsing micrometer magnetic hollow particles as carriers and the pesticide Tiger as a model drug, we researched the release behavior, and compared its properties of carrier. We found that magnetic hollow particles as a carrier, drug loading efficiency was60%, controlled-release effect is excellent. Because of its super paramagnetic, micrometer magnetic hollow particles could be recycle through the external magnetic field. The tests of the magnetic stability properties of carrier showed that, magnetic could remain unchanged. It was confined that the silica played a very good protective for magnetite.3. Preparation of hollow magnetic nanoparticles and using for controlled release behavior of CDDP.The size of drug carriers using for human should be less than200nm. The hollow materials prepared by template synthesis method, the size of template played an important role in the particle size. Based on the1research, we synthesized PS nanoparticles, which had an average size of70nm, Fe3O4/PS nanoparticles were prepared by co-precipitation process, SiO2/Fe3O4/PS nanoparticles were prepared with sol-gel method, and hollow magnetic nanoparticles were obtained through calcination, its size was about90nm. Using hollow magnetic nanoparticles as drug carriers and CDDP as the model drug, we researched its release behavior. The results showed that it possessed preferable release properties and environmental stability. So the hollow magnetic nanoparticles are a good drug carriers used for targeted drug delivery system.