| Electromagnetic energy can be converted into heat by magnetic nanoparticles(MNPs) exposed in radio-frequency(RF) field. Magnetic hyperthermia has been known as a clinically therapeutic method utilizing the heat generated by MNPs in RF field. Targeted cancer treatment by magnetic hyperthermia has been one of hot topics in nanomagnetism. Ferrite nanoparticles were chosen to be an ideal candidate for magnetic hyperthermia because of their excellent biocompatibility and high stability against oxidation. But poor heating generation ability of MNPs has seriously hindered their practical applications on clinic treatment. In this thesis, ferrite NPs with different composition and size were synthesized by thermal decomposition method in organic solution. The dependence of particle size and anisotropy on magnetic properties and heating capacity was investigated to improve the heating capability of ferrite MNPs in radio frequency field, and the capability of synthesized MNPs in magnetic hyperthermia was test by biological pre-experiments.. The main content is following:1. Ferrite nanoparticles were synthesized by thermal decomposition method with the controlled component, size and shape. By changing the reducing agent and refluxing condition, Fe3O4 nanoparticles with bigger size(20~40nm) were synthesized by one-step method, which is simpler than classic thermal decomposition method.2. The effect of particle size on heating ability(SAR) of MNPs exposed in RF field was studied. SAR of core-shell compound Mn Fe2O4@Si O2 with 7nm-21 nm core exposed in RF was increased obviously with the core size increased. field NPs were synthesized and then was coated with silica to be water-soluble. The SAR in RF filed(f=400k Hz, H=25k A/m) of Mn Fe2O4@Si O2 nanoparticles with 21 nm core, which can well mono-dispersed in liquid solution, reached 458W/g, that is higher reported value.3. Mn and Co was add in Fe3O4 nanoparticles, of which the anisotropy was modified by changing the ration of Mn to Co. The synthesized method is simpler than that of core-shell nanoparticle. The optimum anisotropy value of difference size nanoparticles with maxim loss in 400 k Hz RF filed ware theoretically calculated. By changing the size and anisotropy,21-nm Mn0.99Co0.01Fe2O4 MNPs were controlled into the criticalregime of ferromagnetism and superparamagnetism and exhibited the SAR as high as 1200 W/g. The nanoparticles can well mono-dispersed in liquid solution after coating Si O2 shell. The magnetic heating induction theory of Carrey was verified by experiment, which can be foundation to design nanoparticles with high SAR.4. The synthesize nanoparticles heating efficiency was tested by biological pre-experiment, PMMA bone cement containing 0.8wt% MNPs can be heated in RF field, whose temperature could be raised to 50-60℃, the dose is lower than reported value 50wt%, so that the potential side effect of nanoparticles in treatment to bone cancer is reduced. Based on that experimetns, anisotropy PMMA bone cement with higher heating capability could be produced by being exposed in magnetic field, and a new way to improve the effect of nano-magnetic bone cement in magnetic hyperthermia was provided. |
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