Tunable Synthesis Of Magnetic Iron Oxide Nanoparticles And The Related Structures

The research background of this paper is based on the preparation of magnetic materials for tumour therapy by magnetic fluid hyperthermia (MFH). The materials in this application are required to be biocompatible, of which the Fe3O4,γ-Fe2O3 with low biotoxicity are rational candidates. At the same time the heating ability of the iron oxide nanoparticles is due to the synthesis route and is directly related with the efficiency of the therapy. So a tunable synthesis route of iron oxide nanoparticles is necessary. Further, a research of the tunable synthesis and the development of related iron oxide nanostructures are of importance to the research of MFH therapy.Firstly, aeration bubbling oxidization of acidified Fe3O4 nanoparticles suspension prepared with coprecipitation method at 90 oC is used to synthesis γ-Fe2O3 nanoparticles, which nearly have the same heating ability with the Fe3O4 ones. After this, the effects of initial experimental conditions, such as the ratio of Fe3+,Fe2+,reaction time and reaction volume, on the final products are studied. The results show that the size can be tuned in 14 nm-30 nm. Subsequently the heating ability of the Fe3O4 nanoparticles can be altered due to the size differences. Based on these results stable water-dispersed magnetic fluid is obtained with glutamic acid modifying 17 nm γ-Fe2O3 nanoparticles and can be used for the MFH tumor therapy.Secondly, purified oleic acid is used to modify the Fe3O4 nanoparticles by coprecipitation method and γ-Fe2O3 by aeration bubbling oxidization method. Magnetic fluid of nonpolar organic dispersant is obtained and the chelating structures of oleic acid on iron oxide surface are confirmed to be bidentate and oleate-bridge-biodentate configurations. At the same time, ionic magnetic fluid is prepared by modifying 7 nm Fe3O4 nanoparticles produced by reduction coprecipitation method. Fe3O4@SiO2 core-shell nanostructures are obtained by the conventional St?ber polycondensation with dilute silicate solution treatment directly in ethanol. Furthermore the thickness of the silica shell and the stability increase with the amount of TEOS. As to 18 nm Fe3O4 nanoparticles, magnetic dipole chains encapsulated with silica are obtained compared with the cluster aggregates of 7 nm Fe3O4 core shell structures. The difference in aggregate forms is due to the different magnetic dipole interactions according to the point dipoles model. Finally, magnetic fields of different strengths are imposed on the process of oxidizing the Fe(OH)2 gels by KNO3. Discrete Fe3O4 particles are produced in zero field and Fe3O4 particle chains are obtained with field imposed. The average particle diameters, the chain lengths and the morphology can be tuned by the field strength. Furthermore, the random, ordered one-dimensional (1D) and fractal patterns are deposited on silicon wafer and slide substrates from the magnetic 1D Fe3O4 particle chains under different conditions. The ordered 1D pattern shows a uniaxial anisotropy originating from the cooperative effects of shape anisotropy and the multi-domain of the each Fe3O4 particle.