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Preparation of Magnetic Fe3O4 Nanoparticles and the Study of Their Relaxation Properties

Author: WangLiSha
Tutor: GuHongChen
School: Shanghai Jiaotong University
Course: Materials Science
Keywords: Fe3O4 Superparamagnetic nanoparticles Co-precipitation method Magnetization curve Magnetic resonance imaging Relaxation time
CLC: TB383.1
Type: Master's thesis
Year: 2011
Downloads: 166
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Abstract


The the magnetic Fe 3 O 4 nano-particles due to their unique physical and chemical properties, is widely used in magnetic transfection, protein purification, magnetic resonance imaging and other biomedical research in the field. Among them, MRI is more and more attention. We usually relaxation rate of water dispersion characterization of Fe 3 O 4 nanoparticles in magnetic resonance imaging contrast enhanced efficiency. The relaxation rate and particle size of nano-materials are closely related. Therefore, the controlled preparation of nanoparticles application of magnetic resonance imaging is important. First article citric acid surface modifier, co-precipitation prepared magnetic Fe 3 O 4 nanoparticles to obtain a stable aqueous phase Fe 3 O 4 nano-particle dispersion liquid, and the characterization of its various features. Added in an amount of citric acid in the reaction process in this study based on the particle size. The results showed that with the increase in the amount of citric acid was added, the particle size of the nanoparticles is reduced, per unit mass of the particle surfaces coated with the amount of citric acid is increased, the ratio of the saturation magnetization is reduced. We assume that the nanoparticles in accordance with the log-normal volume distribution, a core-shell structure of the model, based on the Langevin equation fitting μ0M-μ0H curve fitting parameters for the different size of the citric acid-modified nanoparticles. The particle diameter calculated by fitting the data with the experimental data measured away from small, to prove that it is feasible to calculate the different particle size of the nanoparticles according to the magnetization curve, we assume that the nanoparticles lognormal volume distribution is believed to be reliable, nanoparticles is a core-shell structure. Relaxation meter for measuring the relaxation time, while ScS iron concentration, the waiting time for relaxation performance found with increasing iron concentration, the longitudinal relaxation time and the transverse relaxation time are reduced, and the relaxation time detecting the dependence of the waiting time does not exist. With the gradual reduction of nano-particle, the longitudinal relaxation rate and the transverse relaxation rates are significantly reduced, that citric small molecule may be the synthesis of magnetic nanoparticles contrast agent effective regulatory molecules. Finally, we measured the oleic acid coated the Fe 3 O 4 nano-particles for the four magnetic nanoparticles relaxation starting material synthesis performance. Study particle size, the thickness of the surface modification layer, the material structure on the relaxation properties of the material. Found that the thickness of the surface modification layer, the relaxation time decreases with increasing particle size, the relaxation rate increase; particle size is the same, the thicker the surface-modified layer, the smaller the relaxation rate; under the same conditions as the thickness of the particle size, surface modification layer, the mesoporous structure of the nano-particles greater relaxation rate.

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