Preparation And Preliminary Study On MRI Of Carboxymethylated Chitosan Magnetic Nanopaticles

Magnetic iron oxide nanoparticle is a kind of powder material, with a diameter ranged of 5-100 nm. Because of its sensitivity to magnetic and humidity, it can be used as high-density of magnetic recording materials, gas humidity sensor and so on. However, it is easy to aggregate for its extreme small size. The application in the biomedical field of magnetic iron oxide nanoparticle is constrained by its poor stability. Superparamagnetic iron oxide (SPIO) is a type of magnetic particle, composed with Fe3O4/γ-Fe2O3 nanoparticle core and polymer coat such as polysaccharides, peptides. While retaining the original characteristics of Fe3O4/γ-Fe2O3, SPIO, which is endued with water-solubility and biocompatibility, can be used in magnetic separation of immune cells, tumor targeting hyperthermia, MRI imaging, targeting drug delivery and drug controlled release.In this dissertation, two parts of research work were carried out, with the purpose of obtaining well distributed superparamagnetic MRI contrast agent for the application of brain diseases and tumor targeted diagnosis.In partⅠ, the subject was the preparation and characterization of carboxymethylated chitosan magnetic nanoparticles(CCMN). As an important component of CCMN, carboxymethylated chitosan was synthesized. The carboxymethylated structure of reaction product was comfirmed by the results of Fourier Transform Iinfrared Spectroscopy (FTIR) and NMR Spectrometer. In adittion, nano magnetic iron oxide was prepared by coprecipitation method. In order to gain the best parameters for preparing nano magnetic iron oxide, different factors which could affect the preparing progress were evaluated. Finally, CCMN were prepared by both two-step and one-step methods. The reaction condition was optimized to obtain product with excellent properties. The morphology, magnetic property, size and zeta potentia of magnetic iron oxide and CCMN were investigated in detail by using Transmission Electronic Microscope (TEM), Vibration Sample Magnetometer(VSM), Zeta potential analysis and laser dynamic scattering. As a result, magnetic iron oxide, which possessed the properties of 5-10 nm in size and 73.64 emu/g saturation magnetization, was obtained at the optimal condition. CCMN with particle size ranged from 15-25 nm and saturation magnetization of 47.55 emu/g was prepared by two-step method, while the result was particle size below 5 nm and saturation magnetization of 4.13 emu/g by one-step method.In partⅡ, the subject was to explore the biomedical application of CCMN such as MRI contrast agent. Therefore, in vitro MRI experiment of CCMN was carried out, Feridex as control sample.The result showed the potential application of CCMN in MRI. Besides, the research of conjugating CCMN with IgG was also carried out. Three conditons proved to be effective: 1)the material ratio was 21.5:100; 2)the reaction time of conjugation was controlled to be 12 hours; 3)25℃was better than any other known temperature.