A Study On Magnetic Resonance Imaging Of Fe3O4 Nanoparticles Modified With A Variety Of Surface Ligands T₁/T₂

Magnetic resonance imaging（MRI）is one of the most important bases in the early diagnosis of primary tumors and metastasis.Because the signal of early tumors is very weak,it is difficult to detect them,so the rational use of contrast media has become the key to early diagnosis of tumors.Ferric oxide nanoparticles have been used as contrast agents in MRI for many years.However,most of the traditional ferric oxide nanoparticles are intercepted by reticuloendothelial tissue because of their large particle size,and their blood circulation time is short,so they can only be used as contrast agents in liver and spleen.Nanoparticles with a diameter of less than 10 nm can effectively avoid a large number of phagocytosis of reticuloendothelial tissue,prolong the blood circulation time,and passively target the tumor site by the high permeability and high retention effect of the tumor.In this paper,a kind of water-soluble thioether polymer ligand was used to synthesize ultra-small water-soluble ferric oxide nanoparticles,and its basic characterization and magnetic resonance imaging effect were studied.Subsequently,the materials were expanded to synthesize ultra-small water-soluble tetra with different surface ligands using other different ligands.The ferric oxide nanoparticles were characterized and studied.The main contents of this paper are as follows:Chapter 1:The principle of NMR imaging,the synthesis method based on ferric oxide nanoparticles,the classification of surface modifiers and the application of biomedicine are briefly introduced.The significance and research content of this paper are also described.Chapter 2:The water-soluble thioether polymer ligand PTMP-PMAA was synthesized.The water-soluble ultrasmall ferric oxide nanoparticles with a diameter of 5 nm were synthesized by coprecipitation method.The results of in vitro solution magnetic resonance imaging showed that the material had good T₁/T₂ bimodal imaging effect.In vivo magnetic resonance imaging experiments The T₁ effect was observed in the liver,kidney and tumor sites.Chapter 3:Two other water-soluble ultra-small ferric oxide nanoparticles were synthesized by using two synthetic polymer ligands as modifiers,and the two materials were characterized and studied.Chapter 4:Three kinds of water-soluble ultra-small nanoparticles were synthesized by using three kinds of bio-natural polymers as modifiers.The basic characterization and in vivo NMR imaging of the three materials were carried out.