Study On Preparation Of New Nano-cell Imaging And Contrast Agents For Magnetic Resonance

Magnetic Resonance Imaging (MRI) is a commonly used diagnostic technique in clinical practice. The composition of the body is basically the same except the bones and blood. So we need contrast agent to increase the contrast of the diseased sites to improve the diagnostic accuracy and reliability. This thesis report design and synthesis of some T1and T2MRI contract agents and explored their applications for intracellular imaging.In Chapter2of this thesis, we synthesized Fe3O4magnetic nanoparticles with different size by pyrolysis method. Then the nanoparticles were modified with DMSA to render them excellent water solubility. Next, the Fe3O4NPs were conjugated to GO-PEI through EDC chemistry to assemble Fe3O4NPs into GO, forming a magnetic GO. We demonstrated that the GO-Fe3O4nanocomposites exhibit much higher MRI T2relaxation rate than the isolated Fe3O4nanoparticles.T2MRI contrast agent makes the image darker to enhance the MRI effect. But for organs such as liver that usually shows dark signal, making it difficult to differentiate the diseased and normal area. In this case the use of T1contrast agent is necessary, since it produces brighter image. Therefore, in Chapter3, we synthesized manganese oxide nanoparticles with different sizes by solvothermal method. The as-prepared manganese oxide nanoparticles exhibit excellent water solubility, stability and T1-weighted MRI effect.In Chapter4, on the basis of the work discussed in the preceding chapter, we synthesized multifunctional ferromanganese composite nanoparticles. We utilized the T1-weighted effect of Fe3O4nanoparticles and T2-weighted effect of manganese oxide nanoparticles to achieve the dual-mode MRI effect. The nanoparticles were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energy dispersive X-ray Spectroscopy (EDX) and Physical property measurement system (PPMS).In the last chapter, we developed a transferrin-conjugated ferromanganese composite nanoparticles with drug delivery and MR/fluorescence imaging functionalities. With glioma A172cells as a cell model, we demonstrated that the transferrin-modified ferromanganese composite nanoparticles can be uptaken effectively by the brain cancer cells, and can be used for cellular MR imaging.