Synthesis And Characterization Of Two Novel Magnetic Resonance Imaging Contrast Agents

Magnetic resonance imaging (MRI) is a new and rapid developing clinical diagnostic modality, and MRI contrast agent is an important component of this technology. MRI contrast agents are paramagnetic materials that can increase the proton relaxation rates of water, thus enhance the contrast between the normal and abnormal tissue pathologically. The one of most challenging aspects in the field MRI contrast agent is the development of new contrast agent with high relaxivity, low toxicity as well as tissue targeting. In this thesis, the research progress of Bio-responsive MRI contrast agent was reviewed, and the main research results were summarized as follows:(1) A new peptide-based MRI contrast agent was designed and synthesized. This novel MRI contrast agent was composed of paramagnetic unit, cell-penetrating peptide polyarginine, and RGD peptide sequence which is important in targeting tumor. The main intermediates and ligands were characeterized by IR, 1H NMR, and ESI-MS.(2) An important intermediate, 1,4,7-Tris(tert-butoxycarbonylmethyl)-1,4,7,10- tetraazacyclododecane-10-acetic acid was synthesized. The synthesis route and experimental conditions were investigated and optimized.(3) The method for synthesis of 1,4,7-Tris(tert-butoxycarbonylmethyl)-1,4,7,10- tetraazacyclododecane hydrobromide salt was improved, which is an easy way to operate and has higher yield than literature reported.(4) An indole-3-acetic acid based MRI contrast agent was synthesized by connection of paramagnetic unit with indole-3-acetic acid. This kind of contrast agent maybe used for the study of plant growth. The main intermediates and ligand were characeterized by 1H NMR and ESI-MS.