Synthesis Of MRI Contrast Agent Ligands Of3-Aminopropyl-Heptakis(Isobutyl)Polyhedral Oligomeric Silsesquioxane

Because of its non-invasive, high resolution and good flexibility, magnetic resonanceimaging （MRI） has become a widely used new clinical diagnostic imagingtechnology. MRI contrast agent is a kind of reagent that can have a large improvement oncontrast-enhanced effect of MR imaging. And its function and effect depends mainly onthe ligand structure. So the design and synthesis of next-generation magnetic resonanceimaging contrast agent ligands are one of the most attractive and challenging work in thecurrent MRI areas.3-Aminopropyl-heptakis（isobutyl） polyhedral oligomeric silsesquioxane （POSS） isan unit of nano material, which can make drug carried to be reality.1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid （DOTA） is the classic ligandunit of MRI contrast agent. Considering these two kinds of functions in the same time, thenew ligand with the structure which combining these two units together should showbifunctional （drug carried and high efficiency of relaxation）. This is the innovationaldesign for this thesis. Our works were as following:（1） First of all, one DOTA reacted with POSS through condensation reaction toprovide one novel ligand containing two special functional units（13, POSS-DOTA）.Synthesis product has high purity and its chemical structure was confirmed bycharacterization. This work not only has already introduced POSS into MRI contrast agentligand, but also expanded the DOTA reagent type. This work is the innovative work indesign and synthesis multi-functional reagent.（2） The synthesis of dimeric ligand based dipeptide HO-GK-（DOTA）₂（10） wascompleted by solid phase peptide synthesis. And the product was measured by APCI-MS.The fellowing work is the synthesis of bonding polypeptide HO-GK-（DOTA）₂to POSS inorder to synthetic novel ligand containing POSS and two DOTA units. We have beentrying many time to find out the correct synthetic route, and investigating the influence ofsome important factors to the reaction, such as alkali content （DIPEA）, reaction time aswell as solvent.