A Novel Magnetic Resonance Imaging Contrast Agents Based On Amphiphilic Gadolinium (â…¢) Complex

Magnetic resonance imaging (MRI) is one of the most important medical diagnostic methods in clinic for its multi-parameter imaging and non-trauma features. However, clinic MRI still has the problem of low sensitivity and low contrast between different tissues in some cases, which can be partly resolved by addition of contrast agents (CAs). Currently, most of MRI CAs are based on gadolinium (â…¢) complexes.In this thesis, we synthesized a type of amphiphilic gadolinium (â…¢) complexes with a D03A core and quaternary ammonium salt with different chain lengths which shows good water solubility. NMR, ESI-HRMS and MALDI-TOF-MS were used to characterize the structures of ligands and complexes.1.5T MRI measurements showed that the long chain complex exhibited high longitudinal relaxivity (r1), while the complexes with medium-length chain showed r1similar or exceed the clinic MRI CAs.Furthermore, the sensitivity to anion experiments of these complexes were conducted. Preliminary results on1.5T MRI measurement indicated that the long chain ones showed better performance after mixed with sodium polyacrylate (PAAS) and r1increased significantly. The reason for this phenomenon is the synergistic effect of hydrophobic-hydrophobic interactions and electrostatic forces. The contrast agents that we synthesized show the potential to be anion probes and further used as a kind of smart MRI CAs when combined with surface electronegative substances.