Trends in NMR studies of paramagnetic Gd(III) complexes as potential contrast agents in MRI

The paramagnetic Gd(III) complexes with polyaminocarboxylate ligands are intensively studied as possible Contrast Agents for Magnetic Resonance Imaging (M.R.I.). Their ability to enhance the solvent proton relaxation rate is mainly determined by the molecular reorientational time (τ_R). In order to increase τ_R we studied the formation of non-covalent interactions between functionalized Gd(III)-complexes and micelles. The N.M.R.D. (Nuclear Magnetic Relaxation Dispersion) profiles of aqueous solutions of these paramagnetic complexes with hexadecyltrimethylammonium bromide (CTABr) were measured and the results could be accounted for by difference in negative charge and number of hydrophobic aromatic residues among the different complexes.