Liver-targeting macromolecular MRI contrast agents

Macromolecular ligands with liver-targeting group (pyridoxamine, PM) PHEA-D TPA-PM and PAEA-DTPA-PM were prepared by the incorporation of different amo unt of diethylenetriaminepentaacetic acid monopyridoxamine group (DTPA-PM) into poly-alpha, beta-[N-(2-hydroxyethyl)-L-aspartamide] (PHEA) and poly-al pha, beta-[N-(2-aminoethyl)-L-aspartamide] (PAEA). The macromolecular ligan ds thus obtained were further complexed with gadolinium chloride to give ma cromolecular MRI contrast agents with different Gd(III) contents. These mac romolecular ligands and their gadolinium complexes were characterized by H- 1 NMR, IR, UV and elementary analysis. Relaxivity studies showed that these polyaspartamide gadolinium complexes possess higher relaxation effectivene ss than that of the clinically used Gd-DTPA. Magnetic resonance imaging of the liver in rats and experimental data of biodistribution in mice indicate that these macromolecular MR] contrast agents containing pyridoxamine exhi bit liver-targeting property.