Tumor-selective macromolecular MRI contrast agents

Tumor-selective macromolecular ligands containing 5-(p-Carbonyloxyphenyl)-10,15,20-triphenylporphyrin (HPTP) moiety (PHEA-DTPA-HPTP and PAEA-DTPA-HPTP) were prepared by the incorporation of diethylenetriaminepentaacetic acid (DTPA) and 5-(p-hydroxylphenyl)-10,15, 20-triphenylporphyrin (HPTP) as the tumor-selective group in poly [alpha,beta-(N(2-hydroxyethyl)-L-aspartamide)] (PHEA) and poly-[alpha,beta-(N-(2-aminoethyl)-L-aspartamide)] (PAEA). These ligands were further complexed with gadolinium chloride to form two tumor-selective macromolecular MRI contrast agents PHEA-Gd-DTPA-HPTP and PAEA-Gd-DTPA-HPTP. Relaxivity studies showed that both the polyaspartamide-gadolinium complexes possess higher relaxation effectiveness than that of the clinically used Gd-DTPA. Magnetic resonance imaging of tumors in mice indicated that these two polyaspartamide MRI contrast agents containing 5-(p-Carbonlyoxyphenyl)-10,15,20-triphenylporphyrin moiety can significantly enhance the contrast MRIs of Hepatoma (H-22) and Ehrlich ascites carcinoma after injection and are taken up selectively by these cancers in mice.