Synthesis and characterization of a new water-soluble endohedral metallofullerene for MRI contrast agents

摘要

Water-soluble ammo acid derivatives of gadolinium (Gd) endohedral metallofullerenes (AAD-EMFs), Gd@C_(82)O_m(OH)_n (NHCH_2CH_2COOH)_l (m approx = 6, n approx = 16 and l approx = 8) are synthesized by a direct reaction of the pure endohedral metallofullerene Gd@C_(82) with an excess of alkaline solution of beta-alanine. The structure of the AAD-EMFs is characterized by FTIR, XPS and laser-desorption time-of-flight (LD-TOF) mass spectrometries. Water proton relaxivity analysis indicates that the longitudinal relaxivity R_1 (the effect on 1/T_1, 9.1 mM~(-1) s~(-1)) of AAD-EMFs is higher than that of the commercial MRI contrast agent, Magnevist (gadolinium-diethylenetri-aminepentaacetic acid, Gd-DTPA, 5.6 mM~(-1) s~(-1)). The MRI phantom studies are performed to confirm the high efficiency of this sample as MRI contrast agents.