Synthesis and Properties of a Novel Contrast Agent

Chitosan oligosaccharides(CSn,n=6,8,11) with narrow molecular weight distribution and low polymerization degree were introduced into diethylenetriamine pentaacetic(DTPA) by acylation reaction.The synthesized novel ligands were coordinated to Mn2+,then the paramagnetic Mn2+-based complexes were gained.The structures of synthesized ligands and the corresponding complexes were characterized by IR,elemental analysis,and ICP-AES.The longitudinal relaxivities(r1) were measured.The results show that r1 of Mn-DTPA-CSn are higher than that of commercial contrast agent Gd-DTPA.Besides,the thermodynamical parameters of the interaction between the functional complexes and bovine serum albumin(BSA) were conducted by isothermal titration calorimetry(ITC).