Studies on amino group terminated polyether urethane-amide) ligand and magnetic resonance imaging contrast agent

To develop and characterize a new class of potential blood pooi magnetic resonance (MR) contrast agents which could be used as cancer target gene delivery carrier, novel gadolinium amino group terminated poiy ( etherurethane-amide)/diethylenetriamine pentaacetic acid (PEU-Gd-DTPA) polymeric chelate( 1Y) was synthesized. The amino group terminated poly (ether-urethane- amide ) /diethylenetriamine pentaacetic acid (PEU/DTPA) copolymer ligand (ifi ) could be designed and obtained from the reaction of diethylenetriamine pentaacetic acid dianhydride (DTPAA, I ) with amino group terminated PEU (PEU- ( (CH₂ ) NH₂ )₂) (II ) ,which was prepared in high yield by the reaction of polyethylene glycol (PEG) with isophorone diisocyanate (IPDI) and then with hexamethylene diamine. Ligand lIE was then coordinated with Gd3 + ion to give the macromolecular contrast agent 1V in water at room temperature. The structure analysis and characterization of DTPAA, II , ifi were studied by IR, NMR, GPC ,and functional group titration methods. Gadolinium content of the polymeric chelate N was 0.88 wt %, which was determined by radio frequency inductively coupled plasma (ICP) spectra. In vitro relaxivity (R1) studies of N showed a 38.40% increase in R1 relaxivity compared with gadolinium- diethylenetriamine pentaacetic acid.