MRI-Visible Poly(ε-caprolactone) with ControlledContrast Agent Ratios for Enhanced Visualization in Temporary ImagingApplications.

Hydrophobic macromolecular contrastagents (MMCAs) are highly desirableto provide safe and efficient magnetic resonance (MR) visibility toimplantable medical devices. In this study, we report on the synthesisand evaluation of novel biodegradable poly(ε-caprolactone)-basedMMCAs. Poly(α-propargyl-ε-caprolactone-co-ε-caprolactone)s containing 2, 5, and 10 mol % of propargylgroups have been prepared by ring-opening copolymerization of ε-caprolactoneand the corresponding propargylated lactone. In parallel, a diazidoderivative of the clinically used diethylenetriaminepentaacetic acid(DTPA)/Gd3+complex has been synthesized. Finally, MRI-visiblepoly(ε-caprolactone)s (PCLs) were obtained by the efficientclick ligation of these compounds via a CuI-catalyzed [3+ 2] cycloaddition. ICP-MS analyses confirmed the efficient couplingof the complex on the PCL backbone with the MRI-visible PCLs containing1.0, 2.6, and 3.6 wt % of Gd3+. The influence of the Gd3+grafting density on the T1relaxationtimes and on the MRI visibility of the novel biodegradable MMCAs wasevaluated. Finally, their stability and cytocompatibility were assessedwith regard to their potential as innovative MRI-visible biomaterialsfor biomedical applications. [ABSTRACT FROM AUTHOR]