Iodinated Polymers Visible To X-Rays

A new class of iodinated polymers may provide a way to monitor medical implants and drug delivery devices in the body. The iodine in these polymers makes them opaque to X-rays (radiopaque) and thereby visible in X-ray images. Previous attempts to make radiopaque polymers have involved incorporating iodine into nondegradable or slowly degrading polymers. Kathryn E. Uhrich and coworkers at Rutgers University, Piscataway, N.J., report radiopaque salicylate-based poly(anhydride-esters) that have iodine atoms incorporated into the backbone (Biomacromolecules, DOI: 10.1021/bm8000759). The polymers, which are fully biodegradable, demonstrate that it is "possible to combine iodine-based radiopacity with controlled biodegradation," comments Leo H. Koole, a professor of biomaterials science at the University of Maastricht, in the Netherlands. The Rutgers researchers compared two methods to make the polymers. The melt-condensation polymerization method formed stiffer polymers with higher molecular weights and higher radiopacity than did the low-temperature solution-based polymerization method. The radiopacity depended on the number of iodine atoms in the polymer. Polymers made by either method were biocompatible with mouse fibroblast cells at low polymer concentrations.