We’ve been writing at Design News for a few years on the exciting work in developing new polymers for coronary-opening stents. First there was the compound that releases drugs over a defined span of time. And then there was work to develop bioabsorbable plastic stents that would disappear into the body after completing their work. Now one of the developers is receiving the coveted Lemelson-MIT Prize for innovation – and a check for $500,000.
The winner is Joseph M. DeSimone, chancellor’s eminent professor of chemistry at the University of North Carolina at Chapel Hill and William R. Kenan Jr. distinguished professor of chemical engineering at North Carolina State University. He worked with Richard Stack, president of SyneCor LLC, in developing a fully bioabsorbable, polymer-based stent to provide an alternative to metallic stents. The technology is being commercialized by Abbott Laboratories, and clinical trials are under way. The Abbott stent is made of polylactic acid—the workhorse for bioabosrbable implants—and coated with a drug called Everolimus.
One of DeSimone’s contributions is development of a safe method of removing potentially toxic additives used in plastic implants. Devices are immersed in a densified carbon dioxide composition to absorb toxic materials. The densified carbon dioxide containing the toxic materials is then removed from the polymeric material and the toxic materials are separated from the carbon dioxide composition by decreasing the density of the carbon dioxide.
In another breakthrough, DeSimone helped develop polymers with selectively modified crystallinity so that mechanical properties could be varied within a stent, a feature that directly relates to material degradation.