Issue Date: July 19, 2010
CO2 Solvent Could Enhance Stitches
Carbon dioxide, despite its bad reputation as a greenhouse gas, is an inert, nonflammable, recyclable, and inexpensive solvent that is becoming popular for processing pharmaceuticals and biomedical polymers. In one of the latest studies, a team led by Randy D. Weinstein of Villanova University used liquid and supercritical CO2 to infuse biodegradable suture material with the anti-inflammatory drug ketoprofen for sustained-release applications (Ind. Eng. Chem. Res., DOI: 10.1021/ie901913x). The researchers dissolved ketoprofen in CO2 and then added sutures made from poly(lactide-co-glycolide), a copolymer commonly used in drug delivery and medical implants. The team studied ketoprofen loading at different temperatures (25 to 55 °C), pressures (65 to 300 bar), and time of exposure, achieving up to 60% by weight of ketoprofen in the sutures without affecting the strength or mechanical properties of the material. On the basis of modeling and diffusion studies, the researchers determined that the solvent swells the copolymer, opening up spaces for ketoprofen molecules to enter and become embedded throughout, ready to go to work as the copolymer degrades. Carbon dioxide’s ability to swell the copolymer while remaining inert makes it “an excellent solvent for creating polymeric drug delivery devices,” the researchers write.
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