Influence of CO2 Blowing Agent on Porous Bioresorbable Stent Structure

Bioresorbable stents with limited functional lifetimes and with drug delivery capabilities are desired. Various methods have been investigated to induce porosity in bioresorbable polymeric stent fibers, thereby to permit increased drug reservoir capacity versus polymer-coated metal stents. We developed microporous surface layers on PLLA fibers to serve as the drug reservoir, but found that impurities, the use of chemicals, and multiple step procedures associated with our, and other published methods limited utility. Thus we investigated theoretically attractive CO ₂ blowing methods, in which gas under pressure and temperature induces porosity. We report the results of initial studies of CO ₂-induced porosity in PLLA stent fibers.