Kinetics of Release of the TEMPONE Nitroxyl Radical from Poly-D,L-Lactide Foamed in the Supercritical Carbon Dioxide Medium

Abstract—The electron spin resonance method was used to quantitatively describe the release of a paramagnetic bioactive substance from a biodegradable polymer matrix. A standard spin probe TEMPONE was chosen as the paramagnetic compound and poly-D,L-lactide foamed in supercritical carbon dioxide (SC–CO2) was used as the polymer. The release of TEMPONE from a porous poly-D,L-lactide to phosphate buffer saline (pH 7.4) was shown to occur gradually (without periods of burst and stagnation), which suggests that the used process of polymer impregnation and foaming can be applied to design materials for medical purposes.