Solvent-free protein encapsulation within biodegradable polymer foams.

Microporous poly(D,L-lactide-co-glycolide) matrices containing encapsulated proteins were fabricated in a solvent-free manner. Microporous foam was generated by saturating a mixture of polymer and protein particles in supercritical carbon dioxide (SC-CO2), dispersing the protein particles in the polymer melt followed by a rapid evaporation of the CO2 phase. The release rates of protein encapsulated within porous poly(lactide-co-glycolide)(PLGA) constructs produced in SC-CO2 were measured in vitro. Although a substantial amount of protein was released within the first 48 h, results indicated that protein may be dispersed throughout the polymer phase and released over 3 weeks using this solvent-free technique. Basic fibroblast growth factor (bFGF), known to promote angiogenesis in vivo, was encapsulated within the polymer matrix. In addition, retention of biological activity was measured for bFGF encapsulated within PLGA foams. Encapsulated bFGF was released from the porous constructs for up to 10 days in vitro with little loss of biological activity.