Fabrication of three dimensional porous biodegradable polymer scaffolds by thermally-induced phase separation process

Abstract

Poly(L-lactic acid) and its copolymers with D-lactic and glycolic acid were used to fabricate various porous biodegradable scaffolds suitable for tissue engineering and drug delivery based on a thermally induced phase separation(TIPS) technique. A variety of parameters involved in TIPS process such as types of polymers, polymer concentration, solvent/nonsolvent ratio, quenching temperature, and the presence of an additive were examined in detail to produce a wide array of micro- and macroporous structures. A mixture of dioxane and water was used for a binary composition of solvent and nonsolvent, respectively. Particularly, the coarsening effect of pore enlargement affected by controlling the quenching temperature was utilized for the generation of macroporous open cellular structure having above 100μm pore diameters. the use of amorphous polymers with a slow cooling rate resulted in macroporous open cellular structure, whereas that of semi-crystalline polymers with a fast cooling rate generated microporous closed cellular structure. the fabricated porous devices loaded with recombinant human growth hormone(rhGH) by an immersion-soaking method were tested for the controlled delivery of rhGH, as a potential additional means to cell delivery. The produced microcellular scaffolds with and without lipid-impregnation in their pores were also demonstrated as protein delivery carriers, which was shown by using carbonic anhydrase as a model protein drug.