Polyactide Biodegradable Scaffolds for Tissue Engineering Applications: Phase Separation-Based Techniques

One of the most reliable techniques for the preparation of biodegradable scaffolds suitable for tissue engineering applications (e.g. regeneration of wounded/damaged tissues) is based on liquid/liquid phase separation of ternary solvent/antisolvent/polymer solutions. In particular, two phase separation protocols are examined here: Thermally Induced Phase Separation (TIPS) and Diffusion Induces Phase Separation (DIPS). According to the former protocol, a thermodynamically stable polymeric ternary solution is brought below its metastability/instability point (spinodal/binodal curve) by quench in a cooling medium: under opportune conditions, a foam-like structure is formed by nucleation and 3-D growth of the polymer lean phase, which, after solvent removal by rinsing and drying, will constitute the voids of the as-generated “open-pore” architecture. Two ternary polymeric solutions were examined in detail: Poly-L-Lactic Acid (PLLA)/Dioxane (solvent)/TetrahydroFurane (THF, antisolvent) and PLLA/Dioxane/Water (antisolvent). For both systems (PLLA/Dioxane/THF and PLLA/Dioxane/Water) the solvent (dioxane) to antisolvent (THF or water) ratio and the polymer concentration were varied; moreover, different cooling paths from the stable ternary solution down to the instable zone were examined.