Fabrication of porous poly(L-lactide) (PLLA) scaffolds for tissue engineering using liquid–liquid phase separation and freeze extraction

PLLA scaffolds were successfully fabricated using liquid-liquid phase separation with freeze extraction techniques. The effects of different processing conditions, such as method of cooling (direct quenching and pre-quenching), freezing temperature (-80 degrees C and -196 degrees C) and polymer concentration (3, 5 and 7 wt%) were investigated in relations to the scaffold morphology. SEM micrographs of scaffolds showed interconnected porous network with pore size ranging from 20 to 60 microm. The scaffolds had porosity values ranging from 80 to 90%. Changes to the interconnected network, porosity and pore size were observed when the method of cooling and polymer concentration was changed. Direct quenching to -80 degrees C gave a more porous interconnected microstructure with uniform pore size compared to samples prepared using pre-quenching method. Larger pores were observed for samples quenched at -80 degrees C compared to -196 degrees C. Scaffolds prepared using direct quenching to -196 degrees C had higher elastic modulus and compressive stress compared to those quenched to -80 degrees C. The compressive elastic modulus ranged from 4 to 7 MPa and compressive stress at 10% strain was from 0.13 to 0.18 MPa.