Preparation and Characterization of Porous Bioglass (R) and PLLA Scaffolds for Tissue Engineering Applications

Three-dimensional porous scaffold network structures of Bioglass (R) and poly-l-lactide (PLLA) have been fabricated using camphene-based freeze cast reticulation technique using polyurethane foam templates of appropriate structures and solvent extraction methods. Sublimation of camphene was controlled during freeze casting of Bioglass (R) slurries at -78 degrees C. PLLA scaffolds were prepared by solvent extraction at temperatures between 25 degrees C and -196 degrees C. Both methods produced open, uniform and interconnected porous structures with 1801100 mu m and porosities of 80%90% for Bioglass (R) and wide pore size ranges 150600 mu m with porosities up to 90% for PLLA scaffolds. PLLA scaffolds exhibited a strong dependence on freezing temperature and type of the solvent used. Camphene sublimation resulted in micropores of 110 mu m, known to facilitate cell adhesion and proliferation. Compressive yield strength of 0.8 MPa close to the upper range of cancellous bone was achieved. The mean compressive strength of Bioglass (R) scaffolds compared favorably with the theoretical model of porosity variation with strength and was higher than reported values. A maximum of 25% shrinkage resulted, but the original foam template structure was accurately replicated within 4% experimental limit and the conformity was maintained even at high temperatures. The strut sizes of both type of scaffolds varied between 4-10 mu m. Surface crystallization up to 5 mu m was evident at 900 degrees C.