PLLA Scaffold via TIPS for Bone Tissue Engineering

Tissue engineering offers a promising new approach to repair bone fractures, fractures that do not heal, andfractures due to bone tumors. In this work, two different approaches were tested in order to obtain Poly-LLacticAcid (PLLA) porous scaffolds via Thermally Induced Phase Separation (TIPS) for bone tissueengineering application. First, the possibility to produce a composite material, by incorporating Hydroxyapatite(HA) particles in a Poly-L-lactic acid (PLLA) matrix was investigated. Two PLLA/HA weight ratios (70/30 and50/50) were tested. The results showed that the presence of HA does not influence the phase separationprocess, i.e. the composite scaffolds microstructure is similar to pure PLLA scaffolds. WAXD analysisconfirmed the full incorporation of HA particles into the polymer matrix. Moreover, compression tests showed afourfold increase of Young module with respect to pure PLLA scaffold. Since the production of scaffolds forbone tissue regeneration is a challenging target, scaffolds must mimic the bone morphology, thus requiring agradient of pore dimension and morphology along one dimension. To attain this goal, the second part of thework describes the design, set up and test of an experimental apparatus able to set different thermal historieson the two sides of a sample. Scaffolds were produced by following various thermal protocols on both samplesurfaces. The results showed that through this technique it is possible to produce scaffolds with a pore sizethat increases along sample thickness. As a matter of fact, the obtained average pore dimension on one sideof the sample was about 70 μm, whereas it was around 240 μm on the opposite surface. By moving along thesample thickness, the pore dimension increased steadily. All things considered, a reliable route for theproduction of composite PLLA/HA scaffolds with a controlled pore size distribution was assessed, thus offeringa valid support to bone tissue engineering.