Processing/Structure/Property Relationship of Multi-Scaled PCL and PCL–HA Composite Scaffolds Prepared via Gas Foaming and NaCl Reverse Templating

In this study, we investigated the processing/ structure/property relationship of multi-scaled porous bio- degradable scaffolds prepared by combining the gas foaming and NaCl reverse templating techniques. Poly(e-caprolac- tone) (PCL), hydroxyapatite (HA) nano-particles and NaCl micro-particles were melt-mixed by selecting different com- positions and subsequently gas foamed by a pressure-quench method. The NaCl micro-particles were finally removed from the foamed systems in order to allow for the achieve- ment of the multi-scaled scaffold pore structure. The control of the micro-structural properties of the scaffolds was obtained by the optimal combination of the NaCl templat- ing concentration and the composition of the CO2–N2 mixture as the blowing agent. In particular, these parameters were accurately selected to allow for the fabrication of PCL and PCL–HA composite scaffolds with multi-scaled open pore structures. Finally, the biocompatibility of the scaffolds has been assessed by cultivating pre-osteoblast MG63 cells in vitro, thus demonstrating their potential applications for bone regeneration.