New insights in the morphological characterization and modelling of poly(ε-caprolactone) bone scaffolds obtained by supercritical CO₂ foaming

Hierarchically porous synthetic bone grafts (scaffolds) are gaining attention in the clinical arena. Scaffolds should combine morphological (macro- and microporosity, pore interconnectivity), mechanical and biological (biocompatibility, degradation rate) properties to fit this specific use. Supercritical (sc-) foaming is a versatile scaffold processing technology. However, the selection of the optimum operating conditions to obtain a defined scaffold structure is hampered by the lack of a single characterization technique able to fully elucidate the porous features of the resulting scaffolds. In this work, the effect of soaking time (1, 3 and 5 h) on the preparation of poly(ε-caprolactone) (PCL, 50 kDa) scaffolds by sc-foaming was evaluated by a combined X-ray microtomography (μ-CT) and mercury intrusion porosimetry (MIP) 3D-morphological analysis. Mechanical tests and in silico modelling for cell penetration and water permeability of the scaffolds were also conducted. Results evidenced the relevance of μ-CT and MIP as a synergistic analytical duo to fully elucidate the morphology of the sc-foamed scaffolds and the soaking time effect.