Subcritical carbon dioxide foaming of polycaprolactone for bone tissue regeneration

The preparation of three-dimensional polycaprolactone scaffolds using dense CO₂ as foaming agent, without supercritical conditions, was evaluated in this study towards future applications in bone repair. Herein, 3D foams were obtained at 5.0 MPa and 45 °C. To induce bioactivity, β-tricalcium phosphate (β-TCP, 10 wt%) and dexamethasone (5 and 10 wt%) were dispersed in the scaffolds. Foams revealed a pore size range of 164–882 μm, 73–99% porosity and 79–99% interconnectivity, assessed by micro-computed tomography, and a Young modulus of 1.76–2.92 MPa. Dexamethasone did not impair morphology of the matrices in comparison with PCL+β-TCP, which presented a water uptake of nearly 100% after 14 days. A sustained release of dexamethasone was achieved over 35 days in physiologic solution. This study reports the feasibility of using dense CO₂ to produce in one-step a porous matrix loaded with active agents opening new possibilities towards injectable systems for in situ foaming.