Freeze-casting for PLGA/carbonated apatite composite scaffolds: Structure and properties

- Shrinkage-free porous PLGA-biomimetic apatite composite scaffolds can be prepared by freeze-casting using DMC as a solvent.
- Freeze-casting induced homogeneously distributed porosity (mainly two-dimensional) related to anisotropic macro-domains.
- An optimum apatite ratio was reached to combine good mechanical properties and material cohesion.
- Rigidity of pore walls was improved in the presence of biomimetic apatite particles.
- Higher apatite filler ratios limited PLGA degradation and enhanced the hydrophilicity of the scaffolds.

This paper focuses on the fabrication of three-dimensional porous PLGA-biomimetic carbonated apatite composite scaffolds by freeze-casting and using dimethyl carbonate as a solvent. Several charge/polymer ratios were tested in order to finely understand the influence of the filler rate on the scaffold porosity and mechanical and degradation properties using complementary characterization techniques (SEM, mercury porosimetry and X-ray microtomography). It was demonstrated that the apatite ratio within the composite scaffold has a strong influence in terms of architecture, material cohesion, mechanical properties and in vitro degradation properties. An optimum biomimetic apatite ratio was reached to combine good mechanical properties (higher rigidity) and material cohesion. In vitro degradation studies showed that higher apatite filler rates limited PLGA degradation and enhanced the hydrophilicity of the scaffolds which is expected to improve the biological properties of the scaffolds in addition to the bioactivity related to the presence of the apatite analogous to bone mineral.