Porosity and mechanical properties relationship in PCL-based porous scaffolds

Scaffold design plays a pivotal role in tissue engineering and regenerative medicine approaches for creating biological alternatives for implants. The crucial aspect in scaffold design consists of the development of highly porous scaffolds, with strict control of porosity features (porosity degree and pore sizes), continuing to provide an adequate mechanical response, mainly in compressive loading, both in vitro and in vivo conditions. A study was undertaken of three-dimensional (3D) porous scaffolds obtained from poly µ-caprolactone solution through the phase inversion/salt leaching technique. In particular, the influence of structural porosity features on mechanical response was investigated to establish the correlation between structural parameters and compressive response. Scaffold porosity features can be controlled by changing the amount and size of the porogen agent used. Mechanical response in compression is consistent with porosity features: elastic modulus calculated in the toe region range (0-0.1 of total strain) shows an increase from 0.24-1.85 MPa coherently, with a reduction in pore volume fraction from 84.9 to 45.7%. Such behavior can be predicted by using analytical models for the determination of the elastic modulus of cellular solids based on the morphological assumption of cubic cell structure (cubic open cell (COC) and cubic closed cells (CCC)). Compressive behavior prediction offered by the proposed models is in agreement with the experimental results in the case of higher pore volume fractions according to the theoretical results of other investigators.