Development by robocasting and mechanical characterization of hybrid HA/PCL coaxial scaffolds for biomedical applications

Porous structures consisting of a tetragonal three-dimensional mesh of interpenetrating coaxial tubes were fabricated by robocasting from hydroxyapatite (HA) inks. After sintering the structures, polycaprolactone (PCL) was infiltrated within the tubes core by injection of a polymer solution . The addition of the polymer enhanced the mechanical performance in terms of toughness over dense- and hollow-strut all-ceramic scaffolds, specially under bending stresses. PCL impregnation improved also the compressive strength over hollow-strut scaffolds —although dense-strut structures remained stronger especially in compression. Thus, this coaxial core-shell strut configuration combines the best features of each material: the necessary stiffness and excellent osteoconductivity of the bioceramic , with the high toughness and ductility of the biopolymer ; and allows the fabrication of hybrid scaffolds with the interconnected macroporosity necessary for cell ingrowth. Hence, this work successfully provides a proof-of-concept of this novel strategy for the mechanical enhancement of bioceramic-based scaffolds while preserving their osteoconductive properties.