3D polyurethane/α-TCP composite scaffolds for bone tissue engineering

This work deals with the design of biointegrable porous composite scaffolds, made of biocompatible and relatively biostable polyurethane foams (PUF) loaded with bioabsorbable inorganic salts (α-TCP), to be used as bone graft substitutes. 3D porous composites were prepared by co-expanding polyurethane formulations with α-TCP particles in a one-step bulk polymerization, using water as expanding agent. Density, porosity, cell size, thermal properties (TGA), and compressive mechanical properties of these composites were evaluated. For comparison, PU foams were obtained with the same procedure, but with no added TCP. Compared to unloaded foams, the composites did not show relevant differences in density and porosity. Compressive properties were similar or lower. The content of the inorganic residue detected with TGA corresponded to the quantity of α-TCP introduced. Some composite samples were incubated in Simulated Body Fluid, up to 21 days at 37°C. Structure and morphology of the SBF-treated samples were analyzed by TGA, X-ray diffractometry and scanning electron microscopy (SEM). SEM observations confirmed the presence of a new inorganic phase (Ca/P) at the surface and inside the pores of the PUF/α-TCP composites.