Functionalization of 3-d porous thermoplastic polyurethane scaffolds by two-stage polydopamine/hydroxyapatite composite nanoparticles

In this work, the polydopamine (PDA) coating layer was first applied to modify hydroxyapatite (HA) nanoparticles and then the functional PDA/HA (pHA) composite nanoparticles were obtained. Subsequently, a 3-D porous thermoplastic polyurethane (TPU) scaffold modified by two-stage pHA nanoparticles ( pHA-TPU/pHA ) was fabricated by vacuum-assisted solvent casting and ultrasonication-assisted methods. The results demonstrated that the pHA nanoparticles were successfully prepared and introduced into the pHA-TPU/pHA composite scaffold both internally and externally. The pHA-TPU/pHA composite scaffold had an excellent interconnected network structure with high porosity of 85.7% and large pore sizes ranging from 100–500 μm. The hydrophilicity and comprehensive mechanical properties of the pHA-TPU/pHA composite scaffold were significantly higher than those of the TPU scaffold due to the addition of the pHA nanoparticles. The attachment and viability of mouse embryonic osteoblast cells (MC3T3-E1) cultured on the pHA-TPU/pHA composite scaffold were also higher than those on the TPU scaffold. These results suggest that the functional pHA-TPU/pHA composite scaffold has superior mechanical and biological properties, which makes it potentially useful for tissue engineering scaffolds.