β-Tricalcium phosphate/poly(glycerol sebacate) scaffolds with robust mechanical property for bone tissue engineering

Despite good biocompatibility and osteoconductivity, porous beta-TCP scaffolds still lack the structural stability and mechanical robustness, which greatly limit their application in the field of bone regeneration. The hybridization of beta-TCP with conventional synthetic biodegradable PLA and PCL only produced a limited toughening effect due to the plasticity of the polymers in nature. In this study, a beta-TCP/poly(glycerol sebacate) scaffold (beta-TCP/PGS) with well interconnected porous structure and robust mechanical property was prepared. Porous beta-TCP scaffold was first prepared with polyurethane sponge as template and then impregnated into PGS pre-polymer solution with moderate viscosity, followed by in situ heat crosslinking and freezing-drying process. The results indicated that the freezing-drying under vacuum process could further facilitate crosslinking of PGS and formation of Ca2+-COO- ionic complexing and thus synergistically improved the mechanical strength of the beta-TCP/PGS with in situ heat crosslinking. Particularly, the beta-TCP/PGS with 15% PGS content after heat crosslinking at 130 degrees C and freezing-drying at -50 degrees C under vacuum exhibited an elongation at break of 375 +/- 25% and a compressive strength of 1.73 MPa, 3.7-fold and 200-fold enhancement compared to the beta-TCP, respectively. After the abrupt drop of compressive load, the beta-TCP/PGS scaffolds exhibited a full recovery of their original shape. More importantly, the PGS polymer in the beta-TCP/PGS scaffolds could direct the biomineralization of Ca/P from particulate shape into a nanofiber-interweaved structure. Furthermore, the beta-TCP/PGS scaffolds allowed for cell penetration and proliferation, indicating a good cytobiocompatibility. It is believed that beta-TCP/PGS scaffolds have great potential application in rigid tissue regeneration. (C) 2015 Elsevier B.V. All rights reserved.