Poly(L-lactide)-grafted Bioglass/Poly(lactide-co-glycolide) Scaffolds with Supercritical CO2 Foaming Reprocessing for Bone Tissue Engineering

The bioglass particles/poly(lactide-co-glycolide)(BG/PLGA) scaffold has been extensively explored for biomedical applications due to its excellent advantages of mechanical property and controllable degradation rate. In our previous studies, the BG nanoparticle surface-grafted with poly(L-lactide)(PLLA) could substantially improve the phase compatibility between the polymer matrix and the inorganic phase and the biocompatibility of the scaffolds. However, using the traditional preparation methods to prepare the composite scaffold can barely achieve a high porosity and porous connectivity. In this work, the PLLA-grafted bioglass/PLGA(g-BG/PLGA) scaffolds were prepared by supercritical carbon dioxide foaming(Sc-CO2) with before or after particulate leaching(PL) method(Sc-CO2-PL or PL-Sc-CO2 method, PL/Sc-CO2 methods) and their applications in bone replacement and tissue engineering were investigated. The porosities of the g-BG/PLGA scaffolds prepared by the PL/Sc-CO2 methods were higher than 90%, and their mechanical properties had similar values with human cancellous bone. The proliferations of osteoblasts on the scaffolds were dependent on different preparation methods. The PL/Sc-CO2 methods significantly increased the proliferations of the cells. Computed tomography(CT) three-dimensional(3D) reconstruction tomographies of the implantation study for repairing calvarium defects of rabbits demonstrated that the calvarium defects were almost completely filled by the osteotylus in PL/Sc-CO2 method group at 12 week post-surgery, while there was little callus formation in PL method group and untreated control group. These results indicate that the g-BG/PLGA scaffolds prepared by the PL/Sc-CO2 methods exhibit rapid mineralization and osteoconductivity and are the optimal composites for bone repair.