3D-printed graphene oxide/bioactive glass/BMP-2 composite scaffolds enhance osteogenesis in bone defect repair

Clinical repair of critical-sized bone defects is currently hindered by the insufficient bioactivity of existing materials and mechanical property mismatches. This study aims to develop a 3D-printed graphene oxide (GO)/bioactive glass (BG)/bone morphogenetic protein-2 (BMP-2) composite biomimetic scaffold that integrates structural support with biochemical induction. In this work, polycaprolactone-based scaffolds loaded with different gradients of GO (1, 5, 10 wt.%) were fabricated using 3D printing technology, and surface functionalization of BMP-2 was achieved through EDC/NHS coupling. The optimal composition (5% GO) was determined through electron microscopy and mechanical screening, and a rat proximal femoral penetrating defect model was established. Micro-CT, Masson staining, and molecular biology techniques (IHC/WB) were utilized to evaluate its multidimensional regulatory effects on bone regeneration. Results showed that the 5% GO/BG/BMP-2 scaffold exhibited excellent mechanical stability and an appropriate porous structure, with compressive strength and modulus superior to other formulations. Animal experiments confirmed that the bone mineral density (BMD) and bone volume fraction (BV/TV) of the GO/BG/BMP-2 group were significantly higher than those of other groups (p < 0.001). At 4 weeks post-operation, the new bone area fraction reached 75.50% ± 3.17%, achieving high mineralization and functional remodeling of the bone tissue. Molecular mechanism studies indicated that the scaffold induces efficient osteogenic differentiation of mesenchymal stem cells by strongly activating core signaling pathways such as BMP-2, RUNX2, and EGFR during the early stages of repair. In conclusion, the 5% GO/BG/BMP-2 composite scaffold possesses both precise mechanical support and powerful molecular regulatory capabilities, providing a highly promising biomimetic alternative for the clinical treatment of complex bone defects.