Magnesium oxide nanoparticles modulate phase separation to form trabecular-structured cryogels for bone defect repair.

Critical-sized bone defects pose notable therapeutic challenges and often require extensive bone grafts for effective intervention, leading to a substantial medical burden. The scarcity of autologous bone and the complex architecture of trabecular bone necessitate the development of cost-effective biomimetic graft materials. In this study, we developed a MgO nanoparticle-incorporated hydrogel scaffold (P-G-C-MgO2) using a freeze-induced phase separation approach. The scaffold achieved a porous structure with 56.48 ± 7.062 % porosity and an average pore size of 565.7 ± 53.62 μm, closely mimicking natural trabecular bone. It demonstrated exceptional mechanical stability during degradation and consistently released bioactive components, including Mg(2+), type I collagen, and gelatin. These features facilitated early cell recruitment and osteogenic differentiation. In a distal femoral bone defect model, P-G-C-MgO2 exhibited excellent osseointegration and significantly enhanced new bone regeneration. This biomimetic design offers a promising solution for bone defect repair. Moreover, it established a novel phase-separation-based strategy for fabricating porous hydrogel scaffolds.