Ceo₂/Dfo Dual-Loaded Scaffolds For Sequential Bone Repair

This study designed a dual-release Ce@MSN-DFO/CS/nHAp scaffold to promote vascularization and osteogenesis during bone regeneration in sequential reparation. DFO was encapsulated in genipin-crosslinked CS microspheres, while Ce@MSNs were synthesized via hydrothermal wet-impregnation. Both components were embedded into CS/nHAp scaffolds by freeze-drying. Physicochemical characterization (TEM, SEM, XRD, XPS, FTIR, porosity, compressive strength) and drug release profiles (UV-Vis, ICP-OES) were analyzed. In vitro MC3T3-E1 tests assessed biocompatibility and osteogenesis (CCK-8, ALP, RT-qPCR), while rat cranial defect regeneration was evaluated through Micro-CT/histology. The Ce@MSN-DFO/CS/nHAp scaffold exhibits high porosity (81.48% ± 1.89%) and optimal compressive strength (6.69 ± 0.20 MPa with 20% Ce@MSNs). DFO showed day 3 burst release (58.21 ± 4.22%) followed by sustained release to 76.36% by day 7, indicating CS-mediated protection. CeO₂ release slowed post-burst until day 28. In vitro, 20% Ce@MSN maximally upregulated osteogenic genes (ALP, RUNX2, COL-I; P<0.001). In vivo, 20% Ce@MSN enhanced bone regeneration with 45.2± 3.1% BV/TV, 1.57 ± 0.031mm Tb.N, elevated BMD (all P<0.01 vs controls), and reduced Tb.Sp (0.27 ± 0.01 mm; P<0.0001). Histology confirmed dense collagen/mineralization without inflammation, validating efficacy and biocompatibility. Ce@MSN-DFO/CS/nHAp scaffold integrates sequential drug release, mechanical strength, and osteogenic enhancement, synchronizing vascularization and bone regeneration for critical defect repair.