Magnetically responsive micro-clustered calcium phosphate-reinforced cell-laden microbead sodium alginate hydrogel for accelerated osteogenic tissue regeneration.

The rising prevalence of bone injuries has increased the demand for minimally invasive treatments. Microbead hydrogels, renowned for cell encapsulation, provide a versatile substrate for bone tissue regeneration. They deliver bioactive agents, support cell growth, and promote osteogenesis, aiding bone repair and regeneration. In this study, we synthesized superparamagnetic iron oxide nanoparticles (Sp) coated with a calcium phosphate layer (m-Sp), achieving a distinctive flower-like micro-cluster morphology. Subsequently, sodium alginate (SA) microbead hydrogels containing m-Sp (McSa@m-Sp) were fabricated using a dropping gelation strategy. McSa@m-Sp is magnetically targetable, enhance cross-linking, control degradation rates, and provide strong antibacterial activity. Encapsulation studies with MC3T3-E1 cells revealed enhanced viability and proliferation. These studies also indicated significantly elevated alkaline phosphatase (ALP) activity and mineralization in MC3T3-E1 cells, as confirmed by Alizarin Red S (ARS) and Von Kossa staining, along with increased collagen production within the McSa@m-Sp microbead hydrogels. Immunocytochemistry (ICC) and gene expression studies supported the osteoinductive potential of McSa@m-Sp, showing increased expression of osteogenic markers including RUNX-2, collagen-I, osteopontin, and osteocalcin. Thus, McSa@m-Sp microbead hydrogels offer a promising strategy for multifunctional scaffolds in bone tissue engineering.