Strontium-Doped Whitlockite Scaffolds for Enhanced Bone Regeneration.

Bone graft substitutes to repair critical-sized bone fractures have experienced significant development over the last few decades. Among them, whitlockite (WH)-based bone grafts have proven to be effective in mediating bone healing. In the current study, a next generation, nature-inspired scaffold was developed with strontium-functionalized whitlockite nanoparticles (nSrWH) to enhance the intrinsic properties of WH. A series of nSrWH (with 2.5, 5, 7.5% Sr atomic substitution) were fabricated using a rapid-mixing wet precipitation route. Subsequently, the functionalized whitlockite was integrated into a gelatin-chondroitin sulfate scaffold and subjected to both and studies to investigate its osteogenic potential. Results indicated that nSrWH-containing scaffolds promoted osteogenic differentiation while inhibiting osteoclast activity. The positive impact of nSrWH was found to be dose-dependent, with the 7.5% Sr atomic substitution exhibiting the most significant results. Furthermore, the scaffold induced superior bone regeneration compared to its undoped counterpart in the mouse calvarial critical-sized defect model. Collectively, these findings suggest that nSrWH nanoparticles inherit the beneficial properties of whitlockite, coupled by the therapeutic effects of Sr, operating in concert for an overall enhanced bone regeneration. As such, they constitute promising candidates to meet the biomedical requirements for bioactive bone graft substitutes.