Nanosecond Laser-Assisted Direct Integration of Whitlockite onto Bone Implant Surfaces for Enhanced Bone Regeneration

Whitlockite (WH), a magnesium-enriched bone mineral, offers significant potential for bone regeneration due to its high bioresorbability and osteogenic properties. Despite these advantages, its application has been hindered by challenges in synthesizing WH directly on implant surfaces. To address this, a laser-assisted strategy is developed for the in situ formation of WH-containing coatings on bone implants. To overcome the thermodynamic and kinetic barriers of WH synthesis, a magnesium calcium phosphate (MCP) intermediate is employed, a kinetically accessible and magnesium-rich phase, as a precursor to WH. The MCP intermediate is readily produced via laser-induced hydrothermal processing from a magnesium-enriched solution. Subsequent localized laser irradiation enabled partial transformation of the MCP into WH. Multiscale analyses confirmed successful WH formation, showing rhombohedral morphology and distinct chemical features. In vivo testing in a rat femoral defect model showed that WH-integrated implants significantly enhanced bone-implant integration and early-stage vascularization, attributed to the sustained release of osteogenic calcium and magnesium ions. This laser-assisted method can offer a scalable and effective strategy for implant surface modification in regenerative medicine.