Development of hierarchical osteotropic-antibacterial NiTi surfaces via synergistic femtosecond laser texturing and anodization

Bone defects caused by trauma or severe diseases present significant clinical challenges. In this study, a multifunctional, multiscale therapeutic platform based on NiTi alloy was developed, exhibiting enhanced osteointegration and antibacterial performance. Femtosecond laser direct writing was first used to create micro-grooves with periodic ripple structures, promoting osteointegration via contact guidance effects. Subsequent anodizing generated a nanostructured porous layer on this microstructure, further enhancing biocompatibility and osteointegration. Finally, a polydopamine coating was applied to facilitate the in-situ incorporation of nanosilver, imparting strong antibacterial properties while simultaneously enhancing cell adhesion. MC3T3-E1 cell adhesion and differentiation assays confirmed the platform's robust osteogenic capacity. Additionally, the system achieved bactericidal efficiencies of 99.86 % against E. coli and 99.69 % against S. aureus. Overall, this study presents a comprehensive and effective method with high potential for bone defect repair.