Efficient Powder Removal and Micro-Nano Structural Formation in 3D-Printed Porous Titanium Implants for Enhanced Osteogenesis

Powder bed fusion-laser beam enables the fabrication of patient-specific medical implants; however, the complete removal of residual powders from complex porous architectures remains a major challenge, compromising biological performance. In this study, a high-voltage (90 V) anodic oxidation (AO) surface polishing strategy was developed to achieve efficient powder removal and surface optimization of triply periodic minimal surface gyroid porous titanium implants. AO treatment markedly reduced surface roughness, slightly enlarged the pore size by approximately 30 to 50 μm while maintaining an overall pore size of 300 to 600 μm, and generated a honeycomb-like microstructure favorable for cell adhesion and bone ingrowth. X-ray photoelectron spectroscopy analysis confirmed the formation of a stable and compact TiO₂ film, which enhanced hydrophilicity and negative surface charge, thereby promoting calcium phosphate deposition and osteogenic mineralization. Both in vitro and in vivo evaluations demonstrated significantly improved early-stage cell adhesion, long-term mineralization, and bone regeneration after AO treatment compared with untreated controls. Polished CP-Ti-AU-45 specimens achieved a new bone mineral density of 0.19 g/cm³ and a bone volume fraction of 33.8%. The molecular mechanism may involve the activation of extracellular matrix-receptor interactions, adhesion plaques, and PI3K-Akt signaling pathways while inhibiting ferroptosis-related signaling pathways, leading to a significant increase in the messenger RNA levels of Runx2 and Mef2c. The AO polishing strategy preserved the mechanical integrity of porous metals while integrating efficient powder removal with surface functionalization, thereby substantially enhancing the osseointegration potential of porous metallic implants.