Improving the cytocompatibility and functionality of titanium implants by adjusting the electrolyte of the...

Titanium implants are widely used in prosthodontics, but their bioinert surfaces can limit early osseointegration. This study examined whether electrolyte-tuned anodization can tailor TiO₂ nanotube (TNT) coatings to improve in vitro osteogenesis, angiogenesis, and inflammation-related responses.

Titanium was anodized in three electrolytes to produce TNT, TNT-H, and TNT-B coatings. Morphology and roughness were assessed by scanning electron microscope, phase/chemistry by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and wettability by contact angle. Cytocompatibility and functional responses were evaluated using bone marrow-derived mesenchymal stem cells, human umbilical vein endothelial cells, and RAW264.7 cells, including viability/adhesion assays, macrophage polarization and cytokine expression, and osteogenic/angiogenic assays.

TNT-B (mean pore diameter ∼188 nm) showed the most consistent improvements across endpoints, enhancing cell adhesion/proliferation, osteogenesis-associated markers, and angiogenesis-associated signals in vitro, while reducing pro-inflammatory cytokine expression and promoting M2-skewed polarization. TNT-H showed measurable responses versus TNT but did not outperform TNT-B in angiogenic assays under the tested conditions. XRD/XPS indicated minor Ti₆O- and defect-related signatures in TNT-B that are relevant to these responses. After annealing, corrosion resistance ranked TNT-H > TNT-B > TNT.

Electrolyte modulation enables the controllable fabrication of TNT architectures and surface chemistry. TNT-B demonstrates promising in vitro performance but exhibits reduced electrochemical stability relative to TNT-H, highlighting a bioactivity-stability trade-off and the need for further optimization and validation before clinical use.