Interplay between corrosion behaviour and bioactivity of TiO₂ nanotubes on Ti6Al4V in physiological and inflammatory environments

Titanium and its alloys are widely used for biomedical applications in orthopedics and dentistry; however, achieving optimal osseointegration while maintaining corrosion resistance under inflammatory conditions remains challenging. In this study, TiO2nanotubes (NTs) were fabricated on Ti6Al4V alloy by electrochemical anodization and characterized to assess corrosion behaviour and bioactivity in both physiological and inflammatory simulated environments. Photoelectrochemical analysis revealed that the NTs-modified samples exhibit localized electronic states within the mobility gap, enhancing electronic conduction through the nanostructured oxide. Long-term immersion tests, combined with electrochemical impedance spectroscopy and ICP-OES measurements, demonstrated that NT-modified surfaces exhibit superior corrosion resistance compared to bare Ti6Al4V alloy, with cumulative ion release approximately half an one order of magnitude lower after 168 h of immersion . SEM analysis confirmed the morphological stability of NTs after 168 h of immersion in inflammatory media, whereas bare samples showed preferential dissolution of the beta-phase. Despite an increase in corrosion current density and a reduction of the passive region under inflammatory conditions, the nanotubular oxide facilitated Ca/P accumulation and hydroxyapatite formation in physiological environment. These results highlight that controlling the top-layer morphology through anodic TiO2nanotubes enables an effective balance between corrosion resistance and biological performance in implant-relevant environments.