The osteogenic, anti-oncogenic and antibacterial activities of selenium-doped titanium dioxide coatings on titanium

There is an urgent need to develop multifunctional titanium (Ti)-based bone implants exhibiting osteogenic, anti-oncogenic, and antibacterial properties in patients undergoing bone cancer resection. Herein, we explored the use of a micro-arc oxidation approach to generate Ti substrates coated with microporous titanium dioxide (TiO2) coatings containing fixed Ca and P contents (TO) but different levels of Se (TO-S3, TO-S8, and TO-S14, with numbers corresponding to mean Se contents). X-ray photoelectron spectroscopy was used to confirm Se incorporation into these TO preparations, and Se incorporation was found to have no impact on overall TO microstructure, TiO2 phase composition, wettability, and surface roughness. All tested coatings were able to firmly bond to the Ti substrate and exhibited good long-term adhesion strength in biological settings. We additionally assessed the impact of these coatings on the behavior of bone mesenchymal stem cells (MSCs), cancerous osteoblasts, S. aureus, and E. coli bacteria cells, revealing the observed effects to be positively correlated with Se amount. Indeed, high-dose Se incorporation (TO-S14) markedly suppressed the proliferation and osteogenic differentiation of these cells, indicating that properly optimized Se doses are essential in order to achieve enhanced osteogenic, anti-oncogenic, and antibacterial efficacy. Of the tested coatings, TO-S8 exhibited the most robust osteogenic, anti-oncogenic, and antibacterial activity. Our findings thus demonstrate that Se doping is a feasible approach to enhancing the osteogenic, anti-oncogenic, and antibacterial properties of orthopedic Ti implants, thus potentially improving their overall clinical performance.