Characterization and Investigation of Biological Properties of Ag-Doped TiO2 Coatings Fabricated on Titanium

In present study, Ag-doped TiO2 bioceramic coatings were fabricated on cp-Ti by plasma electrolytic oxidation (PEO) and physical vapor deposition (PVD). The phase composition, surface microstructure, elemental composition, surface topography, wettability and chemical state of the PEO and Ag-doped TiO2 surfaces were characterized by using powder- and thin film-X-ray diffraction (TF-XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), surface profilometer and contact angle measurement system (CAM), respectively. The PEO coating’ surface was porous and rough due to the nature of process. The Ti, anatase-TiO2, rutile-TiO2 and Ag2O phases were detected on the Ag-doped PEO surfaces by TF-XRD while The Ti, anatase and rutile phases were obtained on the PEO surfaces. The surface morphology structure of the PEO coating was not changed by PVD process. The Ti, O, P and Ag elements were observed on the Ag-doped PEO surfaces by EDS. Also, the amount of Ag existed on the surface was below cytotoxic limit. The Ag-doped PEO surfaces indicated better hydrophilic character to the PEO surface owing to increasing polarity of the surfaces. In vitro hydroxyapatite-forming ability was evaluated by immersion in simulated body fluid (SBF) at 36.5 °C for 28 days. The Ag-doped PEO surfaces showed good hydroxyapatite formation ability compared to the PEO surface. The antibacterial activity was evaluated by exposing the samples to Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) and they were compared by the reaction of the pathogens to Ag-doped PEO with the PEO controls. The antibacterial ability of the Ag-doped PEO surfaces was significantly improved respect to the PEO surfaces for S. aureus and E. coli.