Effect of the ratio of oxygen to nitrogen on the physicochemical and biocompatibility properties of titanium oxynitride

In this work, titanium surfaces were treated by plasma assisted thermochemical treatments in a plasma atmosphere containing Ar–N2 – O2 mixtures. Different N2/O2 ratios were used to investigate their effects on the physicochemical and biocompatibility properties of titanium. The crystalline and topographic phases of the surfaces by grazing incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM) were performed. The sessile drop test to measurements of contacts angles of both distilled water and platelet-rich plasma (PRP) was used to evaluate the wettability. Platelet adhesion was determined by the distance and platelet aspect ratio, in addition to the visual aspect of the formed platelet clusters by scanning electron microscopy (SEM) and AFM. In general, higher concentrations of nitrogen in the plasma showed greater platelet adhesion, indicating a biocompatible surface potential application in different areas such as in dental and orthopedic implants. On the other hand, samples treated with higher concentration of oxygen in the plasma showed low platelet adhesion, indicating that they are appropriate for application in devices such as stents, in which the maintenance of the blood flow pattern is essential. •Surfaces treated with higher N/O ratio caused higher platelet activation and aggregation.•Surfaces treated with a lower N/O ratio caused less platelet aggregation, suggesting an anti-thrombotic effect.•By adjusting the N/O ratio, extreme platelet adhesion properties can be obtained.