Evaluation of in vitro corrosion behavior of titanium oxynitride coated stainless steel stents

Coronary artery disease (CAD) affects every fifth person in the world. In general, stent implantation is a common treatment procedure for CAD. In recent years, titanium oxynitride (TiOxNy) coatings on bare metal stents (BMS) attracted the attention of many researchers around the world due to their promising results and improved surface properties. However, good coating adhesion and coverage of the inner surface in stent applications is a challenging task. Moreover, enhanced corrosion resistance and durability over a longer period under the influence of an aggressive biological environment is one of the main requirements in designing coated bare-metal stents. In this work, the titanium oxynitride (TiOxNy) coated stainless steel stents were fabricated by magnetron sputtering and the corrosion behavior of coated and uncoated stents has been studied by using immersion, fluid dynamic, and electrochemical corrosion tests. For the first time, the entire stent surface has been used for quantitative corrosion tests on stents. To this context, we discuss and compare the in vitro biostability and corrosion behavior of stainless steel (316L) stents coated with titanium oxynitride films (TiOxNy) investigated by immersion, fluid dynamic, and electrochemical corrosion tests. TiOxNy coatings provide valuable stability to the BMS against harsh environments or conditions. Significantly, the coated stents are remarkably stable compared with the reference uncoated stents (316L BMS) regardless of the feeding ratio of O2 and N2. The variation of stent parameters in future works is possible to get more anticorrosive and biostable behavior; therefore, the results could provide the basis for further research.