Influence of passive layer fabrication method on physicochemical and antimicrobial properties of the Ta2O5 layer on NiTi alloy.

The use of nickel-titanium (NiTi) alloy in implants, despite its good biocompatibility, is not entirely inert to the human body. To reduce nickel ions and improve the hemocompatibility of implants for blood contact, a thin layer of tantalum oxide (Ta 2 O 5) was proposed. Although nitinol self-coats a thin layer of TiO 2 titanium dioxide to protect against corrosion, many studies emphasized the need to enhance this protection. Therefore, in the first stage of this study, the alloy surface was prepared by four different methods, producing a passive interlayer. Then a Ta 2 O 5 coating was applied, and the properties with and without the layer were investigated. The resulting coating was applied to the NiTi alloy in the initial state and passivated in water, and perhydrol showed a high adhesion to the substrate. However, the coating deteriorated resistance to pitting corrosion and increased surface wettability. For the initial condition and passivation in perhydrol, the coating affected the reduction of bacterial adhesion to the substrate. Surface preparation directly influenced the optimization of the deposition of this layer on implants in contact with blood. The results suggest that the properties studied were strongly correlated with the type of passive interlayer. • The results of corrosion resistance tests showed that the Ta2O5 layer improves pitting corrosion resistance regardless of the method of passivation substrate. • The application of Ta2O5 coating, regardless of the application parameters and surface preparation, decreased the number of attached bacterial colonies to the NiTi alloy substrate. • The scratch test results confirmed an excellent adhesion of the layer to the substrate compared to other layers applied with the ALD method. • Surface wettability tests showed that the Ta2O5 film reduced the wetting angle, providing hydrophilic properties (θ < 90°), which could negatively affect hemocompatibility. [ABSTRACT FROM AUTHOR]