Surface modification of NiTi alloys: Biological effects of tantalum oxide coatings

In recent years, issues related to improving implant biocompatibility have focused on the development of various types of coatings. This paper presents data on surface modification of NiTi alloy for cardiovascular applications using the example of occluders, implants applied to close heart defects. The use of this alloy, despite its good biocompatibility and pseudoelastic effect, is associated with the risk of allergies, thrombosis, or problems occurring during tissue overgrowth. The current challenges in NiTi-based implants are primarily centered on improving biocompatibility and reducing adverse biological responses, which have been achieved through the development of innovative surface treatments and coatings. To reduce these negative effects, we evaluated a surface modification involving the application of a tantalum oxide coating by atomic layer deposition on a substrate subjected to electrochemical polishing. To complement physicochemical tests, in vitro biological tests were performed, including cytotoxicity, cell proliferation, thrombogenicity, and proinflammatory cytokine levels. We also evaluated whether the produced coating improved the fluoroscopic visibility of the material. The results showed a favorable effect of the coating on the properties of the tested material, reducing cytotoxicity, thrombogenicity, and cytokine levels and enhancing cell proliferation.