Nickel Free Alloy for Cardiovascular Stents Application Against Restenosis Associated with Nickel: A Review

The commercialized coronary stents are generally made of biomedical stainless steels (316L) and biomedical cobalt-based alloy (for example L605 alloy) due to their good combination of properties, especially their excellent mechanical properties. However, there are above 10% nickel content in these stents materials, which was known to trigger the inflammation and allergic responses around stents implant location, and contradiction associated with in-stent restenosis when the nickel ions began to release from stents for various corrosion. Consequently, the potential adverse effect of nickel ions release has prompted the development of many nickel free alloy stents materials. In this paper, the controversy of nickel and in-stent restenosis, and the development of nickel free alloy for cardiovascular stents application are reviewed. Nickel free cobalt alloy maybe a good choice for stent materials, but further research is needed. Many research results have proved the high nitrogen nickel-free stainless steel is a good potential stents material and suitable for clinical use, therefore the austenitic high nitrogen nickel-free stainless steels may offer an alternative to further improve the performance of the current coronary stents.