In vitro corrosion and cytotoxicity on microcrystalline, nanocrystalline and amorphous NiTi alloy fabricated by high pressure torsion

Bulk nanocrystalline and amorphous Ni50.2Ti49.8 alloy samples were successfully prepared from commercial microcrystalline Ni50.2Ti49.8 alloy discs by high pressure torsion (HPT) technique. Then their corrosion resistance, surface wettability and cytotoxicity were further studied from the viewpoint of biomaterials. In both Hank's solution and artificial saliva, bulk nanocrystalline and amorphous Ni50.2Ti49.8 alloys showed significantly higher pitting corrosion potentials than that of microcrystalline Ni50.2Ti49.8 alloy. Meanwhile, the amount of Ni ion release after immersion in Hank's solution was minor, far below the threatening threshold of daily diet. Murine fibroblast and osteoblast cell lines were indirectly co-cultured with experimental sample extracts, indicating no cytotoxicity. Amongst all samples, the nanocrystalline Ni50.2Ti49.8 shows promising as best biomaterial candidate for its good combination of mechanical property, corrosion resistance and cytocompatibility.