LAUSR

Abstract Ni-Ti-O nanotubes (NTs) anodically grown on nearly equiatomic NiTi alloy are promising in biomedical field, but mechanical polishing pretreatment of the substrate usually results in severe pitting. The present work proposes to use electropolishing (EP) as pretreatment of anodization of the NiTi alloy to eliminate the side effect of mechanical polishing. Scanning electron microscopy was used to observe the morphology of the samples. Potentiodynamic polarization test was carried out to evaluate the corrosion behavior. Biological experiments were performed to assay their cytocomaptibility and antibacterial ability. Our results show pitting can be completely avoided after substrate EP pretreatment, yielding a macro smooth surface, while micro ordered nanotubular structure is well preserved. EP pretreatment enhances the corrosion resistance and antibacterial ability of the NiTi alloy when compared with that of mechanically polished sample, and all the samples show no appreciable cytotoxicity, clearly indicating EP is a promising pretreatment for fabricating Ni-Ti-O NTs on the NiTi alloy for biomedical applications.