Synthesis of nanoscale oxide scaffold on Nitinol surface using hydrothermal treatment

Abstract

Nanostructured scaffolds were synthesized on the surface of equiatomic NiTi alloy (Nitinol) via hydrothermal treatment at 120 ± 1°C and 250 kPa using alkali (NaOH) solution of different strength. The scaffolds were found to be composed of intermingled nanopetals with varying morphology and phase content depending on the treatment time and alkali concentration. Single or mixed Ni₃Ti₃O, NiTiO₃, H₂Ti₃O₇ and TiO₂ (anatase and rutile) phases were observed in the scaffold by X-ray diffraction study. Standard hemolysis testing showed significant biocompatibility improvement of the scaffolds grown in low strength alkali. Measurement of Ni release in the simulated body fluid (SBF) revealed that Ni release can be decreased from ∼60 μg L^− 1 for the mechanically polished bare NiTi surface to ∼2·7 μg L^− 1 for the scaffolded surface (scaffolds grown in low strength alkali).