Nanostructured Ti6Al4V alloy fabricated using modified alkali-heat treatment: Characterization and cell adhesion.

In order to optimize the creation of a nanostructured surface on Ti6Al4V titanium alloy, an alkali treatment was performed using a 10-M NaOH solution at various temperatures (30, 40, 50, and 60°C) so as to determine the optimal temperature. This was combined with subsequent heat treatments (200, 400, 600, and 800°C) in air. The effects of different temperatures for the latter treatments on the nanostructure surface and the initial cell adhesion were evaluated, and the optimal temperature of the alkali solution was found to be 30°C. Further, the nanotopography, surface chemistry, and surface roughness of the nanoporous structure were retained after heat treatments performed at 200, 400, and 600°C, and only the phase structure was altered. The amorphous sodium titanate phase, the content of which increased with increased heat-treatment temperature, may have played a role in promoting cell adhesion on the nanoporous surface. However, heat treatment at 800°C did not enhance the cell-surface attachment. Rather, the nanostructure degraded significantly with the reappearance of Al and V.