Enhanced Biocompatibility in Anodic TaO _x Nanotube Arrays

This study first investigates the biocompatibility of self-organized TaO _x nanotube arrays with different nanotube diameters fabricated by electrochemical anodization. All as-anodized TaO _x nanotubes were identified to be an amorphous phase. The transition in surface wettability with TaO _x nanotube diameters can be explained based on Wenzel's model in terms of geometric roughness. In vitro biocompatibility evaluation further indicates that fibroblast cells exhibit an obvious wettability-dependent behavior on the TaO _x nanotubes. The 35-nm-diameter TaO _x nanotube arrays reveal the highest biocompatibility among all samples. This enhancement could be attributed to highly dense focal points provided by TaO _x nanotubes due to higher surface hydrophilicity. This work demonstrates that the biocompatibility in Ta can be improved by forming TaO _x nanotube arrays on the surface with appropriate nanotube diameter and geometric roughness.