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.