Transparent Titanium Dioxide Nanotubes: Processing, Characterization, and Application in Establishing Cellular Response Mechanisms

The therapeutic applications of titanium dioxide nanotubes (TiO 2 NTs) as osteogenic surface treatments for titanium (Ti)-based implants are largely due to the finely tunable physical characteristics of these nanostructures. As these characteristics change, so does the cellular response, yet the exact mechanisms for this relationship remains largely undefined. We present a novel TiO 2 NT imaging platform that is suitable for use with live-cell imaging techniques, thereby enabling, for the first time, dynamic investigation of those mechanisms. In this work, fabrication methods for producing transparent TiO 2 NTs with diameters of 56 ± 6 nm, 75 ± 7 nm, 92 ± 9 nm, and 116 ± 10 nm are described. To demonstrate the diagnostic potential of these TiO 2 NT imaging platforms, the focal adhesion protein vinculin and actin cytoskeletal filaments were fluorescently tagged in osteoblasts and real-time, high-resolution fluorescent microscopy of live-cell interactions with TiO 2 NT substrates were observed. The scope of such a platform is expected to extend far beyond the current proof-of-concept, with great potential for addressing the dynamic response of cells interacting with nanostructured substrates.