Interaction of osteoblast -TiO2 nanotubes in vitro: The combinatorial effect of surface topography and other physico-chemical factors governs the cell fate

In the context of surface modification of implants by TiO2 nanotubes, the topography of the nanotubes has been considered as a sole modulator of cellular response of adherent cells. However, a recent report has indicated about the existence of other contributing factors. Keeping this contradiction in mind, here we have performed a comprehensive study to account the contribution of the various factors such as morphological aspects, physico chemical aspects and the topographical features of TiO2 nanotubes on the cellular response. Here, the TiO2 nanotubes of varied topography were synthesized on the Ti6Al4V surface through anodic oxidation. SEM analysis showed that there was a variation in tube diameter, cross-sectional length, tube density and wall thickness along with the variation in oxidation time and voltage. An attempt to co-relate the cellular response of osteoblast cells (MG-63) cultured on the nanotubes has revealed that except cell proliferation; cell adhesion, spreading, vinculin distribution (focal adhesion) and differentiation (ALP activity) do not possess any direct relationship with the nanotube topography. Further, by comprehending the cellular responses with the variation in the extent of anatase phase (XRD study), surface roughness and wettability of nanotube surfaces, we established that the variation in cellular responses is a combinatorial effect of surface topography and other physico-chemical properties of TiO2 nanotubes. This study will help in developing bioactive implant surfaces modified with TiO2 nanotubes, for clinical application.