Biocompatibility of TiO2 nanotubes with different topographies

The biological response of osteoblast cells to implant materials depends on the topography and physicochemistry of the implant surface and this determines the cell behavior such as shaping, adhesion and proliferation, and finally the cell fate. In this study, titanium (Ti) was anodized to create different topographies of titania nanotubes (TNTs) to investigate the cell behavior to them. TNTs with and without a highly ordered nanoporous layer on their top surface were fabricated using two-step and one-step anodizing processes, respectively. The TNTs without a highly ordered nanoporous layer on the top surface exhibited a rougher surface, higher surface energy and better hydrophilicity than the TNTs with such a layer. Osteoblast-like cells (SaOS2) were used to assess the biocompatibility of the TNTs with different topographies in comparison to bare cp-Ti. Results indicated that TNTs can enhance the proliferation and adhesion of osteoblast-like cells. TNTs without a highly ordered nanoporous layer exhibited better biocompatibility than the TNTs covered by such a nanoporous layer. Cell morphology observation using confocal microscopy and SEM indicated that SaOS2 cells that were adhered to the TNTs without the highly ordered nanoporous layer showed the longest filopodia compared to TNTs with a highly ordered nanoporous layer and bare cp-Ti.