Titanium oxide nanotube layers by anodization have received considerable attention in biomedical application. Previous studies have demonstrated increased osteoblast (bone-forming cell) adhesion and function on nanotube layers compared with unanodized counterparts. More recently, one study showed amorphous TiO(2) nanotube diameter determined cell fate. The anatase phase is known to be much more beneficial for bone growth than amorphous phase, so there is increasing demand to explore the response of osteoblast on anatase phase TiO(2) nanotube layers. For this reason, we evaluated MC3T3-E1 preosteoblast behavior on different diameter nanotube layers with anatase phase. The results showed that the diameter of 20-70 nm provided an effective length scale for cell adhesion, alkaline phosphatase activity, and mineralization. However, cell adhesion, alkaline phosphatase activity, and mineralization were severely impaired on nanotube layers with 100-120 nm. Interestingly, the filopodia seemed not spread into the nanotubular and like extending anatase nanotube walls, where there may be higher numbers of atoms at the surface compared to the nanotubular architecture. To our surprise, the proliferation rates of cells cultured on anatase nanotube layers increased with increasing tube diameter from 20 to 120 nm, which may be attributed to different length and nanometer-scale roughness of the nanotube layers.
(c) 2010 Wiley Periodicals, Inc.