Titania nanotubes with controlled diameters direct cell fate. P. Schmuki and co-workers at Friedrich Alexander University of Erlangen–Nuremberg (Erlangen, Germany) generated self-assembled TiO2 nanotubes in a highly regular arrangement by anodizing titanium sheets in a phosphate–fluoride electrolyte at voltages that ranged from 1 to 20 V. The tube diameters could be precisely controlled.
The authors used green fluorescent protein–labeled rat mesenchymal stem cells to determine cell response to tube diameter. Cell adhesion and spreading were greatest on tubes with 15-nm diam and declined significantly with increasing diameter.
TiO2 tubes with pore sizes <30 nm provided an effective length scale for accelerated formation and strongly enhanced cell activity compared with nonporous TiO2 surfaces. Tubes with >50-nm diam resulted in dramatically reduced cell activity and a high degree of programmed cell death. The use of TiO2 nanotubes with controlled diameters can provide a powerful tool to improve cell adhesion and tissue integration of various cell types. (Nano Lett.2007,7,1686–1691; George Xiu Song Zhao