Improved attachment of mesenchymal stem cells on super-hydrophobic TiO2 nanotubes

Self-organized layers of vertically orientated TiO2 nanotubes providing defined diameters ranging from 15 up to 100 nm were grown on titanium by anodic oxidation. These TiO2 nanotube layers show super-hydrophilic behavior. After coating TiO2 nanotube layers with a self-assembled monolayer (octadecylphosphonic acid) they showed a diameter-dependent wetting behavior ranging from hydrophobic (108 ± 2°) up to super-hydrophobic (167 ± 2°). Cell adhesion, spreading and growth of mesenchymal stem cells on the unmodified and modified nanotube layers were investigated and compared. We show that cell adhesion and proliferation are strongly affected in the super-hydrophobic range. Adsorption of extracellular matrix proteins as fibronectin, type I collagen and laminin, as well as bovine serum albumin, on the coated and uncoated surfaces showed a strong influence on wetting behavior and dependence on tube diameter.