The role of nanometer and sub-micron surface features on vascular and bone cell adhesion on titanium.

The quantified contribution of pure nanometer (features less than 100 nm in both the lateral and vertical scale) and sub-micron (features larger than 100 nm in the lateral scale) surface structures on the adhesion of vascular (endothelial) and bone (osteoblasts) cells were demonstrated in this study. Compared with flat titanium surfaces, sub-micron surface features led to a 27% increase in surface energy and promoted endothelial cell adhesion density by 200%. In addition, nanometer surface features also led to a 10% increase in surface energy and a 50% increase in endothelial cell adhesion density compared to flat titanium surfaces. Using aligned patterns of such features on titanium, it was clearly identified that both endothelial and bone cells selectively adhered onto sub-micron and nanometer surface features by 400% and 50% more than onto flat regions, respectively. Thus, the surface patterns developed in this study clearly confirmed that sub-micron to nanometer titanium surface features enhanced cytocompatibility properties for both endothelial and bone cells. Although sub-micron features on titanium had the highest surface energy and the greatest cell adhesion densities, nanometer surface features in this study were more efficient surface features increasing both surface energy and cell adhesion more with respect to smaller changes in surface area and surface roughness (compared to sub-micron surface features on titanium which had considerably larger changes in surface area and surface roughness).