Protein adsorption and the resulting surface-bound protein layer have long been recognized to play a significant role in cellular response, such as cell migration, proliferation etc.. To tailor the protein-surface affinity, the surface can be modified through various chemical and physical surface treatments. In particular, the possibility to enhance bioactivity and osseointegration via topographic surface modifications at nanometer scales has recently received considerable interest. As an established implant material, titanium with its passivating oxide layer is of particular relevance for many medical applications. However, the influence of nanoscale surface topography on protein adsorption onto titanium surfaces is so far not fully understood.
To investigate the effects of the nanostructured surface topography on protein adsorption, nano-rippled silicon substrates with varying periodicities were prepared using low-energy ion bombardment. The nanoscale ripple patterns form spontaneously by self-organization on the Si surface during off-normal irradiation with low-energy Ar+-ions. By optimizing the sputtering conditions, such as ion energy, the periodicity of ripple has been tuned between 20 nm to 50 nm. Magnetron sputter deposition under optimized conditions results in thin titanium films that perfectly follow the ripple patterns. The so fabricated nanopatterned titanium surfaces are employed to investigate the effect of nanoscale surface topography on the adsorption of various proteins by ellipsometry and atomic force microscopy.