Molecular modelling of protein adsorption on the surface of titanium dioxide polymorphs.

This paper reports a molecular modelling study of the adsorption of protein subdomains with unlike secondary structures on different surfaces of ceramic titanium dioxide (TiO(2)), forming a passivating film on titanium biomaterials that provides the interface between the bulk metal and the physiological environment, affecting its biocompatibility and performance. Using molecular dynamics methods, we study the effect of the nanoscale structure of the common TiO(2) polymorphs (rutile, anatase and brookite) on the adsorption of an albumin subdomain and on two connected fibronectin modules, respectively containing α-helices and β-sheets. We find that the larger protein subdomain shows a stronger adsorption, as expected because of its size, but also that the three surfaces behave differently. In particular, brookite shows the weakest adsorption, whereas anatase leads to the strongest intrinsic adsorption, in particular for the fibronectin modules. Moreover, the simulations indicate a significant conformational change of the adsorbed protein subdomains with extensive surface nanopatterning. These results show that classical molecular dynamics methods can provide useful information about the influence of nanostructure and topology on protein physisorption at a fixed surface chemistry.