Molecular modeling of fibronectin adsorption on topographically nanostructured rutile (110) surfaces

To investigate the topographical dependency of protein adsorption, molecular dynamics simulations were employed to describe the adsorption behavior of the tenth type-III module of fibronectin (FN-III ₁₀ ) on nanostructured rutile (110) surfaces. The results indicated that the residence time of adsorbed FN-III ₁₀ largely relied on its binding mode (direct or indirect) with the substrate and the region for protein migration on the periphery (protrusion) or in the interior (cavity or groove) of nanostructures. In the direct binding mode, FN-III ₁₀ molecules were found to be 'trapped' at the anchoring sites of rutile surface, or even penetrate deep into the interior of nanostructures, regardless of the presented geometrical features. In the indirect binding mode, FN-III ₁₀ molecules were indirectly connected to the substrate via a hydrogen-bond network (linking FN-III ₁₀ and interfacial hydrations). The facets created by nanostructures, which exerted restraints on protein migration, were suggested to play an important role in the stability of indirect FN-III ₁₀ -rutile binding. However, a doubly unfavorable situation - indirect FN-III ₁₀ -rutile connections bridged by a handful of mediating waters and few constraints on movement of protein provided by nanostructures - would result in an early desorption of protein.