Albumin and fibronectin adsorption on treated titanium surfaces for osseointegration: An advanced investigation

Protein adsorption has a central role in the outcome of implants. However, there is no consensus about the impact of the different surface properties on the material-protein interactions. Here, the adsorption of albumin and fibronectin in near-physiological concentration is investigated on three differently treated titanium-based surfaces and compared after a thorough characterization. The different titanium surfaces have very different surface properties, in particular regarding roughness, oxide porosity, wettability, surface energy, and zeta potential, which are all known to deeply affect protein adsorption. By merging several characterization techniques, some conventional and some innovative, it was possible to discriminate the effect of surface properties on different aspects of protein adsorption. Despite forming a continuous layer on all samples, the amount of proteins bound to the surface is mainly due to surface roughness and topography, which can overcome the effect of wettability and surface energy. On the other hand, the secondary structure of albumin and fibronectin and their orientation are determined by the hydroxyl groups exposed on the surfaces, depending on their surface concentration and acidic reactivity in the former, and the surface zeta potential in the latter.