Crystal Surfaces Crystallographic orientation, and therefore the arrangement and coordination number of surface atoms, defines the surface energy and wettability, subsequently controlling the cellular response to blood-contacting biomaterials. Depending on the crystallographic orientation of TiO2 (rutile) surfaces, fibrinogen adsorbs typically in a trinodular and/or globular conformation, determining platelet adhesion and activation. Rutile surface crystallographic orientation may determine the risk of blood clotting. This work is highlighted in article 2202508 by Klaus D. Jandt and co-workers.