The disclosure features blood compatible articles and methods of making the articles. The methods include providing a substrate and forming a rough surface on the substrate. The rough surface includes a plurality of three-dimensionally curved features each having a radius of curvature of less than about 50 nm. The surface includes a sufficient concentration of features per unit area to limit blood coagulation activity on the substrate and to limit the number of platelets that adhere to the surface when the substrate is exposed to blood.
