Influence of surface textures and patterns produced by laser ablation on blood compatibility of stainless steel

Laser surface texturing (LST) is applied to modify the morphology of surface topographic features, inducing the corresponding effects on surface chemistry and wettability. This study focuses on application of this technique to treatment of materials surface used in cardiovascular stents. It is built upon an optimised LST process from previous work, and hemocompatibility test is carried out using whole human blood. Three different types of surface textures are prepared on 316 stainless steel as smooth grooved, rough grooved, and rough isotropy textures, respectively, using nano-second laser ablation. The characterization of surface morphology, roughness, chemistry and wettability are carried out following laser treatment. Depending on the geometry of the patterns produced, treated surfaces became more super-hydrophilic or more hydrophobic (water contact angle from 0° or up to 146.20 ± 1.37°). Blood contact test revealed the topographic effects on attachment and spreading of blood cells, with more cells observed on a smooth surface than on a rough surface. Hence, LST with nano-second laser can be used to introduce a large range of topographic features, from micro- to nano-scales. It would be a robust process to be included in the manufacturing of cardiovascular stents to improve the hemocompatibility of stainless steel.