Multi scale topography in titanium alloys by electron beam technique: influence on the tissue adhesion and bacterial contamination

Topographical surface modification in implants is an interesting topic of investigation to improve the tissue regeneration. Different cell types preferentially adhere to specific topographies. In the case of osteoblast cells, a rough surface improves the adherence and spreading of the cells, while fibroblasts are more sensitive to micro-surface patterns. Electron beam structuring has the potential to serve as a technique for controlling the surface topography as well as for increasing the tribological behavior on the surface of titanium alloys. This work shows examples of surface design in three different titanium alloys and the effect of the multi scale topography on the adherence, spreading and alignment of different cells and the bacterial adhesion. The in vitro investigations reveal a positive cell behavior on all structured titanium alloys for each cultivation time. The osteoblastic cells are even distributed with a polygonal morphology and build connections through elongated actin filaments, with significant increase of cell spreading area on surface structure with a finer canal shape in polygonal figures. Aligned and parallel micro grooves of 10 and 30µm wide shows positive effect on fibroblast, with strong alignment of the cells in 10µm grooves. Bacterial reduction in the first 48hs is observed and it might be related to microstructural features of the material on the surface.
On the other hand, the heat input given during the structuring modifies the microstructure of the material, observing an increment of the hardness by martensite formation in cp TiGr2 and Ti-6Al-4V and metastable phases with fine dispersed alpha grains in Ti15Mo