DLC for medical-technical applications modified by electron beam

The number of investigations on diamond like carbon (DLC) coatings for biomedical applications have increased strongly during the last years. The main advantages of DLC coatings are the excellent wear and friction behavior, depending on the deposition process a very high hardness and good biocompatibility. In this work, varying doses of low energy electron beam irradiation (eBeam) were applied on DLC coated samples for surface modification to generate new functional characteristics. The samples were characterized by contact angle measurement and calculation of the surface free energy including dispersive and polar components. The polar components increased significantly with rising eBeam dose. The cell biological response was investigated using human fibroblasts. Assessment of the cell number revealed a significantly reduced cell attachment on eBeam modified DLC coatings. In addition, the metabolic activity of the cells on these samples was reduced to the same extent. Nevertheless, using flow cytometric analysis, it was proved that the modified DLC surfaces had no cytotoxic effects on the investigated primary human fibroblasts. No increase in apoptosis and necrosis were recorded and the relative amount of vital cells was comparable to the standard reference. The reduced cell number on modified DLC coatings can be attributed to changes in the protein adsorption process on these surfaces. With this finding, it is possible to modify DLC coatings by eBeam treatment in order to direct cell adhesion and furthermore define areas with reduced cell attachment.