Long-term stable surface modification of DLC coatings

The use of coatings based on diamond like carbon (DLC) for medical applications was established during the last years. Main advantages of these coatings are its high hardness, good wear and friction behavior and its biocompatibility. Using low-energy electron-beam treatment, we addressed the surface modification of DLC coatings. The aim was to generate new biofunctional surface characteristics that are long-term stable.Electron-beam modification resulted in significantly increased surface hydrophilicity, giving rise to the conclusion, that biological reaction on these surfaces will also be influenced by the modification. Furthermore, the stability of the surface modification was investigated. Therefore, the modified samples were stored for 8 weeks under ambient conditions. Additionally, the samples were stored in physiological saline solution at 37°C for 8 weeks. The stability of the modification was analyzed by contact angle measurement confirming no changes over the whole period of storage. In addition, the stability against standard cleaning and sterilization procedures was investigated. The durability of the modification to withstand these cleaning procedures was also proven.With these findings, the low-energy electron-beam modification seems to be a suitable tool for surface modification of DLC coatings. Thereby, the very good long-term stability is a great improvement in comparison to conventional surface modification methods like plasma treatment. In order to investigate the suitability of the modified coatings for biomedical applications, the cellular response was investigated using human fibroblasts, revealing a significantly reduced cell count on modified surfaces while maintaining their biocompatibility. By modification of the DLC surfaces, it is possible to adapt the cell adhesion on the treated surface areas. These findings demonstrate electron-beam treatment to be applicable for partial surface modification and functionalization within biomedical applications.