Low-energy electron-beam modification of DLC coatings reduces cell count while maintaining biocompatibility

Surface coating is a well investigated process to adapt surface properties for special biomedical applications. Over the past two decades, DLC coatings and their modification have been the subject of intense research for such purposes. As only the surface dictates an implant's interaction with the surrounding tissue and its specific cells, the surface modification is an appropriate tool to adapt certain surface characteristics of a material or coating, while leaving its bulkproperties untouched.DLC coatings allow the combination of characteristics of diamond and carbon. Especially the hydrogen content and the different bonding structures play a crucial role in determining the properties of these coatings. Several deposition methods are available. In most cases, vapor deposition is the basic physical principle. Currently, plasma-activated chemical vapor deposition, magnetron sputtering, and cathodic-arc deposition represent the most established deposition methods. For many substrates to be coated, the coating is realized by surface pre-treatment, adhesion-promoting intermediate layers or the incorporation of other elements like Si.DLC coatings can be used as barrier layers. This point is often addressed within medical applications to prevent corrosion and biocorrosion phenomena and therewith improve biocompatibility. Another goal is the improvement of wear and friction characteristics within these applications. Theuse of DLC coatings in hematologically compatible applications and implants are under investigation as well.The adaption and improvement of the performance and capabilities ofDLC coatings are realized using surface modification technologies. Thereby, the modification methods can vary from doping with different elements to post-treatment with ionizing radiation. By these techniques the improvement of the bactericidal activity as well as the biocompatibility of the DLC coatings are addressed. The partial modification of DLC coated surfaces is also under investigation in order to control cell adhesion by scribing particular surface patterns or adapting distinct characteristics of the surface. Within this work, the suitability of DLC coatings for medical applications modified by non-thermal electron-beam was investigated. Besides surface characterization using contact angle measurement, also cell biological investigations were conducted to determine cell behavior on the modified surfaces. The investigation focused especially on cell adhesion as well as possible toxic effectsresulting from the modified surfaces.