1. Department of Dental Materials and Biomaterials Research RWTH Aachen University Hospital Pauwelsstrasse 30 52074 Aachen Germany
2. Electron Microscopy Facility Institute of Pathology RWTH Aachen University Hospital Pauwelsstrasse 30 52074 Aachen Germany
3. Institute of Physical Chemistry RWTH Aachen University Landoltweg 2 52074 Aachen Germany
4. Physical Chemistry DWI–Leibniz Institute for Interactive Materials Forckenbeckstr. 50 52074 Aachen Germany