1. Biomedical Materials Group, Institute of Pharmacy; Martin Luther University Halle-Wittenberg; Heinrich-Damerow-Strasse 4 06120 Halle (Saale) Germany
2. Department of Applied Physics; Chalmers University of Technology; 412 96 Göteborg Sweden
3. Biomedical Engineering Laboratory; Faculty of Mechanical Engineering, University of Patras; Rion 26500 Patras Greece