1. Technical and Macromolecular ChemistryPaderborn University Warburger Strasse 100 33098 Paderborn Germany
2. Present address: Structural Biophysics LaboratoryCenter for Cancer ResearchNational Cancer Institute Frederick MD 21702-1201 USA
3. Biohybrid Materials, Department of Bioproducts and BiosystemsAalto University P. O. Box 16100 00076 Aalto Finland
4. HYBER Center of Excellence, Department of Applied PhysicsAalto University P. O. Box 16100 00076 Aalto Finland