1. Fachbereich Physik, Philipps Universität Marburg, 35037 Marburg, Germany
2. Fachbereich Physik und Chemie, and Center for Hybrid Nanostructure (CHyN), Universität Hamburg, 22761 Hamburg, Germany
3. Department of Laboratory Medicine (LABMED), Karolinska Institutet, 171 77 Stockholm, Sweden
4. Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Dublin 4, Ireland
5. CIC Biomagune, 20014 San Sebastian, Spain