1. Bio-Nanotechnology Laboratory, Department of Neuroscience and Pharmacology & Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
2. Niels Bohr Institute, Center for Quantum Devices & Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100, Copenhagen, Denmark
3. Institut de Biologie Physico-Chimique, UMR 7099, CNRS/Université Paris-7, 13 Rue Pierre et Marie Curie, F-75005 Paris, France