1. Istituto Italiano di Tecnologia, Center for Life NanoScience, Viale Regina Elena 291, I-00161 Roma, Italy
2. Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, I-00185 Roma, Italy
3. Humboldt-Universität zu Berlin, Institut für Biologie, Invalidenstraße 42, D-10115 Berlin, Germany
4. Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin, Germany
5. Department of Physical and Chemical Sciences, University of L’Aquila, Via Vetoio, I-67010 L’Aquila, Italy
6. Department of Chemical Sciences, University of Padova, Via Marzolo 1, I-35131 Padova, Italy
7. CNR Institute of Nanoscience, Via Campi 213/A, I-41125 Modena, Italy
8. Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy