[1] Univ Tubingen, NMI Nat & Med Sci Inst, D-72770 Reutlingen, Germany
[2] Univ Aarhus, Interdisciplinary Nanosci Ctr, DK-8000 Aarhus C, Denmark
[3] Univ Aarhus, Dept Mol Biol, DK-8000 Aarhus C, Denmark
[4] Univ Porto, INEB, Div Biomat, P-4150180 Oporto, Portugal
[5] Univ Porto, Fac Engn, P-4200465 Oporto, Portugal