1. Institute of Medical Physics and Biophysics, University of Szeged, Szeged, Hungary, Institute of Biophysics, Biological Research Center, Szeged, Hungary, Institute of Physics of Complex Matter, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland, Department of Applied and Environmental Chemistry, University of Szeged, Szeged, Hungary