1. VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland, Programme for Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, FIN-00014, Helsinki, Finland, Institute of Materials Chemistry, P.O. Box 541, Tampere University of Technology, FI-33101 Tampere, Finland, and Department of Physical Chemistry, Åbo Akademi University, Porthansgatan 3-5, FIN-20500 Turku, Finland