1. Center for Functional Materials, Department of Physical Chemistry, Åbo Akademi University, Porthansgatan 3-5, FI-20500, Turku, Finland, Department of Biology, Åbo Akademi University, Artillerigatan 6A, FI-20520 Turku, Finland, and Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, P.O. Box 123, FI-20521, Turku, Finland