1. Biomolecular and Organic Electronics, IFM, Linköping University, 581 83 Linköping, Sweden, Fax: (+46) 13‐28‐89‐69
2. Current address: Institute of Neuropathology, University Hospital Zürich, 8091 Zürich, Switzerland, Fax: (+41) 44‐255‐54‐02
3. Chemistry, IFM, Linköping University, 581 83 Linköping, Sweden
4. Division of Cell Biology and Diabetes Research Centre, Linköping University, 581 83 Linköping, Sweden
5. Department of Physics, The Norwegian University of Science and Technology, 7491 Trondheim, Norway