1. Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, N-0315 Oslo, Norway
2. Department of Pharmaceutics, School of Pharmacy, University of Oslo, P.O. Box 1068, Blindern, N-0316, Oslo, Norway
3. Department of Chemistry and iNANO Interdisciplinary NanoScience Center, Aarhus University, Langelandsgade140, DK-8000 Århus C, Denmark