1. School of Pharmacy, Queen’s University Belfast, 97 Lisburn Rd, Belfast BT9 7BL, U.K.
2. University of Ljubljana, Faculty of Medicine, Institute of Cell Biology, Ljubljana, Slovenia
3. Department for Nanostructured Materials, Jozef Stefan Institute, Ljubljana, Slovenia
4. Electron Microscopy, University of Groningen, Nijenborgh 7, 9747AG Groningen, The Netherlands