1. BioNanomaterials,
Adolphe Merkle Institute, University of Fribourg, CH-1700 Fribourg, Switzerland
2. In Vitro Toxicology Group, Swansea University Medical School, Swansea SA2 8PP, Wales, U.K.
3. Laboratory
for Materials-Biology Interactions, Empa, Swiss Federal Laboratories for Materials, Science and Technology, 9014 St Gallen, Switzerland
4. Department
of Chemistry, University of Fribourg, CH-1700 Fribourg, Switzerland