1. a Group of Applied Physics, University of Geneva, 20 rue de l'Ecole de Medecine, 1211 Geneva 4, Switzerland
2. b Group of Applied Physics, University of Geneva, 20 rue de l'Ecole de Medecine, 1211 Geneva 4, Switzerland, Division of Infectious Disease, University Hospital of Geneva, 1211 Geneva 4, Switzerland
3. c Department of Chemistry, University of Siena, Pian dei Mantellini 44, 53100 Siena, Italy
4. d Department of Materials, Federal Institute of Technology, 1015 Lausanne, Switzerland
5. e Department of Materials, Federal Institute of Technology, 1015 Lausanne, Switzerland
6. f Department of Chemistry, University of Siena, Pian dei Mantellini 44, 53100 Siena, Italy
7. g Division of Infectious Disease, University Hospital of Geneva, 1211 Geneva 4, Switzerland
8. h Group of Applied Physics, University of Geneva, 20 rue de l'Ecole de Medecine, 1211 Geneva 4, Switzerland