1. Department of Analytical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden, Department of Applied Microbiology, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden, Faculty of Health and Society, Malmö University, SE-205 06 Malmö, Sweden, and DTU Nanotech - Department of Micro and Nanotechnology, Technical University of Denmark, OerstedsPlads 345 East, DK-2800 Kongens Lyngby, Denmark