1 Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland; Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland.
2 Center for Infectious Medicine, Department of Medicine Huddinge, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden. Electronic address: malin.flodstrom-tullberg@ki.se.