1. Department of Biology; Technion - Israel Institute of Technology; Haifa 32000 Israel
2. Department of Physics; Technion - Israel Institute of Technology; Haifa 32000 Israel
3. The Russell Berrie Nanotechnology Institute; Technion - Israel Institute of Technology; Haifa 32000 Israel
4. Department of Molecular Microbiology and Biotechnology, The George S. Wise Faculty of Life Sciences; Tel Aviv University; Ramat Aviv Tel Aviv 69978 Israel