1. Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA
2. Department of Bioengineering, University of Illinois at Urbana-Champaign, 1270 Digital Computer Laboratory, MC-278, Urbana, Illinois 61801, USA
3. Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, Illinois 61801, USA