1. Nanoscale Science Program, Department of Chemistry, The University of North Carolina at Charlotte, Charlotte, North Carolina 28223, United States
2. Nanotechnology Characterization Lab, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland 21702, United States
3. Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
4. Wyss Institute for Biologically Inspired Engineering, Boston, Massachusetts 02115, United States
5. Harvard Graduate Program in Biological and Biomedical Sciences, Boston, Massachusetts 02115, United States
6. Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States