1. Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA.
2. Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA.
3. Department of Cancer Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA.
4. Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
5. IBM Almaden Research Center, San Jose, CA 95120, USA.
6. IBM Thomas J. Watson Research Center, Yorktown Heights, NY 10598, USA.
7. Materials Science and Engineering Division, National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899, USA.