[1] Columbia Univ, Dept Chem, New York, NY 10027 USA
[2] Univ Calif Berkeley, Dept Chem, Berkeley, CA 94720 USA
[3] Univ Calif Berkeley, Dept Mol & Cell Biol, Berkeley, CA 94720 USA
[4] Univ Calif Berkeley, Howard Hughes Med Inst, Berkeley, CA 94720 USA
[5] Lawrence Berkeley Natl Lab, Div Mat Sci, Berkeley, CA 94720 USA
[6] Columbia Univ, Dept Chem Engn, New York, NY 10027 USA