1. Department of Chemistry and Chemical Biology; Harvard University; Cambridge MA 02138 USA
2. Institut de Chimie Moléculaire et des Matériaux d'Orsay; CNRS; Université Paris Sud 11; 91405 Orsay CEDEX France
3. School of Engineering and Applied Sciences; Harvard University; Cambridge MA 02138 USA
4. Kavli Institute for Bionano Science and Technology; Harvard University; Cambridge MA 02138 USA
5. Grenoble Institute of Technology; The International School of Paper; Print Media and Biomaterials (PAGORA); CS10065 38402 Saint-Martin-d'Héres France
6. Wyss Institute for Biologically Inspired Engineering; Harvard University; Cambridge MA 02138 USA