1. Beijing Engineering Research Center for BioNanotechnology & CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, China
2. State
Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
3. Interdisciplinary
Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus
C, Denmark
4. National
Creative Research Initiative Center for Single-Molecule Systems Biology
and Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, South Korea