1Research
Center for Bioengineering and Sensing Technology, School of Chemistry
and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, P. R. China
2Department
of Medical Engineering, California Institute of Technology, Pasadena, California 91125, United States
3CAS
Key Laboratory of Bio-inspired Materials and Interfacial Science,
CAS Center for Excellence in Nanoscience, Tech-nical Institute of
Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
4University of Chinese Academy of Sciences, Beijing 100049, P.R. China