1. Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Materials Science & Engineering, Beijing Institute of Technology, 5 Zhongguancun South Street, Beijing 100081, P. R. China
2. Cancer
Research Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037, United States
3. Micro
Nano Technology Center, Beijing Institute of Technology, 5 Zhongguancun
South Street, Beijing 100081, P. R. China