1. CAS Center for Excellence in Nanoscience CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety National Center for Nanoscience and Technology (NCNST) No. 11 Beiyitiao, Zhongguancun Beijing 100190 P. R. China
2. Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences No. 19 (A) Yuquan Road, Shijingshan District Beijing 100049 P. R. China