1. CAS Key Laboratory for Biomedical Effects of Nanomaterials & Nanosafety; National Center for Nanoscience and Technology; Beijing 100190 China
2. Institute of Optical Imaging and Sensing, Shenzhen Key Laboratory for Minimal Invasive Medical Technologies; Graduate School at Shenzhen, Tsinghua University; Shenzhen 518055 China
3. Department of Physics; Tsinghua University; Beijing 100084 China
4. Laboratory of Nanomaterials; National Center for Nanoscience and Technology; Beijing 100190 China