1. CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology of China, Beijing 100190, People’s Republic of China
2. Department of Pharmaceutics, School of Pharmaceutical Science, Peking University, Beijing 100191, People’s Republic of China
3. Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
4. Molecular Imaging Laboratory, Department of Radiology, Howard University, Washington DC 20060, United States