1. CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology, No. 11, First North Road, Zhongguancun, Beijing, China 100190
2. School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin, China 300387
3. Laboratory of Molecular Imaging, Department of Radiology, Howard University, Washington, D.C. 20060, United States
4. Laboratory of Pharmaceutics, School of Medicine, Tsinghua University, Beijing, China 100084