1. State Key Laboratory of Organic–Inorganic Composites Beijing Laboratory of Biomedical Materials College of Materials Science and Engineering Beijing University of Chemical Technology 15 North Third Ring Road Beijing 100029 P. R. China
2. CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety CAS Center for Excellence in Nanoscience National Center for Nanoscience and Technology of China No. 11, First North Road, Zhongguancun Beijing 100190 P. R. China
3. University of Chinese Academy of Sciences Beijing 100049 P. R. China
4. Department of Chemistry and Nanoscience Ewha Womans University Seoul 03760 Korea