1. CAS Key Lab for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology of China, Beijing 100190, P. R. China
2. Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, P. R. China
3. Key Laboratory of Biomedical Engineering of the Ministry of Education, Zhejiang University, Hangzhou 310058, P. R. China
4. Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-742, Korea
5. School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Korea