1. Qingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of Sciences Qingdao 266101 P. R. China
2. CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety & CAS Center for Excellence in NanoscienceNational Center for Nanoscience and Technology Beijing 100190 P. R. China
3. Institute of ChemistryChinese Academy of Sciences Beijing 100190 P. R. China