1. Department of Biomedical Engineering, Peking University, Beijing, People's Republic of China
2. Division of HIV/AIDS and Sex-transmitted Virus Vaccines, Institute for Biological Product Control, National Institutes for Food and Drug Control (NIFDC), Beijing, People's Republic of China
3. College of Chemistry, University of California Berkeley, Berkeley, CA, USA
4. Institute of Health Service and Transfusion Medicine, Beijing, People's Republic of China