1. Institute of Biomedical Engineering, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300192, China
2. Department of Biomedical Engineering, University of Tennessee Health Science Center-Memphis Joint Graduate Biomedical Engineering Program, The University of Memphis, Memphis, TN 38152, USA
3. Department of Chemistry, The University of Memphis, Memphis, TN 38152, USA
4. Integrated Microscopy Center, The University of Memphis, Memphis, TN 38152, USA