1. Center for Functional Biomaterials, School of Materials Science and Engineering, Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Sun Yat-sen University, Guangzhou 510275, China
2. Sinovac Biotech Co. Ltd, No. 39 Shangdi Xi Road, Beijing 100085, China
3. Department of Materials Science and Engineering, and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, Maryland 21218, United States
4. Department of Biomedical Engineering, Columbia University, New York, New York 10027, United States