1. Huaxi MR Research Center (HMRRC), Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, West China Hospital, Sichuan University, Chengdu 610041, P. R. China
2. National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610041, P. R. China
3. College of Materials Science and Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, P. R. China
4. The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Science, Nankai University, Tianjin 300071, P. R. China
5. Amgen Bioprocessing Centre, Keck Graduate Institute, Claremont, California 91711, United States