1. Engineering Research Center in Biomaterials, Sichuan University, Chengdu, Sichuan 610065, P. R. China
2. College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan 610065, P. R. China
3. College of Biomedical Engineering, Sichuan University, Chengdu, Sichuan 610065, P. R. China
4. Analytical & Testing Center, Sichuan University, Chengdu, Sichuan 610065, P. R. China
5. Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610065, P. R. China