1. Engineering Research Center in Biomaterials, Sichuan University, Chengdu, Sichuan 610065, P. R. China
2. College of Biomedical Engineering, Sichuan University, Chengdu, Sichuan 610065, P. R. China
3. Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610065, P. R. China