1. National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, P. R. China.
2. School of Biomedical Engineering, Sichuan University, Chengdu 610064, P. R. China.
3. Institute of Regulatory Science for Medical Device, Sichuan University, Chengdu 610064, P. R. China.
4. Departments of Bioengineering and Chemical and Biomolecular Engineering, Rice University, Houston, TX 77251, USA.