1. Frontier Institute of Science and Technology; Xi'an Jiaotong University; Xi'an 710054 China
2. Department of Biologic and Materials Sciences; The University of Michigan; Ann Arbor MI 48109-1078 USA
3. Department of Biomedical Engineering; University of Michigan; Ann Arbor MI 48109-1078 USA
4. Macromolecular Science and Engineering Center; University of Michigan; Ann Arbor MI 48109-1078 USA
5. Department of Materials Science and Engineering; University of Michigan; Ann Arbor MI 48109-1078 USA
6. National Engineering Research Center for Tissue Restoration and Reconstruction; Guangzhou 510006 China
7. State Key Laboratory for Manufacturing Systems Engineering; Xi'an 710054 China