1. National Engineering Laboratory for Modern Silk & Collaborative Innovation Center of Suzhou Nano Science and Technology; Soochow University; Suzhou 215123 P. R. China
2. College of Textile and Clothing Engineering; Soochow University; Suzhou 215123 P. R. China
3. School of Biology and Basic Medical Sciences; Soochow University; Suzhou 215123 P. R. China
4. Key Laboratory of Molecular Engineering of Polymers of Ministry of Education; Laboratory of Advanced Materials; Department of Macromolecular Science; Fudan University; Shanghai 200433 P. R. China
5. Research Center of Materials Science; Beijing Institute of Technology; Beijing 100081 P. R. China
6. Department of Biomedical Engineering; Tufts University; Medford MA 02155 USA