1. National Engineering Laboratory for Modern Silk; College of Textile and Clothing Engineering; Soochow University; Suzhou 215123 P. R. China
2. Institute of Functional Nano and Soft Materials (FUNSOM); Soochow University; Suzhou 215123 P. R. China
3. School of Materials Science and Engineering; Nanyang Technological University; 50 Nanyang Avenue Singapore 639798 Singapore
4. Physikalisches Institut and Center for Nanotechnology (CeNTech); Westfaelische Wilhelms-Universitat Muenster; Muenster 48149 Germany