1. National Engineering Laboratory for Modern Silk College of Textile and Clothing Engineering Soochow University Suzhou 215123 P. R. China
2. College of Chemical Engineering Fuzhou University Fuzhou 350116 P. R. China
3. Division of Medicine University College London London WC1E 6JF UK
4. School of Materials Science and Engineering Nanyang Technological University 50 Nanyang Avenue Singapore 639798 Singapore