1. National Engineering Research Centre for Tissue Restoration and Reconstruction and School of Material Science and Engineering; South China University of Technology; Guangzhou 510640 China
2. Department of Stomatology; Chinese PLA General Hospital; Beijing 100853 China
3. Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center; Institute for Biomedical Engineering, Science and Technology; University of Oklahoma; Norman OK 73019-5300 USA
4. Department of Reproductive Medicine; Third Affiliated Hospital of Guangzhou Medical University; Guangzhou 510150 China
5. Department of Chemistry; The Hong Kong University of Science and Technology; Hong Kong Kowloon China
6. School of Materials Science and Engineering; Zhejiang University; Hangzhou 310027 China