1. School of Life and Health SciencesThe Chinese University of Hong Kong Shenzhen 518172 P. R. China
2. Department of Applied Biology and Chemical TechnologyHong Kong Polytechnic University Kowloon Hong Kong SAR P. R. China
3. Department of Materials Science and Engineering, and Centre for Functional Photonics (CFP)City University of Hong Kong Kowloon Hong Kong SAR P. R. China
4. Shenzhen Research InstituteCity University of Hong Kong Shenzhen 518057 P. R. China