1. Shenzhen Key Laboratory of Micro/Nano Biosensing Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenzhen 518055 P. R. China
2. University of Chinese Academy of Sciences Beijing 100049 P. R. China
3. Hubei Three Gorges Laboratory Yichang Hubei 443007 P. R. China
4. Department of Physics Department of Materials Science and Engineering and Department of Biomedical Engineering City University of Hong Kong Tat Chee Avenue, Kowloon Hong Kong P. R. China