1. Guangdong Key Laboratory of Nanomedicine Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenzhen 518055 P. R. China
2. Paul C. Lauterbur Research Center for Biomedical Imaging Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenzhen 518055 P. R. China
3. Guangdong Key Laboratory for Research and Development of Natural Drugs Key Laboratory for Nanomedicine Guangdong Medical University Dongguan 523808 P. R. China
4. Guangdong Provincial Key Lab of Robotics and Intelligent System Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenzhen 518055 P. R. China