1. Department
of Chemistry and Medicinal Chemistry Program, National University of Singapore, Singapore 117543
2. Key
Laboratory of Smart Drug Delivery, Ministry of Education, School of
Pharmacy, Fudan University, Shanghai 201203, P. R. China
3. Laboratory
of Bioimaging Probe Development, Singapore Bioimaging Consortium, Singapore 117543
4. State
Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry
and Chemical Engineering, Hunan University, Changsha 410082, P. R. China