1. School of Chemistry and Biochemistry, 901 Atlantic Drive, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
2. Department of Chemistry and MedChem Program of Life Sciences Institute, National University of Singapore, Singapore 117543
3. Laboratory of Bioimaging Probe Development, Singapore Bioimaging Consortium, Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore 138667