1. Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
2. Robert F. Smith School for Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
3. Department of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, United States
4. Program in Quantitative Molecular Therapeutics, Washington University School of Medicine, St. Louis, Missouri 63110, United States
5. Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63110, United States
6. Life Science Division, TRIUMF, Vancouver, British Columbia V6T 2A3, Canada
7. Chemistry Department, University of British Columbia, Vancouver, British Columbia V6T 2A3, Canada