1. Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
2. Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
3. Department of Pathology and Lab Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095-1569, United States