1. Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
2. California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
3. Department of Bioengineering, University of California, Los Angeles, Los Angeles, California 90095, United States
4. Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, and Hatos Center for Neuropharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095, United States
5. Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States