1. Department of Bioengineering, University of California, Los Angeles, Los Angeles, California 90025, United States
2. Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
3. Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, California 90095, United States
4. California NanoSystems Institute, University of California, Los Angeles, California 90095, United States
5. Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, India