1. ViQi Inc., Santa Barbara, California 93109, United States
2. Nanoimaging Core Facility at the University of Nebraska Medical Center, Omaha, Nebraska 68198, United States
3. Nanotechnology Characterization Laboratory, Cancer Research Technology Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, United States
4. Department of Physics, University of Nebraska at Omaha, Omaha, Nebraska 68182, United States