1. Nanotechnology Characterization Lab, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland 21702-1201, United States
2. Small Animal Imaging Program, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland 21702-1201, United States
3. Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon 97006, United States
4. Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
5. Division of Pathobiology & Immunology, Oregon National Primate Research Center, Oregon Health & Science University, Portland, Oregon 97239, United States