1. Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599;
2. Carolina Center for Nanotechnology Excellence, Chapel Hill, North Carolina, 27599;
3. Departments of Chemistry, Chemical Engineering, and Mechanical Engineering, and Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139;
4. Massachusetts Institute of Technology–Harvard Center for Cancer Nanotechnology Excellence, Cambridge, Massachusetts 02139
5. Laboratory of Nanomedicine and Biomaterials, Department of Anesthesiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115;