[1] Univ N Carolina, Dept Chem, Lineberger Comprehens Canc Ctr, Carolina Ctr Canc Nanotechnol Excellence, Chapel Hill, NC 27599 USA
[2] Univ N Carolina, Dept Pharmacol, Inst Adv Mat, Inst Nanomed, Chapel Hill, NC 27599 USA
[3] N Carolina State Univ, Dept Chem & Biomol Engn, Raleigh, NC 27695 USA
[4] Mem Sloan Kettering Canc Ctr, Sloan Kettering Inst Canc Res, New York, NY 10021 USA