[1] Univ North Carolina Chapel Hill, Joint Dept Biomed Engn, Raleigh, NC 27695 USA
[2] North Carolina State Univ, Raleigh, NC 27695 USA
[3] Univ N Carolina, Div Pharmacoengn & Mol Pharmaceut, Chapel Hill, NC 27599 USA
[4] Univ N Carolina, Ctr Nanotechnol Drug Delivery, Eshelman Sch Pharm, Chapel Hill, NC 27599 USA
[5] Univ N Carolina, Sch Med, Dept Med, Chapel Hill, NC 27599 USA