1 Center for Nanotechnology in Drug Delivery, University of North Carolina, Chapel Hill, NC, USA.
2 Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE, USA.
3 Macromolecules and Interfaces Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
4 Nanocenter, G. R. Derzhavin Tambov State University, Tambov, 392000, Russian Federation.
5 Laboratory of Chemical Design of Bionanomaterials, Faculty of Chemistry, M. V. Lomonosov Moscow State University, Moscow, 117234, Russian Federation.
6 Center for Nanotechnology in Drug Delivery, University of North Carolina, Chapel Hill, NC, USA. msokolsk@email.unc.edu.
7 Center for Nanotechnology in Drug Delivery, University of North Carolina, Chapel Hill, NC, USA. kabanov@email.unc.edu.