[1] Univ Illinois, Dept Biochem, Urbana, IL 61801 USA
[2] Johns Hopkins Univ, Inst NanoBioTechnol, Dept Mat Sci & Engn, Baltimore, MD 21218 USA
[3] Univ Illinois, Dept Chem, 1209 W Calif St, Urbana, IL 61801 USA
[4] Univ Illinois, Dept Biomol & Chem Engn, Urbana, IL 61801 USA
[5] Univ Illinois, Ctr Quantitat Biol & Biophys, Urbana, IL 61801 USA