[1] Univ Calif San Diego, Dept Nanoengn, La Jolla, CA 92093 USA
[2] Lanzhou Univ, Dept Chem, Lanzhou 730000, Peoples R China
[3] Sandia Natl Labs, Dept Biosensors & Nanomat, Albuquerque, NM 87185 USA
[4] Univ Utah, Dept Chem & Mat Sci & Engn, Salt Lake City, UT 84112 USA