[1] Univ Calif Los Angeles, Dept Chem & Biochem, Los Angeles, CA 90095 USA
[2] Univ Calif Los Angeles, Dept Chem & Biomol Engn, Los Angeles, CA 90095 USA
[3] Univ Calif Los Angeles UCLA, Calif NanoSyst Inst CNSI, Los Angeles, CA 90095 USA
[4] Univ Calif Los Angeles UCLA, Dept Mat Sci & Engn, Los Angeles, CA 90095 USA