1. Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, Department of Engineering Mechanics and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, Nanobiology Laboratory, Bio-X Life Science Research Center, College of Life Science and Biotechnology, Shanghai JiaoTong University, Shanghai 200030, P. R. China, and Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800, P. R....