1. Biomedical Research Center, Korea Institute of Science and Technology, 39-1 Hawolgok-dong, Seongbuk-gu, Seoul, 136-791, Korea, Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering (NIBIB), National Institutes of Health (NIH), 31 Center Drive, Suite 1C14, Bethesda, Maryland 20892-2281, United States, and Research Institute of Advanced Materials (RIAM), Department of Materials Science and Engineering, Seoul National University, San 56-1, Sillim,...