1. Department of Chemistry, and Bioengineering Graduate Program, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, SAR Hong Kong, 8sens.biognostic AG, Robert-Roessle-Strasse 10, D-13125 Berlin, Germany, Division of Bioengineering and Department of Chemical & Biomolecular Engineering, National University of Singapore (NUS), Singapore, and Elan NanoSystems, 3500 Horizon Drive, King of Prussia, Pennsylvania 19406