1. School of Chemistry and Chemical Engineering Huazhong University of Science and Technology 1037 Luoyu Load Wuhan 430074 China
2. The Molecular Foundry Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
3. Nanomaterials for Bioimaging Group (nanoBIG) Departamento de Física de Materiales Facultad de Ciencias Universidad Autónoma de Madrid 28049 Madrid Spain
4. Department of Chemistry University of California at Berkeley Berkeley CA 94720 USA
5. Department of Mechanical Engineering Columbia University New York NY 10027 USA
6. Division of Molecular Biophysics & Integrated Bioimaging Lawrence Berkeley National Laboratory Berkeley CA 94720 USA