@article {1303716, title = {A Ligand System for the Flexible Functionalization of Quantum Dots via Click Chemistry}, journal = {Angew Chem Int Ed Engl}, volume = {57}, number = {17}, year = {2018}, month = {2018 Apr 16}, pages = {4652-4656}, abstract = {We present a novel ligand, 5-norbornene-2-nonanoic acid, which can be directly added during established quantum dot (QD) syntheses in organic solvents to generate "clickable" QDs at a few hundred nmol scale. This ligand has a carboxyl group at one terminus to bind to the surface of QDs and a norbornene group at the opposite end that enables straightforward phase transfer of QDs into aqueous solutions via efficient norbornene/tetrazine click chemistry. Our ligand system removes the traditional ligand-exchange step and can produce water-soluble QDs with a high quantum yield and a small hydrodynamic diameter of approximately 12 nm at an order of magnitude higher scale than previous methods. We demonstrate the effectiveness of our approach by incubating azido-functionalized CdSe/CdS QDs with 4T1 cancer cells that are metabolically labeled with a dibenzocyclooctyne-bearing unnatural sugar. The QDs exhibit high targeting efficiency and minimal nonspecific binding.}, issn = {1521-3773}, doi = {10.1002/anie.201801113}, author = {Chen, Yue and Cordero, Jose M and Wang, Hua and Franke, Daniel and Achorn, Odin B and Freyria, Francesca S and Coropceanu, Igor and Wei, He and Chen, Ou and Mooney, David J and Bawendi, Moungi G} }