title: Photoligation of an amphiphilic polymer with mixed coordination provides compact and reactive quantum dots.
abstract: We introduce a new set of multicoordinating polymers as ligands that combine two distinct metal-chelating groups, lipoic acid and imidazole, for the surface functionalization of QDs. These ligands combine the benefits of thiol and imidazole coordination to reduce issues of thiol oxidation and weak binding affinity of imidazole. The ligand design relies on the introduction of controllable numbers of lipoic acid and histamine anchors, along with hydrophilic moieties and reactive functionalities, onto a poly(isobutylene-alt-maleic anhydride) chain via a one-step nucleophilic addition reaction. We further demonstrate that this design is fully compatible with a novel and mild photoligation strategy to promote the in situ ligand exchange and phase transfer of hydrophobic QDs to aqueous media under borohydride-free conditions. Ligation with these polymers provides highly fluorescent QDs that exhibit great long-term colloidal stability over a wide range of conditions, including a broad pH range (3-13), storage at nanomolar concentration, under ambient conditions, in 100% growth media, and in the presence of competing agents with strong reducing property. We further show that incorporating reactive groups in the ligands permits covalent conjugation of fluorescent dye and redox-active dopamine to the QDs, producing fluorescent platforms where emission is controlled/tuned by Förster Resonance Energy Transfer (FRET) or pH-dependent charge transfer (CT) interactions. Finally, the polymer-coated QDs have been coupled to cell-penetrating peptides to facilitate intracellular uptake, while subsequent cytotoxicity tests show no apparent decrease in cell viability.
authors: †Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.
authors: Wentao
authors: W
authors: Wang
authors: †Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.
authors: Anshika
authors: A
authors: Kapur
authors: †Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.
authors: Xin
authors: X
authors: Ji
authors: †Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.
authors: Malak
authors: M
authors: Safi
authors: †Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.
authors: Goutam
authors: G
authors: Palui
authors: ‡Department of Chemistry and Department of Cell Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States.
authors: Valle
authors: V
authors: Palomo
authors: ‡Department of Chemistry and Department of Cell Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States.
authors: Philip E
authors: PE
authors: Dawson
authors: †Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.
authors: Hedi
authors: H
authors: Mattoussi
mesh_terms: D003102:Colloids / Q000737:chemistry; D056831:Coordination Complexes / Q000737:chemistry*; D004298:Dopamine / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D007093:Imidazoles / Q000737:chemistry; D008027:Light; D061848:Optical Imaging; D011108:Polymers / Q000737:chemistry*; D045663:Quantum Dots / Q000737:chemistry*; D012542:Scattering, Radiation; D013501:Surface-Active Agents / Q000737:chemistry*; D008063:Thioctic Acid / Q000737:chemistry
chemical_list: D003102:Colloids; D056831:Coordination Complexes; D005456:Fluorescent Dyes; D007093:Imidazoles; D011108:Polymers; D013501:Surface-Active Agents; D008063:Thioctic Acid; C029899:imidazole; D004298:Dopamine