title: Collective fluorescence switching of counterion-assembled dyes in polymer nanoparticles.
abstract: The current challenge in the field of fluorescent nanoparticles (NPs) for bioimaging is to achieve extreme brightness and external control of their emission using biodegradable materials. Here we propose a new concept of fluorescent polymer NPs, doped with ionic liquid-like salts of a cationic dye (octadecyl rhodamine B) with a bulky hydrophobic counterion (fluorinated tetraphenylborate) that serves as spacer minimizing dye aggregation and self-quenching. The obtained 40-nm poly(D,L-lactide-co-glycolide) NPs containing up to 500 dyes are brighter than quantum dots and exhibit photo-induced reversible on/off fluorescence switching, never reported for dye-doped NPs. We show that this collective switching of hundreds of dyes is due to ultrafast excitation energy transfer and can be used for super-resolution imaging. These NPs, being spontaneously endocytosed by living cells, feature high signal-to-noise ratio and absence of toxicity. The counterion-based concept opens the way to a new class of nanomaterials for sensing, imaging and light harvesting.
authors.affiliation: Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, 74, Route du Rhin, 67401 Illkirch, France.
authors.forename: Andreas
authors.initials: A
authors.lastname: Reisch
authors.affiliation: Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, 74, Route du Rhin, 67401 Illkirch, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Didier
authors.affiliation: Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, 74, Route du Rhin, 67401 Illkirch, France.
authors.forename: Ludovic
authors.initials: L
authors.lastname: Richert
authors.affiliation: Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, 74, Route du Rhin, 67401 Illkirch, France.
authors.forename: Sule
authors.initials: S
authors.lastname: Oncul
authors.affiliation: Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, 74, Route du Rhin, 67401 Illkirch, France.
authors.forename: Youri
authors.initials: Y
authors.lastname: Arntz
authors.affiliation: Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, 74, Route du Rhin, 67401 Illkirch, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Mély
authors.affiliation: Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, 74, Route du Rhin, 67401 Illkirch, France.
authors.forename: Andrey S
authors.initials: AS
authors.lastname: Klymchenko
mesh_terms: D005456:Fluorescent Dyes / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D008856:Microscopy, Fluorescence; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology; D011108:Polymers / Q000737:chemistry*; D012235:Rhodamines / Q000737:chemistry*; D059629:Signal-To-Noise Ratio; D013775:Tetraphenylborate / Q000737:chemistry*
chemical_list: D005456:Fluorescent Dyes; D011108:Polymers; D012235:Rhodamines; D013775:Tetraphenylborate; C044542:octadecyl Rhodamine B chloride