title: Comparing intracellular stability and targeting of sulfobetaine quantum dots with other surface chemistries in live cells.
abstract: The in vivo labeling of intracellular components with quantum dots (QDs) is very limited because of QD aggregation in the cell cytoplasm and/or QD confinement into lysosomal compartments. In order to improve intracellular targeting with QDs, various surface chemistries and delivery methods have been explored, but they have not yet been compared systematically with respect to the QD intracellular stability. In this work, the intracellular aggregation kinetics of QDs for three different surface chemistries based on ligand exchange or encapsulation with amphiphilic polymers are compared. For each surface chemistry, three delivery methods for bringing the nanoparticles into the cells are compared: electroporation, microinjection, and pinocytosis. It is concluded that the QD intracellular aggregation behavior is strongly dependent on the surface chemistry. QDs coated with dihydrolipoic acid-sulfobetaine (DHLA-SB) ligands diffuse freely in cells for longer periods of time than for QDs in the other chemistries tested, and they can access all cytoplasmic compartments. Even when conjugated to streptavidin, these DHLA-SB QDs remain freely diffusing inside the cytoplasm and unaggregated, and they are able to reach a biotinylated target inside HeLa cells. Such labeling was more efficient when compared to commercial streptavidin-conjugated QDs, which may be due to the smaller size of DHLA-SB QDs and/or to their superior intracellular stability.
authors.affiliation: Laboratoire Physique et Etude des Matériaux UMR8213, ESPCI ParisTech-CNRS - UPMC Sorbonne Universités, 10 rue Vauquelin, 75005 Paris, France.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Muro
authors.forename: Alexandra
authors.initials: A
authors.lastname: Fragola
authors.forename: Thomas
authors.initials: T
authors.lastname: Pons
authors.forename: Nicolas
authors.initials: N
authors.lastname: Lequeux
authors.forename: Andriani
authors.initials: A
authors.lastname: Ioannou
authors.forename: Paris
authors.initials: P
authors.lastname: Skourides
authors.forename: Benoit
authors.initials: B
authors.lastname: Dubertret
mesh_terms: D000818:Animals; D001622:Betaine / Q000031:analogs & derivatives* / Q000737:chemistry; D003593:Cytoplasm / Q000378:metabolism; D018274:Electroporation; D004625:Embryo, Nonmammalian / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008845:Microinjections; D045663:Quantum Dots; D008063:Thioctic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D014982:Xenopus laevis
chemical_list: D001622:Betaine; D008063:Thioctic Acid; C015144:dihydrolipoic acid; C483727:sulfobetaine