title: Labeling nanoparticles: Dye leakage and altered cellular uptake.
abstract: In vitro and in vivo behavior of nanoparticles (NPs) is often studied by tracing the NPs with fluorescent dyes. This requires stable incorporation of dyes within the NPs, as dye leakage may give a wrong interpretation of NP biodistribution, cellular uptake, and intracellular distribution. Furthermore, NP labeling with trace amounts of dye should not alter NP properties such as interactions with cells or tissues. To allow for versatile NP studies with a variety of fluorescence-based assays, labeling of NPs with different dyes is desirable. Hence, when new dyes are introduced, simple and fast screening methods to assess labeling stability and NP-cell interactions are needed. For this purpose, we have used a previously described generic flow cytometry assay; incubation of cells with NPs at 4 and 37°C. Cell-NP interaction is confirmed by cellular fluorescence after 37°C incubation, and NP-dye retention is confirmed when no cellular fluorescence is detected at 4°C. Three different NP-platforms labeled with six different dyes were screened, and a great variability in dye retention was observed. Surprisingly, incorporation of trace amounts of certain dyes was found to reduce or even inhibit NP uptake. This work highlights the importance of thoroughly evaluating every dye-NP combination before pursuing NP-based applications. © 2016 International Society for Advancement of Cytometry.
authors.affiliation: Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Sofie
authors.initials: S
authors.lastname: Snipstad
authors.affiliation: Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Sjoerd
authors.initials: S
authors.lastname: Hak
authors.affiliation: Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Habib
authors.initials: H
authors.lastname: Baghirov
authors.affiliation: Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.|SINTEF Materials and Chemistry, Trondheim, Norway.
authors.forename: Einar
authors.initials: E
authors.lastname: Sulheim
authors.affiliation: SINTEF Materials and Chemistry, Trondheim, Norway.
authors.forename: Ýrr
authors.initials: Ý
authors.lastname: Mørch
authors.affiliation: Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Lélu
authors.affiliation: Pharmaceutical Sciences Laboratory, Åbo Akademi University, Turku, Finland.|Laboratory of Physical Chemistry, Åbo Akademi University, Turku, Finland.
authors.forename: Eva
authors.initials: E
authors.lastname: von Haartman
authors.affiliation: Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
authors.forename: Marcus
authors.initials: M
authors.lastname: Bäck
authors.affiliation: Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
authors.forename: K Peter R
authors.initials: KPR
authors.lastname: Nilsson
authors.affiliation: Laboratoire de Biophotonique et Pharmacologie, UMR CNRS 7213, Université de Strasbourg, Strasbourg, France.
authors.forename: Andrey S
authors.initials: AS
authors.lastname: Klymchenko
authors.affiliation: Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Catharina
authors.initials: C
authors.lastname: de Lange Davies
authors.affiliation: Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Andreas K O
authors.initials: AKO
authors.lastname: Åslund
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000502:physiology; D002460:Cell Line; D045744:Cell Line, Tumor; D005434:Flow Cytometry / Q000379:methods; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D053758:Nanoparticles / Q000737:chemistry* / Q000378:metabolism*; D051381:Rats; D013194:Staining and Labeling / Q000379:methods; D014018:Tissue Distribution / Q000502:physiology
chemical_list: D005456:Fluorescent Dyes
keywords: cellular uptake; flow cytometry; leakage; liposomes; nanoemulsions; polymeric nanoparticles