title: Cellular Uptake of Gold Nanoparticles and Their Behavior as Labels for Localization Microscopy.
abstract: Gold nanoparticles (GNPs) enhance the damaging absorbance effects of high-energy photons in radiation therapy by increasing the emission of Auger-photoelectrons in the nm-μm range. It has been shown that the incorporation of GNPs has a significant effect on radiosensitivity of cells and their dose-dependent clonogenic survival. One major characteristic of GNPs is also their diameter-dependent cellular uptake and retention. In this article, we show by means of an established embodiment of localization microscopy, spectral position determination microscopy (SPDM), that imaging with nanometer resolution and systematic counting of GNPs becomes feasible, because optical absorption and plasmon resonance effects result in optical blinking of GNPs at a size-dependent wavelength. To quantify cellular uptake and retention or release, SPDM with GNPs that have diameters of 10 and 25 nm was performed after 2 h and after 18 h. The uptake of the GNPs in HeLa cells was either achieved via incubation or transfection via DNA labeling. On average, the uptake by incubation after 2 h was approximately double for 10 nm GNPs as compared to 25 nm GNPs. In contrast, the uptake of 25 nm GNPs by transfection was approximately four times higher after 2 h. The spectral characteristics of the fluorescence of the GNPs seem to be environment-dependent. In contrast to fluorescent dyes that show blinking characteristics due to reversible photobleaching, the blinking of GNPs seems to be stable for long periods of time, and this facilitates their use as an appropriate dye analog for SPDM imaging.
authors.affiliation: Kirchhoff-Institute for Physics, Faculty of Physics and Astronomy, Medical Faculty Mannheim, Universitätsmedizin Mannheim.
authors.forename: Felipe
authors.initials: F
authors.lastname: Moser
authors.affiliation: Kirchhoff-Institute for Physics, Faculty of Physics and Astronomy, Medical Faculty Mannheim, Universitätsmedizin Mannheim; Department of Radiation Oncology, Medical Faculty Mannheim, Universitätsmedizin Mannheim.
authors.forename: Georg
authors.initials: G
authors.lastname: Hildenbrand
authors.affiliation: Kirchhoff-Institute for Physics, Faculty of Physics and Astronomy, Medical Faculty Mannheim, Universitätsmedizin Mannheim.
authors.forename: Patrick
authors.initials: P
authors.lastname: Müller
authors.affiliation: Kirchhoff-Institute for Physics, Faculty of Physics and Astronomy, Medical Faculty Mannheim, Universitätsmedizin Mannheim.
authors.forename: Alexander
authors.initials: A
authors.lastname: Al Saroori
authors.affiliation: Kirchhoff-Institute for Physics, Faculty of Physics and Astronomy, Medical Faculty Mannheim, Universitätsmedizin Mannheim; Department of Radiation Oncology, Medical Faculty Mannheim, Universitätsmedizin Mannheim.
authors.forename: Abin
authors.initials: A
authors.lastname: Biswas
authors.affiliation: Kirchhoff-Institute for Physics, Faculty of Physics and Astronomy, Medical Faculty Mannheim, Universitätsmedizin Mannheim.
authors.forename: Margund
authors.initials: M
authors.lastname: Bach
authors.affiliation: Department of Radiation Oncology, Medical Faculty Mannheim, Universitätsmedizin Mannheim.
authors.forename: Frederik
authors.initials: F
authors.lastname: Wenz
authors.affiliation: Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany; Institute of Molecular Biology, Mainz, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Cremer
authors.affiliation: Department of Radiation Oncology, Medical Faculty Mannheim, Universitätsmedizin Mannheim.
authors.forename: Nina
authors.initials: N
authors.lastname: Burger
authors.affiliation: Department of Radiation Oncology, Medical Faculty Mannheim, Universitätsmedizin Mannheim.
authors.forename: Marlon R
authors.initials: MR
authors.lastname: Veldwijk
authors.affiliation: Kirchhoff-Institute for Physics, Faculty of Physics and Astronomy, Medical Faculty Mannheim, Universitätsmedizin Mannheim. Electronic address: hausmann@kip.uni-heidelberg.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Hausmann
mesh_terms: D001692:Biological Transport; D006046:Gold / Q000737:chemistry* / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D053768:Metal Nanoparticles; D008853:Microscopy; D010316:Particle Size; D013194:Staining and Labeling
chemical_list: D006046:Gold