@article{6bc67b3cc5f14513ae30858858c1f34c,
title = "Quantifying the cellular uptake of semiconductor quantum dot nanoparticles by analytical electron microscopy",
abstract = "Semiconductor quantum dot nanoparticles are in demand as optical biomarkers yet the cellular uptake process is not fully understood; quantification of numbers and the fate of internalized particles are still to be achieved. We have focussed on the characterization of cellular uptake of quantum dots using a combination of analytical electron microscopies because of the spatial resolution available to examine uptake at the nanoparticle level, using both imaging to locate particles and spectroscopy to confirm identity. In this study, commercially available quantum dots, CdSe/ZnS core/shell particles coated in peptides to target cellular uptake by endocytosis, have been investigated in terms of the agglomeration state in typical cell culture media, the traverse of particle agglomerates across U-2 OS cell membranes during endocytosis, the merging of endosomal vesicles during incubation of cells and in the correlation of imaging flow cytometry and transmission electron microscopy to measure the final nanoparticle dose internalized by the U-2 OS cells. We show that a combination of analytical transmission electron microscopy and serial block face scanning electron microscopy can provide a comprehensive description of the internalization of an initial exposure dose of nanoparticles by an endocytically active cell population and how the internalized, membrane bound nanoparticle load is processed by the cells. We present a stochastic model of an endosome merging process and show that this provides a data-driven modelling framework for the prediction of cellular uptake of engineered nanoparticles in general. Lay summary: Engineered nanoparticles offer potential for improved medical diagnosis and treatment. The particles are small enough to enter cells and we can monitor this process using electron microscopy. The microscopy provides the resolution to count numbers of nanoparticles internalized by cells so that we can know the exact dose received by a cell or cell population and the final fate of the nanoparticles.",
keywords = "Cellular uptake, Energy-filtered TEM, Nanoparticle dose, Quantum dots, SBF SEM, TEM",
author = "Nicole Hondow and Brown, {M. Rowan} and Tobias Starborg and Monteith, {Alexander G.} and Rik Brydson and Summers, {Huw D.} and Paul Rees and Andy Brown",
note = "Funding Information: This work was supported by the Engineering and Physical Science s Research Council, UK under Grants EP/H008578/1 (Leeds) and EP/H008683/1 (Swansea). NH is supported by an AXA research fellowship. AGM is employed by Gatan UK, which makes the 3View attachment for SBF SEM. He does not hold shares in Roper Industries Inc., the parent company of Gatan. We acknowledge A. Warley, K. Brady and F. Winning (Centre for Ultrastructural Imaging, King''s College, London, UK) for pelleting and sectioning the cells for TEM. We thank Neil Wilkinson, of Gatan UK, for help with image processing. The Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, is supported by core funding from the Wellcome Trust [grant number 088785/Z/09/Z]. We acknowledge the assistance of Professor Martin Saunders and the facilities of the Australian Microscopy & Microanalysis Research Facility at the Centre for Microscopy, Characterization & Analysis, The University of Western Australia, a facility funded by the University, State and Commonwealth Governments. This facility was accessed using a World Universities Network Research Mobility Grant (University of Leeds). Funding Information: This work was supported by the Engineering and Physical Science s Research Council, UK under Grants EP/H008578/1 (Leeds) and EP/H008683/1 (Swansea). NH is supported by an AXA research fellowship. AGM is employed by Gatan UK, which makes the 3View attachment for SBF SEM. He does not hold shares in Roper Industries Inc., the parent company of Gatan. We acknowledge A. Warley, K. Brady and F. Winning (Centre for Ultrastructural Imaging, King''s College, London, UK) for pelleting and sectioning the cells for TEM. We thank Neil Wilkinson, of Gatan UK, for help with image processing. The Wellcome Trust Centre for Cell-Matrix Research, University of?Manchester, is supported by core funding from the Wellcome Trust [grant number 088785/Z/09/Z]. We acknowledge the assistance of Professor Martin Saunders and the facilities of the Australian Microscopy & Microanalysis Research Facility at the Centre for Microscopy, Characterization & Analysis, The University of Western Australia, a facility funded by the University, State and Commonwealth Governments. This facility was accessed using a World Universities Network Research Mobility Grant (University of Leeds). Publisher Copyright: {\textcopyright} 2016 Royal Microscopical Society. Copyright: Copyright 2016 Elsevier B.V., All rights reserved.",
year = "2016",
month = feb,
day = "1",
doi = "10.1111/jmi.12239",
language = "English (US)",
volume = "261",
pages = "167--176",
journal = "Journal of Microscopy",
issn = "0022-2720",
publisher = "Wiley",
number = "2",
}