title: Engineered Upconversion Nanoparticles for Resolving Protein Interactions inside Living Cells.
abstract: Upconversion nanoparticles (UCNPs) convert near-infrared into visible light at much lower excitation densities than those used in classic two-photon absorption microscopy. Here, we engineered <50 nm UCNPs for application as efficient lanthanide resonance energy transfer (LRET) donors inside living cells. By optimizing the dopant concentrations and the core-shell structure for higher excitation densities, we observed enhanced UCNP emission as well as strongly increased sensitized acceptor fluorescence. For the application of these UCNPs in complex biological environments, we developed a biocompatible surface coating functionalized with a nanobody recognizing green fluorescent protein (GFP). Thus, rapid and specific targeting to GFP-tagged fusion proteins in the mitochondrial outer membrane and detection of protein interactions by LRET in living cells was achieved.
authors: Abteilung für Biophysik, Fachbereich Biologie/Chemie, Universität Osnabrück, Barbarastrasse 11, 49076, Osnabrück, Germany.
authors: Christoph
authors: C
authors: Drees
authors: Institut für Chemie Neuer Materialien, Fachbereich Biologie/Chemie, Universität Osnabrück, Barbarastrasse 7, 49069, Osnabrück, Germany.
authors: Athira Naduviledathu
authors: AN
authors: Raj
authors: Center for Advanced Light Microscopy, Fachbereich Biologie/Chemie, Universität Osnabrück, Barbarastrasse 11, 49076, Osnabrück, Germany.
authors: Rainer
authors: R
authors: Kurre
authors: Fachbereich Biologie, Universität Münster, Schlossplatz 5, 48149, Münster, Germany.
authors: Karin B
authors: KB
authors: Busch
authors: Institut für Chemie Neuer Materialien, Fachbereich Biologie/Chemie, Universität Osnabrück, Barbarastrasse 7, 49069, Osnabrück, Germany. markus.haase@uni-osnabrueck.de.
authors: Markus
authors: M
authors: Haase
authors: Abteilung für Biophysik, Fachbereich Biologie/Chemie, Universität Osnabrück, Barbarastrasse 11, 49076, Osnabrück, Germany. piehler@uos.de.
authors: Jacob
authors: 0000-0002-2143-2270
authors: J
authors: Piehler
mesh_terms: D031541:Fluorescence Resonance Energy Transfer; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000276:immunology; D006367:HeLa Cells; D006801:Humans; D028581:Lanthanoid Series Elements / Q000737:chemistry; D026901:Membrane Transport Proteins / Q000378:metabolism; D053768:Metal Nanoparticles / Q000737:chemistry*; D018613:Microscopy, Confocal; D051336:Mitochondrial Membranes / Q000378:metabolism; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D010316:Particle Size; D011956:Receptors, Cell Surface / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D061905:Single-Domain Antibodies / Q000276:immunology
chemical_list: D028581:Lanthanoid Series Elements; D026901:Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D061905:Single-Domain Antibodies; C084008:TOMM20 protein, human; D049452:Green Fluorescent Proteins
keywords: LRET; TOM complexes; biosensors; nanoparticles; upconversion