title: Cell membrane penetration and mitochondrial targeting by platinum-decorated ceria nanoparticles.
abstract: In this work we investigate the interaction between endothelial cells and nanoparticles emitted by catalytic converters. Although catalyst-derived particles are recognized as growing burden added to environmental pollution, very little is known about their health impact. We use platinum-decorated ceria nanoparticles as model compounds for the actual emitted particles and focus on their fast uptake and association with mitochondria, the cell's powerhouse. Using live-cell imaging and electron microscopy we clearly show that 46 nm platinum-decorated ceria nanoparticles can rapidly penetrate cell membranes and reach the cytosol. Moreover, if suitably targeted, these particles are able to selectively attach to mitochondria. These results are complemented by cytotoxicity assays, thus providing insights into the biological effects of these particles on cells. Interestingly, no permanent membrane disruption or any other significant adverse effects on cells were observed. The unusual uptake behavior observed for 46 nm nanoparticles was not observed for equivalent but larger 143 nm and 285 nm platinum-decorated particles. Our results demonstrate a remarkable particle size effect in which particles smaller than ∼50-100 nm escape the usual endocytic pathway and translocate directly into the cytosol, while particles larger than ∼150 nm are internalized by conventional endocytosis. Since the small particles are able to bypass endocytosis they could be explored as drug and gene delivery vehicles. Platinum-decorated nanoparticles are therefore highly interesting in the fields of nanotoxicology and nanomedicine.
authors.affiliation: Department of Chemistry and Center for NanoScience (CeNS), University of Munich (LMU), 81377 Munich, Germany. christoph.braeuchle@cup.uni-muenchen.de and Nanosystems Initiative Munich (NIM), 80799 Munich, Germany.
authors.forename: Adriano A
authors.initials: AA
authors.lastname: Torrano
authors.affiliation: Experimental Physics I, Institute of Physics, University of Augsburg, 86159 Augsburg, Germany.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Herrmann
authors.affiliation: Department of Experimental Radiology, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, 07747 Jena, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Strobel
authors.affiliation: Experimental Physics I, Institute of Physics, University of Augsburg, 86159 Augsburg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Rennhak
authors.affiliation: Department of Chemistry and Center for NanoScience (CeNS), University of Munich (LMU), 81377 Munich, Germany. christoph.braeuchle@cup.uni-muenchen.de.
authors.forename: Hanna
authors.initials: H
authors.lastname: Engelke
authors.affiliation: Resources Strategy, Institute of Physics, University of Augsburg, 86159 Augsburg, Germany.
authors.forename: Armin
authors.initials: A
authors.lastname: Reller
authors.affiliation: Department of Experimental Radiology, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, 07747 Jena, Germany.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Hilger
authors.affiliation: Nanosystems Initiative Munich (NIM), 80799 Munich, Germany and Experimental Physics I, Institute of Physics, University of Augsburg, 86159 Augsburg, Germany.
authors.forename: Achim
authors.initials: A
authors.lastname: Wixforth
authors.affiliation: Department of Chemistry and Center for NanoScience (CeNS), University of Munich (LMU), 81377 Munich, Germany. christoph.braeuchle@cup.uni-muenchen.de and Nanosystems Initiative Munich (NIM), 80799 Munich, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Bräuchle