title: Detection of silver nanoparticles inside marine diatom Thalassiosira pseudonana by electron microscopy and focused ion beam.
abstract: In the following article an electron/ion microscopy study will be presented which investigates the uptake of silver nanoparticles (AgNPs) by the marine diatom Thalassiosira pseudonana, a primary producer aquatic species. This organism has a characteristic silica exoskeleton that may represent a barrier for the uptake of some chemical pollutants, including nanoparticles (NPs), but that presents a technical challenge when attempting to use electron-microscopy (EM) methods to study NP uptake. Here we present a convenient method to detect the NPs interacting with the diatom cell. It is based on a fixation procedure involving critical point drying which, without prior slicing of the cell, allows its inspection using transmission electron microscopy. Employing a combination of electron and ion microscopy techniques to selectively cut the cell where the NPs were detected, we are able to demonstrate and visualize for the first time the presence of AgNPs inside the cell membrane.
authors.affiliation: European Commission-Joint Research Centre, Institute for Health and Consumer Protection, Ispra (VA), Italy.
authors.forename: César Pascual
authors.initials: CP
authors.lastname: García
authors.affiliation: European Commission-Joint Research Centre, Institute for Environment and Sustainability, Ispra (VA), Italy; FU-Berlin, Fachbereich Biologie, Chemie, Pharmazie, Berlin, Germany.
authors.forename: Alina D
authors.initials: AD
authors.lastname: Burchardt
authors.affiliation: European Commission-Joint Research Centre, Institute for Environment and Sustainability, Ispra (VA), Italy.
authors.forename: Raquel N
authors.initials: RN
authors.lastname: Carvalho
authors.affiliation: European Commission-Joint Research Centre, Institute for Health and Consumer Protection, Ispra (VA), Italy.
authors.forename: Douglas
authors.initials: D
authors.lastname: Gilliland
authors.affiliation: European Commission-Joint Research Centre, Institute for Health and Consumer Protection, Ispra (VA), Italy; Departamento de Biologia and CESAM, Universidade de Aveiro, Aveiro, Portugal.
authors.forename: Diana C
authors.initials: DC
authors.lastname: António
authors.affiliation: European Commission-Joint Research Centre, Institute for Health and Consumer Protection, Ispra (VA), Italy.
authors.forename: François
authors.initials: F
authors.lastname: Rossi
authors.affiliation: European Commission-Joint Research Centre, Institute for Environment and Sustainability, Ispra (VA), Italy.
authors.forename: Teresa
authors.initials: T
authors.lastname: Lettieri
mesh_terms: D059001:Aquatic Organisms / Q000378:metabolism* / Q000648:ultrastructure*; D017377:Diatoms / Q000378:metabolism* / Q000648:ultrastructure*; D053768:Metal Nanoparticles; D046529:Microscopy, Electron, Transmission; D012834:Silver / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D012834:Silver