title: Transmission electron microscopy of unstained hybrid Au nanoparticles capped with PPAA (plasma-poly-allylamine): structure and electron irradiation effects.
abstract: Hybrid (organic shell-inorganic core) nanoparticles have important applications in nanomedicine. Although the inorganic components of hybrid nanoparticles can be characterized readily using conventional transmission electron microscopy (TEM) techniques, the structural and chemical arrangement of the organic molecular components remains largely unknown. Here, we apply TEM to the physico-chemical characterization of Au nanoparticles that are coated with plasma-polymerized-allylamine, an organic compound with the formula C3H5NH2. We discuss the use of energy-filtered TEM in the low-energy-loss range as a contrast enhancement mechanism for imaging the organic shells of such particles. We also study electron-beam-induced crystallization and amorphization of the shells and the formation of graphitic-like layers that contain both C and N. The resistance of the samples to irradiation by high-energy electrons, which is relevant for optical tuning and for understanding the degree to which such hybrid nanostructures are stable in the presence of biomedical radiation, is also discussed.
authors.affiliation: Instituto de Ciencia de Materiales de Sevilla (CSIC), 41092 Sevilla, Spain. Electronic address: lionel.cervera@icmse.csic.es.
authors.forename: Lionel C
authors.initials: LC
authors.lastname: Gontard
authors.affiliation: Instituto de Ciencia de Materiales de Sevilla (CSIC), 41092 Sevilla, Spain.
authors.forename: Asunción
authors.initials: A
authors.lastname: Fernández
authors.affiliation: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich, Germany.
authors.forename: Rafal E
authors.initials: RE
authors.lastname: Dunin-Borkowski
authors.affiliation: Center for Electron Nanoscopy, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kasama
authors.affiliation: University of Oxford, Department of Materials, Parks Road, Oxford OX1 3PH, UK.
authors.forename: Sergio
authors.initials: S
authors.lastname: Lozano-Pérez
authors.affiliation: NARILIS - NAmur Research Institute for LIfe Sciences, Research Center in Physics of Matter and Radiation (PMR), Laboratoire d'Analyses par Réactions Nucléaires (LARN), FUNDP University of Namur, Belgium.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Lucas
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry / Q000528:radiation effects; D003460:Crystallization; D006046:Gold; D053768:Metal Nanoparticles / Q000528:radiation effects / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission
chemical_list: D000180:Acrylic Resins; C552516:poly(2-propylacrylic acid); D006046:Gold
keywords: EFTEM; Hybrid nanoparticles; Irradiation effects; Organic–inorganic nanoparticles; Poly-allylamine; Transmission electron microscopy