title: Internal structure of magnetic endosomes.
abstract: The internal structure of biological vesicles filled with magnetic nanoparticles is investigated using the following complementary analyses: electronic transmission microscopy, dynamic probing by magneto-optical birefringence and structural probing by Small Angle Neutron Scattering (SANS). These magnetic vesicles are magnetic endosomes obtained via a non-specific interaction between cells and anionic magnetic iron oxide nanoparticles. Thanks to a magnetic purification process, they are probed at two different stages of their formation within HeLa cells: (i) adsorption of nanoparticles onto the cellular membrane and (ii) their subsequent internalisation within endosomes. Differences in the microenvironment of the magnetic nanoparticles at those two different stages are highlighted here. The dynamics of magnetic nanoparticles adsorbed onto cellular membranes and confined within endosomes is respectively 3 and 5 orders of magnitude slower than for isolated magnetic nanoparticles in aqueous media. Interestingly, SANS experiments show that magnetic endosomes have an internal structure close to decorated vesicles, with magnetic nanoparticles locally decorating the endosome membrane, inside their inner-sphere. These results, important for future biomedical applications, suggest that multiple fusions of decorated vesicles are the biological processes underlying the endocytosis of that kind of nanometric materials.
authors.affiliation: Laboratoire des Liquides Ioniques et Interfaces Chargées, UMR CNRS-UPMC-ESPCI 7612, 140 rue de Lourmel, 75015 Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Rivière
authors.forename: C
authors.initials: C
authors.lastname: Wilhelm
authors.forename: F
authors.initials: F
authors.lastname: Cousin
authors.forename: V
authors.initials: V
authors.lastname: Dupuis
authors.forename: F
authors.initials: F
authors.lastname: Gazeau
authors.forename: R
authors.initials: R
authors.lastname: Perzynski
mesh_terms: D000327:Adsorption; D001703:Biophysics / Q000379:methods*; D002462:Cell Membrane / Q000378:metabolism; D011992:Endosomes / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D007477:Ions; D008280:Magnetics; D015233:Models, Statistical; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods; D009502:Neutrons; D012542:Scattering, Radiation
chemical_list: D005290:Ferric Compounds; D007477:Ions; C000499:ferric oxide