title: Deformation of intracellular endosomes under a magnetic field.
abstract: We present a non-invasive method to monitor the membrane tension of intracellular organelles using a magnetic field as an external control parameter. By exploiting the spontaneous endocytosis of anionic colloidal ferromagnetic nanoparticles, we obtain endosomes possessing a superparamagnetic lumen in eukaryotic cells. Initially flaccid, the endosomal membrane undulates because of thermal fluctuations, restricted in zero field by the resting tension and the curvature energy of the membrane. When submitted to a uniform magnetic field, the magnetized endosomes elongate along the field, resulting in the flattening of the entropic membrane undulations. The quantification of the endosome deformation for different magnetic fields allows in situ measurement of the resting tension and the bending stiffness of the membrane enclosing the intracellular organelle.
authors.affiliation: Laboratoire des Milieux Désordonnés et Hétérogènes, UMR7603, and FR2438 CNRS Matière et Systèmes Complexes, Université Pierre et Marie Curie, Tour 13, Case 86, 4 place Jussieu, 75005 Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Wilhelm
authors.forename: A
authors.initials: A
authors.lastname: Cebers
authors.forename: J-C
authors.initials: JC
authors.lastname: Bacri
authors.forename: F
authors.initials: F
authors.lastname: Gazeau
mesh_terms: D002462:Cell Membrane / Q000502:physiology / Q000528:radiation effects* / Q000648:ultrastructure*; D048429:Cell Size / Q000502:physiology / Q000528:radiation effects; D004548:Elasticity; D004574:Electromagnetic Fields; D011992:Endosomes / Q000502:physiology / Q000528:radiation effects* / Q000648:ultrastructure*; D005290:Ferric Compounds; D040542:Mechanotransduction, Cellular / Q000502:physiology; D008560:Membrane Fluidity / Q000528:radiation effects*; D008846:Micromanipulation / Q000295:instrumentation / Q000379:methods*; D010812:Physical Stimulation; D013314:Stress, Mechanical
chemical_list: D005290:Ferric Compounds