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Université de Fribourg

Hybrid magnetic iron oxide nanoparticles with tunable field-directed self-assembly

Malik, Vikash ; Pal, Antara ; Pravaz, Olivier ; Crassous, Jérôme J. ; Granville, Simon ; Grobety, Bernard ; Hirt, Ann M. ; Dietsch, Hervé ; Schurtenberger, Peter

In: Nanoscale, 2017, vol. 9, p. 14405-14413

We describe the synthesis of hybrid magnetic ellipsoidal nanoparticles that consist of a mixture of two different iron oxide phases, hematite (α-Fe2O3) and maghemite (γ-Fe2O3), and characterize their magnetic field-driven self-assembly. We demonstrate that the relative amount of the two phases can be adjusted in a continuous way by varying the reaction time during the synthesis, leading to...

Université de Fribourg

Preparation and characterization of functional silica hybrid magnetic nanoparticles

Digigow, Reinaldo G. ; Dechézelles, Jean-François ; Dietsch, Hervé ; Geissbühler, Isabelle ; Vanhecke, Dimitri ; Geers, Christoph ; Hirt, Ann M. ; Rothen-Rutishauser, Barbara ; Petri-Fink, Alke

In: Journal of Magnetism and Magnetic Materials, 2014, vol. 362, p. 72–79

We report on the synthesis and characterization of functional silica hybrid magnetic nanoparticles (SHMNPs). The co-condensation of 3-aminopropyltriethoxysilane (APTES) and tetraethyl orthosilicate (TEOS) in presence of superparamagnetic iron oxide nanoparticles (SPIONs) leads to hybrid magnetic silica particles that are surface-functionalized with primary amino groups. In this work, a...

Université de Fribourg

A general method to label metal oxide particles with fluorescent dyes using aryldiazonium salts

Dechézelles, Jean-François ; Griffete, Nébéwia ; Dietsch, Hervé ; Scheffold, Frank

In: Particle & Particle Systems Characterization, 2013, p. -

Different metal oxide particles are dye labeled by a novel and versatile approach based on aryldiazonium salt chemistry. For dye labeling the particles, the simplicity of aryldiazonium salts to be grafted onto metallic or metal oxide surface is advantageous. The salt is used as a linking agent for attaching the fluorescent molecules.

Université de Fribourg

Amino covalent binding approach on iron oxide nanoparticle surface: toward biological applications

Griffete, Nébéwia ; Clift, Martin J.D. ; Lamouri, Aazdine ; Digigow, Reinaldo G. ; Mihut, Adriana M. ; Fink, Alke ; Rothen-Rutishauser, Barbara ; Dietsch, Hervé

In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2012, p. -

We report on the synthesis and the surface modification of different types of magnetic iron oxide particles by developing an original process based on diazonium salts chemistry. Particles were first coated with amino groups and then subjected to polyethylene glycol (PEG) surface modification. They were subsequently characterized by Transmission electron microscopy, infrared spectroscopy,...

Université de Fribourg

Magnetic orientation of soft particles in a jammed solid

Dagallier, Camille ; Cardinaux, Frédéric ; Dietsch, Hervé ; Scheffold, Frank

In: Soft Matter, 2012, vol. 8, no. 15, p. 4067-4071

Densely packed atoms, molecules, or small particles can get trapped in a jammed state thereby avoiding crystallization. The resulting amorphous structures display complex, spatially heterogeneous, trapping potentials in stark contrast to the uniform case of a crystal. Here we study active and passive rotational motion in a jammed colloidal dispersion of particles consisting of an...

Université de Fribourg

Single step hybrid coating process to enhance the electrosteric stabilization of inorganic particles

Rufier, Chantal ; Reufer, Mathias ; Dietsch, Hervé ; Schurtenberger, Peter

In: Langmuir, 2011, vol. 27, no. 11, p. 6622–6627

We report on a single-step coating process and the resulting colloidal stability of silica-coated spindle-type hematite nanoparticles (NPs) decorated with a layer of poly(acrylic acid) (PAA) polyelectrolyte chains that are partially incorporated into the silica shell. The stability of PAA coated NPs as a function of pH and salt concentration in water was compared to bare hematite particles and...

Université de Fribourg

Orientational behavior of ellipsoidal silica-coated hematite nanoparticles integrated within an elastomeric matrix and its mechanical reinforcement

Sánchez-Ferrer, Antoni ; Mezzenga, Raffaele ; Dietsch, Hervé

In: Macromolecular Chemistry and Physics, 2011, vol. 212, no. 6, p. 627–634

The mechanical and orientational properties of IOENs consisting of integrated ellipsoidal SCH spindle-type nanoparticles within an elastomeric matrix are reported. The influence of the SCH surface chemistry, leading either to dispersed nanoparticles or crosslinked nanoparticles within the surrounding elastomeric matrix, is studied by mechanical uniaxial deformation (stress-strain) and SAXS...

Université de Fribourg

Magnetic properties of silica coated spindle-type hematite particles

Reufer, Mathias ; Dietsch, Hervé ; Gasser, U. ; Grobety, Bernard ; Hirt, A. M. ; Malik, Vivek Kumar ; Schurtenberger, Peter

In: Journal of Physics: Condensed Matter, 2011, vol. 23, no. 6, p. 065102

Magnetic properties of particles are generally determined from randomly oriented ensembles and the influence of the particle orientation on the magnetic response is neglected. Here, we report on the magnetic characterization of anisotropic spindle-type hematite particles. The easy axis of magnetization is within the basal plane of hematite, which is oriented perpendicular to the spindle axis. Two...

Université de Fribourg

Morphology and orientational behavior of silica-coated spindle-type hematite particles in a magnetic field probed by small-angle x-ray scattering

Reufer, Mathias ; Dietsch, Hervé ; Gasser, Urs ; Hirt, Ann ; Andreas Menzel ; Schurtenberger, Peter

In: Journal of Physical Chemistry B, 2010, vol. 114, no. 14, p. 4763-4769

Form factor and magnetic properties of silica-coated spindle-type hematite nanoparticles are determined from SAXS measurements with applied magnetic field and magnetometry measurements. The particle size, polydispersity and porosity are determined using a core−shell model for the form factor. The particles are found to align with their long axis perpendicular to the applied field. The...