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Université de Fribourg

Polyvinyl alcohol as a biocompatible alternative for the passivation of gold nanorods

Kinnear, Calum ; Burnand, David ; Clift, Martin J. D. ; Kilbinger, Andreas F. M. ; Rothen-Rutishauser, Barbara ; Petri-Fink, Alke

In: Angewandte Chemie International Edition, 2014, vol. 53, no. 46, p. 12613–12617

The functionalization of gold nanorods (GNRs) with polymers is essential for both their colloidal stability and biocompatibility. However, a bilayer of the toxic cationic surfactant cetyl trimethylammonium bromide (CTAB) adsorbed on the nanorods complicates this process. Herein, we report on a strategy for the biocompatible functionalization of GNRs with a hydrophobic polymeric precursor,...

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

Arrested fluid-fluid phase separation in depletion systems: Implications of the characteristic length on gel formation and rheology

Conrad, J. C. ; Wyss, H. M. ; Trappe, Véronique ; Manley, S. ; Miyazaki, K. ; Kaufman, L. J. ; Schofield, A. B. ; Reichman, D. R. ; Weitz, D. A.

In: Journal of Rheology, 2010, vol. 54, no. 2, p. 421-438

We investigate the structural, dynamical, and rheological properties of colloid-polymer mixtures in a volume fraction range of Φ=0.15–0.35. Our systems are density-matched, residual charges are screened, and the polymer-colloid size ratio is ~0.37. For these systems, the transition to kinetically arrested states, including disconnected clusters and gels, coincides with the fluid-fluid phase...

Université de Fribourg

Scattering information obtained by optical microscopy: Differential dynamic microscopy and beyond

Giavazzi, Fabio ; Brogioli, Doriano ; Trappe, Véronique ; Bellini, Tommaso ; Cerbino, Roberto

In: Physical Review E, 2009, vol. 80, no. 3, p. 031403

We describe the use of a bright-field microscope for dynamic light scattering experiments on weakly scattering samples. The method is based on collecting a time sequence of microscope images and analyzing them in the Fourier space to extract the characteristic time constants as a function of the scattering wave vector. We derive a theoretical model for microscope imaging that accounts for (a) the...

Université de Fribourg

A simple patchy colloid model for the phase behavior of lysozyme dispersions

Gögelein, Christoph ; Nägele, Gerhard ; Tuinier, Remco ; Gibaud, Thomas ; Stradner, Anna ; Schurtenberger, Peter

In: The Journal of Chemical Physics, 2008, vol. 129, no. 8, p. 085102

We propose a minimal model for spherical proteins with aeolotopic pair interactions to describe the equilibrium phase behavior of lysozyme. The repulsive screened Coulomb interactions between the particles are taken into account assuming that the net charges are smeared out homogeneously over the spherical protein surfaces. We incorporate attractive surface patches, with the interactions between...

Université de Fribourg

Temperature-sensitive poly(N-Isopropyl-Acrylamide) microgel particles: A light scattering study

Reufer, Mathias ; Díaz-Leyva, P. ; Lynch, I. ; Scheffold, Frank

In: European Physical Journal E, 2009///doi:10.1140/epje/i2008-10387-2

We present a light scattering study of aqueous suspensions of microgel particles consisting of poly(N-Isopropyl-Acrylamide) cross-linked gels. The solvent quality for the particles depends on temperature and thus allows tuning of the particle size. The particle synthesis parameters are chosen such that the resulting high surface charge of the particles prevents aggregation even in the maximally...