Université de Fribourg

Gelation, phase behavior, and dynamics of β-Lactoglobulin amyloid fibrils at varying concentrations and ionic strengths

Bolisetty, Sreenath ; Harnau, Ludger ; Jung, Jin-mi ; Mezzenga, Raffaele

In: Biomacromolecules, 2012, vol. 13, no. 10, p. 3241–3252

We have investigated the thermodynamic and dynamic behavior of multistranded β-lactoglobulin protein fibrils in water, by combining static, dynamic, and depolarized dynamic light scattering (SLS, DLS, DDLS), small angle neutron scattering (SANS), rheology, and cryogenic transmission electron microscopy (cryo-TEM). We focus on the region of the phase diagram at which ionic strength and...

Université de Fribourg

Unravelling adsorption and alignment of amyloid fibrils at interfaces by probe particle tracking

Isa, Lucio ; Jung, Jin-Mi ; Mezzenga, Raffaele

In: Soft Matter, 2011, vol. 7, p. 8127-8134

We report the first direct, non-invasive experimental evidence of a 2D isotropic–nematic transition for highly anisotropic nanoparticles at liquid–liquid interfaces by using passive fluorescent particle tracking. In order to illustrate the potential of this approach on systems of high real practical and biological relevance, we select as a model anisotropic nanoparticles β-lactoglobulin...

Université de Fribourg

Controlling hierarchical self-assembly in supramolecular tailed-dendron systems

Merlet-Lacroix, Nathalie ; Rao, Jingyi ; Zhang, Afang ; Schlüter, A. Dieter ; Bolisetty, Sreenath ; Ruokolainen, Janne ; Mezzenga, Raffaele

In: Macromolecules, 2010, vol. 43, no. 10, p. 4752–4760

We study the self-assembly of a dendritic macromolecular system formed by a second-generation dendron with pH-responsive end groups and with a polymer chain emanating from its focal point, typically referred to as dendron-coil system. We use supramolecular ionic interactions to attach to the periphery of the dendrons sulfate-terminated alkyl tails of various lengths. The resulting ionic complexes...

Université de Fribourg

Liquid crystalline phase behavior of protein fibers in water: experiments versus theory

Jung, Jin-Mi ; Mezzenga, Raffaele

In: Langmuir, 2010, vol. 26, no. 1, p. 504–514

We have developed a new method allowing the study of the thermodynamic phase behavior of mesoscopic colloidal systems consisting of amyloid protein fibers in water, obtained by heat denaturation and aggregation of β-lactoglobulin, a dairy protein. The fibers have a cross section of about 5.2 nm and two groups of polydisperse contour lengths: (i) long fibers of 1−20 μm, showing semiflexible...

Université de Fribourg

A new supramolecular route for using rod-coil block copolymers in photovoltaic applications

Sary, Nicolas ; Richard, Fanny ; Brochon, Cyril ; Leclerc, Nicolas ; Lévêque, Patrick ; Audinot, Jean-Nicolas ; Berson, Solenn ; Heiser, Thomas ; Hadziioannou, Georges ; Mezzenga, Raffaele

In: Advanced Materials, 2010, vol. 22, no. 6, p. 763-768

A new polymer blend formed by poly(3-hexylthiophene)-poly(4-vinylpyridine) (P3HT- P4VP) block copolymers and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is reported. The P4VP and PCBM are mixed together by weak supramolecular interactions, and the resulting materials exhibit microphase separated morphologies of electron-donor and electron-acceptor rich domains. The properties of the blend,...

Université de Fribourg

a new level of hierarchical structure control by use of supramolecular self-assembled dendronized block copolymers

Li, Chaoxu ; Schlüter, Dieter A. ; Zhang, Afang ; Mezzenga, Raffaele

In: Advanced Materials, 2008, vol. 20, no. 23, p. 4530 - 4534

Complexation of dendronized block copolymers with sulfate alkyl tails forms unprecedented hierarchically ordered bulk structures, including rectangular-in-lamellar, tetragonal-in-lamellar, hexagonal-in-lamellar and lamellar-in-lamellar. These novel liquid-crystalline morphologies, which can be designed at low length scales in these systems, are expected to provide final materials with not only...

Université de Fribourg

Oleoylethanolamide-based lyotropic liquid crystals as vehicles for delivery of amino acids in aqueous environment

Mohammady, Sayed Z. ; Pouzot, Matthieu ; Mezzenga, Raffaele

In: Biophysical Journal, 2009, vol. 96, no. 4, p. 1537-1546

We have investigated the phase behavior of self-assembled lyotropic liquid crystals (LC) formed by ternary mixtures of oleoylethanolamide (OEA), water and arginine. OEA, a natural analog of the endogenous cannabinoid anandamide involved in the peripheral regulation of feeding, was selected as a main component due to its capacity to induce efficient decreases in food intake and gains in body mass....

Université de Fribourg

Novel phase morphologies in a microphase-separated dendritic polymer melt

Lee, Won Bo ; Elliott, Richard ; Mezzenga, Raffaele ; Fredrickson, Glenn H.

In: Macromolecules, 2009, vol. 42, no. 3, p. 849–859

Equilibrium phase morphologies of two different dendritic block copolymer melts are calculated and compared. These copolymers have a pitchfork-like architecture and consist of three distinct blocks that correspond roughly to the handle, the connecting middle dendron structure, and the attached tines of a pitchfork. The first melt considered consists of a copolymer that has a simple Y-junction...

Université de Fribourg

Frustrated self-assembly of dendron and dendrimer-based supramolecular liquid crystals

Mezzenga, Raffaele ; Ruokolainen, Janne ; Canilho, Nadia ; Kasëmi, Edis ; Schlüter, Dieter A. ; Lee, Won Bo ; Fredrickson, Glenn H.

In: Soft Matter, 2009, vol. 5, p. 92-97

A new "inverted" topological configuration is demonstrated both experimentally and theoretically for self-assembled dendron and dendrimer-based supramolecular liquid crystals in which the dendrons/dendrimers occupy the continuous domain and the ionically attached pendant chains are confined in discrete domains. All previous studies on dendrimer and dendron-based liquid crystals have reported...

Université de Fribourg

Direct imaging of nanoscopic plastic deformation below bulk Tg and chain stretching in temperature-responsive block copolymer hydrogels by Cryo-TEM

Nykänen, Antti ; Nuopponen, Markus ; Hiekkataipale, Panu ; Hirvonen, Sami-Pekka ; Soininen, Antti ; Tenhu, Heikki ; Ikkala, Olli ; Mezzenga, Raffaele

In: Macromolecules, 2008, vol. 41, no. 9, p. 3243–3249

This work describes the thermoresponsive transition in polystyrene-block-poly(N-isopropylacrylamide)-block-polystyrene (PS-block-PNIPAM-block-PS) triblock copolymer hydrogels, as observed by both direct and reciprocal space in-situ characterization. The hydrogel morphology was studied in both the dry and wet state, at temperatures below and beyond the coil−globule transition of PNIPAM, using...