Université de Fribourg

Structure of β-lactoglobulin microgels formed during heating as revealed by small-angle X-ray scattering and light scattering

Moitzi, Christian ; Donato, Laurence ; Schmitt, Christophe ; Bovetto, Lionel ; Gillies, Graeme ; Stradner, Anna

In: Food Hydrocolloids, 2011, vol. 25, no. 7, p. 1766-1774

We have investigated the structure of microgels formed during heating of demineralized β-lactoglobulin (βlg) solutions at pH 5.9 by small-angle X-ray scattering (SAXS) and light scattering. First, unheated βlg solutions were characterized at different pH values between 2.0 and 7.0. At pH 5.9, βlg solutions contain mainly dimers (with a radius of approx. 2 nm), which coexist with a small...

Université de Fribourg

A photopatternable superparamagnetic nanocomposite: Material characterization and fabrication of microstructures

Suter, M. ; Ergeneman, , O. ; Zürcher, J. ; Moitzi, Christian ; Pané, S. ; Rudin, T. ; Pratsinis, S.E. ; Nelson, B.J. ; Hierold, C.

In: Sensors and Actuators B: Chemical, 2011, vol. 156, no. 1, p. 433-443

A superparamagnetic nanocomposite obtained by dispersing superparamagnetic magnetite nanoparticles in the epoxy SU-8 is used to fabricate microstructures by photolithography. The dispersion of the nanoparticles and the level of agglomerations are analyzed by optical microscopy, TEM (transmission electron microscope), SAXS (small-angle X-ray scattering), XDC (X-ray disc centrifuge) and XRD (X-ray...

Université de Fribourg

The pH induced sol-gel transition in skim milk revisited. a detailed study using time-resolved light and X-ray scattering experiments

Moitzi, Christian ; Menzel, Andreas ; Schurtenberger, Peter ; Stradner, Anna

In: Langmuir, 2011, vol. 27, no. 6, p. 2195–2203

We present a detailed study of the evolution of the size, structure and stability of casein micelles upon acidification of skim milk typically applied in yogurt-making processes using a combination of time-resolved light and small-angle X-ray scattering experiments. While most of the available light scattering studies on casein acidification have been restricted to transparent and therefore...

Université de Fribourg

Internal structure and colloidal behaviour of covalent whey protein microgels obtained by heat treatment

Schmitt, Christophe ; Moitzi, Christian ; Bovay, Claudine ; Rouvet, Martine ; Bovetto, Lionel ; Donato, Laurence ; Leser, Martin E. ; Schurtenberger, Peter ; Stradner, Anna

In: Soft Matter, 2010, vol. 6, no. 19, p. 4876-4884

Covalently cross-linked whey protein microgels (WPM) were produced without the use of a chemical cross-linking agent. The hierarchical structure of WPM is formed by a complex interplay of heat denaturation, aggregation, electrostatic repulsion, and formation of disulfide bonds. Therefore, well-defined spherical particles with a diameter of several hundreds of nanometers and with relatively low...

Université de Fribourg

DMSO-induced denaturation of hen egg white lysozyme

Voets, Ilja K. ; Cruz, Willemberg A. ; Moitzi, Christian ; Lindner, Peter ; Arêas, Elizabeth P. G. ; Schurtenberger, Peter

In: The Journal of Physical Chemistry B, 2010, vol. 114, p. 11875–11883

We report on the size, shape, structure, and interactions of lysozyme in the ternary system lysozyme/DMSO/water at low protein concentrations. Three structural regimes have been identified, which we term the “folded” (0 DMSO DMSO DMSO < 1.0) regime. Lysozyme resides in a...

Université de Fribourg

A new instrument for time-resolved static and dynamic light-scattering experiments in turbid media

Moitzi, Christian ; Vavrin, Ronny ; Bhat, Suresh Kumar ; Stradner, Anna ; Schurtenberger, Peter

In: Journal of Colloid and Interface Science, 2009, vol. 336, no. 2, p. 565-574

We present a new 3D cross-correlation instrument that not only allows for static and dynamic scattering experiments with turbid samples but measures at four angles simultaneously. It thus extends the application of cross-correlation light scattering to time-resolved studies where we can, for example, efficiently investigate the temporal evolution of aggregating or phase separating turbid...

Université de Fribourg

Improved cooperativity of spin-Labile iron(III) centers by self-assembly in solution

Gandolfi, Claudio ; Moitzi, Christian ; Schurtenberger, Peter ; Morgan, Grace G. ; Albrecht, Martin

In: Journal of the American Chemical Society, 2008, vol. 130, no. 44, p. 14434–14435

Supramolecular principles have been applied for improving the spin crossover activity of metal centers due to cooperative effects in solution. Thus, incorporation of alkyloxy tails at the phenyl group of Fe(sal₂trien) 2a provides amphiphilic complexes Fe(sal-OR₂trien) 2b−d (b, R = C₆H₁₃; c, R = C₈H₁₇; d, R = C₁₈H₃₇) comprising an apolar...