Dynamics and structure of complex fluids from high frequency mechanical and optical rheometry

Willenbacher, Norbert; Oelschlaeger, Claude

doi:10.1016/j.cocis.2007.03.004

Cited by 58 publications

(28 citation statements)

References 68 publications

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“…61−63 DWS offers a noninvasive method to access the high frequency linear rheology of biomaterials, beyond the capabilities of conventional mechanical rheometers and particle tracking microrheology methods, enabling precise characterization of their mechanical properties. 64 This technique has previously been applied to colloidal gels, 65,66 emulsions, 65 worm-like micelles, 67−69 and F-actin solutions. 70,71 Here, we use DWS for the first time to measure the stiffness of peptide fibrils, namely, those formed by pure MAX1, DMAX1, and their corresponding racemate.…”

Section: Resultsmentioning

confidence: 99%

Molecular, Local, and Network-Level Basis for the Enhanced Stiffness of Hydrogel Networks Formed from Coassembled Racemic Peptides: Predictions from Pauling and Corey

Beltramo²,

et al. 2017

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Hydrogels prepared from self-assembling peptides are promising materials for medical applications, and using both l- and d-peptide isomers in a gel’s formulation provides an intuitive way to control the proteolytic degradation of an implanted material. In the course of developing gels for delivery applications, we discovered that a racemic mixture of the mirror-image β-hairpin peptides, named MAX1 and DMAX1, provides a fibrillar hydrogel that is four times more rigid than gels formed by either peptide alone—a puzzling observation. Herein, we use transmission electron microscopy, small angle neutron scattering, solid state NMR, diffusing wave, infrared, and fluorescence spectroscopies, and modeling to determine the molecular basis for the increased mechanical rigidity of the racemic gel. We find that enantiomeric peptides coassemble in an alternating fashion along the fibril long axis, forming an extended heterochiral pleat-like β-sheet, a structure predicted by Pauling and Corey in 1953. Hydrogen bonding between enantiomers within the sheet dictates the placement of hydrophobic valine side chains in the fibrils’ dry interior in a manner that allows the formation of nested hydrophobic interactions between enantiomers, interactions not accessible within enantiomerically pure fibrils. Importantly, this unique molecular arrangement of valine side chains maximizes inter-residue contacts within the core of the fibrils resulting in their local stiffening, which in turn, gives rise to the significant increase in bulk mechanical rigidity observed for the racemic hydrogel.

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Section: Resultsmentioning

confidence: 99%

Molecular, Local, and Network-Level Basis for the Enhanced Stiffness of Hydrogel Networks Formed from Coassembled Racemic Peptides: Predictions from Pauling and Corey

Beltramo²,

et al. 2017

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“…Capturing these relaxations requires measurements over many decades in frequency, but this requirement is hard to meet experimentally: Inertia limits the scope of conventional rheometers to a range typically below 100 Hz. Rheometers based on torsional resonators do provide complex shear modulus data up to the order of 10 5 Hz, but only at a single frequency for a given device geometry [6,7]. Microrheology experiments consist in tracking the Brownian motion of tracer particles dispersed in the sample using either multiple light scattering or direct observation [4,8].…”

Section: Introductionmentioning

confidence: 99%

Laser-speckle-visibility acoustic spectroscopy in soft turbid media

Wintzenrieth¹,

Cohen-Addad²,

Merrer³

et al. 2014

Phys. Rev. E

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We image the evolution in space and time of an acoustic wave propagating along the surface of turbid soft matter by shining coherent light on the sample. The wave locally modulates the speckle interference pattern of the backscattered light, which is recorded using a camera. We show both experimentally and theoretically how the temporal and spatial correlations in this pattern can be analyzed to obtain the acoustic wavelength and attenuation length. The technique is validated using shear waves propagating in aqueous foam. It may be applied to other kinds of acoustic waves in different forms of turbid soft matter such as biological tissues, pastes, or concentrated emulsions.

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“…Wormlike micelles (WLMs) are long, flexible threadlike surfactant aggregates exhibiting a hierarchy of length scales [1] and associated rheology [2], which can be tuned through a number of physicochemical conditions, including temperature, pressure, and various chemical additives [3]. For example, in a solution of sufficient concentration, WLMs will entangle to form a viscoelastic network, much like an entangled polymer solution [4].…”

Section: Introductionmentioning

confidence: 99%

A systematic study of equilibrium structure, thermodynamics, and rheology of aqueous CTAB/NaNO3 wormlike micelles

Helgeson

Hodgdon

Kaler

et al. 2010

Journal of Colloid and Interface Science

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Dynamics and structure of complex fluids from high frequency mechanical and optical rheometry

Cited by 58 publications

References 68 publications

Molecular, Local, and Network-Level Basis for the Enhanced Stiffness of Hydrogel Networks Formed from Coassembled Racemic Peptides: Predictions from Pauling and Corey

Molecular, Local, and Network-Level Basis for the Enhanced Stiffness of Hydrogel Networks Formed from Coassembled Racemic Peptides: Predictions from Pauling and Corey

Laser-speckle-visibility acoustic spectroscopy in soft turbid media

A systematic study of equilibrium structure, thermodynamics, and rheology of aqueous CTAB/NaNO3 wormlike micelles

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