In situ viscoelastic properties of insoluble and porous polysaccharide biopolymer dextran produced by Leuconostoc mesenteroides using particle-tracking microrheology

The fundamentals and best practices of multiple particle tracking microrheology are discussed, including methods for producing video microscopy data, analyzing data to obtain mean-squared displacements and displacement correlations, and, critically, the accuracy and errors (static and dynamic) associated with particle tracking. Applications presented include two-point microrheology, methods for characterizing heterogeneous material rheology, and shell models of local (non-continuum) heterogeneity. Particle tracking has a long history. The earliest descriptions of Brownian motion relied on precise observations, and later quantitative measurements, using light microscopy.

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Compliance of actin filament networks measured by particle-tracking microrheology and diffusing wave spectroscopy

Rheologica Acta ◽

10.1007/s003970050125 ◽

1998 ◽

Vol 37 (4) ◽

pp. 387-398 ◽

Cited By ~ 93

Author(s):

Jingyuan Xu ◽

Virgile Viasnoff ◽

D. Wirtz

Keyword(s):

Actin Filament ◽

Particle Tracking ◽

Diffusing Wave Spectroscopy ◽

Particle Tracking Microrheology ◽

Filament Networks

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Plate reader microrheology

10.1101/2020.07.10.197723 ◽

2020 ◽

Author(s):

Robert F. Hawkins ◽

Gregg A. Duncan

Keyword(s):

Particle Tracking ◽

Fluorescence Polarization ◽

Rotational Diffusion ◽

Polymeric Materials ◽

Soft Materials ◽

Clinical Samples ◽

Clinical Settings ◽

Particle Tracking Microrheology ◽

Plate Reader ◽

Potential Applications

AbstractIn this work, we report the development of a simplified microrheological method that can be used to rapidly study soft materials. This approach uses fluorescence polarization and a plate reader format to measure the rotational diffusion of nanoparticles within a sample of interest. We show that this measurement is sensitive to viscosity-dependent changes in polymeric soft materials and is correlated with particle tracking microrheology, a previously validated measure of microrheology. Using these fluorescence polarization-based measurements, we describe formalism that enables reasonable estimation of viscosity in polymeric materials after accounting for length-scale dependent effects of the polymer environment on the nanoparticle rotational diffusion. The use of a plate reader format allows this approach to be higher throughput, less technically challenging, and more widely accessible than standard macro- and microrheological methods, making it available to non-experts. This approach has potential applications in academic and industry settings where conventional rheological equipment may not be available, as well as in clinical settings to rapidly characterize human clinical samples.

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Viscoelastic properties of woody hemp core

Holzforschung ◽

10.1515/hf.2010.111 ◽

2011 ◽

Vol 65 (2) ◽

Cited By ~ 14

Author(s):

Rahime Bag ◽

Johnny Beaugrand ◽

Patrice Dole ◽

Bernard Kurek

Keyword(s):

Cell Wall ◽

Viscoelastic Properties ◽

Specific Effect ◽

Mechanical Analysis ◽

Low Molecular Weight ◽

Dielectric Analysis ◽

Technological Transformation ◽

Chain Mobility ◽

Cell Wall Polymers

Abstract The aim of this study was to determine the effect of removing extractives from the woody core of hemp (chènevotte) on the chain mobility of hemicelluloses and lignins, which can react during technological transformation such as de-fibering and/or composite materials production. Extractives are molecules with low molecular weight, which are present in the cell wall matrix and can be readily removed by solvents. In the present paper, the nature and amounts of extractives, removed under different conditions and with solvents of different polarities, were determined. The mobility and structural relaxations of lignins and hemicelluloses were stu-died in situ by dynamic mechanical analysis and dielectric analysis under controlled moisture content. Extractions at low temperature led to rigidification of lignins and plasticizing of hemicelluloses, probably due to local changes by the selective removal of molecules interacting with the polymers. Probably, the accessibility of hemicelluloses to plasticizing water was increased at controlled humidity. In contrast, hot extractions including water induced rigidification of the hemi-celluloses and plasticizing of lignins. This could be related to a combination of molecule extractions and chemical modi-fications of both polymers. This interpretation is supported by the variation of activation energy for relaxation of hemi-celluloses. It can be concluded that each type of extraction has a clear specific effect on the relaxation properties of the amorphous cell wall polymers.

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