Two-point particle tracking microrheology of nematic complex fluids

Numerical models developed to study high frequency ultrasound scattering during apoptosis require knowledge of mechanical properties of cells. Particle Tracking Microrheology (PTM) is a technique for studying the mechanical properties of soft materials. By tracking the Brownian movement of particles embedded in a material, its mechanical properties can be extracted. In this thesis, PTM is used to measure the relative changes in the viscoelasticity of apoptotic PC3 cells. PTM was first validated in purely viscous and viscoelastic phantoms. It was found to work well in viscous phantoms, but was limited to only measuring relative changes of the viscoelasticity of viscoelastic materials. After validation, PTM measurements in cells showed that the elastic and viscous modulus increased by over 50 Pa and 20 Pa respectively over the course of the treatment. Preliminary development of another technique known as Two-Point Particle Tracking Microrheology (TPM) is also presented in this thesis.

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Measuring the mechanical properties of apoptotic cells using particle tracking microrheology

10.32920/ryerson.14655153.v1 ◽

2021 ◽

Author(s):

Ahmed El Kaffas

Keyword(s):

Mechanical Properties ◽

Particle Tracking ◽

Numerical Models ◽

Soft Materials ◽

Point Particle ◽

High Frequency Ultrasound ◽

Particle Tracking Microrheology ◽

Viscous Modulus ◽

Pc3 Cells ◽

Frequency Ultrasound

Numerical models developed to study high frequency ultrasound scattering during apoptosis require knowledge of mechanical properties of cells. Particle Tracking Microrheology (PTM) is a technique for studying the mechanical properties of soft materials. By tracking the Brownian movement of particles embedded in a material, its mechanical properties can be extracted. In this thesis, PTM is used to measure the relative changes in the viscoelasticity of apoptotic PC3 cells. PTM was first validated in purely viscous and viscoelastic phantoms. It was found to work well in viscous phantoms, but was limited to only measuring relative changes of the viscoelasticity of viscoelastic materials. After validation, PTM measurements in cells showed that the elastic and viscous modulus increased by over 50 Pa and 20 Pa respectively over the course of the treatment. Preliminary development of another technique known as Two-Point Particle Tracking Microrheology (TPM) is also presented in this thesis.

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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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Particle Tracking Microrheology of Complex Fluids

Physical Review Letters ◽

10.1103/physrevlett.79.3282 ◽

1997 ◽

Vol 79 (17) ◽

pp. 3282-3285 ◽

Cited By ~ 534

Author(s):

T. G. Mason ◽

K. Ganesan ◽

J. H. van Zanten ◽

D. Wirtz ◽

S. C. Kuo

Keyword(s):

Particle Tracking ◽

Complex Fluids ◽

Particle Tracking Microrheology

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Multiple particle tracking

10.1093/oso/9780199655205.003.0004 ◽

2018 ◽

Cited By ~ 1

Author(s):

Eric M. Furst ◽

Todd M. Squires

Keyword(s):

Brownian Motion ◽

Best Practices ◽

Particle Tracking ◽

Heterogeneous Material ◽

Quantitative Measurements ◽

Particle Tracking Microrheology ◽

Shell Models ◽

Multiple Particle Tracking ◽

Microscopy Data ◽

Multiple Particle

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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