scholarly journals Measuring the mechanical properties of apoptotic cells using particle tracking microrheology

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.

scholarly journals Measuring the mechanical properties of apoptotic cells using particle tracking microrheology

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.

scholarly journals Two-point particle tracking microrheology of nematic complex fluids

Soft Matter ◽  
2016 ◽  
Vol 12 (26) ◽  
pp. 5758-5779 ◽  
Author(s):  
Manuel Gómez-González ◽  
Juan C. del Álamo
Keyword(s):  
Particle Tracking ◽  
Actin Filaments ◽  
Complex Fluids ◽  
Soft Materials ◽  
Point Particle ◽  
Shear Moduli ◽  
Technological Complex ◽  
Particle Tracking Microrheology

Many biological and technological complex fluids exhibit microstructural alignment and nematic rheology. We provide a directional two-pont particle tracking microrheology formulation to measure the directional shear moduli of soft materials. We apply it to study the directional rheology of a solution of aligned F-actin filaments.

scholarly journals A human skin ultrasonic imaging to analyse its mechanical properties

2009 ◽  
pp. 105-116
Author(s):  
Alexandre Delalleau ◽  
Gwendal Josse ◽  
Jérôme George ◽  
Yassine Mofid ◽  
Frédéric Ossant ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
High Frequency ◽  
Complex Structure ◽  
Mechanical Parameters ◽  
High Frequency Ultrasound ◽  
Specific Procedure ◽  
Complex Behaviour ◽  
Behaviour Law ◽  
Frequency Ultrasound

The analysis of the skin mechanical behaviour is a key-point for different field of investigation. As the skin is a complex structure, studies are usually based on inverse methods that compare experimental and finite element numerical results. Besides the considered behaviour law, one of the most important question concerns the geometrical aspects of the skin tissue. In this paper, it is shown how high frequency ultrasound imaging helps the calculation of skin mechanical parameters. The hypodermis influence is firstly discussed through elastographic analyses. A specific procedure to measure the dermis thickness is then proposed to highlight that such a measurement must be considered to draw reliable conclusions. The obtained results are finally discussed to point out the interest of such simplifications for the study of more complex behaviour laws.

scholarly journals Plate reader microrheology

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.

Extraction of Mechanical Properties of Articular Cartilage From Osmotic Swelling Behavior Monitored Using High Frequency Ultrasound

2006 ◽  
Vol 129 (3) ◽  
pp. 413-422 ◽  
Author(s):  
Q. Wang ◽  
Y. P. Zheng ◽  
H. J. Niu ◽  
A. F. T. Mak
Keyword(s):  
Mechanical Properties ◽  
Articular Cartilage ◽  
High Frequency ◽  
Weight Bearing ◽  
Ultrasound Measurement ◽  
High Frequency Ultrasound ◽  
Water Fraction ◽  
Layer Interface ◽  
Osmotic Loading ◽  
Frequency Ultrasound

Articular cartilage is a biological weight-bearing tissue covering the bony ends of articulating joints. Negatively charged proteoglycan (PG) in articular cartilage is one of the main factors that govern its compressive mechanical behavior and swelling phenomenon. PG is nonuniformly distributed throughout the depth direction, and its amount or distribution may change in the degenerated articular cartilage such as osteoarthritis. In this paper, we used a 50MHz ultrasound system to study the depth-dependent strain of articular cartilage under the osmotic loading induced by the decrease of the bathing saline concentration. The swelling-induced strains under the osmotic loading were used to determine the layered material properties of articular cartilage based on a triphasic model of the free-swelling. Fourteen cylindrical cartilage-bone samples prepared from fresh normal bovine patellae were tested in situ in this study. A layered triphasic model was proposed to describe the depth distribution of the swelling strain for the cartilage and to determine its aggregate modulus Ha at two different layers, within which Ha was assumed to be linearly dependent on the depth. The results showed that Ha was 3.0±3.2, 7.0±7.4, 24.5±11.1MPa at the cartilage surface, layer interface, and deep region, respectively. They are significantly different (p<0.01). The layer interface located at 70%±20% of the overall thickness from the uncalcified-calcified cartilage interface. Parametric analysis demonstrated that the depth-dependent distribution of the water fraction had a significant effect on the modeling results but not the fixed charge density. This study showed that high-frequency ultrasound measurement together with triphasic modeling is practical for quantifying the layered mechanical properties of articular cartilage nondestructively and has the potential for providing useful information for the detection of the early signs of osteoarthritis.

Lubricin Interaction With Hyaluronate Promotes Interchain Association Leading to Network Formation

2005 ◽  
Author(s):  
J. R. Torres ◽  
G. D. Jay ◽  
M. L. Warman ◽  
R. M. Laxer ◽  
M. Laderer ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Synovial Fluid ◽  
Particle Tracking ◽  
Network Formation ◽  
Molecular Layering ◽  
Cartilage Surface ◽  
Particle Tracking Microrheology ◽  
Boundary Lubricant ◽  
Multiple Particle Tracking ◽  
Multiple Particle

The present work is the first instance where a novel multiple-particle tracking microrheology technique has been applied to study molecular interactions of clinical significance. Herein we describe the molecular changes due to lubricin-hyaluronate interaction and their effect on mechanical properties of synovial fluid. Along with bulk rheology studies it was found that lubricin, a boundary lubricant, increases the HA network formation conducive to the enhanced molecular layering of HA under stress which results in increased shear thinning. This interaction may also allow HA molecules to bind to the cartilage surface, providing boundary lubrication, by virtue of its interaction with lubricin.

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