Estimation of Cell Young’s Modulus of Adherent Cells Probed by Optical and Magnetic Tweezers: Influence of Cell Thickness and Bead Immersion

2006 ◽  
Vol 129 (4) ◽  
pp. 523-530 ◽  
Author(s):  
Alain Kamgoué ◽  
Jacques Ohayon ◽  
Philippe Tracqui
Keyword(s):  
Young’S Modulus ◽  
External Force ◽  
Elasticity Modulus ◽  
Young's Modulus ◽  
Magnetic Tweezers ◽  
Cell Stiffness ◽  
Cell Cortex ◽  
Geometrical Parameters ◽  
Adherent Cells ◽  
Cell Thickness

A precise characterization of cell elastic properties is crucial for understanding the mechanisms by which cells sense mechanical stimuli and how these factors alter cellular functions. Optical and magnetic tweezers are micromanipulation techniques which are widely used for quantifying the stiffness of adherent cells from their response to an external force applied on a bead partially embedded within the cell cortex. However, the relationships between imposed external force and resulting bead translation or rotation obtained from these experimental techniques only characterize the apparent cell stiffness. Indeed, the value of the estimated apparent cell stiffness integrates the effect of different geometrical parameters, the most important being the bead embedding angle 2γ, bead radius R, and cell height h. In this paper, a three-dimensional finite element analysis was used to compute the cell mechanical response to applied force in tweezer experiments and to explicit the correcting functions which have to be used in order to infer the intrinsic cell Young’s modulus from the apparent elasticity modulus. Our analysis, performed for an extensive set of values of γ, h, and R, shows that the most relevant parameters for computing the correcting functions are the embedding half angle γ and the ratio hu∕2R, where hu is the under bead cell thickness. This paper provides original analytical expressions of these correcting functions as well as the critical values of the cell thickness below which corrections of the apparent modulus are necessary to get an accurate value of cell Young’s modulus. Moreover, considering these results and taking benefit of previous results obtained on the estimation of cell Young’s modulus of adherent cells probed by magnetic twisting cytometry (MTC) (Ohayon, J., and Tracqui, P., 2005, Ann. Biomed. Eng., 33, pp. 131–141), we were able to clarify and to solve the still unexplained discrepancies reported between estimations of elasticity modulus performed on the same cell type and probed with MTC and optical tweezers (OT). More generally, this study may strengthen the applicability of optical and magnetic tweezers techniques by insuring a more precise estimation of the intrinsic cell Young’s modulus (CYM).

scholarly journals Cholesterol-Dependent Modulation of Stem Cell Biomechanics: Application to Adipogenesis

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Shan Sun ◽  
Djanybek Adyshev ◽  
Steven Dudek ◽  
Amit Paul ◽  
Andrew McColloch ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Stem Cell ◽  
Young’S Modulus ◽  
Cell Mechanics ◽  
Young's Modulus ◽  
Adipogenic Differentiation ◽  
Stem Cell Differentiation ◽  
Cell Stiffness ◽  
Cholesterol Depletion

Cell mechanics has been shown to regulate stem cell differentiation. We have previously reported that altered cell stiffness of mesenchymal stem cells can delay or facilitate biochemically directed differentiation. One of the factors that can affect the cell stiffness is cholesterol. However, the effect of cholesterol on differentiation of human mesenchymal stem cells remains elusive. In this paper, we demonstrate that cholesterol is involved in the modulation of the cell stiffness and subsequent adipogenic differentiation. Rapid cytoskeletal actin reorganization was evident and correlated with the cell's Young's modulus measured using atomic force microscopy. In addition, the level of membrane-bound cholesterol was found to increase during adipogenic differentiation and inversely varied with the cell stiffness. Furthermore, cholesterol played a key role in the regulation of the cell morphology and biomechanics, suggesting its crucial involvement in mechanotransduction. To better understand the underlying mechanisms, we investigated the effect of cholesterol on the membrane–cytoskeleton linker proteins (ezrin and moesin). Cholesterol depletion was found to upregulate the ezrin expression which promoted cell spreading, increased Young's modulus, and hindered adipogenesis. In contrast, cholesterol enrichment increased the moesin expression, decreased Young's modulus, and induced cell rounding and facilitated adipogenesis. Taken together, cholesterol appears to regulate the stem cell mechanics and adipogenesis through the membrane-associated linker proteins.

scholarly journals Investigation of the influence of elasticity modulus variation in the ice beam bending model

2020 ◽  
pp. 18-23
Author(s):  
А.А. Симакина
Keyword(s):  
Young’S Modulus ◽  
Numerical Experiments ◽  
Elasticity Modulus ◽  
Young's Modulus ◽  
Physical And Mechanical Properties ◽  
Random Variable ◽  
Beam Length ◽  
System Parameters ◽  
Beam Bending ◽  
Layered Beam

В работе исследуется влияние неравномерности распределения модуля Юнга в ледяной клавише при ее взаимодействии с наклонным сооружением. Неоднородности в модели отдельно рассматриваются по длине и толщине клавиши. Изменение модуля Юнга по толщине происходит, как правило, в связи с температурным градиентом. При этом лед рассматривается как слоистая балка, в каждом слое которой физико-механические свойства остаются постоянными. При изменении модуля Юнга по длине клавиши рассматривается как простая линейная зависимость, так и представление его как случайной величины. Проведено сравнение результирующих параметров разрушения балки при перечисленных постановках задачи. При помощи статистического моделирования получены кривые, определяющие при различных величинах разброса модуля Юнга границы интервала, в которые значения точек разлома попадают с вероятностью 95% The paper investigates the influence of uneven distribution of Young's modulus in an ice beam during its interaction with an inclined structure. Inhomogeneities in the model considered separately along the length and along the height. The change in Young's modulus along the width occurs in connection with the temperature gradient, when viewed as a layered beam. In each layer of the beam, the physical and mechanical properties of ice remain constant. When Young's modulus is changing along the beam length, its representation is considered as a random variable. The comparison is made of the values of the system parameters with and without taking into account inhomogeneities in the model along the length and width. The study involved a series of numerical experiments to determine the dependence of the standard deviation value of Young's modulus and the interval boundaries in which the values of the breaking point falls with a probability of 95%.

Investigation of Effect of Geometrical Parameters of Vertically Aligned Carbon Nanotubes on their Mechanical Properties

2014 ◽  
Vol 894 ◽  
pp. 355-359 ◽  
Author(s):  
Oleg. A. Ageev ◽  
Oleg I. Ilin ◽  
Alexei S. Kolomiytsev ◽  
Marina V. Rubashkina ◽  
Vladimir A. Smirnov ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Bending Stiffness ◽  
Geometrical Parameters ◽  
Vertically Aligned Carbon Nanotubes ◽  
Force Microscopy ◽  
Aligned Carbon Nanotubes ◽  
Vertically Aligned ◽  
Experimental Researches

In the work the results of experimental researches of geometric and mechanical parameters of vertically aligned carbon nanotubes (VACNT) by atomic force microscopy (AFM) and nanoindentation are presented. Here is also shown the influence of diameter and length of the carbon nanotube on the value of bending stiffness and Young's modulus of nanotubes. The analysis of the experimental researches shows that the magnitude of bending stiffness significantly increases with the increasing of the diameter of the nanotubes and decreases with increasing length of the CNT. Diameter and length of the carbon nanotubes also have the most significant influence on Young's modulus of CNTs. The obtained results can be used to develop the processes of formation of micro-and nanoelectronic elements based on the VACNT.

scholarly journals An Auxetic System Based on Interconnected Y-Elements Inspired by Islamic Geometric Patterns

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 865
Author(s):  
Teik-Cheng Lim
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Limited Range ◽  
Geometrical Parameters ◽  
Full Extension ◽  
Geometric Patterns ◽  
The North ◽  
Spiral Spring ◽  
Elastically Restrained ◽  
Deformation Models

A 2D mechanical metamaterial exhibiting perfectly auxetic behavior, i.e., Poisson’s ratio of , is proposed in this paper drawing upon inspiration from an Islamic star formed by circumferential arrangement of eight squares, such as the one found at the exterior of the Ghiyathiyya Madrasa in Khargird, Iran (built 1438–1444 AD). Each unit of the metamaterial consists of eight pairs of pin-jointed Y-shaped rigid elements, whereby every pair of Y-elements is elastically restrained by a spiral spring. Upon intermediate stretching, each metamaterial unit resembles the north dome of Jameh Mosque, Iran (built 1087–1088 AD), until the attainment of the fully opened configuration, which resembles a structure in Agra, India, near the Taj Mahal. Both infinitesimal and finite deformation models of the effective Young’s modulus for the metamaterial structure were established using strain energy approach in terms of the spiral spring stiffness and geometrical parameters, with assumptions to preserve the eight-fold symmetricity of every metamaterial unit. Results indicate that the prescription of strain raises the effective Young’s modulus in an exponential manner until full extension is attained. This metamaterial is useful for applications where the overall shape of the structure must be conserved in spite of uniaxial application of load, and where deformation is permitted under limited range, which is quickly arrested as the deformation progresses.

Vibration Propagation Characteristics of Binary Periodic Sandwich Panels

2012 ◽  
Vol 226-228 ◽  
pp. 172-175 ◽  
Author(s):  
Pei Pei Ge ◽  
Gui Lan Yu
Keyword(s):  
Band Gap ◽  
Young’S Modulus ◽  
Frequency Band ◽  
Vibration Isolation ◽  
Young's Modulus ◽  
Low Frequency ◽  
Sandwich Panels ◽  
Geometrical Parameters ◽  
The Finite Element Method ◽  
Steel Cylinder

By using the finite element method, the band structures of the periodic hollow cylinder sandwich panels are investigated, and the influences of the material and geometrical parameters on the band gap are discussed in detail. The results show that The Young's modulus of panel and the coated layer have the greatest influences on the band gap of binary periodic hollow steel cylinder sandwich panels. The smaller the Young's modulus, the lower the frequency band gap. The material and geometrical parameters of the core have important influences on the lower edges of the band gap. Thicker and higher hollow steel cylinder with large density is favorable to gain a wide low-frequency band gap. The work presented will provide a theoretical guidance in the vibration isolation research.

scholarly journals Cardiomyocyte mechanodynamics under conditions of actin remodelling

2019 ◽  
Vol 374 (1786) ◽  
pp. 20190081 ◽  
Author(s):  
Ricardo H. Pires ◽  
Nithya Shree ◽  
Emmanuel Manu ◽  
Ewa Guzniczak ◽  
Oliver Otto
Keyword(s):  
Stem Cells ◽  
Real Time ◽  
Young’S Modulus ◽  
Mechanical Performance ◽  
Young's Modulus ◽  
Mechanical Analysis ◽  
Adherent Cells ◽  
Filamentous Actin ◽  
Important Indicator ◽  
Compound Exposure

The mechanical performance of cardiomyocytes (CMs) is an important indicator of their maturation state and of primary importance for the development of therapies based on cardiac stem cells. As the mechanical analysis of adherent cells at high-throughput remains challenging, we explore the applicability of real-time deformability cytometry (RT-DC) to probe cardiomyocytes in suspension. RT-DC is a microfluidic technology allowing for real-time mechanical analysis of thousands of cells with a throughput exceeding 1000 cells per second. For CMs derived from human-induced pluripotent stem cells, we determined a Young's modulus of 1.25 ± 0.08 kPa which is in close range to previous reports. Upon challenging the cytoskeleton with cytochalasin D (CytoD) to induce filamentous actin depolymerization, we distinguish three different regimes in cellular elasticity. Transitions are observed below 10 nM and above 10 3 nM and are characterized by a decrease in Young's modulus. These regimes can be linked to cytoskeletal and sarcomeric actin contributions by CM contractility measurements at varying CytoD concentrations, where we observe a significant reduction in pulse duration only above 10 3 nM while no change is found for compound exposure at lower concentrations. Comparing our results to mechanical cell measurements using atomic force microscopy, we demonstrate for the first time to our knowledge, the feasibility of using a microfluidic technique to measure mechanical properties of large samples of adherent cells while linking our results to the composition of the cytoskeletal network. This article is part of a discussion meeting issue ‘Single cell ecology'.

scholarly journals Estimating Young’s Modulus of Single-Walled Zirconia Nanotubes Using Nonlinear Finite Element Modeling

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Ibrahim Dauda Muhammad ◽  
Mokhtar Awang ◽  
Othman Mamat ◽  
Ku Zilati Ku Shaari
Keyword(s):  
Finite Element ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Reaction Force ◽  
Cubic Phase ◽  
Geometrical Parameters ◽  
Element Analysis ◽  
Axial Tensile ◽  
Energy Equivalence ◽  
Element Approach

The single-walled zirconia nanotube is structurally modeled and its Young’s modulus is valued by using the finite element approach. The nanotube was assumed to be a frame-like structure with bonds between atoms regarded as beam elements. The properties of the beam required for input into the finite element analysis were computed by connecting energy equivalence between molecular and continuum mechanics. Simulation was conducted by applying axial tensile strain on one end of the nanotube while the other end was fixed and the corresponding reaction force recorded to compute Young’s modulus. It was found out that Young’s modulus of zirconia nanotubes is significantly affected by some geometrical parameters such as chirality, diameter, thickness, and length. The obtained values of Young’s modulus for a certain range of diameters are in agreement with what was obtained in the few experiments that have been conducted so far. This study was conducted on the cubic phase of zirconia having armchair and zigzag configuration. The optimal diameter and thickness were obtained, which will assist in designing and fabricating bulk nanostructured components containing zirconia nanotubes for various applications.

IL-1β decreases the elastic modulus of human tenocytes

2006 ◽  
Vol 101 (1) ◽  
pp. 189-195 ◽  
Author(s):  
Jie Qi ◽  
Ann Marie Fox ◽  
Leonidas G. Alexopoulos ◽  
Liqun Chi ◽  
Donald Bynum ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Young’S Modulus ◽  
Mechanical Loading ◽  
Actin Filaments ◽  
Young's Modulus ◽  
Length Change ◽  
Cellular Responses ◽  
Cell Stiffness ◽  
Mechanical Stimuli ◽  
Equilibrium Length

Cellular responses to mechanical stimuli are regulated by interactions with the extracellular matrix, which, in turn, are strongly influenced by the degree of cell stiffness (Young's modulus). It was hypothesized that a more elastic cell could better withstand the rigors of remodeling and mechanical loading. It was further hypothesized that interleukin-1β (IL-1β) would modulate intracellular cytoskeleton polymerization and regulate cell stiffness. The purpose of this study was to investigate the utility of IL-1β to alter the Young's modulus of human tenocytes. Young's modulus is the ratio of the stress to the strain, E = stress/strain = (F/ A)/(Δ L/ L0), where L0 is the equilibrium length, Δ L is the length change under the applied stress, F is the force applied, and A is the area over which the force is applied. Human tenocytes were incubated with 100 pM recombinant human IL-1β for 5 days. The Young's modulus was reduced by 27–63%. Actin filaments were disrupted in >75% of IL-1β-treated cells, resulting in a stellate shape. In contrast, immunostaining of α-tubulin showed increased intensity in IL-1β-treated tenocytes. Human tenocytes in IL-1β-treated bioartificial tendons were more tolerant to mechanical loading than were untreated counterparts. These results indicate that IL-1β reduced the Young's modulus of human tenocytes by disrupting the cytoskeleton and/or downregulating the expression of actin and upregulating the expression of tubulins. The reduction in cell modulus may help cells to survive excessive mechanical loading that may occur in damaged or healing tendons.

scholarly journals Single Cell Mechanotype and Associated Molecular Changes in Urothelial Cell Transformation and Progression

2020 ◽  
Vol 8 ◽  
Author(s):  
Weibo Yu ◽  
Qing-Yi Lu ◽  
Shivani Sharma ◽  
Chau Ly ◽  
Dino Di Carlo ◽  
...  
Keyword(s):  
Single Cell ◽  
Young’S Modulus ◽  
Transit Time ◽  
Young's Modulus ◽  
Metastatic Cancer ◽  
Urothelial Cell ◽  
Cell Stiffness ◽  
Mesenchymal Transition ◽  
Deformability Cytometry

Cancer cell mechanotype changes are newly recognized cancer phenotypic events, whereas metastatic cancer cells show decreased cell stiffness and increased deformability relative to normal cells. To further examine how cell mechanotype changes in early stages of cancer transformation and progression, an in vitro multi-step human urothelial cell carcinogenic model was used to measure cellular Young’s modulus, deformability, and transit time using single-cell atomic force microscopy, microfluidic-based deformability cytometry, and quantitative deformability cytometry, respectively. Measurable cell mechanotype changes of stiffness, deformability, and cell transit time occur early in the transformation process. As cells progress from normal, to preinvasive, to invasive cells, Young’s modulus of stiffness decreases and deformability increases gradually. These changes were confirmed in three-dimensional cultured microtumor masses and urine exfoliated cells directly from patients. Using gene screening and proteomics approaches, we found that the main molecular pathway implicated in cell mechanotype changes appears to be epithelial to mesenchymal transition.

scholarly journals Sliding Interaction for Coated Asperity with Power-Law Hardening Elastic-Plastic Coatings

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2388
Author(s):  
Bin Zhao ◽  
Hanzhang Xu ◽  
Xiqun Lu
Keyword(s):  
Friction Coefficient ◽  
Yield Strength ◽  
Young’S Modulus ◽  
Contact Force ◽  
Young's Modulus ◽  
Contact Forces ◽  
Geometrical Parameters ◽  
Asperity Contact ◽  
Strength Ratio ◽  
Modulus Ratio

Sliding between asperities occurs inevitably in the friction pair, which affects the efficiency and reliability in both lubricated and non-lubricated conditions. In this work, the contact parameters in the coated asperity sliding process are studied, and the universal expressions of the average contact force and the friction coefficient are obtained. The effect of the interference between asperities, the material and geometrical parameters including the Young’s modulus ratio and yield strength ratio of the coating and substrate, and the hardening exponent and thickness of the coating on the average contact forces and friction coefficient is considered. It shows both normal and tangential contact forces increase with the increasing interference, increasing Young’s modulus ratio, decreasing yield strength ratio, and decreasing coating thickness; while the trend is different for the effect of the hardening exponent of the coating. The normal force increases and the tangential force decreases as the hardening exponent increases. Based on this, the influence of these parameters on the effective friction coefficient is obtained further. It reveals that the friction coefficient increases as the interference and Young’s modulus ratio enlarge and decreases as the yield strength ratio, the coating’s hardening exponent, and thickness increase. The universal expressions for the contact force and friction coefficient in the sliding process are obtained. This work might give some useful results to help choose the optimum coatings for specific substrates to reduce friction in cases where the asperity contact exists, especially in the focused field of the journal bearing in the marine engine under poor lubrication conditions.

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