Constitutive Material Modeling of Cell: A Micromechanics Approach

Shin

et al. 2011

Med Biol Eng Comput

The mechanical characterization of cells is important for understanding cellular behavior and physiological functions. We used atomic force microscopy (AFM) to obtain a force-displacement curve and estimate the elastic modulus of hepatocellular carcinoma cells (HEP-G2) utilizing both linear Hertz-Sneddon (HS) and non-linear elastic models. In order to overcome the limitations of HS model, which assumes a linear homogeneous cell body, a cell is modeled as a double-layered body with an outer cytoplasmic layer made mostly of interconnected fibers of cytoskeleton proteins and a nucleus. By disrupting all cytoskeletal protein networks, we estimate the elastic modulus of the core nucleus using FEM for a single ellipsoid. Based on the nucleic modulus and cellular dimensions found by 3D confocal imaging, we develop a novel double-layered cellular (DLC) finite element model. The DLC model provides a more reliable estimate of the elastic modulus of the cell than conventionally used HS model and correlates closely with experimental results.

mentioning

confidence: 96%

mentioning

confidence: 99%

Characterization of cellular elastic modulus using structure based double layer model

Shin

et al. 2011

Med Biol Eng Comput

“…Nonetheless, these results demonstrated the feasibility of similar data to be used for the purpose of increasing the accuracy of cancer diagnosis. Because the tip geometry and indentation depth dependence on elasticity could lead to unavoidable discrepancies in terms of the cell properties or incorrect diagnostic evaluations, especially for spherical tips (Mathur et al 2001;Costa 2003;Kamgoué et al 2007;Unnikrishnan et al 2007), conical tips are considered to be more suitable.…”

Section: Cellular Properties According To the Hertz á Sneddon Modelmentioning

confidence: 99%

“…The HertzÁSneddon (HS) model has been most widely and conveniently used to estimate the elastic moduli of cells for the forceÁdisplacement curves obtained from AFM measurements (Cross et al 2007). However, the elastic modulus estimated using the HS model depends on the tip geometry and indentation depth (Mathur et al 2001;Costa 2003;Kamgoué et al 2007; Unnikrishnan et al 2007). To improve the diagnostic significance of the measured elasticity, tip geometry and indentation depths need to be optimized so that the measured values are reproducible and reliable.…”

Section: Introductionmentioning

confidence: 99%

Comparative study on the differential mechanical properties of human liver cancer and normal cells

Hong

Animal Cells and Systems

et al. 2013

Although cancerous cells and normal cells are known to have different elasticity values, there have been inconsistent reports in terms of the actual and relative values for these two cell types depending on the experimental conditions. This paper investigated the mechanical characterization of normal hepatocytes (THLE-2) and hepatocellular carcinoma cells (HepG2) using atomic force microscopy indentation experiments and the HertzÁSneddon model, and the results were confirmed by an independent de-adhesion assay. To improve the reliability of the data, we considered the effects of tip geometry and indentation depth on the measured elasticity of the cells. This study demonstrated that THLE-2 cells had a higher elastic modulus compared with the HepG2 cells and that this difference was more significant when a conical tip was used. The inhibitor study indicated that this difference in the mechanical properties of THLE-2 and HepG2 cells was mainly attributed to differential arrangements in the cytoskeletal networks of actin filaments. An independent de-adhesion assay also confirmed that THLE-2 cells had a higher elastic modulus compared with the HepG2 cells, which resulted in a shorter time constant for cellular contractility.

Journal of the Mechanical Behavior of Materials

“…This bridging of the spatial scales into a continuum approximation can be carried out by volume averaging of the constituent properties of the atomistic system. This volume averaging can be carried out by using the equivalence of the strain energy due to deformation of the continuum system and a corresponding change in the potential energy during an iso-thermal mechanical straining process in an atomistic system [11]. In most of the atomistic studies on nanotube-based composites, it is implicitly assumed that strong bonds Brought to you by | New York University Bobst Library Technical Services Authenticated Download Date | 5/30/15 6:50 AM exist between the nanotube and matrix molecules leading to a perfect load transfer between the components [12].…”

Section: Introductionmentioning

confidence: 99%

Recent advances in the analysis of nanotube-reinforced polymeric biomaterials

Reddy

Unnikrishnan

2013

Conventional experimental or computational techniques are often inadequate for the analysis and development of nanocomposite-based materials as they are tedious (e.g., experimental methods) or are unsuitable to capture the properties of these novel materials (e.g., conventional computational techniques), thereby requiring multiscale computational strategies. During the last 5 years, major developments were made by the authors on the formulation and implementation of multiscale computational models, using atomistic simulation and micromechanics-based techniques, to study the mechanical and thermal behavior of nanocomposite-based materials. In this article, the advances made in the computational analysis of nanocomposites for tissue engineering applications (e.g., scaffolds and bioreactors) would be discussed. The material properties of the nanocomposites in the lower scales were determined using molecular dynamics, and were then transferred to the macroscale using various homogenization techniques. Also in this article, the authors discuss the development of a theory of mixturebased finite element model for nutrient flow in a hollow fiber membrane bioreactor and the use of computational tools to improve the efficiency of the bioreactor.