Compression Testing and Modeling of Spherical Cells – Comparison of Yeast and Algae

Overbeck, Achim; Günther, Steffi; Kampen, Ingo; Kwade, Arno

doi:10.1002/ceat.201600145

Cited by 9 publications

(5 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, if the primary mode of deformation is stretching, the bending energy can be neglected, simplifying the model. Similar assumptions have been adopted in the model by Overbeck et al [20] and are common in liquid drop models [18].…”

Section: Resultsmentioning

confidence: 95%

“…The first segment is in contact with the spherical indenter, and its radius equals R0. The size of the segment is given by the radius distance a, defined as follows: (6) The principal curvatures of the first segment, and , are both equal to 1/R0. The curvature of the second arc is denoted as R1.…”

Section: Fig 1 Geometry Of Spherical Afm Tip and Membrane Interactionmentioning

confidence: 99%

See 1 more Smart Citation

Nonlinear Cell Deformation Model

Mendová,

Otáhal,

Daniel

2023

Strojnícky Časopis - Journal of Mechanical Engineering

View full text Add to dashboard Cite

Cytoskeletal mechanics is a field that heavily relies on mathematical models to interpret experimental data related to forces and deformations. In this paper, we present a novel mathematical model designed specifically for analysing the mechanical properties of liposomes, which serve as model systems for studying biological membranes. Our model takes into account various factors such as stretching, bending, and contact adhesion during atomic force microscopy (AFM) indentation using a spherical tip. By applying our model to liposomes, we demonstrate that these structures exhibit nonlinear behaviour characterized by low stiffness at small deformations. Furthermore, we find that the mechanical response of liposomes is influenced by their size. Additionally, we observe that the presence of adhesion energy contributes to the generation of negative tip forces upon initial contact.

show abstract

Section: Resultsmentioning

confidence: 95%

Section: Fig 1 Geometry Of Spherical Afm Tip and Membrane Interactionmentioning

confidence: 99%

Nonlinear Cell Deformation Model

Mendová,

Otáhal,

Daniel

2023

Strojnícky Časopis - Journal of Mechanical Engineering

View full text Add to dashboard Cite

show abstract

“…However, in this study, the 90% value of the cumulative SE distribution was used to calculate

. Nevertheless, excessive normal forces can also cause individual cells to burst ( Taubert et al, 2000 ; Günther et al, 2016 ; Overbeck et al, 2017 ). Furthermore, Dittmann et al (2019) , suggested that pellet compression may alter the internal pellet structure due to plastic deformation or cell adhesion effects.…”

Section: Resultsmentioning

confidence: 99%

Quantification and modeling of macroparticle-induced mechanical stress for varying shake flask cultivation conditions

Schrader,

Schrinner,

Polomsky

et al. 2023

Front. Bioeng. Biotechnol.

Self Cite

View full text Add to dashboard Cite

In biotechnological processes, filamentous microorganisms are known for their broad product spectrum and complex cellular morphology. Product formation and cellular morphology are often closely linked, requiring a well-defined level of mechanical stress to achieve high product concentrations. Macroparticles were added to shake flask cultures of the filamentous actinomycete Lentzea aerocolonigenes to find these optimal cultivation conditions. However, there is currently no model concept for the dependence of the strength and frequency of the bead-induced stress on the process parameters. Therefore, shake flask simulations were performed for combinations of bead size, bead concentration, bead density and shaking frequency. Contact analysis showed that the highest shear stresses were caused by bead-bottom contacts. Based on this, a newly generated characteristic parameter, the stress area ratio (SAR), was defined, which relates the bead wall shear and normal stresses to the total shear area. Comparison of the SAR with previous cultivation results revealed an optimum pattern for product concentration and mean product-to-biomass related yield coefficient. Thus, this model is a suitable tool for future optimization, comparison and scaling up of shear-sensitive microorganism cultivation. Finally, the simulation results were validated using high-speed recordings of the bead motion on the bottom of the shake flask.

show abstract

“…Therefore, liposomes adhered to the surface considerably and were excluded from the analysis. Overbeck et al, 2017 showed that, in addition to cell size, osmotic pressure could affect cell response, where higher osmolarity of the culture contributes to a decrease in cell stiffness .…”

Section: Discussionmentioning

confidence: 99%

“…In this study, we will address one particular effect, cell size. Although theoretical and experimental cell studies based on elastic shell theory [33] and liquid drop theory [23] suggest that cell stiffness is considerably affected by its dimensions, it is neglected in Hertz theory. We hypothesized that larger cells will have a smaller stiffness and therefore a smaller Young's modulus, and vice versa.…”

Section: Introductionmentioning

confidence: 99%

Size Matters: Rethinking Hertz Model Interpretation for Cell Mechanics Using AFM

Mendová,

Otáhal,

Drab

et al. 2024

Preprint

View full text Add to dashboard Cite

Cell mechanics is a biophysical indicator of cell state, such as cancer metastasis, leukocyte activation, and cell cycle progression. Atomic force microscopy (AFM) is a widely used technique to measure cell mechanics, where the Young modulus of a cell is usually derived from the Hertz contact model. However, the Hertz model assumes that the cell is an elastic, isotropic, and homogeneous material and that the indentation is small compared to the cell size. These assumptions neglect the effects of the cytoskeleton, cell size and shape, and cell environment on cell deformation. In this study, we investigated the influence of cell size on the estimated Young’s modulus using liposomes as cell models. Liposomes were prepared with different sizes and filled with phosphate buffered saline (PBS) or hyaluronic acid (HA) to mimic the cytoplasm. AFM was used to obtain the force indentation curves and fit them to the Hertz model. We found that the larger the liposome, the lower the estimated Young’s modulus for both PBS-filled and HA-filled liposomes. This suggests that the Young modulus obtained from the Hertz model is not only a property of the cell material, but also depends on the cell dimensions. Therefore, when comparing or interpreting cell mechanics using the Hertz model, it is essential to account for cell size.

show abstract

Compression Testing and Modeling of Spherical Cells – Comparison of Yeast and Algae

Cited by 9 publications

References 34 publications

Nonlinear Cell Deformation Model

Nonlinear Cell Deformation Model

Quantification and modeling of macroparticle-induced mechanical stress for varying shake flask cultivation conditions

Size Matters: Rethinking Hertz Model Interpretation for Cell Mechanics Using AFM

Contact Info

Product

Resources

About