Size matters : rethinking Hertz model interpretation for cell mechanics using AFM

Mendová, Katarina (author), Otáhal, Martin (author), Drab, Mitja (author), Daniel, Matej (author)

Cell mechanics are 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.

• Language: English
• Keywords: atomic force microscopy (AFM), cell mechanics, cell stiffness, Hertz contact model
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FE - Faculty of Electrical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2024
• Number of pages: 12 str.
• Numbering: Vol. 25, iss. 13, [article no.] 7186
• PID: 20.500.12556/RUL-159192
• UDC: 620.3
• ISSN on article: 1422-0067
• DOI: 10.3390/ijms25137186
• COBISS.SI-ID: 200434179
• Publication date in RUL: 02.07.2024

Record is a part of a journal

• Title: International journal of molecular sciences
• Shortened title: Int. j. mol. sci.
• Publisher: MDPI
• ISSN: 1422-0067
• COBISS.SI-ID: 2779162

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: mikroskopija na atomsko silo (AFM), celična mehanika, togost celic, Hertzov kontaktni model

Projects

• Funder: Other - Other funder or multiple funders
• Funding programme: Czech Science Foundation
• Project number: SGS22/149/OHK2/3T/12
• Name: Research and development of methods and applications for diagnostic and therapeutic biomechanics