An explicit model to extract viscoelastic properties of cells from AFM force-indentation curves
Shada Abuhattum,
Dominic Mokbel,
Paul Müller,
Despina Soteriou,
Jochen Guck,
Sebastian Aland
Affiliations
Shada Abuhattum
Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und Medizin, Staudstr. 2, 91058 Erlangen, Germany; Technische Universität Dresden, Biotechnology Center, Center for Molecular and Cellular Bioengineering, Tatzberg 47-51, 01307 Dresden, Germany; Corresponding author
Dominic Mokbel
Fakultät Mathematik und Informatik, Technische Universität Freiberg, 09599 Freiberg, Germany
Paul Müller
Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und Medizin, Staudstr. 2, 91058 Erlangen, Germany; Technische Universität Dresden, Biotechnology Center, Center for Molecular and Cellular Bioengineering, Tatzberg 47-51, 01307 Dresden, Germany
Despina Soteriou
Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und Medizin, Staudstr. 2, 91058 Erlangen, Germany
Jochen Guck
Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und Medizin, Staudstr. 2, 91058 Erlangen, Germany; Technische Universität Dresden, Biotechnology Center, Center for Molecular and Cellular Bioengineering, Tatzberg 47-51, 01307 Dresden, Germany
Sebastian Aland
Fakultät Mathematik und Informatik, Technische Universität Freiberg, 09599 Freiberg, Germany; Fakultät Informatik/Mathematik, Hochschule für Technik und Wirtschaft Dresden, 01069 Dresden, Germany; Corresponding author
Summary: Atomic force microscopy (AFM) is widely used for quantifying the mechanical properties of soft materials such as cells. AFM force-indentation curves are conventionally fitted with a Hertzian model to extract elastic properties. These properties solely are, however, insufficient to describe the mechanical properties of cells. Here, we expand the analysis capabilities to describe the viscoelastic behavior while using the same force-indentation curves. Our model gives an explicit relation of force and indentation and extracts physically meaningful mechanical parameters. We first validated the model on simulated force-indentation curves. Then, we applied the fitting model to the force-indentation curves of two hydrogels with different crosslinking mechanisms. Finally, we characterized HeLa cells in two cell cycle phases, interphase and mitosis, and showed that mitotic cells have a higher apparent elasticity and a lower apparent viscosity. Our study provides a simple method, which can be directly integrated into the standard AFM framework for extracting the viscoelastic properties of materials.
