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BP: Fachverband Biologische Physik

BP 15: Cell Mechanics I

BP 15.4: Vortrag

Dienstag, 18. März 2025, 12:45–13:00, H44

Living Cells Feel the Surface Tension of Soft Solids — •Johannes Rheinlaender, Hendrik von Eysmondt, and Tilman E. Schäffer — Institute of Applied Physics, University Tübingen, Germany

For about 20 years it has been known that living cells actively respond to the stiffness of their microenvironment - most obviously - by a change in cell spreading area but also other properties such as stiffness, nucleus shape, and gene expression, denoted as mechanosensing. These effects are commonly investigated using hydrogels with a bulk Young's modulus in the kPa range, where cells respond to substrate stiffnesses typically between 1 and 100 kPa. On other soft materials such as elastomers, cell behavior has been shown to be different and weaker, plateauing below about 10 kPa, but the reason remained a matter of debate. On the microscale, surface properties such as surface tension are of increasing relevance, but probing interfaces with micro-indentation techniques such as atomic force microscopy is challenging due to adhesion effects. We therefore use scanning ion conductance microscopy (SICM), a unique scanning probe method benefiting from its non-contact measurement principle, to probe the surface tension of soft solids showing that elastomers exhibit surface tensions of about 10 mN/m, relatively independent of their bulk Young's modulus and surface treatment. Hence, cells mostly "feel" the bulk properties of elastomers for Young's moduli above about 10 kPa, but below mostly the surface tension, demonstrating that the substrate's surface tension is an important yet underestimated aspect in mechanobiology.