4D force detection of cell adhesion and contractility combining FluidFM and confocal reference-free TFM
Digital FluidFM Conference 2021
4D force detection of cell adhesion and contractility combining FluidFM and confocal reference-free TFMProposed by Xinyu Zhang
Fluid Force Microscopy (FluidFM) combines a hollow microchannel cantilever with conventional AFM and has proven to be a promising tool in biological applications, especially in cell mechanics.  FluidFM and Atomic Force Microscopy (AFM) provide abundant force sensitivity in the perpendicular direction but lack information in the xy lateral direction. Confocal reference-free Traction force microscopy (cTFM) is a powerful tool for the quantification of cellular forces and allows the continuous high-resolution recording of force field without the need of a reference image.  By combining these two methods for the first time, a full time-resolved volumetric force detection (4D) is feasible, more specifically contractile force detection by cTFM and z interaction force detection by FluidFM. This opens opportunities in answering biological questions relative to cell mechanics with unprecedented spatial and temporal resolution. How cells interact with their surrounding is an essential topic because the mechanical machinery and cell signaling are fundamental to complex biological processes such as tissue development and crucial to biomaterials design and study of pathology. The generation of cellular forces is mainly based on the actomyosin apparatus and their transmission to the substrates is through integrin-based adhesions.  Although FluidFM is proficient in measuring the local elasticity and adhesion strength quantitatively, the broader microscopic traction force information at the basal side, where interaction with the substrate is established, is not available. In this frame, cTFM measuring the traction forces generated by cells provides an additional, all-round perspective. By combining the main features of these two techniques, it is possible to decouple the cell adhesion and contractility during active manipulation of individual cells. To obtain quantitatively the adhesion force of single cells, an individual cell will be pulled from the substrate until detachment. This measurement is commonly referred as Single Cell Force Spectroscopy (SCFS).  However, the basal contractile forces during SCFS measurements have not yet been investigated. The simultaneous recording of forces transmitted to the substrate (in and out of plane) could potentially provide more information in how adhesion forces and actomyosin contractility are working together. Furthermore, we are able to indent the cells with the FluidFM probe to investigate the mechanical impedance of single cells. By comparing the impedance difference between control cells and drug treated cells we could infer the role of actin-myosin while applying controlled force. In conclusion, we demonstrated that the combination of two innovative techniques is opening up a wealth of possibilities to answer biological questions by bringing force sensing quantitatively into 4D.
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Xinyu Zhang1, Nafsika Chala2, Dimos Poulikakos2, Aldo Ferrari2, Tomaso Zambelli1
1Laboratory of Biosensors and Bioelectronics, Institute for Biomedical Engineering, ETH Zürich
2Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092 Zürich, Switzerland
PhD Student, ETH Zürich, Switzerland
Dec 01, 2021 10:45 AM (Europe/Zurich)