Single cell biomechanical properties analyzed by atomic force microscopy

Cell mechanics is essential for understanding the mechanical performance and physiological functions of cells, as well as for the early detection of diseases and advancements in biomedical engineering. In this study, we utilized atomic force microscopy (AFM) to measure and compare the cellular elasticity (elastic modulus) and viscoelastic properties of normal cells—human normal cervical epithelial cells (HTX26136) and human mammary epithelial cells (MCF-12A)—with those of cancer cells (cervical cancer cells (HeLa) and human breast cancer cells (MCF-7)). We varied the probe geometry, spherical tip radius, and loading rate to assess their impact on these properties. AFM force-indentation curves were fitted using the Hertz and Sneddon models to extract elastic properties. However, these models alone were insufficient to fully describe cellular mechanics; thus, the stress relaxation curve was employed to characterize viscoelastic behavior.Our results indicate that the elastic and viscoelastic properties of cancer cells are lower than those of normal cells. Notably, the elastic modulus measured with a cone probe was significantly higher than that obtained with a spherical probe, and elastic properties decreased with increasing probe diameter. Additionally, the loading rate had a significant effect on the measured mechanical properties, with an increase in loading rate corresponding to an increase in cell mechanical properties.This study enhances our understanding of the mechanical behavior of single cells and offers new insights into distinguishing different cell types under varying loading conditions based on AFM-derived elastic and viscoelastic properties.