Single cell mechanics analyzed by atomic force microscopy and finite element simulation

Cell mechanics plays a key role in determining physical performances and physiological functions of cells, as well as the early detection of diseases and development of biomedical engineering. In this study, we utilized a combination of atomic force microscopy (AFM) and finite element method (FEM) to compare the cellular elasticity (Young's modulus) and viscoelasticity (stress-relaxation time) of living and fixed endothelial cells (ECs) across varying loading rates. The results showed that both mechanical properties of normal ECs are more sensitive to loading speed compared with fixed ECs. The Young's modulus of normal endothelial cells (ECs) exhibits an increasing trend with the growing loading rate, whereas the Young's modulus of fixed ECs is almost not affected by the loading rate. Among various viscoelastic properties of cells under varying loading rates, the long-term relaxation time, especially at a loading rate of 5 mu m s-1, showed the most significant difference between living and fixed cells. This work comprehensively evaluated the effectiveness of using different mechanical properties to distinguish cells with different physiological characteristic. This research would improve our knowledge of single-cell mechanical behaviors and provide new ideas for distinguishing various types of cells by AFM-based cellular elastic and viscoelastic properties with varying loading rates.