Effects of substrate stiffness on the viscoelasticity of breast cells using atomic force microscopy

The development of tumor is closely related to extracellular matrix, which changes the biomechanical behavior of cells. Research have prepared polyacrylamide hydrogel substrates of differing stiffness according to the hardness values of breast tissue under normal and tumor physiological conditions. Then AFM was used to measure the mechanical properties of breast cells with different degrees of malignancy grown on different stiffness substrates. To explore the reasons for the changes in the young's modulus of three breast cells, the distribution of cellular actin filaments were observed with a confocal microscope. These results showed that when the substrate hardened, the viscoelasticity of benign breast cells increased significantly, and the other two cancer cells also changed to some extent. We also found that the harder the substrate, the more conducive to the spreading behavior of cells, and the weaker response of malignant cells to substrates. These results provide us insights into new ways to distinguish benign tumor cells from malignant ones.