Intracellular network deformation of the cell plays an important role in cellular shape formation. Recent studies suggest that cell reshaping and deformation due to external forces involves cellular volume, pore size, elasticity, and intracellular filaments polymerization rate changes. This behavior of live cells can be described by poroelastic models because of the porous structure of the cytoplasm. In this study, the poroelasticity of human mammary basel/claudin low carcinoma cell (MDA-MB-231) was investigated using indentation-based atomic force microscopy. The effects of cell deformation (i.e., indentation) rate on the poroelasticity of MDA-MB-231 cells were studied. Specifically, the cell poroelastic behavior (i.e., the diffusion coefficient) was quantified at different indenting velocities (0.2, 2, 10, 20, 100, 200 μm/s) by fitting the force-relaxation curves using a poroelastic model. It was found that the in general the MDA-MB-231 cells behaved poroelastic, and they were less poroelastic (i.e., with lower diffusion coefficient) at higher indenting velocities due to the local stiffening up caused by faster force loads. Poor poroelastic relaxation was observed when the indenting velocity was lower than 10 μm/s due to the intracelluar fluid redistribution during the slow indenting process to equilibrate the intracellular pressure. Moreover, the measurement results showed that the pore size reduction caused by local stiffening at faster indenting velocities is more dominant than the Young’s modulus in affecting the cell poroelasticity.

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