Effect of F-Actin Organization in Lamellipodium on Viscoelasticity and Migration of Huh-7 Cells Under pH Microenvironments Using AM-FM Atomic Force Microscopy

Cytoskeleton is responsible for fundamental cellular processes and functions. The filamentous actin (F-actin) a key constituent of the cytoskeleton system which intrinsically viscoelastic greatly determines mechanical properties cells. organization polymerization F-actin are relevant to viscoelasticity distribution migration living cells responding pH microenvironments. Recently, progression in various diseases such as cancers have been found that related alterations lamellipodium. However, correlation among organization, cancer under different microenvironments still poorly understood. Conventional experimental methods optical microscopy atomic force (AFM) can neither break trade-off between resolution rate imaging, nor achieve structural characterization measurement simultaneously. Although multifrequency AFM with amplitude modulation-frequency modulation (AM–FM) enables us probe both surface topography cells, it difficult image cytoskeletal filaments diameter down scale tens nanometers. Here, we improved AM-FM by employing high damping cell culture medium increase signal-to-noise ratio stable imaging 50 nm situ microenvironment. approach successfully visualize structures measure simultaneously enable understand relationship Huh-7 values. Our results demonstrated that, unlike randomly distributed homogeneous at normal level 7.4, reduced 6.5 show highly oriented organized along lamellipodium direction associated significant gradient elasticity viscosity, confirmed immunofluorescence confocal microscopy. provide understanding on adhesion undergo metastasis malignant transformation.