Calculation of the intracellular elastic modulus based on an atomic force microscope micro-cutting system

Abstract

Better understanding of variations in the mechanical properties of cancer cells could help to provide novel solutions for the diagnosis, prevention, and treatment of cancers. We therefore developed a calculation model of the intracellular elastic modulus based on the contact pressure between the silicon tip of an atomic force microscope and the target cells, and cutting depth. Ovarian cells (UACC-1598) and colon cancer cells (NCI-H716) were cut into sequential layers using an atomic force microscope silicon tip. The cutting area on the cells was 8 m × 8 m, and the loading force acting on the cells was increased from 17.523 to 32.126 N. The elastic modulus distribution was measured after each cutting process. There were significant differences in contact pressure and cutting depth between different cells under the same loading force, which could be attributed to differences in their intrinsic structures and mechanical properties. The differences between the average elastic modulus and surface elastic modulus for UACC-1598 and NCI-H716 cells were 0.288±0.08 kPa and 0.376±0.16 kPa, respectively. These results demonstrate that this micro-cutting method can be used to measure intracellular mechanical properties, which could in turn provide a more accurate experimental basis for the development of novel methods for the diagnosis and treatment of various diseases. The cytoskeleton has a major effect on the responsiveness of cells to external stimuli [1][2][3][4][5] and is composed of a variety of protein filaments of different sizes and degrees of stiffness [6][7][8][9][10]. Cells can be cut into sequential layers using an atomic force microscope (AFM) tip, which allows the elastic modulus of the cytoskeleton and the organelles to be determined. The sequential distribution of the intracellular elastic modulus can thus also be plotted, allowing an overall understanding of the mechanical properties of the cells to be determined. This in turn can provide a more detailed experimental basis for studying cytopathology and disease processes. Investigations into intracellular mechanical properties are therefore crucial.In this study, cells were cut into sequential layers using an AFM-based nano-cutting system, and the contact properties between the AFM silicon tip and the cell were analyzed to measure the distribution of the intracellular elastic modulus. In addition, the cell morphology after each cutting process was also examined.