Cellular Shear Adhesion Force Measurement and Simultaneous Imaging by Atomic Force Microscope
This paper presents a sensitive and fast cellular shear adhesion force measurement method that uses atomic force microscopy (AFM). AFM is used both as a tool for imaging cells on the nano-scale and as a force sensor for the measurement of the shear adhesion force between a cell and the substrate. After cell imaging, the measurement of cellular shear adhesion force is made based on the different positions of the cell on the nano-scale. Moreover, various pushing speeds of probe and various locations of cells were used in experiments to study their influences. It was found that the measurement of cell adhesion in the upper portion of the cell is different from that in the lower portion. This may reveal that cancer cells have high metastasis tendency after culture for 16–20 h, which is significant for preventing metastasis in patients diagnosed with early cancer lesions. Furthermore, the cellular shear adhesion forces of two types of living cancer cell were obtained based on the measurements of AFM cantilever deflections in the torsional and vertical directions. The results demonstrate that the shear adhesion force of cancer cells is twice as much as that of the same type of cancer cells with tumor-necrosis-factor-related apoptosis-inducing ligand. The proposed method can also be used to measure the cellular shear adhesion force between a cell and the substrate, and for the simultaneous exploration of cells using AFM imaging and manipulation.