| Summary: | Biology and cellular mechanics have benefited from recent technological advances in physics and materials science, allowing researchers to make quantitative nanoscale force measurements to explore aspects of biological systems that were previously inaccessible. Atomic force microscopy (AFM) can be used to acquire high-resolution topographical images of cell surfaces in vivo and possesses the ability to detect the local mechanical properties of single cells on the nanometer scale. Interactions between the tip and sample cause the cantilever to deflect, which is measured using an optical lever system composed of a laser, cantilever, and photodiode. Deflections on the order of tens of picometers can be detected, which correspond to forces of less than 10 pN when using an appropriate cantilever. Highly sensitive force detection with AFM has been used to measure differences in the surface brush of normal and cancerous cells and to determine the mechanical hardness of cellular cytoskeletal structures. The AFM probe has further been employed to perform surgical operations on cells, which enabled the injection of plasmid DNA into a living cell to modulate gene expression. The application of AFM for nanoscale force control and unique cellular surgery provides new methods for investigating cell properties for therapeutic purposes. Keywords: AFM, Mechanical property, Force curve, Extracellular matrix, Matrix stiffness
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