Atomic force microscopy and scanning tunneling microscopy of live cells

Scanning tunneling microscopy (STM) has led to significantly improved imaging and manipulation techniques using a range of probes and working principles. The atomic force microscope (AFM) is a device integrated into a high-magnification optical microscope that allows the stabilization of the electrochemical potentials of interest. AFM has unique capabilities such as imaging material surface topography with (sub)nanometer lateral resolution, examining biological samples under physiological conditions, and measuring local features and the interaction forces. The development of AFM has made it one of the very robust devices for the characterization of the surfaces of materials, specifically at the nanostructured scale. Small live cells are immersed in a microcapillary and contacted by a cantilever for imaging. Living cells are thus maintained alive under suitable physiological conditions while retaining high definition for visualizing their molecular structures. AFM is increasingly used to investigate the local mechanical features of live cell surface layers and single live cells. It is of great importance to know the structural features of living cell surfaces at the nanometer scale to comprehend their function in the natural environment and to productively utilize their potential in a related critical investigation. In this chapter, we examined the application of AFM and STM to probe the ultrastructure and physical characteristics of live cell surfaces.