Atomic force microscopy (AFM) is a widely used imaging tool for obtaining a variety of information for a range of samples. Although it was initially intended to serve as a method of observing very flat solid surfaces, its use expanded into several other fields, such as high-speed biomolecular imaging, mechanical property measurement, and sample disruption. As a result, AFM continues to be an indispensable tool in research, contributing significantly to advancements in nanotechnology, biophysics, materials science, and numerous other interdisciplinary domains.
In this work, we apply a specific mode of high-speed AFM (HS-AFM) imaging called photothermal off-resonance tapping mode (PORT), which allows us to directly control the forces exerted on the sample. We use this method to image 2D assembly of DNA 3-point stars (3PS) to investigate the impact of structural flexibility and binding strength in the growth of supramolecular networks.
We then use a variation of slow off-resonance imaging called force volume to obtain the mechanical properties of biological membranes for organs-on-a-chip. We compare the utility and reliability of AFM to the bulge test assessment for known samples as well as a membrane aimed at mimicking the extracellular matrix (ECM) scaffold of in vivo barriers of lung tissue.
In the penultimate chapter, we demonstrate promising preliminary data on imaging clathrin mediated endocytosis on unroofed cells with AFM, and the effects of using cholesterol depletion to modify the biological process.
Finally, we discuss the contributions and remaining challenges related to imaging dynamic bioprocesses in vitro and in-vivo, particularly with the use of PORT. Through further development of individual AFM components, such as the cantilever, scanner, controller, and software, and combining them with fluorescent microscopy, we hope to obtain valuable information on self-assembling biosamples that would not be possible with other imaging methods.