ABSTRACT
Molecular biology requires an understanding of the physics of the nanoscale, the realm of nanometer-sized objects, such as proteins, lipids or deoxyribonucleic acids. Scanning probe microscopy is based on scanning a sharp probe across a surface to obtain a surface map. Scanning tunneling microscope can map electron densities and Atomic Force Microscopy (AFM) can map forces by moving across a surface at constant tip-sample distance. AFM can perform two types of measurements: Imaging and force-distance measurements. In dynamic mode imaging, a third channel can be collected: the phase difference of the oscillation. The phase difference is the angular difference between the oscillation state of the actuator that oscillates the cantilever and the actual motion of the tip. Indentation measurements are used extensively in biological studies to determine the mechanical properties of membranes, vesicles and micelles, cells, bacteria, extracellular components such as gels, or bone. Chemical bonding refers to covalent bonding between atoms due to the sharing of electrons.
