Nucleic acids, DNA, RNA and various proteins are the most common biomacromolecules examined with AFM. Visualization of conformations of individual DNA strands, DNA-protein complexes and other single macromolecules brings unique information that is hardly accessible by other methods.

An example of an AFM image of DNA is given in Fig 1a. Supercoiling is one of the most interesting DNA-related phenomenon, which is the focus of many studies with emphasis on high-resolution imaging with ultra sharp AFM probes. High-resolution visualization of DNA is also the subject of studies addressing the formation of DNA-protein complexes and the results of enzyme cleavage. Other properties that have been successfully investigated with AFM are DNA stiffness and elasticity and the segmental dynamics of DNA. In the past five years, there has been intense research into the construction of 2D and 3D architectures using self-assembly of single stranded DNA macromolecules. AFM has become the most useful technique for the characterization of these arrays. One such example is the hexagonal DNA array is seen in Fig. 1b.

An example of AFM images of another biomacromolecule is given below.

Two AFM images of plasma protein fibrinogen and its assemblies known as fibrin are presented in Figures 2a-b. These images demonstrate that Hi'Res-C probes provide higher resolution in images of the fibrin, making fine features of the aggregate visible.