Ultrastructural characterizations of DNA nanotubes using scanning tunneling and atomic force microscopes.

The potential applications of scanning tunneling microscopy and atomic force microscopy for the characterizations of DNA nanotubes in nanoscale have been described here. The nanotubes were designed using the Cadnano software according to M(13) mp(18) DNA as a scaffold. DNA nanotubes were fabricated using the origami technique assisted with ligase treatment subsequently. Transmission electron microscopy confirmed the morphology of DNA nanotubes. For the topographic characterization of DNA nanotubes, an atomic force microscope was used in comparison to a scanning tunneling microscope. The scanning tunneling microscopy results revealed a high-resolution topography of DNA nanotubes in the constant-current mode; however, more details of the self-assembly in DNA strands in nanotubes were explored by atomic force microscopy with contact mode (or constant height). Our findings suggested that those two microscopes could be candidates for ultrastructural characterizations of DNA nanotubes for obtaining two- and three-dimensional micrographs.