The chiral index theory, widely used in carbon nanotubes, has been introduced to describe the chiral structures of E-tiling DNA nanotubes precisely. In particular, we define a general equation of tube curvature with a clear physical picture by modifying its mathematical definition. Furthermore, we summarize the recent progress on defining the left- or right-handedness of E-tiling DNA nanotubes through differentiating their inside and outside surfaces by fluorescence or electron or atomic force microscopic imaging.

Abstract

In structural DNA nanotechnology, E-tiling DNA nanotubes are evidenced to be homogeneous in diameter and thus have great potential in biomedical applications such as cellular transport and communication, transmembrane ion/molecule channeling, and drug delivery. However, a precise structural description of chiral DNA nanotubes with chiral parameters was lacking, thus greatly hindering their application breadth and depth, until we recently raised and partly solved this problem. In this perspective, we summarize recent progress in defining the chiral indices and handedness of E-tiling DNA nanotubes by microscopic imaging, especially atomic force microscopy (AFM) imaging. Such a detailed understanding of the chiral structures of E-tiling DNA nanotubes will be very helpful in the future, on the one hand for engineering DNA nanostructures precisely, and, on the other, for realizing specific physicochemical properties and biological functions successfully.