Sturdier DNA Nanotubes via Ligation

TLDR

DNA nanotubes are crystalline self‑assembled structures about 10 nm wide that can grow tens of micrometers, yet they melt below 40 °C, rupture on mica or during AFM, and disintegrate in water because of backbone nicks. The studied nanotubes contain five nicks—one in the tile core and one at each of the four corners. Ligation of all four corner nicks with T4 DNA ligase leaves stiffness unchanged but enables the tubes to survive temperatures above 70 °C, resist AFM‑induced breakage, and remain stable in pure water for over a month, making them suitable for technological use.

Abstract

DNA nanotubes are crystalline self-assemblies of DNA tiles ∼10 nm in diameter that readily grow tens of micrometers in length. Easy assembly, programmability, and stiffness make them interesting for many applications, but DNA nanotubes begin to melt at temperatures below 40 °C, break open when deposited on mica or scanned by AFM, and disintegrate in deionized water. These weaknesses can be traced to the presence of discontinuities in the phosphate backbone, called nicks. The nanotubes studied here have five nicks, one in the core of a tile and one at each corner. We report the successful ligation of all four corner nicks by T4 DNA ligase. Although ligation does not change the nanotubes' stiffness, ligated nanotubes withstand temperatures over 70 °C, resist breaking during AFM, and are stable in pure water for over a month. Ligated DNA nanotubes are thus physically and chemically sturdy enough to withstand the manipulations necessary for many technological applications.