Poster Presentation Royal Australian Chemical Institute National Congress 2026

Reversible curling of unmodified DNA origami rectangles into nanoribbons and nanotubes through pH modulation (#118)

Diego A. Uehara 1 , Yasmin H. Khazid 1 , Willi R. Berg 1 , Felix J. Rizzuto 1
  1. UNSW Sydney, Kensington, NSW, Australia

DNA origami enables the construction of nanoscale structures with high precision, but dynamic function typically requires the incorporation of responsive motifs or chemical triggers. In this work, we show that Rothemund’s classic DNA origami rectangle1 – one of the most widely used designs in the field – exhibits an intrinsic and reversible pH‑responsive structural transition without any sequence modifications or added responsive elements.

We find that the rectangle undergoes a clear shift from a flat, planar geometry at alkaline conditions (pH ≥8) to a compact, tubular conformation below pH 7. This behaviour extends to assemblies of rectangles: dimers and nanoribbons likewise curl into nanotubes at low pH and uncurl at high pH, demonstrating that the effect propagates across larger architectures. This reversible conformational change arises from the inherent mechanical strain encoded in the square‑lattice design.2,3

Unlike previously used chemical triggers, such as DNA intercalators (e.g., ethidium bromide, TMPyP4)4,5 or other invader strands, pH provides a simple, tunable, and biologically relevant stimulus. As DNA nanostructures gain prominence in drug‑delivery systems, biosensing platforms, and other biomedical applications, understanding how they mechanically respond to diverse physiological pH environments becomes increasingly important. Such insight not only expands the functional landscape of DNA nanotechnology but also supports the rational design of next‑generation dynamic materials that operate without chemical modification or specialised responsive sequences.

References

[1]   P. W. K. Rothemund, “Folding DNA to create nanoscale shapes and patterns,” Nature. 2006, 440, 297–302.

[2]   Z. Li, M. Liu, L. Wang, J. Nangreave, H. Yan, Y. Liu, “Molecular behavior of DNA origami in higher-order self-assembly,” J. Am. Chem. Soc. 2010, 132, 13545–13552.

[3]   H. Dietz, S. M. Douglas, W. M. Shih, “Folding DNA into twisted and curved nanoscale shapes,” Science. 2009, 325, 725–730.

[4]   H. Chen, H. Zhang, J. Pan, T.-G. Cha, S. Li, J. Andréasson, and J. H. Choi, “Dynamic and progressive control of DNA origami conformation by modulating DNA helicity with chemical adducts,” ACS Nano, 2016, 10, 4989–499.

[5]   Z. Li, L. Wang, H. Yan, and Y. Liu, “Effect of DNA hairpin loops on the twist of planar DNA origami tiles,” Langmuir, 2012, 28, 1959–1965.