Owing to its robustness, precise addressability, and recognition capabilities, DNA is an excellent building block for complex structures.1 Embedding stimuli responsive DNA sequences into larger DNA constructs drives our structures to transform and exert certain functions.2
Herein, we utilise a DNA origami spring3 with 37x2 equidistant, pH-responsive bridging moieties that form non-canonical secondary structures at low pH. When coupled to a small molecule pH regulator, we can use an external source of visible light to activate the curling of our DNA origami spring. In the dark, the spring uncurls. The system is recyclable, does not require any DNA modifications and is waste-free.
We envision nanomachines that do not simply switch between on and off states but rather modulate how fast or slow they reach each state. Knocking on the properties of the photoacid onto the DNA origami structure allows us to modify the persistence of the pH responsive unit, thus controlling the speed of uncurling of the overall structure. By modifying the pre-irradiation conditions, we can program the time it takes for the spring to uncurl. Understanding the correlation between photoacid kinetics and DNA actuation will allow us to build diverse light-activated DNA nanomachines, functioning in out-of-equilibrium conditions similar to biological systems.
References
1 N. D. Seeman, H. F. Sleiman, Nat. Rev. Mat. 2017, 3, 17068.
2 W. R. Berg, J. F. Berengut, C. Bai, L. Wimberger, L. K. Lee, F. J. Rizzuto*, Angew. Chem. Int. Ed., 2023, 62, e202314458.
3 D. Karna, E. Mano, J. Ji, I. Kawamat, Y. Suzuki, H. Mao, Nat. Chem. 2023, 14, 6459.