Reconfigurable pH-Responsive DNA Origami Lattices

DNA nanotechnology enables straightforward fabrication of user-defined and nano-meter-precise templates for a cornucopia of different uses. To date, most of these DNA assemblies have been static, but dynamic structures are increasingly coming into view. The programmability of DNA not only allows encoding of the DNA object shape, but it may be equally used in defining the mechanism of action and the type of stimuli- responsiveness of the dynamic structures. However, these "robotic" features of DNA nanostructures are usually demonstrated for only small, discrete and device-like objects rather than for collectively behaving higher-order systems. Here, we show how a large- scale, two-dimensional (2D) and pH-responsive DNA origami -based lattice can be assembled on a mica substrate and further reversibly switched between two distinct states upon the pH change of the surrounding solution. The control over these two configurations is achieved by equipping the arms of the lattice-forming DNA origami units with "pH-latches" that form Hoogsteen-type triplexes at low pH. In a nutshell, we demonstrate how the electrostatic control over the adhesion and mobility of the DNA origami units on the surface can be used both in the large lattice formation (with the help of directed polymerization) and in the conformational switching of the whole lattice on the substrate. To further emphasize the feasibility of the method, we also demonstrate the formation of reconfigurable 2D gold nanoparticle lattices. We believe this work serves as an important milestone in bridging the nanometer-precise DNA origami templates and higher-order large-scale systems with the stimuli-induced dynamicity. ### Competing Interest Statement The authors have declared no competing interest.