Dynamic Programming of a DNA Walker Controlled by Protons.

We have now constructed a four-legged DNA walker based on toehold exchange reactions whose movement is controlled by alternating pH changes. A well-characterized, pH-responsive CG-C+ triplex DNA was embedded into a tetrameric catalytic hairpin assembly (CHA) walker. The proton-controlled walker could autonomously move on otherwise unprogrammed microparticles surface, and the walking rate and steps of walking were efficiently controlled by pH. The starting and stopping of the walker, and its association and dissociation from the microparticles, could also be dynamically controlled by pH. The simple, programmable, and robust nature of this proton-controlled walker now provides the impetus for the development of a wide variety of more practical nanomachines.