Light-Dissipative and Reprogrammable DNA Hydrogels Enabled by Merocyanine Photoacids

Living organisms operate far from equilibrium in order to maintain their adaptive structures and functions by continuous energy consumption. The development of synthetic out-of-equilibrium systems using light as an input fuel will allow for remote and noninvasive control over a range of important chemical/biological processes. Here, we report on the rational design of light-fueled DNA hydrogels that exhibit life-like nonequilibrium and dissipative features. Such hydrogels are formed through a two-component mixing strategy, where merocyanine photoacid bearing a robust pH-adjustment capability delicately imparts photoinactive but pH-sensitive DNA components with an adaptive response to light. The transient hydrogel spontaneously dissipates to its sol state in the dark, enabling a highly reversible sol–gel transition that is fine-tuned by irradiation conditions. We construct reprogrammable DNA hydrogel shapes/patterns by alternating the photopatterning/dark-erasing processes using a single recyclable ink. Our work provides a general waste-free approach to developing other light-fueled out-of-equilibrium hydrogels for applications in smart materials and soft robotics.