Soft Robotics Programmed with Double Crosslinking DNA Hydrogels

DNA nanotechnology is developed for decades to construct dynamic responsive systems in optics, quantum electronics, and therapeutics. While DNA nanotechnology is a powerful tool in nanomaterials, it is rare to see successful applications of DNA molecules in the macroscopic regime of material sciences. Here, a novel strategy to magnify the nanometer scale DNA self-assembly into a macroscopic mechanical responsiveness is demonstrated. By incorporating molecularly engineered DNA sequences into a polymeric network, a new type of responsive hydrogel (D-gel), whose overall morphology is dynamically controlled by DNA hybridization-induced double crosslinking is able to be created. As a step toward manufacturing, the D-gel in combination with a bottom-up 3D printing technology is employed to rapidly create modular macroscopic structures that feature programmable reconfiguration and directional movement, which can even mimic the complex gestures of human hands. Mechanical operations such as catch and release are demonstrated by a proof-of-concept hydrogel palm, which possessed great promise for future engineering applications. Compared with previously developed DNA hydrogels, the D-gel features an ease of synthesis, faster response, and a high degree of programmable control. Moreover, it is possible to scale up the production of D-gel containing responsive devices through direct 3D printing.