DNA-based long-lived reaction-diffusion patterning in a host hydrogel
The development of living organisms is a source of inspiration for the creation of synthetic life-like materials. Embryo development is divided into three stages that are inextricably linked: patterning, differentiation and growth. During patterning, sustained out-of-equilibrium molecular programs interpret underlying molecular cues to create well-defined concentration profiles. Implementing this patterning stage in an autonomous synthetic material is a challenge that at least requires a programmable and long-lasting out-of-equilibrium chemistry compatible with a host material. Here we show that DNA/enzyme reactions can create reaction-diffusion patterns that are extraordinary long-lasting both in solution and inside an autonomous hydrogel. The life-time and stability of these patterns - here traveling fronts and two-band patterns - are significantly increased by blocking parasitic side reactions and by dramatically reducing the diffusion coefficient of specific DNA sequences. Immersed in oil, hydrogels pattern autonomously with limited evaporation, but can also exchange chemical information from other gels when brought in contact. Our primitive metabolic material thus recapitulates two important properties of living matter: a certain degree of autonomy that makes each piece of material an individual with its own metabolism and, at the same time, the capacity to interact with other individuals.