Synthetic DNA Delay Circuits for Temporal Coordination

Biological systems use chemical circuits to coordinate elaborate sequences of events, from the timing of cell divisions inside the embryo, to the sustained rhythms of circadian clocks. Similar control over the timing of events in synthetic systems remains challenging, in part because of the complexity of designing de novo gene regulatory networks. Here we demonstrate a simple molecular circuit, consisting of only three species of synthetic DNA complexes in buffer, which automatically releases a target sequence of DNA into solution after a tunable delay period. The delay time can be specified on the order of hours to days, and multiple orthogonal delay circuits can be combined to coordinate the release of different sequences at independent times. This bare-bones circuit facilitates precise timing of target events inside of in vitro DNA networks without external stimulation.