Regulable toehold lock for the effective control of strand displacement reaction sequence and circuit leakage

Strand displacement reaction enables the construction of enzyme-free DNA reaction networks, thus has been widely applied to DNA circuit and nanotechnology. It has the characteristics of high efficiency, universality and regulatability. However, the existing regulation tools cannot enable effective control of the reaction sequence, which undoubtedly limits the construction of complex nucleic acid circuits. Herein, we developed a regulation tool, toehold lock, and achieved strict control of reaction sequence without loss of the main reaction signal output. Furthermore, we applied the tool to scenarios such as seesaw circuits, AND/OR logic gates, and entropy-driven circuits, and respectively demonstrated its significant superiority compared to the original method. We believe that the proposed toehold lock has greatly optimized the efficiency of DNA strand displacement-based networks, and we anticipate that the tool will be widely used in multiple fields.