Locked nucleic acids based DNA circuits with ultra-low leakage

DNA circuits based on toehold-mediated DNA strand displacement reaction are powerful tools owing to their programmability and predictability. However, performance and practical application of the circuits are greatly restricted by leakage, which refers to the fact that there is no input (invading strand) in the circuit, and the output signal is still generated. Herein, we constructed locked nucleic acids-based DNA circuits with ultra-low leakage. High binding affinity of LNA (locked nucleic acid)-DNA/LNA suppressed the leakage by inhibiting the breathing effect. Based on the strategy, we have built various low-leakage DNA circuits, including translator circuit, catalytic hairpin assembly (CHA) circuit, entropy-driven circuit (EDC), and seesaw circuit. More importantly, our strategy would not affect the desired main reactions: The output signal remained above 85% for all tested circuits, and the signal-to-noise ratios were elevated to 148.8-fold at the most. We believe our strategy will greatly promote the development and application of DNA circuits-based DNA nanotechnology.