A Smart Deoxyribozyme-Programmable Catalytic DNA Circuit for High-Contrast MicroRNA Imaging.

Synthetic catalytic DNA circuits have been recognized as a promising signal amplification toolbox for sensitive intracellular imaging, yet their selectivity and efficiency are always constrained by uncontrolled off-site signal leakage and inefficient on-site circuitry activation. Thus, the endogenously controllable on-site exposure/activation of DNA circuits is highly desirable for achieving the selective imaging of live cells. Herein, an endogenously activated DNAzyme strategy was facilely integrated with a catalytic DNA circuit for guiding the selective and efficient microRNA imaging in vivo. To prevent the off-site activation, the circuitry constitute was initially caged without sensing functions, which could be selectively liberated by DNAzyme amplifier to guarantee the high-contrast microRNA imaging in target cells. This intelligent on-site modulation strategy can tremendously expand these molecularly engineered circuits in biological systems.