An Intelligent Redox‐Responsive DNA Circuit for Robust On‐Site Profiling of Glutathione‐MicroRNA Signaling Pathway

Abstract Synthetic biochemical circuits (e.g., DNA circuits) remain at the forefront of intracellular biosensing tasks yet are hindered by the undesired off‐site activation and the accompanying signal leakage. Herein, the study attempts to overcome this limitation by developing a simple‐yet‐powerful endogenous glutathione (GSH)‐regulating tactic that permits robust and distinguishable on‐site microRNA (miRNA) imaging under disturbed redox homeostasis. Specifically, a hierarchically activated catalytic DNA (HAD) circuit is fabricated by grafting the disulfide linkage within entropy‐driven DNA circuitry (EDC) reactants. It is exemplified that this HAD system promises the spatiotemporally selective microRNA‐21 (miR‐21) imaging in living cells and the robust differentiation of tumor cells from normal cells. The correlationship between GSH and miRNA is extensively explored in live cells, and can substantially expand the toolbox of DNA circuits for profiling intracellular biochemical processes.