Enzyme‐Activated Programmable Theranostic Platform for Spatiotemporal Imaging of Intracellular MicroRNA and On‐Demand Manipulation‐Mediated Therapy

Imaging the aberrant expression of a single microRNA (miRNA) in living cells is often inadequate for accurately evaluating pathological states or implementing responsive therapies. It is a critical need for advanced molecular tools capable of spatiotemporally sensing miRNA and other biomarkers, accompanying the on-demand therapeutic functions. Here, we present a miRNA molecular strategy, enabling both biomarker detection and biomarker-driven therapy. In this platform, a Cy3-labeled hairpin reporter (EH1) containing an apurinic/apyrimidinic endonuclease 1 (APE1) recognition unit, along with a Cy5-labeled hairpin (H2), is co-loaded onto the cerium-based metal-organic framework (Ce-MOF) in a precisely controlled manner (Ce-MOF/DNA). Upon internalization in tumor cells characterized by the elevated levels of carcinogenic APE1 and miRNA-21, the Ce-MOF/DNA theranostic system is activated. APE1 and miRNA-21 function as endogenous activators that trigger the hybridization chain reaction (HCR), leading to fluorescent resonance energy transfer (FRET) between Cy3 and Cy5, which provides a reliable readout for evaluating disease conditions in real-time. Moreover, the Ce-MOF/DNA system exerts therapeutic effects by upregulating the tumor suppressor gene PTEN and inhibiting the oncogenic functions of miRNA-21, thereby suppressing tumor growth. This approach may pave the way for precise diagnosis and effective treatment for cancers characterized by dysregulated miRNA expression.