Entropy‐Driven Strand Displacements Around DNA Tetrahedron for Sensitive Detection and Intracellular Imaging of mRNA

Messenger RNA (mRNA) is the molecule which carries genetic information from DNA and guides the synthesis of protein. It participates in many cellular cascades and exhibits substantial associations with certain diseases. The development of advanced approaches for mRNA sensing and imaging is of utmost importance for biological studies and early clinical diagnosis. Herein, a novel fluorescent method is demonstrated for highly sensitive analysis of mRNA based on entropy‐driven strand displacements around three‐dimensional DNA nanostructures. Tetrahedral DNA with four pendant linear sequences provides excellent molecular scaffold loading at multiple sites for target mRNA‐initiated cascade toehold strand displacement reactions. The variations of fluorescence resonance energy transfer states can be used to indicate the presence and level of target mRNA. Besides, MnO 2 nanosheets are introduced for intracellular transportation of the reaction system for bioimaging. The operation is relatively simple and the developed approach provides a promising tool for mRNA‐related biological researches and clinical applications.