Two-Dimensional Hybridization Chain Reaction Strategy for Highly Sensitive Analysis of Intracellular mRNA

Messenger RNA (mRNA) is a type of important gene regulation element and reliable biomarker for the early diagnosis of diseases. However, mRNA analysis in live cells cannot be easily realized since conventional techniques always require procedures like mRNA purification or cell fixation. Herein, we propose a powerful two-dimensional hybridization chain reaction (2D HCR) strategy for amplified sensing and imaging of intracellular mRNA. The basis is the design of ternary hairpin or dumbbell-structured DNA fuel strands. In the presence of mRNA, organized 2D DNA assembly reaction can be initiated, which leads to structural changes of a large number of fuel strands and produces an in situ 2D DNA network. An enhanced fluorescence signal is thus generated, allowing direct and quantitative analysis of mRNA with high signal-to-noise ratio. Moreover, MnO₂ nanosheet/glutathione-aided transportation and release association are successfully applied to adapt the 2D HCR nanosystem in live cells. Therefore, this work provides a promising quantitative endogenous mRNA analysis tool for clinical applications.