A novel feedback catalytic hairpin assembly strategy for sensitive mRNA imaging in living cells

Achieving specific and sensitive imaging of mRNA in living cells plays a key role in cancer diagnosis and treatment. Catalytic hairpin assembly (CHA) has been widely used for mRNA imaging. However, it has been significantly constrained by limited in-depth amplifications. Herein, a novel feedback catalytic hairpin assembly (FCHA) with exponential amplification efficiency was proposed for mRNA imaging in living cells. The FCHA system consisted of with two hairpin DNAs (H-1, H-2) and a double stranded DNA (H3L). After the probes enter the cell by using beta-FeOOH nanoparticles (NPs) as delivery vector, the intracellular target Tk1 mRNA acted as catalyst to trigger the FCHA between H-1, H-2 and H3L, which achieved the exponential growth of CHA product. This FCHA system has demonstrated improved reaction kinetics and sensitivity compared to traditional CHA, which was 106 times more sensitive than conventional CHA. This strategy can be used for real-time imaging and indication of changes in the mRNA expression. This strategy slao can distinguish the expression difference of mRNA in normal and tumor cells, and can evaluate the anti-tumor drug's efficacy. Benefiting from these outstanding advantages, we believe that this FCHA will become a powerful tool for early cancer diagnosis.