A cascaded catalytic hairpin 3D DNA walker-assisted dual-targeting biomimetic sensor for intracellular microRNA imaging

Accurate detection and imaging of microRNAs (miRNAs) in living cells are crucial for early cancer diagnosis and prognosis. Although previous studies have focused on developing efficient miRNA detection methods, exploring analytical techniques with high sensitivity, favorable transfection efficiency, and low toxicity remains a pressing challenge due to the low abundance of miRNAs in living cells. To overcome these limitations, we developed a dual-targeting biomimetic sensor for intracellular miRNA-21 imaging. The sensor overcame the limitations of typical catalytic hairpin assembly (CHA) by employing a dual-catalytic cascade amplification strategy that integrated a DNA walker and CHA, enhancing reaction kinetics and signal amplification efficiency. At the same time, benefiting from the dual-targeting effect of the combination of tumor cell membrane coating and aptamers, the sensor achieved specific cellular internalization, thereby enabling specific, rapid, and sensitive detection of intracellular miRNA without interfering with cell activity. Experimental results indicated that our method enabled dynamic and sensitive detection of miRNA in live cells, with a detection limit as low as 0.46 nmol L⁻¹. Owing to the superior analytical performance of the biomimetic sensor, the present strategy holds great potential for clinical cancer diagnostics and real-time monitoring of therapeutic effects and is expected to have broader applications across diverse cancer types.