Intracellular MicroRNA Imaging Using Telomerase-Catalyzed FRET Ratioflares with Signal Amplification

Intracellular MicroRNA (miRNA) detection has attracted more attentions and made great achievements. However, it still remains great challenging to invite an available tool which possess satisfactory signal-to-background ratio and high sensitivity of miRNA detection. Herein, a class of telomerase-catalyzed FRET (fluorescence resonance energy transfer) ratioflares is developed, for accurate sensing of low-abundance cancer-related miRNA both in fluorescence assay and living cells imaging with signal amplification capacity. In this work, endogenous telomerase is for the first time led in miRNA test system with signal amplification, and telomerase will extend hexamer telomeric repeats (TTAGGG) using the 3’ end of capture probe as primer. The synergetic work of telomerase and catalyst strand (CS) makes target miRNA circulate in system, which results in high sensitivity and enhanced FRET signal with improved detection limit to 2.27 × 10-15 M. Meanwhile, telomerase-catalyzed FRET ratioflares provide the ability to increase the difference between cancer cells and normal cells, reliably. Besides, low false positive signals by chemical interferences and minimized the system fluctuations are achieved through ratio-metric measurement.