Simultaneous detection of two hepatocellar carcinoma-related microRNAs using a clever single-labeled fluorescent probe.

The simultaneous detection of two important microRNAs (miRNAs) can potentially evaluate pathological states. The simultaneous detection of miRNA-26a and miRNA-122 is proposed in this study using a cleverly designed single-labeled, dual-functional fluorescent probe with a 2-aminopurine as a fluorophore, which is a G-quadruplex single-stranded DNA. The probe can partly complement cDNA-1 and cDNA-2. cDNA-1 and cDNA-2 are complementary strands of miRNA-26a and miRNA-122, respectively. When the target miRNAs are added simultaneously, these cDNA (cDNA-1 and cDNA-2) can be competed off from the cDNA∖probe duplex to form a cDNA∖RNA heteroduplex. The probe is released and the fluorescent signal is increased. The detection limits of miRNA-26a and miRNA-122 are both 2.5 nM, and their wide linear which ranges from 2.5 to 500 nM are achieved using the assay. This method has potential practical applications.