Simultaneous detection of breast cancer biomarkers HER2 and miRNA-21 based on duplex-specific nuclease signal amplification

The detection of a single biomarker is prone to false negative or false positive results. Simultaneous analysis of two biomarkers can greatly improve the accuracy of diagnosis. In this work, we designed a new method for coinstantaneous detection of two breast cancer biomarkers miRNA-21 and HER2 using the properties of duplex-specific nuclease (DSN). Cy5-labeled DNA1 and FAM-labeled DNA2 are used as signal probes to distinguish the two signals. When the sample contains the targets HER2 and miRNA-21, HER2 binds to the HER2 aptamer on the double-stranded DNA2, while miRNA-21 binds to the complementary DNA1. Then, DSN enzyme is added to cut the DNA probes adsorbed on the HER2 aptamer and miRNA-21, releasing the fluorescent groups, which can be readsorbed to the empty sites, thus repeating the cutting of the probes and producing an exponential signal amplification with two distinct fluorescent signals. The detection limits of miRNA-21 and HER2 are 1.12 pM and 0.36 ng mL^-1, respectively, with linear ranges of 5 pM to 50 pM and 1 ng mL^-1 to 15 ng mL^-1. The method was validated in real biological samples, providing a new approach for synchronous analysis of important markers in breast cancer.