Quantitative SERS detection of multiple breast cancer miRNAs based on duplex specific nuclease-mediated signal amplification

Simultaneous and ultrasensitive detection of multiple microRNA (miRNA) biomarkers is an essential precondition for early cancer diagnosis and treatment. Here we developed a sandwich surface-enhanced Raman scattering (SERS) sensor based on Au@Ag core-shell nanorods combined with duplex specific nuclease-mediated signal amplification (DSNSA) for quantitative detection of multiple breast cancer miRNA biomarkers. The DSNSA strategy enables quantitative detection of target miRNA through rehybridizing the capture probe DNA-SERSnanotag conjugates to trigger signal amplification. The Au@Ag core-shell nanorods coated with an Ag shell exhibit excellent SERS performance, implying that molecules can be concentrated by the Ag shell at the hot spots. By monitoring the Raman signal attenuation of hot spots in the presence of target miRNAs, three breast cancer associated miRNAs (miR-21, miR-155, and let 7b) were simultaneously determined using the sandwich SERS sensor, and their detection limits (LODs) were 0.05 fM, 0.063 fM and 0.037 fM, respectively. These results indicated that our sandwich SERS sensor combined with the DSNSA strategy holds remarkable promise for multiplex detection of cancer biomarkers and contributes to early diagnosis of cancer.