Dual-SERS biosensor for one-step detection of microRNAs in exosome and residual plasma of blood samples for diagnosing pancreatic cancer.

MicroRNAs have been proved to be the biomarker for early detection of pancreatic cancer and the precisely quantitation of the MicroRNA-10b in the blood samples even can distinguish pancreatic cancer from chronic pancreatitis (CP) and normal controls (NC). In this study, we developed a DSN-assisted dual-SERS biosensor for microRNA-10b in exosome and residual plasma of blood samples detection based on the Fe3O4 @Ag-DNA-Au@Ag@DTNB (SERS tag) conjugates. In presence of target microRNA, it can hybridized with the complementary DNA probes. DSN enzyme was then added to selectively cleaves the DNA probe of the DNA/microRNA duplex, SERS tags can be released from the Fe3O4@Ag and SERS intensity quenching can be triggered, the released microRNA can enter the cycle to decluster other DNA and SERS tags. Due to the dual-SERS enhancement of the Fe3O4@Ag-SERS tag conjugates and the recycling signal amplification, a detection limit of 1 aM with single-base recognition can be performed by one step. The target microRNA in plasma-derived exosome and residual supernatant plasma of blood samples from pancreatic ductal adenocarcinoma (PDAC), chronic pancreatitis (CP) and normal controls (NC) were directly quantified and significant SERS signal distinction can be found among them. The precise quantitation, one-step and one-pot operation can ensure this assay a promising future for point-of-care cancer diagnosis technology.