Fluorescent sensor for detection of miR-141 based on target-induced fluorescence enhancement and PicoGreen

Studies have shown that microRNAs affect the development of tumors. In many cases, they can be applied as biomarkers for the diagnosis of cancer; therefore, simple and sensitive analytical methods for detection of miRNAs are necessary. In this study, miR-141, which is used to diagnose several types of cancer, was detected in water and serum samples using a biosensor designed based on streptavidin-coated magnetic beads (SMBs), complementary sequences of miR-141 and PicoGreen as the fluorescent dye. The method is relatively fast and simple. Briefly, in the presence of miR-141, the complementary sequence forms a DNA:RNA double–strand on the surface of SMBs with intercalated PicoGreen. Upon attachment of the PicoGreen, the fluorescence intensity increased significantly (1000-fold). In the absence of a target, only single-stranded DNA (complementary strand of miR-141) existed on the surface of the SMBs. The fluorescence of the PicoGreen was low. The results revealed that the detection limits of the biosensor for miR-141 were 70 and 113.8 nmol L−1 in deionized water and serum samples, respectively.