Duplex micro RNAs assay based on target-triggered universal reporter hybridization

In this paper, we designed and evaluated a duplex detection strategy for micro RNAs（mi RNAs） using universal probe-based target-triggered double hybridization and fluorescent microsphere-based assay system（x MAP array）. In the absence of target mi RNA, reporter DNA cannot hybridize stably with the immobilized capture DNA due to its low melting temperature. Only after adding target mi RNA, can reporter probe hybridize with capture probe to form a stable three-component complex. This targettriggered stable hybridization makes this method possible for highly selective and sensitive detection of multiple mi RNAs. We exemplified a quantitative detection of duplex mi RNAs with a limit of detection of40 p M. The x MAP array platform holds the potential of extending this approach to simultaneous detection of up to 100 mi RNA targets. Considering the simplicity, rapidity and multiplexing, this work promised a potential detection of multiple mi RNA biomarkers for early disease diagnosis and prognosis.

Simultaneous photoelectrochemical detection of dual microRNAs by capturing CdS quantum dots and methylene blue based on target-initiated strand displaced amplification

Herein,we propose a novel photoelectrochemical(PEC) biosensor for dual microRNAs(miRNAs) highly sensitive and simultaneous biosensing based on strand displaced amplification(SDA) reaction.The recognition of HmiR-21 and Hlet-7 a by microRNA-21 and let-7 a leads to their change in hairpin structures,subsequently initiating the immobilization of abundant CdS quantum dots(CdS QD s) and methylene blue(MB) based on SDA reaction.The immobilized CdS QDs and MB produce both high PEC currents under430 nm light and 627 nm light illumination,respectively,and the generated PEC currents are closely relied on target miRNAs amounts.Thus,highly sensitive and simultaneous detection of microRNA-21 and let-7 a was readily achieved with detection limit at 6.6 fmol/L and 15.4 fmol/L based on 3σ,respectively.Further,this PEC biosensor was applied in simultaneous analysis of miRNA-21 and let-7 a in breast cancer patient’s serum with acceptable results.We expect this biosensor will find more useful application in diagnosis of miRNA-related diseases.