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Electrochemical Sensing of Exosomal MicroRNA Based on Hybridization Chain Reaction Signal Amplification with Reduced False-Positive Signals
journal contribution
posted on 2020-03-17, 18:11 authored by Qunqun Guo, Yongqi Yu, Hui Zhang, Chenxin Cai, Qingming ShenMicroRNAs
(miRNAs) in cancer cell-derived exosomes are important
cancer biomarkers. Herein, a sensitive hybridization chain reaction
(HCR) electrochemical assay was fabricated for the detection of exosomal
microRNA-122 (miR-122). The hairpin DNA (hpDNA) probes were first
immobilized on the surface of a gold electrode. In the presence of
miR-122, the hairpin structure of the hpDNA could be opened and triggered
the HCR through the cross-opening and hybridization of two helper
DNA hairpins. Long nicked double helixes generated from HCR are used
to capture more RuHex and increase the signal of differential pulse
voltammetry (DPV). In this assay, the density of the hpDNA probes
on the surface of the gold electrode was precisely controlled by the
simultaneous immobilization of hpDNA and short 12 nucleotides single-stranded
DNA (S-12), providing a very high amplification efficiency. More importantly,
the false positive signal could be reduced or completely eliminated
by applying exonuclease I (Exo I) before the introduction of target
miR-122. Under optimal conditions, the assay offers very high sensitivity
with an attomolar level detection limit, a linear range with 9 orders
of magnitude, and specificity in single mismatch discrimination. This
sensitive electrochemical assay could successfully evaluate the miR-122
concentration in different cancer-derived exosomes, indicating its
potential use in cancer diagnostics.
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Hybridization Chain Reaction Signal Amplificationprobe12 nucleotides single-stranded DNAmiR -122 concentrationattomolar level detection limitexosomal microRNA -122signaltarget miR -122.helper DNA hairpinsHCRhpDNAcancer cell-derived exosomeshybridization chain reactionelectrochemical assayDPVReduced False-Positive Signals MicroRNAssurfacegold electrode
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