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Homogeneous enzyme-free and entropy-driven isothermal fluorescent assay for nucleic acids based on dual-signal output amplification strategy

Abstract

The development of specific and ultrasensitive strategies which do not involve complex nanomaterials or any enzymes for the assay of nucleic acids is extremely important in medical research and disease diagnosis. Herein, we developed a homogeneous enzyme-free, ultrasensitive and isothermal fluorescent biosensor for nucleic acids detection with dual-signal output by combining entropy-driven catalysis (EDC, Cycle I) strategy with catalytic hairpin assembly reaction (CHA, Cycle II). With the existence of target DNA, the T−DNA could hybridize with the premade three-strand duplex through the toehold region (domain 7) and initiate the EDC process, leading to the release of output strand used as an opener of fluorescent reporter I and expose a prelocked toehold region (domain 5) for the hybridization with a fuel strand. The hybridization between FS and substrate strand resulted in the release of T−DNA used for Cycle I and auxiliary strand used as a trigger of CHA reaction via the toehold region (domain 1). After the reaction of CHA, the newly formed hairpin 1/hairpin 2 duplex was used as an opener of fluorescent reporter II. In particular, the two FR for signal output were introduced for the consumption of the products from Cycle I and Cycle II to push the equilibrium and significantly increase the analysis fold amplification for the improvement of reaction rate and sensitivity. Based on the proposed strategy, the developed fluorescent biosensor displayed a wide linear relationship in the range of 50 fM to 5 nM with a limit of detection (LOD) of 15.6 fM, which made the fluorescent biosensor hold a great potential for convenient assay of nucleic acids in biomedical research and point-of-care diagnostics.

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Publication details

The article was received on 17 Sep 2018, accepted on 12 Oct 2018 and first published on 12 Oct 2018


Article type: Communication
DOI: 10.1039/C8CC07508E
Citation: Chem. Commun., 2018, Accepted Manuscript
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    Homogeneous enzyme-free and entropy-driven isothermal fluorescent assay for nucleic acids based on dual-signal output amplification strategy

    E. Xiong, D. Zhen and L. Jiang, Chem. Commun., 2018, Accepted Manuscript , DOI: 10.1039/C8CC07508E

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