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  • Title: Label-free and ratiometric detection of nuclei acids based on graphene quantum dots utilizing cascade amplification by nicking endonuclease and catalytic G-quadruplex DNAzyme.
    Author: Wang GL, Fang X, Wu XM, Hu XL, Li ZJ.
    Journal: Biosens Bioelectron; 2016 Jul 15; 81():214-220. PubMed ID: 26950646.
    Abstract:
    Herein, we report a ratiometric fluorescence assay based on graphene quantum dots (GQDs) for the ultrasensitive DNA detection by coupling the nicking endonuclease assisted target recycling and the G-quadruplex/hemin DNAzyme biocatalysis for cascade signal amplifications. With o-phenylenediamine acted as the substrate of G-quadruplex/hemin DNAzyme, whose oxidization product (that is, 2,3-diaminophenazine, DAP) quenched the fluorescence intensity of GQDs (at 460nm) obviously, accompanied with the emergence of a new emission of DAP (at 564nm). The ratiometric signal variations at the emission wavelengths of 564 and 460nm (I564/I460) were utilized for label-free, sensitive, and selective detection of target DNA. Utilizing the nicking endonuclease assisted target recycling and the G-quadruplex/hemin DNAzyme biocatalysis for amplified cascade generation of DAP, the proposed bioassay exhibited high sensitivity toward target DNA with a detection limit of 30fM. The method also had additional advantages such as facile preparation and easy operation.
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