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.
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.
authors.affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China; Public Health Research Center at Jiangnan University, Wuxi 214122, PR China. Electronic address: glwang@jiangnan.edu.cn.
authors.forename: Guang-Li
authors.initials: GL
authors.lastname: Wang
authors.affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Xin
authors.initials: X
authors.lastname: Fang
authors.affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Xiu-Ming
authors.initials: XM
authors.lastname: Wu
authors.affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Xue-Lian
authors.initials: XL
authors.lastname: Hu
authors.affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Zai-Jun
authors.initials: ZJ
authors.lastname: Li
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA / Q000032:analysis*; D021881:DNA, Catalytic / Q000737:chemistry*; D004720:Endonucleases / Q000737:chemistry; D054856:G-Quadruplexes; D006108:Graphite / Q000737:chemistry*; D006427:Hemin / Q000737:chemistry; D057230:Limit of Detection; D010619:Phenazines / Q000737:chemistry; D045663:Quantum Dots / Q000737:chemistry* / Q000648:ultrastructure; D013050:Spectrometry, Fluorescence / Q000379:methods
chemical_list: D021881:DNA, Catalytic; D010619:Phenazines; C054312:2,3-diaminophenazine; D006427:Hemin; D006108:Graphite; D004247:DNA; D004720:Endonucleases
keywords: G-quadruplex/hemin DNAzyme; Graphene quantum dots; Ratiometric fluorescence assay; Signal amplification