title: A label-free, G-quadruplex DNAzyme-based fluorescent probe for signal-amplified DNA detection and turn-on assay of endonuclease.
abstract: A novel G-quadruplex DNAzyme molecular beacon (G-DNAzymeMB) strategy is developed for assays of target DNA and restriction endonuclease. The detection system consists of G-DNAzymeMB strand and a blocker DNA by using the fluorescence of 2',7'-dichlorodihydrofluorescein diacetate (H(2)DCFDA) catalyzed by G-DNAzymeMB as a signal reporter. G-DNAzymeMB exhibits peroxidase activity in its free hairpin structure, and forms a catalytically inactive hybrid when hybridized with blocker DNA. Upon displacement of blocker DNA by target DNA or cleavage by restriction endonuclease, G-DNAzymeMB is released and two lateral portions of G-DNAzymeMB form a G-quadruplex structure, resulting in the recovery of catalytic activity which acts as a cofactor to catalyze H(2)O(2)-mediated oxidation of H(2)DCFDA. For DNA detection system, exonuclease III (Exo III)-catalyzed amplification strategy is introduced to improve the sensitivity and target DNA could be detected as low as 0.1 pM. With respect to restriction endonuclease detection system, 0.1 U/mL EcoRI endonuclease could be detected and this method could be easily transported to other restriction endonuclease analysis by simply changing the recognition sequence. These results demonstrate that the proposed G-DNAzymeMB strategy could be used as a label-free, simple, sensitive and cost-effective approach in analysis of target DNA and restriction endonuclease.
authors.affiliation: State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, People's Republic of China.
authors.forename: Zhixue
authors.initials: Z
authors.lastname: Zhou
authors.forename: Yan
authors.initials: Y
authors.lastname: Du
authors.forename: Libing
authors.initials: L
authors.lastname: Zhang
authors.forename: Shaojun
authors.initials: S
authors.lastname: Dong
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA / Q000302:isolation & purification*; D004262:DNA Restriction Enzymes / Q000737:chemistry; D021881:DNA, Catalytic / Q000737:chemistry*; D005452:Fluoresceins / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D054856:G-Quadruplexes; D006861:Hydrogen Peroxide / Q000737:chemistry; D010084:Oxidation-Reduction
chemical_list: C110400:2',7'-dichlorodihydrofluorescein diacetate; D021881:DNA, Catalytic; D005452:Fluoresceins; D005456:Fluorescent Dyes; D004247:DNA; D006861:Hydrogen Peroxide; D004262:DNA Restriction Enzymes