title: Hemin/G-quadruplex-based DNAzyme concatamers for in situ amplified impedimetric sensing of copper(II) ion coupling with DNAzyme-catalyzed precipitation strategy.
abstract: A new signal-amplification strategy based on copper(II) (Cu(2+))-dependent DNAzyme was developed for sensitive impedimetric biosensing of Cu(2+) in aqueous solution by coupling with target-induced formation of hemin/G-quadruplex-based DNAzyme and enzymatic catalytic precipitation technique. Initially, the target analyte cleaved the Cu(2+)-specific DNAzyme to generate an initiator strand on the sensor. Thereafter, the initiator strand underwent an unbiased strand-displacement reaction between hairpin probes in turn to construct a nicked double-helix, accompanying the formation of hemin/G-quadruplex DNAzyme on the long duplex DNA. The newly formed DNAzyme could oxidize the 4-chloro-1-naphthol (4-CN) to produce an insoluble precipitation on the sensor, thus resulting in a local alteration of the conductivity. Under the optimal conditions, the resistance increased with the increasing Cu(2+) in the sample, and exhibited a wide dynamic working range from 0.1 pM to 5.0 nM with a detection limit of 60 fM. The methodology also displayed a high selectivity for Cu(2+) relative to other potentially interfering ions owing to the highly specific Cu(2+)-dependent DNAzyme, and was applicable for monitoring Cu(2+) in real river samples. Thus, our strategy has a good potential in the environment surveys.
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (Ministry of Education & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China.
authors.forename: Mingdi
authors.initials: M
authors.lastname: Xu
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (Ministry of Education & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China.
authors.forename: Zhuangqiang
authors.initials: Z
authors.lastname: Gao
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (Ministry of Education & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China. Electronic address: qhw76@fzu.edu.cn.
authors.forename: Qiaohua
authors.initials: Q
authors.lastname: Wei
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (Ministry of Education & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China.
authors.forename: Guonan
authors.initials: G
authors.lastname: Chen
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (Ministry of Education & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China. Electronic address: dianping.tang@fzu.edu.cn.
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
mesh_terms: D001483:Base Sequence; D015374:Biosensing Techniques / Q000379:methods; D002384:Catalysis; D002413:Cations, Divalent / Q000032:analysis; D011232:Chemical Precipitation; D003300:Copper / Q000032:analysis*; D021881:DNA, Catalytic / Q000737:chemistry*; D017097:Electric Impedance; D055664:Electrochemical Techniques / Q000379:methods; D004784:Environmental Monitoring / Q000379:methods; D054856:G-Quadruplexes; D006427:Hemin / Q000737:chemistry*; D061925:Immobilized Nucleic Acids / Q000737:chemistry; D057230:Limit of Detection; D008969:Molecular Sequence Data; D009284:Naphthols / Q000737:chemistry; D009693:Nucleic Acid Hybridization; D045483:Rivers / Q000737:chemistry*
chemical_list: D002413:Cations, Divalent; D021881:DNA, Catalytic; D061925:Immobilized Nucleic Acids; D009284:Naphthols; C025917:4-chloro-1-naphthol; D006427:Hemin; D003300:Copper
keywords: Copper(II) ion; DNAzyme-catalyzed precipitation; Hemin/G-quadruplex-assembled DNAzyme concatamers; Hybridization chain reaction; Impedimetric biosensor