title: Amplified fluorescence detection of mercury(II) ions (Hg2+) using target-induced DNAzyme cascade with catalytic and molecular beacons.
abstract: In this work, a fluorescent sensing strategy was developed for the detection of mercury(II) ions (Hg(2+)) in aqueous solution with excellent sensitivity and selectivity using a target-induced DNAzyme cascade with catalytic and molecular beacons (CAMB). In order to construct the biosensor, a Mg(2+)-dependent DNAzyme was elaborately designed and artificially split into two separate oligonucleotide fragments. In the presence of Hg(2+), the specific thymine-Hg(2+)-thymine (T-Hg(2+)-T) interaction induced the two fragments to produce the activated Mg(2+)-dependent DNAzyme, which would hybridize with a hairpin-structured MB substrate to form the CAMB system. Eventually, each target-induced activated DNAzyme could catalyze the cleavage of many MB substrates through true enzymatic multiple turnovers. This would significantly enhance the sensitivity of the Hg(2+) sensing system and push the detection limit down to 0.2 nM within a 20 min assay time, much lower than those of most previously reported fluorescence assays. Owning to the strong coordination of Hg(2+) to the T-T mismatched pairs, this proposed sensing system exhibited excellent selectivity for Hg(2+) detection, even in the presence of 100 times of other interferential metal ions. Furthermore, the applicability of the biosensor for Hg(2+) detection in river water samples was demonstrated with satisfactory results. These advantages endow the sensing strategy with a great potential for the simple, rapid, sensitive, and specific detection of Hg(2+) from a wide range of real samples.
authors.affiliation: Key Laboratory of Biomedical Information Engineering of Education Ministry, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, PR China.
authors.forename: Lin
authors.initials: L
authors.lastname: Qi
authors.forename: Yongxi
authors.initials: Y
authors.lastname: Zhao
authors.forename: Hui
authors.initials: H
authors.lastname: Yuan
authors.forename: Kai
authors.initials: K
authors.lastname: Bai
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhao
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Dong
authors.forename: Yayan
authors.initials: Y
authors.lastname: Wu
mesh_terms: D001483:Base Sequence; D055162:Biocatalysis; D015374:Biosensing Techniques / Q000379:methods*; D021881:DNA, Catalytic / Q000737:chemistry* / Q000378:metabolism*; D008628:Mercury / Q000032:analysis* / Q000737:chemistry; D009693:Nucleic Acid Hybridization; D015345:Oligonucleotide Probes / Q000737:chemistry* / Q000235:genetics; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013941:Thymine / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D021881:DNA, Catalytic; D015345:Oligonucleotide Probes; D014867:Water; D008628:Mercury; D013941:Thymine