title: Metallo-Toehold-Activated Catalytic Hairpin Assembly Formation of Three-Way DNAzyme Junctions for Amplified Fluorescent Detection of Hg2.
abstract: Because of their irreversible toxicological impacts on the environment and human body, the development of reliable and sensitive Hg2+detection methods with high selectivity is of great significance. On the basis of the substantial signal amplification by metallo-toehold-triggered, catalytic hairpin assembly (CHA) formation of three-way DNAzyme junctions, we have constructed a highly selective and sensitive fluorescent sensing system for the determination of Hg2+in different environmental water samples. The presence of the target Hg2+ions can lead to the generation of T-Hg2+-T base mismatched metallo-toeholds, which trigger the catalytic assembly of three split-DNAzyme containing hairpins to form many Mg2+-dependent DNAzyme junction structures upon binding to the fluorescently quenched substrate sequences. The Mg2+ions then cyclically cleave the fluorescently quenched substrate sequences of the Mg2+-dependent DNAzymes to generate drastically enhanced fluorescent signals for sensitively detecting Hg2+at the low 4.5 pM level. The developed sensing method offers high selectivity toward the target Hg2+over other possible competing metal ions due to the specific T-Hg2+-T bridge structure chemistry in the metallo-toehold domain, and reliable detection of spiked Hg2+in environmentally relevant water samples with this method is also verified. Considering the nucleic acid nature of the trigger and assembly sequences, the developed approach thus holds great potentials for designing new enzyme-free signal amplification strategies to achieve highly sensitive determination of different DNA and RNA targets.
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, PR China.
authors.forename: Xin
authors.identifier: http://orcid.org/0000-0001-9050-6504
authors.initials: X
authors.lastname: Li
authors.affiliation: School of Chemistry and Chemical Engineering, Chongqing University of Technology , Chongqing 400054, PR China.
authors.forename: Jiaqing
authors.initials: J
authors.lastname: Xie
authors.affiliation: School of Chemistry and Chemical Engineering, Chongqing University of Technology , Chongqing 400054, PR China.
authors.forename: Bingying
authors.initials: B
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, PR China.
authors.forename: Ruo
authors.identifier: http://orcid.org/0000-0003-3664-6236
authors.initials: R
authors.lastname: Yuan
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, PR China.
authors.forename: Yun
authors.identifier: http://orcid.org/0000-0003-2982-425X
authors.initials: Y
authors.lastname: Xiang
mesh_terms: D015374:Biosensing Techniques; D002384:Catalysis; D021881:DNA, Catalytic; D007477:Ions; D008628:Mercury / Q000032:analysis*
chemical_list: D021881:DNA, Catalytic; D007477:Ions; D008628:Mercury
keywords: DNAzyme; catalytic hairpin assembly; fluorescence; mercury(II); strand displacement