期刊
MICROCHIMICA ACTA
卷 185, 期 1, 页码 -出版社
SPRINGER WIEN
DOI: 10.1007/s00604-017-2536-1
关键词
Colorimetric method; Hg(II); AuNPs; G-quadruplex; Exo III; Visual detection; DNA probe; UV-Vis spectrophotometry; TEM; Environmental water analysis
资金
- National Natural Science Foundation of China [21475024, 21575025]
- Program for Changjiang Scholars and Innovative Research Team in University, China [IRT_15R11]
An ultrasensitive conformation-dependent colorimetric assay has been developed for the detection of mercury(II) ions. It is based on the use of exonuclease III (Exo III)-assisted target recycling and gold nanoparticles (AuNPs). In the absence of Hg(II), the hairpin-shaped DNA probe (H-DNA) binds to AuNPs and stabilizes them in solutions of high ionic strength. In the presence of Hg(II), on the other hand, the sticky termini of the H-DNA form a rigid DNA duplex stem with a blunt 3'-terminus. Thus, Exo III is activated as a biocatalyst for selective and stepwise removal of mononucleotides from the 3'-terminus of the H-DNA. As a result, Hg(II) is released from the T-Hg(II)-T complexes. The guanine-rich sequences released from the H-DNA are then self-assembled with potassium ion to form a stable G-quadruplex conformation. In solutions of high ionic strength, this results in aggregation of AuNPs and a color change from red to blue which can be seen with bare eyes. The method is highly sensitive and selective. It has a linear response in the 10 pM to 100 nM Hg(II) concentration range, and the detection limit is as low as 3.2 pM (at an S/N ratio of 3). The relative standard deviation at a level of 0.5 nM of Hg(II) is 4.9% (for n = 10). The method was applied to the detection of Hg(II) in spiked environment water samples, with recoveries ranging from 92% to 106%.
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