Journal
MICROCHIMICA ACTA
Volume 184, Issue 7, Pages 1969-1976Publisher
SPRINGER WIEN
DOI: 10.1007/s00604-017-2182-7
Keywords
T-Hg2+-T; Hairpin; Signal amplification; AuNP; Biosensor; Visualization; UV-Vis absorption; Gel electrophoresis; Aggregates
Categories
Funding
- NSFC [21405060, 1471644]
- Shandong Province Natural Science Funds for Distinguished Young Scholars [JQ201410]
- Shandong Province Natural Science Funds [ZR2015CM027]
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The authors describe a colorimetric method for the determination of Hg(II) ion. It is based on the color change from red to colorless as displayed by gold nanoparticle (AuNP) modified with thymine - rich DNA. Signal amplification is accomplished by free strand displacement recycling. In this strategy, Hg(II) unfolds the arch-trigger duplex due to the high affinity between Hg(II) and the thymines to form T-Hg(II)-T structures, thereby causing the release of trigger. The liberated trigger unfolds the hairpin structure of H1, and unfolded H1 further unfolds with H2. As a result, the H2 hairpin displaces trigger, and the released trigger unfolds another H1. This results in strong and enzyme-free strand displacement recycling amplification. The aggregation of DNA-AuNPs occurs in the presence of the duplex formed by hairpins H2 and H1. This results in a color change from red to colorless that can be visually observed. Under optimal conditions, the assay has a detection range over 4 orders of magnitude and a 3.4 nM detection limit. The assay is selective, sensitive, rapid and cost-effective. In our perception, it represents a useful platform for determination of Hg(II).
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