Control over Surface DNA Density on Gold Nanoparticles Allows Selective and Sensitive Detection of Mercury(II)

We have developed a new highly selective and sensitive technique for the detection of Hg2+ using DNA-functionalized gold nanoparticles (Au NPs) and OliGreen. This system is the first that allows the detection of Hg2+ based on the release of DNA molecules, induced by conformational changes on Au NP s...

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Published inLangmuir Vol. 24; no. 15; pp. 8346 - 8350
Main Authors Liu, Chi-Wei, Huang, Chih-Ching, Chang, Huan-Tsung
Format Journal Article
LanguageEnglish
Published Washington, DC American Chemical Society 05.08.2008
Subjects
Chemistry
Colloidal state and disperse state
Devices and Applications: Sensors, Fluidics, Patterning, Catalysis, Photonic Crystals
DNA - chemistry
Exact sciences and technology
General and physical chemistry
Gold - chemistry
Ions - chemistry
Mercury - chemistry
Metal Nanoparticles - chemistry
Physical and chemical studies. Granulometry. Electrokinetic phenomena
Spectrometry, Fluorescence
Surface physical chemistry
Surface Properties
Gold
Correlation
Nanoparticle
Linear structure
Mercury II
Fluorescence
Ions
Transition metal
Complexes
Density
Recovery
DNA
Release
Conformation
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Summary:We have developed a new highly selective and sensitive technique for the detection of Hg2+ using DNA-functionalized gold nanoparticles (Au NPs) and OliGreen. This system is the first that allows the detection of Hg2+ based on the release of DNA molecules, induced by conformational changes on Au NP surfaces, and its sensitivity is highly dependent upon surface DNA density. When Hg2+ ions interact with the thymidine units of the DNA molecules bound to the Au NPs through Au−S bonds, the conformations of these DNA derivatives change from linear to hairpin structures, causing the release of some of the DNA molecules from the surface of the Au NPs into the bulk solution to react with OliGreen. The fluorescence of OliGreen−DNA complexes increased with increasing concentration of Hg2+, and Hg2+ could be detected at concentrations as low as 25 nM. A linear correlation existed between the fluorescence intensity and the concentration of Hg2+ over the range 0.05−2.5 μM (R 2 = 0.98). This simple and cost-effective probe was applied to determine the spiked Hg2+ in the pond samples; the recoveries (96−102%) suggested low matrix interference and high sensitivity.
Bibliography:TEM images of solutions containing Au NPs and DNA−Au NPs (Figure S1). UV−vis absorbance spectra of solutions containing Au NPs and DNA−Au NPs in the absence and presence of Hg2+ (Figure S2). Ellipicity versus Hg2+ ion concentration (Figure S3). Plot of binding percentage versus Hg2+ concentration (Figure S4). Fluorescence response of control OliGreen−DNA−Au NPs (0.75 nM) upon addition of 5.0 μM Hg2+ ions (Figure S5). Fluorescence response of OliGreen−DNA−Au NPs upon addition of Hg2+ ions to a matrix of pond water (Figure S6). This material is available free of charge via the Internet at http://pubs.acs.org.
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ISSN:0743-7463
1520-5827
DOI:10.1021/la800589m