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Monitoring the presence of ionic mercury in environmental water by plasmon-enhanced infrared spectroscopy.

Hoang CV, Oyama M, Saito O, Aono M, Nagao T - Sci Rep (2013)

Bottom Line: Here, we adopted single-stranded thiolated 15-base DNA oligonucleotides that are immobilized on the Au surface and show strong specificity to Hg²⁺.The mercury-associated distinct signal is located apart from the biomolecule-associated broad signals and is selectively characterized.For example, with natural water from Lake Kasumigaura (Ibaraki Prefecture, Japan), direct detection of Hg²⁺ with a concentration as low as 37 ppt (37 × 10⁻¹⁰%) was readily demonstrated, indicating the high potential of this simple method for environmental and chemical sensing of metallic species in aqueous solution.

View Article: PubMed Central - PubMed

Affiliation: WPI Center for Materials NanoArchitectonics-MANA, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan. Hoang.ChungVu@nims.go.jp

ABSTRACT
We demonstrate the ppt-level single-step selective monitoring of the presence of mercury ions (Hg²⁺) dissolved in environmental water by plasmon-enhanced vibrational spectroscopy. We combined a nanogap-optimized mid-infrared plasmonic structure with mercury-binding DNA aptamers to monitor in-situ the spectral evolution of the vibrational signal of the DNA induced by the mercury binding. Here, we adopted single-stranded thiolated 15-base DNA oligonucleotides that are immobilized on the Au surface and show strong specificity to Hg²⁺. The mercury-associated distinct signal is located apart from the biomolecule-associated broad signals and is selectively characterized. For example, with natural water from Lake Kasumigaura (Ibaraki Prefecture, Japan), direct detection of Hg²⁺ with a concentration as low as 37 ppt (37 × 10⁻¹⁰%) was readily demonstrated, indicating the high potential of this simple method for environmental and chemical sensing of metallic species in aqueous solution.

No MeSH data available.


Mechanism for infrared plasmonic sensing of mercury ions.(a) Schematic of the mercury trapping by a DNA aptamer. A Hg2+ ion bridges two thymine bases (small hexagons) and forms N-Hg-N bonds leading to the conformational change of the DNA. (b) A photo of Lake Kasumigaura and subaqueous environment. (c) Schematic of the EM field-enhancement in the Au nanogap (typical gap-size of about 10 nm) with the presence of DNA aptamers on the plasmonic substrate. Structural and chemical changes in these DNA owing to the adsorption of Hg2+ ions lead to the modification in the optical spectrum, which later plays as a mechanism for the detection of mercury ions.
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f1: Mechanism for infrared plasmonic sensing of mercury ions.(a) Schematic of the mercury trapping by a DNA aptamer. A Hg2+ ion bridges two thymine bases (small hexagons) and forms N-Hg-N bonds leading to the conformational change of the DNA. (b) A photo of Lake Kasumigaura and subaqueous environment. (c) Schematic of the EM field-enhancement in the Au nanogap (typical gap-size of about 10 nm) with the presence of DNA aptamers on the plasmonic substrate. Structural and chemical changes in these DNA owing to the adsorption of Hg2+ ions lead to the modification in the optical spectrum, which later plays as a mechanism for the detection of mercury ions.

Mentions: Figure 1(a) shows a schematic of Hg binding by a DNA aptamer (composed of 15 bases of thymine) immobilized on the Au surface348. First, Hg2+ ions are attracted by negatively charged DNA and then go in between two thymine bases by changing the straight single-stranded DNA conformation into hairpin-like (folded) structures [Fig. 1(b)]. Also, chemical/electronic status of the local bonds near the trapped Hg between the thymines should undergo substantial change such as change in dipole moment, which manifests itself as a change in vibrational signal intensity4.


Monitoring the presence of ionic mercury in environmental water by plasmon-enhanced infrared spectroscopy.

Hoang CV, Oyama M, Saito O, Aono M, Nagao T - Sci Rep (2013)

Mechanism for infrared plasmonic sensing of mercury ions.(a) Schematic of the mercury trapping by a DNA aptamer. A Hg2+ ion bridges two thymine bases (small hexagons) and forms N-Hg-N bonds leading to the conformational change of the DNA. (b) A photo of Lake Kasumigaura and subaqueous environment. (c) Schematic of the EM field-enhancement in the Au nanogap (typical gap-size of about 10 nm) with the presence of DNA aptamers on the plasmonic substrate. Structural and chemical changes in these DNA owing to the adsorption of Hg2+ ions lead to the modification in the optical spectrum, which later plays as a mechanism for the detection of mercury ions.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3569543&req=5

f1: Mechanism for infrared plasmonic sensing of mercury ions.(a) Schematic of the mercury trapping by a DNA aptamer. A Hg2+ ion bridges two thymine bases (small hexagons) and forms N-Hg-N bonds leading to the conformational change of the DNA. (b) A photo of Lake Kasumigaura and subaqueous environment. (c) Schematic of the EM field-enhancement in the Au nanogap (typical gap-size of about 10 nm) with the presence of DNA aptamers on the plasmonic substrate. Structural and chemical changes in these DNA owing to the adsorption of Hg2+ ions lead to the modification in the optical spectrum, which later plays as a mechanism for the detection of mercury ions.
Mentions: Figure 1(a) shows a schematic of Hg binding by a DNA aptamer (composed of 15 bases of thymine) immobilized on the Au surface348. First, Hg2+ ions are attracted by negatively charged DNA and then go in between two thymine bases by changing the straight single-stranded DNA conformation into hairpin-like (folded) structures [Fig. 1(b)]. Also, chemical/electronic status of the local bonds near the trapped Hg between the thymines should undergo substantial change such as change in dipole moment, which manifests itself as a change in vibrational signal intensity4.

Bottom Line: Here, we adopted single-stranded thiolated 15-base DNA oligonucleotides that are immobilized on the Au surface and show strong specificity to Hg²⁺.The mercury-associated distinct signal is located apart from the biomolecule-associated broad signals and is selectively characterized.For example, with natural water from Lake Kasumigaura (Ibaraki Prefecture, Japan), direct detection of Hg²⁺ with a concentration as low as 37 ppt (37 × 10⁻¹⁰%) was readily demonstrated, indicating the high potential of this simple method for environmental and chemical sensing of metallic species in aqueous solution.

View Article: PubMed Central - PubMed

Affiliation: WPI Center for Materials NanoArchitectonics-MANA, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan. Hoang.ChungVu@nims.go.jp

ABSTRACT
We demonstrate the ppt-level single-step selective monitoring of the presence of mercury ions (Hg²⁺) dissolved in environmental water by plasmon-enhanced vibrational spectroscopy. We combined a nanogap-optimized mid-infrared plasmonic structure with mercury-binding DNA aptamers to monitor in-situ the spectral evolution of the vibrational signal of the DNA induced by the mercury binding. Here, we adopted single-stranded thiolated 15-base DNA oligonucleotides that are immobilized on the Au surface and show strong specificity to Hg²⁺. The mercury-associated distinct signal is located apart from the biomolecule-associated broad signals and is selectively characterized. For example, with natural water from Lake Kasumigaura (Ibaraki Prefecture, Japan), direct detection of Hg²⁺ with a concentration as low as 37 ppt (37 × 10⁻¹⁰%) was readily demonstrated, indicating the high potential of this simple method for environmental and chemical sensing of metallic species in aqueous solution.

No MeSH data available.