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Selectable Ultrasensitive Detection of Hg(2+) with Rhodamine 6G-Modified Nanoporous Gold Optical Sensor.

Wang Z, Yang M, Chen C, Zhang L, Zeng H - Sci Rep (2016)

Bottom Line: An extremely sensitive fluorescence sensor has been developed for selectively detection of mercury ions based on metallophilic Hg(2+)-Au(+) interactions, which results in an effective release of pre-adsorbed rhodamine 6G (R6G) molecules from the nanoporous gold substrate, associated with a significant decrease of fluorescence intensity.The optical sensor has a detection sensitivity down to 0.6 pM for Hg(2+) and CH3Hg(+) ions, in particular a superior selectivity in a complex aqueous system containing 13 different types of metal ions, meanwhile maintaining a long-term stability after 10 cycles.Such a fluorescence sensor combining multiple advantages therefore present promising potentials in various applications.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Key Laboratory of Modern Optical System, Engineering Research Center of Optical Instrument and System (Ministry of Education), School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.

ABSTRACT
An extremely sensitive fluorescence sensor has been developed for selectively detection of mercury ions based on metallophilic Hg(2+)-Au(+) interactions, which results in an effective release of pre-adsorbed rhodamine 6G (R6G) molecules from the nanoporous gold substrate, associated with a significant decrease of fluorescence intensity. The optical sensor has a detection sensitivity down to 0.6 pM for Hg(2+) and CH3Hg(+) ions, in particular a superior selectivity in a complex aqueous system containing 13 different types of metal ions, meanwhile maintaining a long-term stability after 10 cycles. Such a fluorescence sensor combining multiple advantages therefore present promising potentials in various applications.

No MeSH data available.


(a) Photoemission spectra of R6G/MPA-NPG in the presence of Hg2+ with different concentrations. (b) Normalized fluorescence intensity variation (I/I0) of R6G/MPA-NPG as a function of Hg2+ concentration in ultrapure water, Yangtse river water and a tributary of the Huangpu river water. I0 is the fluorescence intensity of R6G from the sensor in water only. Excitation wavelength is 532 nm.
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f2: (a) Photoemission spectra of R6G/MPA-NPG in the presence of Hg2+ with different concentrations. (b) Normalized fluorescence intensity variation (I/I0) of R6G/MPA-NPG as a function of Hg2+ concentration in ultrapure water, Yangtse river water and a tributary of the Huangpu river water. I0 is the fluorescence intensity of R6G from the sensor in water only. Excitation wavelength is 532 nm.

Mentions: Sensitive and quantitative detection of mercury ions is performed by monitoring the intensity changes of R6G fluorescence peaks with mercury ions concentrations. Figure 2a shows the fluorescence spectra that obtained on the NPG film with the ligament size of ~38 nm in diameter, and as shown in figure the fluorescence intensity from R6G reduces with increasing of Hg2+ concentration. The normalized fluorescence intensity is given in Fig. 2b. At a low concentration, the number of Hg2+ ions is not sufficient to replace all the pre-absorbed R6G molecules, and some R6G molecules are still noncovalent binding to the NPG surface. Thus, the fluorescence signals only partially decrease. With the increasing adding of Hg2+ to 10−8 M, almost all the R6G molecule have been “washed away” by the mercury ions, and really weak fluorescence signal can be detected. Generally, the fluorescence intensity of the R6G/MPA-NPG sensor toward Hg2+ concentration declined almost linearly to the Hg2+ concentration, and both the detection limit and the dynamic detection range vary with the sizes of the nanopore and ligament of NPG (see Fig. S1 in Supplementary Information). For the NPG with ligament size of ~22 nm, the detective sensitivity is around 10−8 M with a 3 orders of magnitude dynamic range. The detective sensitivity increases with the growing of the ligament size and reaches the ultimate value of 10−13 M for the ligament size of about 38 nm, which results in the optimal detection limit of sub-ppt (0.6 pM) for Hg2+. The detection sensitivity seldom changed when we replaced the laboratory ultrapure water by river water (the Yangtse river water and a tributary of the Huangpu river water), and the decrease of the fluorescence intensity remains at ~20% with 0.6 pM Hg2+ adding in the two kinds of river water. Moreover, the R6G/MPA-NPG sensor does not obvious response to the pH variation (pH value from 4 to 10), and the detective limit is about 10−12 M in alkaline solution and 10−11 M in acid solution (see Fig. S2 in Supplementary Information).


Selectable Ultrasensitive Detection of Hg(2+) with Rhodamine 6G-Modified Nanoporous Gold Optical Sensor.

Wang Z, Yang M, Chen C, Zhang L, Zeng H - Sci Rep (2016)

(a) Photoemission spectra of R6G/MPA-NPG in the presence of Hg2+ with different concentrations. (b) Normalized fluorescence intensity variation (I/I0) of R6G/MPA-NPG as a function of Hg2+ concentration in ultrapure water, Yangtse river water and a tributary of the Huangpu river water. I0 is the fluorescence intensity of R6G from the sensor in water only. Excitation wavelength is 532 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4940742&req=5

f2: (a) Photoemission spectra of R6G/MPA-NPG in the presence of Hg2+ with different concentrations. (b) Normalized fluorescence intensity variation (I/I0) of R6G/MPA-NPG as a function of Hg2+ concentration in ultrapure water, Yangtse river water and a tributary of the Huangpu river water. I0 is the fluorescence intensity of R6G from the sensor in water only. Excitation wavelength is 532 nm.
Mentions: Sensitive and quantitative detection of mercury ions is performed by monitoring the intensity changes of R6G fluorescence peaks with mercury ions concentrations. Figure 2a shows the fluorescence spectra that obtained on the NPG film with the ligament size of ~38 nm in diameter, and as shown in figure the fluorescence intensity from R6G reduces with increasing of Hg2+ concentration. The normalized fluorescence intensity is given in Fig. 2b. At a low concentration, the number of Hg2+ ions is not sufficient to replace all the pre-absorbed R6G molecules, and some R6G molecules are still noncovalent binding to the NPG surface. Thus, the fluorescence signals only partially decrease. With the increasing adding of Hg2+ to 10−8 M, almost all the R6G molecule have been “washed away” by the mercury ions, and really weak fluorescence signal can be detected. Generally, the fluorescence intensity of the R6G/MPA-NPG sensor toward Hg2+ concentration declined almost linearly to the Hg2+ concentration, and both the detection limit and the dynamic detection range vary with the sizes of the nanopore and ligament of NPG (see Fig. S1 in Supplementary Information). For the NPG with ligament size of ~22 nm, the detective sensitivity is around 10−8 M with a 3 orders of magnitude dynamic range. The detective sensitivity increases with the growing of the ligament size and reaches the ultimate value of 10−13 M for the ligament size of about 38 nm, which results in the optimal detection limit of sub-ppt (0.6 pM) for Hg2+. The detection sensitivity seldom changed when we replaced the laboratory ultrapure water by river water (the Yangtse river water and a tributary of the Huangpu river water), and the decrease of the fluorescence intensity remains at ~20% with 0.6 pM Hg2+ adding in the two kinds of river water. Moreover, the R6G/MPA-NPG sensor does not obvious response to the pH variation (pH value from 4 to 10), and the detective limit is about 10−12 M in alkaline solution and 10−11 M in acid solution (see Fig. S2 in Supplementary Information).

Bottom Line: An extremely sensitive fluorescence sensor has been developed for selectively detection of mercury ions based on metallophilic Hg(2+)-Au(+) interactions, which results in an effective release of pre-adsorbed rhodamine 6G (R6G) molecules from the nanoporous gold substrate, associated with a significant decrease of fluorescence intensity.The optical sensor has a detection sensitivity down to 0.6 pM for Hg(2+) and CH3Hg(+) ions, in particular a superior selectivity in a complex aqueous system containing 13 different types of metal ions, meanwhile maintaining a long-term stability after 10 cycles.Such a fluorescence sensor combining multiple advantages therefore present promising potentials in various applications.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Key Laboratory of Modern Optical System, Engineering Research Center of Optical Instrument and System (Ministry of Education), School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.

ABSTRACT
An extremely sensitive fluorescence sensor has been developed for selectively detection of mercury ions based on metallophilic Hg(2+)-Au(+) interactions, which results in an effective release of pre-adsorbed rhodamine 6G (R6G) molecules from the nanoporous gold substrate, associated with a significant decrease of fluorescence intensity. The optical sensor has a detection sensitivity down to 0.6 pM for Hg(2+) and CH3Hg(+) ions, in particular a superior selectivity in a complex aqueous system containing 13 different types of metal ions, meanwhile maintaining a long-term stability after 10 cycles. Such a fluorescence sensor combining multiple advantages therefore present promising potentials in various applications.

No MeSH data available.