Selective Gold-Nanoparticle-Based “Turn-On” Fluorescent Sensors for Detection of Mercury(II) in Aqueous Solution
Resource
Analytical Chemistry 78 (24): 8332-8338
Journal
Analytical Chemistry
Journal Volume
78
Journal Issue
24
Pages
8332-8338
Date Issued
2006
Date
2006
Author(s)
Huang, Chih-Ching
Abstract
A new gold-nanoparticle (AuNP)-based sensor for detecting Hg(II) ions in aqueous solution has been developed. Rhodamine B (RB) molecules that are highly fluorescent in bulk solution fluoresce weakly when they are adsorbed onto AuNP surfaces as a result of fluorescence resonance energy transfer and collision with AuNPs. In the presence of metal ions such as Hg(II), RB molecules are released from the AuNP surface and thus restore the florescence of RB. The modulation of the photoluminescence quenching efficiency of RB-AuNPs in the presence of Hg(II) ions can achieve a large turn-on fluorescence enhancement (400-fold) in aqueous solution, and the entire detection takes less than 10 min. We have improved the selectivity of the probe further by modifying the AuNP surfaces with thiol ligands (mercaptopropionic acid, mercaptosuccinic acid, and homocystine) and adding a chelating ligand (2,6-pyridinedicarboxylic acid) to the sample solutions. Under the optimum conditions, the selectivity of this system for Hg(II) over other metal ions in aqueous solutions is remarkably high (50-fold or more), and its LOD for Hg(II) in the matrix pond water is 2.0 ppb. Our approach demonstrated the feasibility of using the developed nanosensor for rapid determination of Hg(II) in aqueous environmental samples and in batteries.
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