Abstract
In this paper we unveil a new sensing strategy for sensitive and selective detection of Hg2+ through surface-enhanced Raman scattering (SERS) using Ag2Te nanoparticles (NPs) as a substrate and recognition element and rhodamine 6G (R6G) as a reporter. Ag2Te NPs prepared from tellurium dioxide and silver nitrate and hydrazine in aqueous solution containing sodium dodecyl sulfate at 90°C with an average size of 26.8 ± 4.1 nm (100 counts) have strong SERS activity. The Ag2Te substrate provides strong SERS signals of R6G with an enhancement factor of 3.6 × 105 at 1360 cm−1, which is comparable to Ag NPs. After interaction of Ag2Te NPs with Hg2+, some HgTe NPs are formed, leading to decreases in the SERS signal of R6G, mainly because HgTe NPs relative to Ag2Te NPs have weaker SERS activity. Under optimum conditions, this SERS approach using Ag2Te as substrates is selective for the detection of Hg2+, with a limit of detection of 3 nM and linearity over 10–150 nM. The practicality of this approach has been validated for the determination of the concentrations of spiked Hg2+ in a pond water sample.
Highlights
Monitoring the level of mercury ions in ecological systems is an extremely important issue, mainly because they are highly toxic, non-biodegradable, and bioaccumulated (Zahir et al, 2005; Clarkson et al, 2008)
Surface-enhanced Raman scattering (SERS) using Ag NPs conjugated with Tn and organic dyes are alternative for the sensitive detection of Hg2+ (Wang et al, 2009, 2011)
SENSING STRATEGY Scheme 1 shows the detection of Hg2+ based on differential SERS enhancement factors (EFs) of Ag2Te and HgTe NPs
Summary
Monitoring the level of mercury ions in ecological systems is an extremely important issue, mainly because they are highly toxic, non-biodegradable, and bioaccumulated (Zahir et al, 2005; Clarkson et al, 2008) Several techniques such as atomic absorption/emission spectrometry, atomic fluorescence spectrometry, inductively coupled plasma spectrometry (ICP-MS) have been applied to detect Hg2+ in environmental and biological samples (Leermakers et al, 2005; Butler et al, 2006; Li et al, 2006). Upon interaction with Hg2+, the DNA conformation changes, leading to changes in the distance of the reporter from the surfaces of Ag NPs and changes in the SERS signal (Grubisha et al, 2003; Doering et al, 2007) These sensing systems are sensitive and suitable for in-field analysis, the DNA is expensive and their sensitivity and selectivity are highly dependent on the ionic strength of the samples, limiting their wide practicality
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