Surface-Enhancement Raman Scattering Sensing Strategy for Discriminating Trace Mercuric Ion (II) from Real Water Samples in Sensitive, Specific, Recyclable, and Reproducible Manners
2015-01-20T00:00:00Z (GMT) by
It is of essential importance to precisely probe mercury(II) (Hg<sup>2+</sup>) ions for environment-protection analysis and detection. To date, there still remain major challenges for accurate, specific, and reliable detection of Hg<sup>2+</sup> ions at subppt level. We herein employ gold nanoparticles (AuNPs) decorated silicon nanowire array (SiNWAr) as active surface-enhanced Raman scattering (SERS) substrates to construct a high-performance sensing platform assisted by DNA technology, enabling ultrasensitive detection of trace Hg<sup>2+</sup> in ∼64 min and with low sample consumption (∼30 μL). Typically, strong SERS signals could be detected when the single-stranded DNA structure converts to the hairpin structure in the presence of Hg<sup>2+</sup> ions, due to the formation of thymine (T)-Hg<sup>2+</sup>-T. As a result, Hg<sup>2+</sup> ions with a low concentration of 1 pM (0.2 ppt) can be readily discriminated, much lower than those (∼nM) reported for conventional analytical strategies. Water samples spiked with various Hg<sup>2+</sup> concentrations are further tested, exhibiting a good linear relationship between the normalized Raman intensities and the logarithmic concentrations of Hg<sup>2+</sup> ranging from 1 pM to 100 nM, with a correlation coefficient of <i>R</i><sup>2</sup> = 0.998. In addition, such SERS sensor features excellent selectivity, facilely distinguishing Hg<sup>2+</sup> ions from various interfering substances. Moreover, this presented SERS sensor possesses good recyclability, preserving adaptable reproducibility during 5-time cyclic detection of Hg<sup>2+</sup>. Furthermore, unknown Hg<sup>2+</sup> concentration in river water can be readily determined through our sensing strategy in accurate and reliable manners, with the RSD value of ∼9%.