Parole chiave: Mercury Ions, Fluorescence, Dansyl-Aminoacid, Optical Fiber Probe,
*** IBB - CNR *** Optoelectronics Group, Department of Engineering, University of Sannio, I-82100 Benevento, Italy Institute of Biostructure and Bioimaging, National Research Council, I-80143 Naples, Italy Interuniversity Research Centre on Bioactive Peptides (CIRPeB), University “Federico II”, Naples, Italy
Mercury is a pollutant extremely toxic to the environment and human health. Although numerous methods have been reported for the analysis of Hg<sup>2+</sup> ions in water, the development of simple, rapid, inexpensive, and sensitive sensors still represents a challenge. Here, we describe the design, synthesis and spectral characterization of a set of dansyl-amino acids able to recognize Hg<sup>2+</sup> ions via different fluorescence emission modes. The analysis of the binding features of the different chemosensors shows that the stoichiometry of the sensor–Hg<sup>2+</sup> complex depends on the concentration of the sensor and Hg<sup>2+</sup> since it plays an important role in the type of response for Hg<sup>2+</sup> ions. Among those studied here N-dansylated methionine is the best performing chemosensor in terms of sensitivity with a LOD of 140 nM. To improve the LOD of this chemosensor, we evaluated the response of a portable experimental set-up based on optical fiber probes. The new device shows an increase of LOD from 140 nM to about 5 nM, which can meet the requirements imposed by the Environmental Protection Agency for monitoring Hg<sup>2+</sup> in drinkable water. We also show that the chemosensors are not applicable to marine water-based matrices because of the significant coordinating ability of chloride anions with Hg<sup>2+</sup>.<h2 class="section-title">Graphical abstract</h2><img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925400517304343-fx1.jpg" height="245">
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