Fluorescence quenching of MoS2 nanosheets/DNA/silicon dot nanoassembly: effective and rapid detection of Hg2+ ions in aqueous solution.

Mercury (Hg) contamination of aquatic sites represents a serious risk for human health and the environment. Therefore, effective and rapid monitoring of Hg in aqueous samples is a challenge of timely importance nowadays. In the present study, a rapid and sensitive mercury sensor based on the fluorescence quenching of MoS2 nanosheets/DNA/silicon dot nanoassembly has been developed for the efficient detection of mercury(II) in aquatic environments. In this process, silicon dots were synthesized through one-step high-temperature calcinations and thermomagnesium reduction method at 900 °C using rice husk as a silicon source, which demonstrates superior photophysical properties and excitation-dependent fluorescence behavior. The interaction between MoS2 nanosheets/DNA/silicon dot nanoassembly and Hg2+ ions was studied using photoluminescence spectroscopy. The addition of Hg2+ ions to the assay solution induced the detachment of fluorescent probe from the surface of MoS2 nanosheets. Thus, the fluorescent probes sustained its fluorescence intensity. The developed sensor was tested on various concentrations of Hg2+ ions ranging from 0 to 1000 nM as well as on various metal ions. In addition, MoS2 nanosheets/DNA/silicon dot nanoassembly fluorescent Hg sensor efficiently detected the presence of Hg2+ ions in real-time water samples, which was comparably detected by the conventional atomic absorbance spectrometer (AAS). Overall, our results highlighted the high reliability of the present approach for environmental monitoring of Hg2+ ions, if compared to that of the customary method with a lowest detection limit of 0.86 nM.