A dual-functional spectroscopic probe for simultaneous monitoring Cu2+ and Hg2+ ions by two different sensing nature based on novel fluorescent gold nanoclusters

•Novel gold nanocluster synthesized by citrate-stabilized stannous ions as reductant.•Cu2+ induced fluorescence quenching and Hg2+ enhanced resonance light scattering.•Dual-functional spectroscopic probe base on different independent sensing mechanism.•Highly selective, sensitive, simultaneous detection of Cu2+ and Hg2+ ions.

Here a dual-functional spectroscopic probe was developed based on novel gold nanoclusters (Au NCs) for highly selective and sensitive detection of heavy metal ions targeting copper ions (Cu2+) and mercury ions (Hg2+). Small sized Au NCs (3.9 nm) with highly orange emitting fluorescent were synthesized via an one-pot reaction by using citrate-stabilized stannous ions (Sn(II)-citrate) as reducing and capping agent. The dual spectroscopic probe was conceived in such a way to utilize both the fluorescence (FL) quenched by Cu2+ and resonance light scattering (RLS) enhanced by Hg2+. Two different ions in the corresponding discrete spectral response appeared completely independent of each other by different mechanism. The intensity of fluorescence decreasing at 575 nm in FL spectra and the scattering increasing at 520 nm in RLS spectra, show linear relationships with Cu2+ and Hg2+ ion concentrations in the ranges of 0.5-70 and 0.25-10 μmol L−1, respectively. The detection limits are as low as 0.38 μmol L−1 and 0.05 μmol L−1 for Cu2+ and Hg2+ ions, respectively. Furthermore, these Au NCs could be readily applied to Cu2+ and Hg2+ detection in environmental water samples, indicating it is promising to serve as a convenient, dual-functional, and label-free probe for related ions monitoring.

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