Controllable construction of ratiometric fluorescent probe based on Ag/Au nanoclusters and silicon nanoparticles for multivariate detection of Ag+, Cu2+, and Hg2+

The determination of heavy metal ions is critical to both human health, ecosystems, and the environment because it is a prerequisite for separating heavy metal pollutants. Herein, a ratiometric fluorescent strategy based on bimetallic AuAg nanoclusters and Si nanoparticles (AuAg-SiNPs) was constructed and achieved multivariate detection of Ag+, Cu2+, and Hg2+, simultaneously. The AuAg-SiNPs exhibited dual emission centered at 456 nm and 631 nm, with quantum yield of 23.48%, and presented visual distinguishable signal for different ions. Notably, a smartphone visual platform was created to identify Ag+, Cu2+, and Hg2+ with portable and accurate capturing and recognizing changing RGB values. The quantitative evaluation can be confirmed by various noticeable ratiometric evolution responses to three ions, the limits of detection were 1.61 nM, 49.94 nM, and 1.44 nM for Ag+, Cu2+, and Hg2+, respectively. Excellent environmental tolerance as well as reliability and practicability of AuAg-SiNPs enabled their test in real water samples. The synergistic effect of aggregation-caused quenching, static quenching effect, internal filtration effect, and fluorescence resonance energy transfer were revealed in process of detection. Ratiometric fluorescent probes offer great advantages in multiple identification of heavy metals in real sample. Smartphone-assisted detection greatly improves the effectiveness of visual on-site detection and has a promising application in real samples.