Triggering seesaw-like fluctuation of double plasmon peaks of Au@AuAg yolk-shell heterogeneous nanostructures for detection of Cu and Hg in drinking water.

Au@AuAg yolk-shell heterogeneous nanostructures (YSHNSs) with two major plasmonic absorption peaks of equal intensity are designed as multifunctional and multi-informational nanoprobes for detecting Cu and Hg, which are critical heavy metals threatening food safety and human health. By controlling the elemental distribution and morphological structure of Au@AuAg YSHNSs, two major absorption peaks can be accurately modulated. Since changing the thickness and composition ratio of Au@Ag alloy shell triggers a seesaw-like bidirectional conversion of two major absorption peaks, we establish the detection of Cu and Hg. The decrease and increase of intensity ratio of dual-peak show a good linear relationship with the concentration of Cu and Hg, with detection limits of 0.4 nM and 2 nM, respectively. This plasmonic nanoprobe based on Au@AuAg YSHNSs is successfully utilized for detecting Cu and Hg in various drinking water, providing a reliable solution for screening heavy metals with high specificity and sensitivity.