Rapid and sensitive detection of Hg with a SERS-enhanced lateral flow strip.

Mercury ions are some of the most toxic heavy metal ions widely distributed in the environment. Hg cannot be degraded by microorganisms and can accumulate in the body through the food chain, posing a great threat to human health. Herein, a method combining surface-enhanced Raman scattering (SERS) with a lateral flow strip (LFS) (SERS-LFS) was developed for the rapid and quantitative analysis of Hg. The recognition of Hg by the LFS depends on a specific T-Hg-T strategy. Rhodamine 6G (R6G), as a SERS reporter, was assembled on the surface of Au@Ag core-shell nanoparticles, which served as an effective SERS substrate on both the T and C lines of the LFS. Using this SERS-LFS, the presence of target Hg could be measured through the appearance of an orange color on the T line of the LFS. Furthermore, with the direct measurement of SERS on the T lines of the LFS, the SERS signal could be collected even at a low concentration of Hg, at which point the signal on the T lines could not be observed. Based on the intensities of the characteristic peak at 1513 cm of R6G collected on the T lines of the LFS, a linear relationship was obtained in the range of 0.01 nM to 1 nM, and the detection limit of the LFS was greatly improved by at least 20 times over the colorimetric results of the traditional LFS based on naked-eye observation. More importantly, this SERS-LFS did not affect the intrinsic simplicity of the LFS. This developed SERS-LFS holds great potential in practical routine screening in food safety and environmental monitoring.