Colorimetric and SERS dual-mode sensing of mercury (II) based on controllable etching of Au@Ag core/shell nanoparticles

Mercury ion (Hg2+) is a bio-accumulative and toxic heavy metal, which has caused significant damage to our health. It is vital to establish a method for the determination of Hg2+. Here, a new strategy for colorimetric/SERS dual-mode determination of Hg2+ was proposed based on controllable etching [email protected] NPs. The silver shells could be etched by S2O32− causing the orange colloidal solution to turn into brick red. However, after Hg2+ is added, the etching effect is suppressed due to the reaction between Hg2+ and S2O32− to form an insoluble substance HgS. As a result, the UV–vis absorption at 394 nm and Raman intensity of R6 G increase with a silver shell-less etched by S2O32−. About the colorimetric method, the limit of detection was 2 μM and 0.2 μM through the naked eye and UV–vis spectroscopy, respectively. Moreover, the SERS method possesses a linear regression for the concentration of Hg2+ (0.1 nM-1 μM), and the LOD was 0.1 nM. Furthermore, the sensing strategy has been used to determine Hg2+ in traditional Chinese medicine and real water samples. The selectivity and practicability studies indicate that our method has excellent specificity and sensitivity. Thus, this strategy is suitable for on-site fast detecting of Hg2+.