Nanocatalyst/Nanoplasmon-Enabled Detection of Organic Mercury: A One-Minute Visual Test

We present a fast and sensitive nanosensor that can detect organic mercury, exploiting the combination of the catalytic and plasmonic properties of gold nanoparticles (AuNPs). The method is one-step and completely instrument-free, and has a colorimetric readout clearly detectable by simple visual inspection. The AuNPs catalyze efficient organic mercury reduction to the metallic form (Hg0 ), allowing its nucleation and amalgam formation on particle surface, with consequent aggregation-induced plasmon shift. This leads to very rapid (1 min) and specific colorimetric detection of mercury species. The achieved limit of detection (20 ppb) is compliant with current regulatory limits in food.