Specific colorimetric detection of methylmercury based on peroxidase-like activity regulation of carbon dots/Au NPs nanozyme.

Methylmercury (MeHg) is one of the common organic species of mercury, and has much higher toxicity than inorganic mercury. Based on the selective enhancement of the activity of nanozyme (NA-CDs/AuNPs) by MeHg, a novel colorimetric nanoprobe for MeHg assay is proposed. The noradrenaline-based carbon dots (NA-CDs) as the reducing agent was applied to prepare the NA-CDs/AuNPs. The formation of gold amalgamation (Au@HgNPs) between nanozyme and MeHg allows to simultaneously accelerate the electron transfer from Au and Hg to NA-CDs and the generation of radicals (i.e. ∙OH, ∙O and ∙CH). The NA-CDs/AuNPs has an outstanding anti-interference performance even in the presence of different mercury. Further density functionality theory (DFT) calculations revealed that the formation of Au@HgNPs via MeHg contributes to the significantly lowered activation energy, resulting in the peroxidase-like activity generation and acceleration. This leads to rapid (10 min) and specific colorimetric detection of MeHg with the detection limit of 0.06 μg L. This introduces a novel method for simple and sensitive detection of MeHg, giving a new horizon for the assay of organometallic compounds.