Highly sensitive simultaneous detection of mercury and copper ions by ultrasmall fluorescent DNA–Ag nanoclusters

Abstract

Fluorescent metal nanoclusters (NCs) have given rise to a new class of fluorescent nanomaterials for the detection of heavy metals. Here, we design a simple, rapid and highly sensitive sensing nanosystem for the detection of Hg²⁺ and Cu²⁺ based on fluorescence quenching of ultrasmall DNA–Ag NCs. The fluorescence intensity of DNA–Ag NCs was selectively quenched by Hg²⁺ and Cu²⁺, and the limit of detection (LOD) was found to be 5 nM and 10 nM, respectively. The technique was renewably employed by EDTA addition and successfully applied to detection of Hg²⁺ and Cu²⁺ in domestic water samples. The quantum yield (QY) of DNA–Ag NCs was significantly higher (∼30%) compared to traditional water-soluble fluorescent metal NCs. The DNA–Ag NCs detection system is potentially suitable for detecting Hg²⁺ and Cu²⁺ and monitoring water quality in a wide range of samples regulated under the Environmental Protection Agency.