Highly selective and sensitive detection of Hg2+ based on fluorescence enhancement of Mn-doped ZnSe QDs by Hg2+-Mn2+ replacement

Abstract The pollution of Hg 2+ is one of the most serious problems to human health due to their high toxicity, mobility, difficulty in degradation and ability of accumulation in ecological systems. Thus, it is of great importance to develop highly selective and sensitive probe for detecting Hg 2+ in aquatic ecosystems. Here we propose a new turn-on strategy for specific recognition and detection of Hg 2+ . Mn-doped ZnSe quantum dots (QDs) with small size (2.1 nm) were prepared and adopted as probe, the small size of doped QDs makes the replacement of Mn 2+ by Hg 2+ accessible, which eliminates the fluorescence quenching effect of superficial Mn 2+ on Mn-doped ZnSe QDs. Different from traditional semiconductor nanocrystals based turn-off probe for detecting Hg 2+ , we realize a turn-on strategy for the selective detection of Hg 2+ by Hg 2+ -Mn 2+ replacement using semiconductor nanocrystals (Mn-doped ZnSe QDs). This turn-on mechanism was verified by fluorescence spectra, ICP-AES and XPS. In the absence of Hg 2+ , Mn-doped ZnSe QDs possessed low fluorescence intensity. With the addition of Hg 2+ , the fluorescence intensity around 600 nm increased dramatically. Our Mn-doped ZnSe QDs exhibits excellent selectivity and sensitivity for Hg 2+ . The limit of detection is 7.0 nM, which is lower than the mercury toxic level defined by the U.S. Environmental Protection Agency (10 nM). The result of Hg 2+ detection in real samples indicates the feasibility and sensitivity of our probe for application in environmental samples.