A ratiometric fluorescence sensor based on gold silver nanoclusters and tungsten disulfide quantum dots with simple fabrication for the detection of copper ions in river water

Copper plays a key role in the human body; meanwhile, excess Cu2+ ions can result in various diseases. Nanoclusters (NCs) are often used to measure Cu2+ ions, but there are two difficulties. On the one hand, a single probe of NCs is easily affected by environmental factors. On the other hand, it is difficult to mask the interference of Pb2+ ions and Cd2+ ions in the process of detecting Cu2+ ions. As a new type of quantum dots (QDs), tungsten disulfide quantum dots (WS2-QDs) have some advantages of simple synthesis and stable luminescence properties. Stable WS2-QDs with blue fluorescence are used as a reference probe, while gold silver nanoclusters (AuAgNCs) with red fluorescence are used as a response probe. A ratiometric fluorescent sensor was constructed by mixing the two styles of fluorescent probes, which is abbreviated as NCs/QDs. This nano-sensor can be used to detect the concentration of Cu2+ ions, in which the fluorescence of QDs does not change significantly, while the fluorescence of NCs can be quenched by Cu2+ ions. The concentration of Cu2+ ions can be determined as low as 0.12 μM with a linear range from 0.3 to 3 μM. The common interference caused by Pb2+ and Cd2+ ions can be eliminated by the phosphate buffer solution (PBS). This sensor was used to detect the concentration of Cu2+ in river water with satisfactory results.