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 Cu ions can result in various diseases. Nanoclusters (NCs) are often used to measure Cu 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 Pb ions and Cd ions in the process of detecting Cu ions. As a new type of quantum dots (QDs), tungsten disulfide quantum dots (WS-QDs) have some advantages of simple synthesis and stable luminescence properties. Stable WS-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 Cu ions, in which the fluorescence of QDs does not change significantly, while the fluorescence of NCs can be quenched by Cu ions. The concentration of Cu 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 Pb and Cd ions can be eliminated by the phosphate buffer solution (PBS). This sensor was used to detect the concentration of Cu in river water with satisfactory results.