A reverse-signal response fluorescence sensor based on NH2-MIL-101(Fe) and silicon-doped carbon quantum dots for selective determination of copper ions

A fluorescence sensor was developed based on NH 2 -MIL-101(Fe) and silicon-doped carbon quantum dots for the analysis of copper ions. Copper ions enhanced the fluorescence intensity of doped silicon-carbon quantum dots and decreased the intensity of NH 2 -MIL-101(Fe). The addition of copper ions resulted in fluorescence resonance energy transfer, which caused a reverse change in the fluorescence signal. The sensor based on the above mechanism can eliminate false positive interference. The fluorescence sensing system had a remarkable linear range of 0.25–5 µM for copper ions and a detection limit of 11 nM. It was then applied to water samples, resulting in recoveries ranging from 95.43 % to 103.1 %. The successful construction of this optical sensor not only broadened the way to detect copper ions but also provided a new idea for the detection of other targets mediated by copper ions. Finally, an attempt was made to construct a smartphone-assisted colourimetric platforms to detect copper ions in daylight.