Fluorescence on and off sensing platform based on europium nanosheets for the detection of DPA and Cu2+ ions

With the development of society, the modern environment has put forward higher requirements for analysis and detection. This work proposes a new strategy for the construction of fluorescent sensors based on rare-earth nanosheets. Organic/inorganic composites were obtained by the intercalation of 4,4'-stilbene dicarboxylic acid (SDC) into layered europium hydroxide, and then the composites were exfoliated to form nanosheets. Taking advantage of the fluorescence emission characteristics of SDC and Eu3+, a ratiometric fluorescent nanoprobe was constructed, which realized the detection of dipicolinic acid (DPA) and Cu2+ in the same system. With the addition of DPA, the blue emission of SDC gradually decreased and the red emission of Eu3+ gradually increased, when Cu2+ was added, the emission of SDC and Eu3+ were gradually weakened. The experimental results showed that the ratio of fluorescence emission intensity (I619/I394) of the probe had a positive linear relationship with the concentration of DPA, and a negative linear relationship with the concentration of Cu2+, thus realizing the high sensitivity detection of DPA and a wide detection range of Cu2+. In addition, this sensor also exhibits potential visual detection possibilities. This is a multifunctional fluorescent probe that provides a novel and efficient method for the detection of DPA and Cu2+, which broadens the application field of rare-earth nanosheets.