Eu3+-functionalized CQD hybrid material: synthesis, luminescence properties and sensing application for the detection of Cu2+

Abstract

In this study, we developed a novel flexible method to construct a lanthanide dual-emitting ratiometric fluorescence nanoprobe with excellent luminescence properties and significant selectivity for the detection of copper ions, where the central Eu³⁺ ions are coordinated with 2,6-pyridinedicarboxylic acid (DPA) on the surface of CQDs. The structure and chemical sensing photoluminescence properties of the as-prepared fluorescent probe have been investigated in detail. Moreover, the results have shown that Eu-DPA–CQDs exhibit two fluorescence emissions at 450 nm and 613 nm, respectively, under an excitation wavelength of 285 nm. The responses of the two emissions towards Cu²⁺ ions are completely different and can provide references for each other. Therefore, it can be designed as a fluorescence sensor for the detection of Cu²⁺ ions. The emission spectrum at 613 nm is markedly quenched, while that at 450 nm slightly changed after the addition of Cu²⁺ ions. When the Cu²⁺ ion concentration was 0–150 μM, the FL ratio (I_Eu/I_CQDs) showed a good linear relationship with the lowest detection limit (LOD) of 6 nM. Thus, the reported sensor has a high selectivity, satisfactory accuracy and precision, and it may provide the potential application in the biological and environmental fields.