Dual-emissive ratiometric fluorescent nanosensor based on multi-nanomaterials for Ag⁺ determination in lake water

In this study, a sensitive ratiometric fluorescent nanosensor was constructed using a facile one-pot method by encapsulating carbon dots (CDs) and cadmium telluride quantum dots (CdTe QDs) into the pore cavities of a metal-organic framework (ZIF-8). In this nanosensor (CD/CdTe QD@ZIF-8), the fluorescence attributed to CdTe QDs was quenched by silver ions (Ag⁺), and the fluorescence intensity of CDs did not change. The introduction of ZIF-8 into the system can not only adsorb Ag⁺ but also easily separate CDs and CdTe QDs from the matrix. The developed CD/CdTe QD@ZIF-8 composite used as a ratiometric fluorescent probe exhibited high sensitivity and selectivity towards Ag⁺. The working linear range was 0.1-20 μM with a limit of detection (LOD) of 1.49 nM. Finally, the proposed nanosensor was applied to determine Ag⁺ in lake water with satisfactory results.