Dual-Ligand Functionalized Ag₂S Quantum Dots for Turn-On Detection of Lead (II) Ions in Mineral Samples Based on Aggregation-Induced Enhanced Emission

Lead ion (Pb²⁺) is considered as one of the most toxic elements because it damages human health and pollutes the environment. Therefore, it is of great significance to develop convenient assays for the detection of Pb²⁺ with high sensitivity. A simple fluorescent probe for selective Pb²⁺ sensing based on silver sulfide quantum dots (Ag₂S QDs) was developed in this work. The Ag₂S QDs with excellent fluorescence properties were synthesized without the need of oxygen-free condition. In the presence of Pb²⁺, the coordination between Pb²⁺ with glutathione ligand modified on Ag₂S QDs could enhance the signal intensity of Ag₂S QDs via aggregation induced enhanced emission (AIEE). Thus, the Pb²⁺ sensor was successfully developed based on a fluorescence turn-on mechanism. The Pb²⁺ sensor shows a linear detection range from 0.05–20.0 μM, and the detection limit is down to 15.5 nM. Furthermore, the constructed assay have been successfully applied for the detection of Pb²⁺ in the mineral samples. The sensing system for Pb²⁺ detection based 3-MPA/GSH-Ag₂S QDs has outstanding advantages, including fast response, high sensitivity, and easy operation. Therefore, it shows great potential in environmental detection.