Super stable and water-dispersible CsPbBr3 perovskite quantum dots for the efficient detection of Cu (II) and glutathione

Perovskite quantum dots (PQDs) have made substantial advances in solar cells, light-emitting diodes, and photocatalysis due to their distinctive optical and electrical properties. The intrinsic instability of PQDs restricts their practical applications, which makes using them in the food sector difficult. The present work indicates that the long-term stability of ionic crystals by using the two-ligand mechanism of 4-bromo-butyric acid (BBA) and oleylamine (OLA) can provide prospects for the use of PQDs in the food industry. The results reveal that monodispersed CsPbBr3@BBA QDs, obtained in water, exhibit high photoluminescence quantum yields (PLQYs). Notably, the photoluminescence characteristics of CsPbBr3@BBA QDs remained remarkably stable even after dispersing the materials in an aqueous solution for 140 h, indicating the robust structural stability of CsPbBr3@BBA QDs. We used the CsPbBr3@BBA QDs to selectively detect the presence of Cu2+ in food samples such as ordinary fruits and tea. The results exhibited a good linearity within the range of 0 to 80 μM, with the limit of detection of 0.8 μM. At the same time, this sensor proposed here possessed a linear range of 0 to 250 μM and a limit of detection of 2.84 μM for glutathione (GSH) detection. Furthermore, it is shown that the QDs-Cu2+ fluorescent probe also displayed selective fluorescence recovery after exposure to GSH. The low cost and ease of preparation of this sensor offer enormous industrialization potential and opportunity, thereby accelerating the development of the sensor in the field of food safety.