A ratiometric fluorescent sensor for UO22+ detection based on Ag+-modified gold nanoclusters hybrid via photoinduced electron transfer (PET) mechanism

In this study, we prepared a new ratiometric fluorescent sensor by first encapsulating blue-fluorescent carbon dots (B-CDs) with SiO2, coupling gold nanoclusters (GSH-AuNCs) to the surface, and finally anchoring a layer of Ag+. The presence of UO22+ caused fluorescence quenching of the ratiometric fluorescent probe when used in aqueous solutions. Furthermore, HOMO–LUMO orbital analysis suggested that the quenching mechanism was mainly attributed to photoinduced electron transfer (PET) between B-CDs@SiO2@GSH-AuNCs/Ag+ and UO22+. Under optimal conditions, the ratiometric fluorescent probes exhibited excellent selectivity and detected UO22+ at 37 nmol/L. This new “on–off” ratiometric fluorescent sensor exhibits promising potential for convenient monitoring of UO22+ levels with ideal recovery in real-world water samples.