Water-soluble luminous silver nanocluster as well as preparation method and application thereof

The invention provides a water-soluble luminous silver nanocluster as well as a preparation method and an application thereof. The water-soluble luminous silver nanocluster with good luminescent property is prepared by adopting 3,4-dihydroxy-L-phenylalanine as a reducing agent and a ligand protective agent, the preparation process is simple and environment-friendly, common reducing agents such as sodium borohydride and ascorbic acid and chemical reagents such as a surfactant are avoided, the fluorescence emission peak is about 460 nm, strong blue fluorescence is presented when observed with a black background under ultraviolet light, and the fluorescence quantum yield can reach 3.50%. According to the preparation method, the use of strong base NaOH is avoided, the reaction is controllable, the particle size distribution is uniform, the average particle size is 1.58 nm, the photobleaching resistance is good, the room-temperature storage stability can reach 6 months or longer, PPi can be directly detected, and