Layer-by-Layer Ligands Engineered Gold Nanoclusters on Zeolitic Imidazolate Framework-8 for Efficient Sensing of Lead Ions

Highly luminescent gold nanoclusters (AuNCs) are synthesized by manipulating the surface of the gold core with layer-by-layer ligand engineering. 6-Aza-2-thiothymine (ATT) and l-arginine (Arg) are first self-assembled and then encapsulated in zeolitic imidazolate framework-8 (ZIF-8). The multiple ligands effectively suppress the kernel vibration and are involved in the nonradiative relaxation of electron dynamics. Boosted fluorescence emission can thus be observed. Based on the nanomaterials of ZIF-8-Arg-ATT AuNCs, a novel fluorescent nanosensor is fabricated for the specific detection of lead ions with excellent performances. A limit of detection as low as 10 nmol/L is estimated. This nanosensor performs satisfactorily in real water samples including tap water, pool water, river water, and various drinks, showing its promising prospect for practical identification of lead ions.