Metal–organic frameworks-scaffold gold nanoclusters enabled aggregation-induced enhanced fluorescent sensor array for high-throughput detection of heavy metal ions

The ever-expanding set of nanocluster-based sensor array and their programmability exhibit remarkable capacity in sensitive and multiplex quantification of heavy metal ions, especially in complex environments. However, this quantitative performance comes with an ever-present constraint: limited luminescence efficiency of nanoclusters due to the intramolecular vibration and rotation phenomena. Here, we pioneered the development of a fluorescent sensor array utilizing metal–organic framework-scaffold gold nanoclusters (AuNCs@MOFs) as sensing elements, enabling precise identification and sensitive quantification of eight heavy metal ions (Ni 2+ , Cr 3+ , Co 2+ , Pb 2+ , Cd 2+ , Ag + , Cu 2+ , and Zn 2+ ). Three kinds of ligand-protected AuNCs (GSH-AuNCs, MPA-AuNCs, and [2-MBA]-AuNCs) embedded in zeolitic imidazolate framework-8 (ZIF-8) exhibit significantly increased luminescence performance. We demonstrate that the fluorescence intensity of the AuNCs@MOFs can be modulated by heavy metal ions, thereby generating distinct fingerprints, which are further analyzed by the statistical analysis method. The developed sensor array identifies eight heavy metal ions accurately across concentrations ranging from 0.5 to 50 μM. Furthermore, this sensor array recognizes multi-component mixtures of heavy metal ions, exhibiting excellent discriminatory capability in both tap water and traditional Chinese medicine samples. Overall, this study provides a straightforward paradigm to construct a nanocluster-based sensor array for sensitive and multiplex heavy metal ions quantification in a complex environment.