Rational design of L-histidine-stabilized fluorescent copper nanoclusters for highly selective and sensitive...

Consuming Sunset Yellow (SY) in large quantities poses notable health hazards, creating a critical need for dependable analytical techniques to monitor its presence. In this study, we detail the preparation of highly stable copper nanoclusters capped with L-histidine (His-CuNCs), which serve as an effective fluorescent sensor for accurately measuring SY levels. These engineered nanomaterials display a vivid blue-green emission and possess outstanding resilience, especially under conditions of elevated salinity and temperature, rendering them ideal for evaluating complicated food samples. As a diagnostic tool, this sensor provided a broad linear response range from 0.3 to 90.0 µM, with a highly sensitive detection limit of 15.34 nM. Exploration of the underlying mechanisms indicated that the reduction in the fluorescent signal primarily results from a combination of the inner filter effect (IFE) and static quenching. Additionally, these His-CuNCs were effectively utilized to identify SY within commercial food products, yielding excellent recovery percentages. To complement this, a practical visual monitoring platform utilizing smartphone technology was also developed. Ultimately, this work presents a durable, highly responsive, and streamlined approach for tracking artificial food colorings to aid in food safety protocols.