A Highly Sensitive Fluorescence Sensor for Sunset Yellow Based on ZIF‐8‐Encapsulated Copper Nanoclusters

This study developed a novel fluorescent probe for the sensitive and selective detection of Sunset yellow (SY). The probe was constructed by synthesizing blue‐emitting copper nanoclusters stabilized with calconcarboxylic acid (CCA‐CuNCs), which were subsequently encapsulated by a zeolitic imidazolate framework‐8 (ZIF‐8) via in situ self‐assembly to form a ZIF‐8@CCA‐CuNCs nanocomposite. The resulting composite exhibited markedly enhanced fluorescence intensity and stability compared to the original CCA‐CuNCs, attributable to the confinement effect and protective function provided by the ZIF‐8 matrix. Compared to CCA‐CuNCs, the ZIF‐8@CCA‐CuNCs probe exhibited high selectivity toward SY, manifesting as a pronounced fluorescence quenching upon SY addition. Under optimized conditions, the probe enabled quantitative SY detection within a linear range of 1.0–30.0 µM, with a detection limit of 0.94 µM. The method was validated by analyzing spiked lake water and Sprite drink samples, achieving recoveries of 97.4%–101.5% and 100.2%–101.6%, respectively, with low relative standard deviations (< 5.0%). This confirms its accuracy and reliability for SY determination in real samples.