A multicolor fluorescent sensor array based on curcumin and its analogs as a shrimp freshness indicator

The colorimetric sensing label is a simple, cost-effective, and user-friendly tool for monitoring ammonia vapor (NH 3 ) concentrations in food packaging. Numerous natural dyes present excellent NH 3 -sensitivity, but their low solubility in water limits their food-related applications. Herein, a special cellulose-based ink system with an EtOH/water mixture as solvent was proposed to improve the dispersion of non-aqueous dyes (curcumin and its analogs (indexed as Bur and Bur-BF 2 )). Subsequently, three sensing labels containing different dyes were prepared by simple screen-printing after optimizing the inks' rheological properties. Benefiting from the different intramolecular charge-transfer (ICT) behaviors of dyes, each sensing label exhibited various characteristics in terms of the optical property , NH 3 -sensitivity, and fluorescent color-changing routes upon exposure to 0–50 ppm NH 3 . Importantly, all sensing labels showed excellent stability in environments with various relative humidity and temperature. Therefore, three sensing labels were used to construct a multicolor fluorescent sensor array, which aimed to visually monitor the freshness of shrimp for consumers.