A Multicolor Fluorescent Sensor Array Based on Curcumin and its Analogs as a Shrimp Freshness Indicator

Abstract

The colorimetric sensing label is a simple, cost-effective, and user-friendly tool for monitoring ammonia vapor (NH3) concentrations in food packaging. Numerous natural dyes present excellent NH3-sensitivity, but their low solubility in water limits food-related applications. Herein, a special cellulose-based ink system with EtOH/water mixture as a solvent was proposed to improve the dispersion of non-aqueous dyes (curcumin and its analogs (Bur and Bur-BF2)). The rheological properties of the inks during screen printing were optimized for preparing the sensing labels with high-definition anti-counterfeiting patterns. Each sensing label showed a unique fluorescent color-changing route which was associated with the dye structure for detecting NH3 in the concentration range of 0 to 50 ppm. The response time, selectivity, and environmental stability of sensing labels were then characterized. Among them, the sensing label with Bur-BF2 had the highest NH3-sensitivity with a detection limit of 84.85 ppb. Finally, a multicolor fluorescent sensor array (consisting of three sensing labels) has potential for use in providing visual indicators for consumers in shrimp freshness determination.

Keywords: curcumin analogs, fluorescence, ammonia, freshness indicator, multicolor