Preparation of Color and Fluorescence Double Intelligent Response SMA-CUR-CG Labels for Freshness Monitoring Applications

This paper presents a new kind of a SMA-CUR-CG intelligent label. This intelligent label uses uniform particle size styrene-maleic anhydride load curcumin (SMA-CUR) hollow microspheres as a pH indicator and the mixture of gellan gum and carboxymethyl cellulose as a matrix. After casting film and screen-printing, the SMA-CUR-CG intelligent label was prepared. The SMA-CUR-CG intelligent label demonstrates outstanding comprehensive performance: tensile strength was enhanced to 78.3 MPa, water contact angle reached to 143°, with significantly improved thermal stability. This label exhibits high sensitivity to ammonia gas with a visual detection limit as low as 9.9 ppm. More importantly, this label exhibits a dual pH responsiveness through both color and fluorescence. In practical applications, when the label is used to monitor fish freshness, it enables continuous visual monitoring around the clock throughout a 48 h storage period. This is achieved through a color transition from bright yellow to orange-red, accompanied by a simultaneous reduction in the green fluorescence under ultraviolet light.