An AIE and ESIPT based ratiometric fluorescent hydrogel sensor for detecting biogenic amines and chicken breast freshness

Meat quality is closely linked to food safety and human health, with freshness being a key indicator. Therefore, it is crucial to explore reliable and effective methods for detecting meat freshness. This study presented a ratiometric fluorescent hydrogel sensor based on aggregation-induced emission (AIE) and excited state intramolecular proton transfer (ESIPT) for this purpose. Tetraphenylene (TPE) and 2-(2′-hydroxyphenyl)-benzothiazole (HBT) fluorophore were intersected to generate TPE-HBT, and then a novel biogenic amines (BAs) detection ratiometric fluorescent probe, TPE-HBTAc, was successfully prepared by hydroxyl acetylation. TPE-HBTAc displayed a large Stokes shift and good photostability. It showed a significant response to the representative biogenic amine trimethylamine (TMA), with a ratiometric fluorescence change and low detection limit (LOD = 65 nM). Furthermore, BAs detection hydrogel sensor was created by mixing the fluorescent probe TPE-HBTAc in an agarose hydrogel with a 3D polymer network. The hydrogel sensor displayed a distinct color change from blue to yellow when exposed to TMA vapor under UV light and had a low detection limit (LOD = 5.88 ppm). The hydrogel sensor was utilized in conjunction with a smartphone RGB analysis system to determine the freshness of chicken breast samples. Consumers can easily observe the chicken breast freshness in real-time and non-destructively through UV flashlight illumination. The results of this work suggest that ratiometric fluorescent hydrogel sensor based on AIE and ESIPT can serve as a promising strategy to monitor food freshness.