Nondestructive Evaluation of Fish Freshness through Nanometer-Thick Fluorescence-Based Amine-Sensing Films

Reliable and nondestructive monitoring of food quality is of great importance in sustaining life and promoting good health. Herein, we developed sensitive, fast, reversible, and nanometer-thick fluorescent films for the nondestructive evaluation of fish freshness. The nanofilms were prepared via the dynamic condensation of tetraphenylethylene derivative (TPEBA) with Calix[4]­pyrrole derivative (CPTH) at the humid air/DMSO interface. The amorphous nanofilm is uniform with the thickness in the range of 12∼58 nm. Owing to the aggregation-induced emission (AIE) property of TPEBA, the nanofilm is highly emissive with a Stokes shift of ∼175 nm. The typically designed chemical composition and nanostructure endow the film-preferable affinity to amine vapors, and the networked structure allows fast mass transfer, which lays foundation for high-performance sensing. With an optimized nanofilm-based sensor, biogenetic amines were sensitively, selectively, and reversibly detected. The detection limit (DL) for trimethylamine (TMA) is 0.89 ppm. Typically, interference from water can be neglected; thus, the nondestructive evaluation of fish freshness was realized. Moreover, a portable seafood freshness detector was conceptually built.