Amine-Responsive Ratiometric Nanofibre Film Based on FITC/Eu Complex for Real-Time Visual Monitoring of Shrimp Freshness

Developing simple and reliable sensors for food freshness is a key goal in intelligent packaging. In this study, a ratiometric fluorescent nanofibre film was successfully developed for real-time visual monitoring of shrimp freshness. The film was constructed by embedding an amine-responsive fluorophore, fluorescein isothiocyanate (FITC) and a stable reference fluorophore, Eu (DBM) 3 Bpy, into an electrospun polyvinyl alcohol (PVA) matrix. The sensing principle relies on the pH-driven enhancement of FITC's green emission (530 nm) in the presence of biogenic amines, whereas the Eu-complex provides a constant red reference signal (610 nm). This dual-emission system creates a clear fluorescence colour change from orange to yellow-green as shrimp spoils. The sensor exhibited high selectivity and a rapid response, detecting spoilage within 6 h at 25°C. The maximum colour difference (ΔE) reached 64.78, allowing for unambiguous visual detection. This robust and easy-to-fabricate nanofibre film holds great promise for practical applications in food safety and intelligent packaging technology.