A near-infrared fluorescent probe for SO32−/HSO3− and amine detection: an integrated sensing tag/film with a self-developed mobile app for visual fish freshness assessment

Abstract

In this article, a bifunctional near-infrared fluorescent probe (Dma) was synthesized via aldol condensation using 6-(diethylamino)-1,2-dihydrocyclopentadieno[b]chromene-3-carbaldehyde as a fluorophore. Dma is not only able to quickly identify sulfur dioxide derivatives (SO₃²⁻/HSO₃⁻) in DMSO/PBS (2/8, v/v, pH = 7.4) solution, but also able to respond to volatile amines (VOAs) in DMSO/H₂O (4/6, v/v, pH = 6.4) system. A Dma-loaded sensing tag (Dma/FPS) and a sensing film (Dma/PVA) were able to monitor the freshness of salmon via dual channels (colorimetric and fluorescence) at 4 °C and 25 °C. Moreover, the integrated label, containing a sensing tag and the standard colorimetric card, can assess fish freshness in real-time on-site. In addition, we have independently developed a mobile app to evaluate fish freshness, and the results are more accurate and reliable. Meanwhile, Dma can detect HSO₃⁻ in food samples and perform fluorescence imaging of HSO₃⁻ and triethylamine in living cells.