Dual–emission MOF–based ratiometric platform and sensory hydrogel for visible detection of biogenic amines in food spoilage

It is an important task to real-time monitor biogenic amines (BAs) released from perishable seafood for predicting their freshness. To this endeavor, herein we developed a simple and effective strategy for visual determination of BAs by dual-emissive metal-organic framework (MOF) probes and color-transition hydrogels. Through situ encapsulating Ru(bpy)32+ into UiO-OH, the functionalized [email protected] was solvothermally prepared. At a single excitation wavelength, the fluorescence intensity of [email protected] at 537 and 600 nm showed different changes in the case of trimethylamine (TMA), leading to a ratiometric platform with apparent color variation from orange red to bright yellow. The achieved turn-on yellow emission resulted from the inhibition of LMCT and ESIPT process caused by MOF skeleton damage and deprotonation. Intelligently, [email protected] was loaded into hydrogels that acted as "sniffing" trademarks to detect volatile TMA vapor, which was further integrated with a smartphone-based readout to quantify. Meanwhile, the practical applicability of fluorescent sensory hydrogels was confirmed via depicting the spoilage degree of shrimp and fish at 4 and 20 ℃, the results were good consistent with standard method for detection of total volatile basic nitrogen (TVB-N). The current creation holds great significance for precise guidance of sensing seafood freshness with straightforward manner.