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 Ru@UiO-OH was solvothermally prepared. At a single excitation wavelength, the fluorescence intensity of Ru@UiO-OH 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, Ru@UiO-OH 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 celcius, 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.

Automated summary

This study developed a simple and effective method for visual identification of biogenic amines (BAs) in perishable seafood using dual-emissive metal-organic framework probes and color-transition hydrogels. The functionalized Ru@UiO-OH was prepared by encapsulating Ru(bpy)32+ into UiO-OH. The fluorescence intensity of Ru@UiO-OH at 537 and 600 nm showed different changes in the presence of trimethylamine (TMA), resulting in a noticeable color change. Ru@UiO-OH was loaded into hydrogels that acted as sniffing trademarks to detect volatile TMA vapor, which could be quantified using a smartphone-based readout. The practical applicability of the fluorescent sensory hydrogels was confirmed through experiments on shrimp and fish spoilage, with results consistent with the standard method for detecting total volatile basic nitrogen. This research holds great significance for accurately sensing seafood freshness in a straightforward manner.