Monitoring Food Spoilage Biogenic Amines Utilizing a Blue-Emitting Fluorescent Ionic Liquid

Abstract

Biogenic amines are involved in numerous physiological processes and human health. For instance, putrescine and spermine (SPM) influence cell growth and division, while spermidine (SPD) offers neuroprotective, lifespan-promoting, and heart-protective effects. As a result, there is considerable interest in developing fast, simple, and affordable assays for their detection. In this work, we present a fluorescent, room-temperature ionic liquid, trihexyltetradecylphosphonium 2-(naphthalen-1-yl)-1H-phenanthro[9,10-d]imidazolate (TPND), and its low-dimensional material, nTPND, which were characterized by various spectroscopic and microscopic techniques. The neat TPND functioned effectively as a solvent-free fluorescent ink that, upon exposure to SPM and SPD, changes its fluorescence from blue to green. Upon adding SPD and SPM to the nTPND solution, a distinct fluorescence shift from cyan to green was observed, accompanied by a decrease in fluorescence intensity. nTPND is highly specific and selective for SPD and SPM, with LODs of 0.17 µM and 0.52 µM by spectrophotometry and 36 nM and 59 nM by fluorometry, respectively, making nTPND an effective dual-nature sensor. Finally, we tested the neat TPND on real mushroom samples and observed clear changes in fluorescence caused by biogenic amine vapors released from the stored food. The present report evokes a new approach in designing and developing ILs-based sustainable advanced functional optical materials having potential for controlling food safety and environmental monitoring.