Fast and Visual Detection of Biogenic Amines and Food Freshness Based on ICT‐Induced Ratiometric Fluorescent Probes

Abstract

Biogenic amines (BAs) are important indicators for the evaluation of food spoilage and disease diagnosis. Thus, the detection of BAs with high practical potential is of great importance. In this work, a new BAs fluorescent probe design strategy is proposed by the intramolecular charge transfer (ICT) enhancement of the fluorescent probes, which is induced by the hydrogen bond interaction between probes and analyte. The probes T1 and T2 with donor-acceptor structure not only present a 140 nm bathochromic-shifted emission, ultrafast responses (15 s for T1 and 25 s for T2), and high sensitivity (detection limit of 1.3 ppm for T1 and 2.6 ppm for T2) to cadaverine (the typical representative of BAs) but also discriminate a series of BAs and simply reused at least 30 times after air blowing. Further, a quantitative evaluation system is obtained based on T1 and T2 films. Through the Red/Green/Blue analysis with a smartphone, the total volatile basic nitrogen (an international standard to assess food spoilage) value can be output to quantitatively evaluate the freshness of food. The system is fast, visual, accurate, and nondestructive, enabling consumers and all stakeholders in the food supply chain to monitor food freshness.

An Unusual Bismuth–Antimony–Europium Cluster-Imbedded Polyoxotungstate and Its Bidirectional Luminescence Detection

“…The apparent lifetime alterations of 1 in the presence and absence of Mn 2+ ions are suggestive of a dynamic quenching process. It shows that the quenching mechanism is the result of the dynamic collision between Mn 2+ ions and the polyoxoanions of 1 rather than the combination of Mn 2+ and the polyoxoanions of 1 . − Besides, the UV–vis spectrum of Mn 2+ overlaps with in some degree the excitation spectrum of 1 , implying the competitive photon energy absorption between the polyoxoanions of 1 and Mn 2+ cations (Figure S25). , Consequently, the PL gradual quenching mechanism of the 1 -based sensor upon augmenting the Mn 2+ concentration is probably related to dynamic quenching and competitive energy absorption.…”

Design of Highly Efficient Electronic Energy Transfer in Functionalized Quantum Dots Driven Specifically by Ethylenediamine

“…As one of the most representative example of it, ethylenediamine (1,2-diamines, EDA), is one of the primary ingredients used to make the powerful Picatinny liquid explosive . As a typical amine compound, EDA has the typical characteristics of amines (alkalinity and nucleophilicity) as well as corrosivity and toxicity, and due to this reason, WHO has specified 10 ppm as the occupational exposure limit of EDA. , Therefore, it is important to develop highly selective, highly sensitive and rapid response methodologies for on-site EDA detection. − Apparently, especially in resource-limited areas, the detection of EDA has been trending away from bulky and time-consuming instruments as well as complex detecting procedures, which needs to be carried out at designated laboratories with trained personnel in most cases. − Thus, optical method is considered as one of the most promising approaches for on-site EDA sensing coupled with image analysis techniques because of its visual (with naked-eye) and real-time measurement results, easy operating and portable characteristics. − For instance, Lin et al realized a reversible selective fluorescent response for EDA by pillar[5]­arene-based crystalline material (PQ8), although the form of fluorescence quenching made it difficult for naked eye to resolve the concentration of EDA. Huang et al reported nonporous adaptive pillar[4]­arene[1]­quinone crystals for fluorescence turn-on sensing of EDA vapor, while the sensitivity and response time still need to be improved.…”

A donor–acceptor hydrogen-bonded organic framework with the turn-on fluorescence response of phenethylamine (drug analogue) via single-crystal to single-crystal transformation

“…Compared to the “turn off” type, a “turn-on” type of fluorescence response is required to detect the analyte, distinguishing it from environmental quenching effects, which possesses higher accuracy. 39–42 Recently, several luminescent HOFs have been constructed for fluorescence sensing toward various analytes. 43,44 Nevertheless, the “turn-on” type of fluorescence detection on HOF materials has rarely been reported.…”