Polymer films doped with fluorescent sensor for moisture and water droplet based on photo-induced electron transfer

Advances on fluorescence chemosensors for selective detection of water

Water, although an important part of everyday life, is acts as one of the most significant contaminants in various applications such as biomedical monitoring, chemical production, petroleum-based fuel and food processing. In fact, the presence of water in other solvents is a huge concern. For the quantification of trace water content, different methods such as Karl-Fischer, electrochemical, nuclear magnetic resonance, chromatography, and thermogravimetric analysis have been used. Although every technique has its own benefit, each one suffers from several drawbacks that include high detection costs, lengthy procedures and specialized operations. Nowadays, the development of fluorescence-based chemical probes has become an exciting area of research for the quick and accurate estimation of water content in organic solvents. A variety of chemical processes such as hydrolysis reaction, metal ions promoted oxidation reaction, suppression of the -C═N isomerization, protonation and deprotonation reactions, and molecular aggregation have been well researched in the last few years for the fluorescent detection of trace water. These chemical processes eventually lead to different photophysical events such as aggregation-induced emission (AIE), aggregation-induced emission enhancement (AIEE), aggregation-caused quenching (ACQ), fluorescent resonance energy transfer (FRET), charge transfer, photo-induced electron transfer (PET), excited state intramolecular proton transfer (ESIPT) that are responsible for the detection. This review presents a summary of the fluorescence-based chemosensors reported in recent years. The design of water sensors, sensing mechanisms and their potential applications are reviewed and discussed.

Recent advancements in chemosensors for the detection of food spoilage

The need for reliable sensors has become a major requirement to confirm the quality and safety of food commodities. Chemosensors are promising sensing tools to identify contaminants and food spoilage to ensure food safety. Chemosensing materials are evolving and becoming potential mechanisms to enable onsite and real-time monitoring of food safety. This review summarizes the information about the basic four types of chemosensors (colorimetric, optical, electrochemical, and piezoelectric) employed in the food sector, the latest advancements in the development of chemo-sensing mechanisms, and their food applications, with special emphasis on the future outlook of them. In this review, we discuss the novel chemosensors developed from the year 2018 to 2022 to detect spoilage in some common types of food like fish, meat, milk, cheese and soy sauce. This work will provide a fundamental step toward further development and innovations of chemosensors targeting different arenas in the food industry.

Pyrene-based fluorescent chemosensor for rapid detection of water and its applications

This manuscript introduces a pyrene-based Schiff base L by reacting pyrenecarboxaldehyde with 2-aminothiazole in equimolar ratio. The ligand L was characterized by various spectral data and single crystal. The water sensing ability of L was examined in different organic solvents. The weakly emissive L in DMSO showed a fluorescence enhancement upon the addition of water. The water-induced fluorescence enhancement of L was occurred due to the combined effect of aggregation-induced emission (AIE) phenomenon and suppression of photo-induced electron transfer (PET) process. Using L, the water in DMSO can be detected down to 0.50 wt% with a quantification limit of 1.52 wt%. The analytical novelty of the developed sensor L was validated by detecting moisture in a variety of raw food products.

Tetraphenylethene–anthracene-based fluorescence emission sensor for detection of water with photo-induced electron transfer and aggregation-induced emission characteristics

As a fluorescent sensor for water over a wide range from low to high water content regions in organic solvents, we have designed and developed a PET (photo-induced electron transfer)/AIE...

Fluorescent polymer films based on photo-induced electron transfer for visualizing water

As fluorescent materials for visualization, detection, and quantification of a trace amount of water, we have designed and developed a PET (photo-induced electron transfer)-type fluorescent monomer SM-2 composed of methyl methacrylate-substituted anthracene fluorophore-(aminomethyl)-4-cyanophenylboronic acid pinacol ester (AminoMeCNPhenylBPin) and achieved preparation of a copolymer poly(SM-2-co-MMA) composed of SM-2 and methyl methacrylate (MMA). Both SM-2 and poly(SM-2-co-MMA) exhibited enhancement of the fluorescence emission with the increase in water content in various solvents (less polar, polar, protic, and aprotic solvents) due to the formation of the PET inactive (fluorescent) species SM-2a and poly(SM-2-co-MMA)a, respectively, by the interaction with water molecules. The detection limit (DL) of poly(SM-2-co-MMA) for water in the low water content region below 1.0 wt% in acetonitrile was 0.066 wt%, indicating that poly(SM-2-co-MMA) can act as a PET-type fluorescent polymeric sensor for a trace amount of water in solvents, although it was inferior to that (0.009 wt%) of SM-2. It was found that spin-coated poly(SM-2-co-MMA) films as well as 15 wt% SM-2-doped polymethyl methacrylate (PMMA) films produced a satisfactory reversible fluorescence off–on switching between the PET active state under a drying process and the PET inactive state upon exposure to moisture, which is demonstrated by the fact that the both the films are similar in hydrophilicity to each other from the measurement of the water contact angles on the polymer film surface. Herein we propose that PET-type fluorescent polymer films based on a fluorescence enhancement system are one of the most promising and convenient functional dye materials for visualizing moisture and water droplets.

Photo-induced electron transfer (PET)-type fluorescent polymer films based on a fluorescence enhancement system have been prepared as one of the most promising and convenient functional dye materials for visualizing moisture and water droplets.