Fabricating Soft Fluorescent Materials by a Supramolecular Method and a Cost-Effective Approach to Effectively Sense Amine Vapors during Fish Spoilage

Toward High Contrast and Noninvasive Fluorescence Switches via an O-Fused Ring 5,7-Dihydroxy-4-methyl-2,2,3-triphenylbenzofuran-6(2H)-one Strategy

An unprecedented O-fused ring 5,7-dihydroxy-4-methyl-2,2,3-triphenylbenzofuran-6(2H)-one (3) was first time synthesized. Further, a series of novel dialkyl/fluoroalkyl derivatives of compound 3, 5,7-dialkoxy/fluoroalkoxy-4-methyl-2,2,3-triphenylbenzofuran-6(2H)-one, were obtained with noninvasive fluorescence switching characteristics and aggregation-induced emission properties. Compared with fluoroalkyl derivatives, the alkyl analogs exhibited a significant bathochromic shift in solid-state fluorescence emission. Notably, these noninvasive fluorescent molecular switches could be facilely tuned through light and heat stimulation, which successfully achieved high contrast and reversible fluorescent emission between orange and yellow endowing them with potential applications in data encryption materials. In addition, the single crystal data of compounds 3 and 7-CF3 displayed weak intermolecular interactions in different directions, resulting in twisted conformation and antiparallel slip stacking. Interestingly, the polymer dimethyl silicone film doped with 7-C3F7 also showed an evident light-responsive behavior, meeting the criterion for fluorescent materials in the optical field.

Biphenyl-rGO composite room temperature gas sensor for enhanced amine sensing

Amines, which are classified as volatile organic compounds (VOCs), serve a variety of purposes in the fields of environmental monitoring, food safety, and healthcare diagnosis. The present technique for detecting amine levels involves sophisticated setups and bulky equipment. Here. In this study, a chemoresistive gas sensor is developed that is cost-effective and easy to operate at room temperature (RT). The sensor is designed specifically for the detection of Ammonia, dimethylamine (DMA), trimethylamine (TMA), and total volatile basic nitrogen (TVB-N). Using biphenyl-reduced graphene oxide (B-rGO) composite gas sensors effectively addresses the issues of low sensitivity-selectivity and long-term instability commonly observed in conventional amine sensors. B-rGO sensor produced sensitivity of ∼3500 and selectivity above 30 for TVB-N sensing. The sensor is stable for temperature fluctuations below 50 °C and shows stable sensing response for period of over 3 months. A Chemoresistive B-rGO sensor was developed using an ultrasonic spray deposition system with optimized flow rate of 50 mL/h. Rapid evaporation of solvent using hot plate has resulted in unique morphology for B-rGO film sensors. The highest sensitivity, ∼836, is obtained for 100 ppm of ammonia with ammonia > DMA > TMA as a sensitivity order. B-rGO showed almost seven times higher amine sensitivity than rGO which highlights the importance of biphenyl in the B-rGO composite. Sensor calibration curve has been presented in the study to understand change in the sensitivity of sensor with increasing analyte gas concentration. The calibration curve has an average R-squared value of 0.98.

Recent advances in meat freshness "magnifier": fluorescence sensing

To address the serious waste of meat resources and food safety problems caused by the decrease in meat freshness due to the action of microorganisms and enzymes, a low-cost, time-saving and high-efficiency freshness monitoring method is urgently needed. Fluorescence sensing could act as a "magnifier" for meat freshness monitoring due to its ability to sense characteristic signal produced by meat spoilage. Here, the magnification mechanism of meat freshness via sensing the water activity, adenosine triphosphate, hydrogen ion, total volatile basic nitrogen, hydrogen sulfide, bioamines was comprehensively analyzed. The existing "magnifier" forms including paper chips, films, labels, arrays, probes, and hydrogels as well as the application in livestock, poultry and aquatic meat freshness monitoring were reviewed. Future research directions involving innovation of principles, visualization and quantification capabilities for various meats freshness were provided. By critically evaluating the potential and limitations, efficient and reliable meat freshness monitoring strategies wish to be developed for the post-epidemic era.

Simple Way to Fabricate Emissive Boron-Containing Covalent Organic Frameworks

Highly fluorescent covalent organic frameworks (COFs) are rarely obtained because of the π-π stacked layers with aggregation-caused quenching behavior. Unarguably, highly fluorescent COFs with tunable emission colors are even more rarely achieved. Herein, a general strategy to modify the classical COF material (named COF-1) by different fluorescent molecules via N → B interaction was developed. In this method, the boron-containing COF-1 acted as a porous and crystalline matrix as well as a reaction partner of Lewis acid; after interacting with fluorescent molecules with the anchoring group of pyridine (Lewis base), COF-1 takes a gorgeous transfiguration from a non-emissive powder into a highly fluorescent COF material with tunable emission colors. This disclosed method endowed the typical COFs with new emissive life and is speculated with the general research concept for all boron-containing COFs. Benefiting from the prominent fluorescent emission in the aggregation state, sensitive probes toward amines are achieved.

Sustainable aggregation-induced emission material based on pectin-l-lysine: Potential antibacterial and monitoring in food spoilage

The demand of smart food detection system which in detecting food spoilage is increasing. In this work, a new type of aggregation-induced emission (AIE) compound was synthesized based on pectin (P) and l-lysine (Lys). P-Lys is an AIE active compound which has the advantages of simple synthesis, easy modification and processability, it also has good water solubility and biocompatibility. Moreover, P-Lys has potential application in detecting Fe³⁺ (oxidation from Fe²⁺) and bacterial in monitoring pork spoilage. In addition, P-Lys also has spectral antibacterial properties which can prevent pork spoilage. The research results shown that P-Lys, as a new type of food testing agent has a useful future in monitoring and protecting the freshness of food.