Natural Quercetin AIEgen Composite Film with Antibacterial and Antioxidant Properties for in Situ Sensing of Al3+ Residues in Food, Detecting Food Spoilage, and Extending Food Storage Times

Comparison of Polylactide-Based Active Films Containing Berberine and Quercetin as Systems for Maintaining the Quality and Safety of Blueberries

Polymeric thin films based on polylactide with an addition of poly(ethylene glycol) as a plasticizer and flavonoids in the form of quercetin and berberine were subjected to tests that were particularly relevant from the point of view of contact with food. A comparative analysis of the effect of individual flavonoids on the antioxidative properties of tested films and blueberry storage was carried out. The influence of active compounds on the water vapor permeability, as well as UV protection, of the obtained materials was investigated. Also, the specific migration of individual flavonoids from obtained materials to food simulants in the form of acetic acid and ethyl alcohol was determined. The crucial point of this study is the storage of blueberries. The obtained results indicate that the selection of packaging, containing individual active compounds, depends on the purpose and requirements that the packaging must meet for particular types of food.

CO2-Sourced Polymer Dyes for Dual Information Encryption

Large amounts of small molecule dyes leak into the ecosystems annually in harmful and unsustainable ways. Polymer dyes have attracted much attention because of their high migration resistance, excellent stability, and minimized leakage. However, the complex synthesis process, high cost, and poor degradability hinder their widespread application. Herein, green and sustainable polymer dyes are prepared using natural dye quercetin (Qc) and CO2 through a one-step process. The CO2-sourced polymer dyes show strong migration resistance, high stability, and can be degraded on demand. Additionally, the CO2-sourced polymer dyes showed unique responses to Zn2+, leading to significantly enhanced fluorescence, highlighting their potential for information encryption/decryption. The CO2-sourced polymer dyes can solve the environmental hazards caused by small molecule dye leakage and promote the carbon cycle process. Meanwhile, the one-step synthesis process is expected to achieve sustainable and widespread utilization of CO2-sourced polymer dyes.

Aggregation-Induced Emission Luminogens: A New Possibility for Efficient Visualization of RNA in Plants

RNAs play important roles in regulating biological growth and development. Advancements in RNA-imaging techniques are expanding our understanding of their function. Several common RNA-labeling methods in plants have pros and cons. Simultaneously, plants' spontaneously fluorescent substances interfere with the effectiveness of RNA bioimaging. New technologies need to be introduced into plant RNA luminescence. Aggregation-induced emission luminogens (AIEgens), due to their luminescent properties, tunable molecular size, high fluorescence intensity, good photostability, and low cell toxicity, have been widely applied in the animal and medical fields. The application of this technology in plants is still at an early stage. The development of AIEgens provides more options for RNA labeling. Click chemistry provides ideas for modifying AIEgens into RNA molecules. The CRISPR/Cas13a-mediated targeting system provides a guarantee of precise RNA modification. The liquid-liquid phase separation in plant cells creates conditions for the enrichment and luminescence of AIEgens. The only thing that needs to be looked for is a specific enzyme that uses AIEgens as a substrate and modifies AIEgens onto target RNA via a click chemical reaction. With the development and progress of artificial intelligence and synthetic biology, it may soon be possible to artificially synthesize or discover such an enzyme.

Alginate based films integrated with nitrogen-functionalized carbon dots and layered clay for active food packaging applications

The applications of alginate derived from seaweed polysaccharide in food packaging are restricted due to their inherent deficient antibacterial, antioxidant and UV barrier properties. In this study, nitrogen-functionalized carbon dots (NCDs) with active functions (0.5-3 %) and layered clay (1 %) with barrier property were introduced to construct alginate based active films via solution casting method. The results showed that the synthesized spherical NCDs had a particle size of 2-3 nm, and the internal structure of NCDs was similar to graphene, with a large number of active groups (-NH2, -OH, etc.) on the surface. Infrared analysis revealed that NCDs could form strong hydrogen bonds with alginate matrix, which slowed down the deterioration of mechanical properties and reduced the surface wettability. With the addition of NCDs, active functions and surface hydrophobicity of the active films were enhanced significantly (P < 0.05). When the amount of NCDs reached 3 %, UV barrier, antioxidant and antibacterial properties of the active films were increased by 50.0 %, 61.1 % and 70.1 %, respectively. The addition of NCDs could enhance the anti-browning ability of alginate based coatings and extend the shelf life of banana significantly. Therefore, a suitable amount of NCDs (1-2 %) and layered clay (1 %) can synergistically improve comprehensive performance of alginate based films and promote their food packaging application used as active films/inner coatings.

Fabrication, performance, and potential environmental impacts of polysaccharide-based food packaging materials incorporated with phytochemicals: A review

Although food packaging preserves food's quality, it unfortunately contributes to global climate change since the considerable carbon emissions associated with its entire life cycle. Polysaccharide-based packaging materials (PPMs) are promising options to preserve foods, potentially helping the food industry reduce its carbon footprint. PPMs incorporated with phytochemicals hold promise to address this critical issue, keep food fresh and prolong the shelf life. However, phytochemicals' health benefits are impacted by their distinct chemical structures thus the phytochemicals-incorporated PPMs generally exhibit differential performances. PPMs must be thoughtfully formulated to possess adequate physicochemical properties to meet commercial standards. Given this, this review first-time provides a comprehensive review of recent advances in the fabrication of phytochemicals incorporated PPMs. The application performances of phytochemicals-incorporated PPMs for preserving foods, as well as the intelligent monitoring of food quality, are thoroughly introduced. The possible associated environmental impacts and scalability challenges for the commercial application of these PPMs are also methodically assessed. This review seeks to provide comprehensive insights into exploring new avenues to achieve a greener and safer food industry via innovative food packaging materials. This is paramount to preserve not only food shelf life but also the environment, facilitating the eco-friendly development of the food industry.

Aggregation-Induced Emission (AIE), Life and Health

Light has profoundly impacted modern medicine and healthcare, with numerous luminescent agents and imaging techniques currently being used to assess health and treat diseases. As an emerging concept in luminescence, aggregation-induced emission (AIE) has shown great potential in biological applications due to its advantages in terms of brightness, biocompatibility, photostability, and positive correlation with concentration. This review provides a comprehensive summary of AIE luminogens applied in imaging of biological structure and dynamic physiological processes, disease diagnosis and treatment, and detection and monitoring of specific analytes, followed by representative works. Discussions on critical issues and perspectives on future directions are also included. This review aims to stimulate the interest of researchers from different fields, including chemistry, biology, materials science, medicine, etc., thus promoting the development of AIE in the fields of life and health.

Preparation of a multifunctional non-stick tamarind polysaccharide-polyvinyl alcohol hydrogel immobilized with a quorum quenching enzyme for maintaining fish freshness

Hydrogels have become promising materials for food packaging due to their unique microstructure. However, hydrogel materials suitable for seafood preservation have rarely been reported. In this study, a tamarind polysaccharide-polyvinyl alcohol hydrogel with the ability to maintain seafood freshness was prepared and characterized. The hydrogel possesses quick self-healing, good tissue fitting, and freezing tolerance capability. Moreover, a peeling force of only 0.1 N between the hydrogel and the fillet tissue confirmed the non-stick properties. The FTIR characteristic peak at 1600 cm^-1 and 1450 cm^-1 proved the ester bond-based chemical cross-linking of the hydrogel. Release profiles at pH 6.0 to 8.0 verified the pH-responsive release of quorum-quenching (QQ) enzymes over 120 h, which enabled the hydrogel to achieve biofilm and protease inhibitory activities. In vivo spoilage tests showed that the shelf life of hydrogel-coated red snapper fillets was extended by >3 days. These results illustrate the potential of the prepared hydrogel as functional packaging for seafood preservation.

Effects of Quercetin and Organically Modified Montmorillonite on the Properties of Poly(butylene adipate-co-terephthalate)/Thermoplastic Starch Active Packaging Films

The poly(butylene adipate-co-terephthalate) (PBAT)/thermoplastic starch (TPS) film stands out owing to its acceptable price, low impact on the environment, and excellent mechanical properties. The main objective of this study was to improve the antioxidant properties of the PBAT/TPS film by incorporation of quercetin (Q) through the extrusion blow process. Another specific objective was to incorporate the organically modified montmorillonite (OMMT) to prolong the release of Q and improve the poor barrier properties of the PBAT/TPS/Q film. The films were analyzed in terms of their morphology, mechanical properties, gas and water barrier properties, and antioxidant and anti-UV properties. Optimization of the OMMT content resulted in a fiber-like, co-continuous morphology of the PBAT/TPS/Q film. The incorporation of quercetin enhanced the antioxidant and anti-UV properties of the PBAT/TPS film, while OMMT improved the mechanical properties, ultraviolet barriers, and gas and water barrier properties. The results show that the films incorporating Q and OMMT provided the oxygen and water barrier by up to 94 and 54%, respectively. Also, the amount of polymer required for 50% 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition is as low as 0.03 g, and the UV transmission rate was reduced by about 50%. Moreover, PBAT/TPS/Q/OMMT films successfully delayed the decay of the banana and blueberry due to their excellent antioxidant properties and suitable water vapor permeability.

An efficient ethylcellulose fluorescent probe for rapid detection of Fe3+ and its multi-functional applications

Fe³⁺ is the most abundant essential transition metal ion in the human body, plays a vital role in biological and environmental systems. Ethyl cellulose is one of the derivatives of cellulose. Herein, a novel ethylcellulose fluorescent probe EC-HPCB for detecting Fe³⁺ was prepared by grafting a flavonol derivative as both fluorophore and selective recognition group. The probe exhibited a highly specific "turn-off" fluorescence response to Fe³⁺, and the fluorescence color changed from yellow to colorless in the presence of Fe³⁺. The detection limit of EC-HPCB for Fe³⁺ was 2.65 × 10^-7 mol/L, and the response time was as quick as 2 min. The detection mechanism was confirmed by ¹H NMR and DFT calculations. Based on the good solubility and processability in organic solvent, EC-HPCB was made into coating and film with favorable fluorescent performances. Furthermore, EC-HPCB probe was successfully applied to monitor Fe³⁺ in real water samples, and the EC-HPCB-loaded filter paper provided a solid-state platform for detecting Fe³⁺ by naked eye and fluorescence method.

Sensing Leakage of Electrolytes from Magnesium Batteries Enabled by Natural AIEgens

The potential for leakage of liquid electrolytes from magnesium (Mg) batteries represents a large hurdle to future application. Despite this, there are no efficient sensing technologies to detect the leakage of liquid electrolytes. Here, we developed a sensor using laccaic acid (L-AIEgen), a naturally occurring aggregation-induced emission luminogen (AIEgens) isolated from the beetle Laccifer lacca. L-AIEgen showed good selectivity and sensitivity for Mg²⁺, a universal component of electrolytes in Mg batteries. Using L-AIEgen, we then produced a smart film (L-AIE-F) that was able to sense leakage of electrolytes from Mg batteries. L-AIE-F showed a strong "turn-on" AIE-active fluorescence at the leakage point of electrolyte from model Mg batteries. To the best of our knowledge, this is the first time that AIE technology has been used to sense the leakage of electrolytes.

Recent Advances in Aggregation-Induced Emission Active Materials for Sensing of Biologically Important Molecules and Drug Delivery System

The emergence and development of aggregation induced emission (AIE) have attracted worldwide attention due to its unique photophysical phenomenon and for removing the obstacle of aggregation-caused quenching (ACQ) which is the most detrimental process thereby making AIE an important and promising aspect in various fields of fluorescent material, sensing, bioimaging, optoelectronics, drug delivery system, and theranostics. In this review, we have discussed insights and explored recent advances that are being made in AIE active materials and their application in sensing, biological cell imaging, and drug delivery systems, and, furthermore, we explored AIE active fluorescent material as a building block in supramolecular chemistry. Herein, we focus on various AIE active molecules such as tetraphenylethylene, AIE-active polymer, quantum dots, AIE active metal-organic framework and triphenylamine, not only in terms of their synthetic routes but also we outline their applications. Finally, we summarize our view of the construction and application of AIE-active molecules, which thus inspiring young researchers to explore new ideas, innovations, and develop the field of supramolecular chemistry in years to come.

Terpenoids and Polyphenols as Natural Antioxidant Agents in Food Preservation

Synthetic antioxidant food additives, such as BHA, BHT and TBHQ, are going through a difficult time, since these products generate a negative perception in consumers. This has generated an increased pressure on food manufacturers to search for safer natural alternatives like phytochemicals (such as polyphenols, including flavonoids, and essential oils rich in terpenoids, including carotenoids). These plant bioactive compounds have antioxidant activities widely proven in in vitro tests and in diverse food matrices (meat, fish, oil and vegetables). As tons of food are wasted every year due to aesthetic reasons (lipid oxidation) and premature damage caused by inappropriate packaging, there is an urgent need for natural antioxidants capable of replacing the synthetic ones to meet consumer demands. This review summarizes industrially interesting antioxidant bioactivities associated with terpenoids and polyphenols with respect to the prevention of lipid oxidation in high fat containing foods, such as meat (rich in saturated fat), fish (rich in polyunsaturated fat), oil and vegetable products, while avoiding the generation of rancid flavors and negative visual deterioration (such as color changes due to oxidized lipids). Terpenoids (like monoterpenes and carotenoids) and polyphenols (like quercetin and other flavonoids) are important phytochemicals with a broad range of antioxidant effects. These phytochemicals are widely distributed in fruits and vegetables, including agricultural waste, and are remarkably useful in food preservation, as they show bioactivity as plant antioxidants, able to scavenge reactive oxygen and nitrogen species, such as superoxide, hydroxyl or peroxyl radicals in meat and other products, contributing to the prevention of lipid oxidation processes in food matrices.

Phytochemicals toward Green (Bio)sensing

Because of numerous inherent and unique characteristics of phytochemicals as bioactive compounds derived from plants, they have been widely used as one of the most interesting nature-based compounds in a myriad of fields. Moreover, a wide variety of phytochemicals offer a plethora of fascinating optical and electrochemical features that pave the way toward their development as optical and electrochemical (bio)sensors for clinical/health diagnostics, environmental monitoring, food quality control, and bioimaging. In the current review, we highlight how phytochemicals have been tailored and used for a wide variety of optical and electrochemical (bio)sensing and bioimaging applications, after classifying and introducing them according to their chemical structures. Finally, the current challenges and future directions/perspective on the optical and electrochemical (bio)sensing applications of phytochemicals are discussed with the goal of further expanding their potential applications in (bio)sensing technology. Regarding the advantageous features of phytochemicals as highly promising and potential biomaterials, we envisage that many of the existing chemical-based (bio)sensors will be replaced by phytochemical-based ones in the near future.

Application of quercetin flavonoid based hybrid nanocomposites: A review

Natural bioflavonoids are an essential component of dietary supplements possessing antimicrobial properties. Many of the bioflavonoids have resulted in positive antitumor, anticancer, antibacterial, antifungal, anti-inflammatory properties, but the efficacy remains low due to toxicity at the molecular level whereas antiviral property limits to negative. The synergistic link between nanoscience and flavonoid chemistry enhances the epidemiological properties of flavonoid and also diminish the antimicrobial resistivity (AMR) by forming their hybrid nanocomposites. Nanochemistry uses various nanocomposite and nanomaterials for biosensing the flavonoids and their delivery as a drug. The quercetin flavonoid and its derivatives such as rutin, and myricetin are used for sensing and drug delivery. Quercetin with 15Carbon-5Hydroxyl chemical scaffold has been explored for a few decades for the development of hybrid nanocomposite and nanomaterial with metallic as well as organic nano co-composites. This quercetin flavonoid based hybrid nanocomposites seemed to show a significant effect on In vitro and some animal model processes along with attenuating lipid peroxidation, platelet aggregation, and capillary permeability actions. This review mainly focused on the hybrid nanoscience of quercetin bioflavonoid and its application in numerous biological, material fields with a future perspective.

Functional Polymers and Polymer-Dye Composites for Food Sensing

The sensitive, safe, and portable detection of food spoilage is becoming unprecedentedly important because it is closely related to the public health and economic development, particularly given the globalization of food supply chain. However, the existing approaches for food monitoring are still limited to meet these requirements. To address this challenge, much research has been done to develop an ideal food sensor that can indicate food quality in real-time in a sensitive and reliable way. So far, many sensors such as time-temperature indicators, smart trademarks, colorimetric tags, electronic noses, and electronic tongues, have been developed and even commercialized. In this feature article, the recent progress of food sensors based on functional polymers, including the molecular design of polymer structures, sensing mechanisms, and relevant processing techniques to fabricate a variety of food sensor devices is reviewed.

Seeking Answers from Tradition: Facile Preparation of Durable Adhesive Hydrogel Using Natural Quercetin

Adhesive hydrogels containing catechol moieties have many important applications, but the fabrication of effective long-lasting adhesive hydrogels remains a challenge because of oxidative damage. Inspired by the traditional use of quercetin in ancient China, here, we have developed a novel method, based on quercetin-assisted photoradical chemistry, to fabricate a durable adhesive hydrogel, Q-hydrogel. In the presence of light, quercetin generates quinone/semiquinone radicals, which subsequently interact with ammonium persulfate (APS) to produce a large amount of free radicals and initiate polymerization of the hydrogel. As-prepared Q-hydrogel showed good mechanical and adhesive properties, which were attributed to the inherent structural advantages of quercetin. Because of the resistance of quercetin to oxidation, as-prepared Q-hydrogel also showed good adhesive properties even after treatment with oxidizing agents. Capitalizing on its conductivity and adhesive properties, Q-hydrogel was successfully used to produce wearable sensors capable of detecting human motion.

AIEgens: An emerging fluorescent sensing tool to aid food safety and quality control

As a global public health problem, food safety has attracted increasing concern. To minimize the risk exposure of food to harmful ingredients, food quality and safety inspection that covers the whole process of "from farm to fork" is much desired. Fluorescent sensing is a promising and powerful screening tool for sensing hazardous substances in food and thus plays a crucial role in promoting food safety assurance. However, traditional fluorphores generally suffer the problem of aggregation-caused quenching (ACQ) effect, which limit their application in food quality and safety inspection. In this regard, luminogens with aggregation-induced emission property (AIEgens) showed large potential in food analysis since AIEgens effectively surmount the ACQ effect with much better detection sensitivity, accuracy, and robustness. In this contribution, we review the latest developments of food safety monitoring by AIEgens, which will focus on the molecular design of AIEgens and their sensing principles. Several examples of AIE-based sensing applications for screening food contaminations are highlighted, and future perspectives and challenges in this emerging field are tentatively elaborated. We hope this review can motivate new research ideas and interest to aid food safety and quality control, and facilitate more collaborative endeavors to advance the state-of-the-art sensing developments and reduce actual translational gap between laboratory research and industrial production.

Aggregation-Induced Emission: New Vistas at the Aggregate Level

Aggregation-induced emission (AIE) describes a photophysical phenomenon in which molecular aggregates exhibit stronger emission than the single molecules. Over the course of the last 20 years, AIE research has made great strides in material development, mechanistic study and high-tech applications. The achievements of AIE research demonstrate that molecular aggregates show many properties and functions that are absent in molecular species. In this review, we summarize the advances in the field of AIE and its related areas. We specifically focus on the new properties of materials attained by molecular aggregates beyond the microscopic molecular level. We hope this review will inspire more research into molecular ensembles at and beyond the meso level and lead to the significant progress in material and biological science.

Tetranitrile-anthracene as a probe for fluorescence detection of viscosity in fluid drinks via aggregation-induced emission

An AIE-based fluorescent probe was developed for monitoring the viscosity change during the spoilage process of fluid drinks.

Gallic Acid and Quercetin as Intelligent and Active Ingredients in Poly(vinyl alcohol) Films for Food Packaging

Gallic acid (GA) and quercetin (QC) were used as active ingredients in poly(vinyl alcohol) (PVA) film formulations obtained by solvent casting process. The effect of two different percentages (5 and 10 % wt.) on morphological behavior, thermal stability, optical, mechanical, and release properties of PVA were investigated, while migration with food stimulants and antioxidant properties were tested taking into account the final application as food packaging systems. The results showed how different dispersability in PVA water solutions gave different results in term of deformability (mean value of ε PVA/5GA = 280% and ε PVA/5QC = 255%, with 190% for neat PVA), comparable values for antioxidant activity at the high contents (Radical Scavenging Activity, RSA(%) PVA/10GA = 95 and RSA(%) PVA/10QC = 91) and different coloring attitude of the polymeric films. It was proved that GA, even if it represents the best antioxidant ingredient to be used with PVA and can be easily dispersed in water, it gives more rigid films in comparison to QC, that indeed was more efficient in tuning the deformability of the PVA films, due the presence of sole hydroxyl groups carrying agent. The deviation of the film coloring towards greenish tones for GA films and redness for QC films after 7 and within 21 days in the simulated conditions confirmed the possibility of using easy processable PVA films as active and intelligent films in food packaging.

H3PW12O40/ZrO2 and 1-Butyl-3-methylimidazolium Chloride: A Double-Effect Catalyst for the Degradation of Alkali Lignin

Alkali lignin is a component of the waste black liquor produced by the paper-making industry that is difficult to degrade. In recent years, the biological activities of lignin, such as free-radical scavenging and antioxidant capacity, have received increasing attention. Here, we prepared H3PW12O40/ZrO2 and used this catalyst together with the ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) as a double-effect catalyst for the degradation of alkali lignin. Single-factor and orthogonal tests showed that the best degradation conditions were as follows: reaction time, 2 h; reaction temperature, 100 °C; mass ratio of H3PW12O40/ZrO2 to lignin, 1:4; and substrate concentration, 2.5%. The phenolic hydroxyl group content of the lignin degradation product increased by 231.2% and the total hydroxyl group content increased by 337.1% when the double-effect catalyst was used rather than [BMIM]Cl alone. Analysis by gel permeation chromatography showed that both the weight-average molecular weight and the number-average molecular weight of the product were reduced and that the lignin was degraded into small-molecular-weight compounds by the macromolecule. The product after the catalytic degradation of lignin showed a markedly increased antioxidant capacity, which was similar to that of the commercial antioxidant, 2,6-ditert-butyl-4-methylphenol. The study opens up a new direction for the better utilization of lignin.

Broadening AIEgen application: rapid and portable sensing of foodstuff hazards in deep-frying oil

We report the first example of an AIEgen probe, QM-TPA, for sensing of triacylglycerol-based polymers in frying oil.