Melanin-mediated synthesis of silver nanoparticle and its use for the preparation of carrageenan-based antibacterial films

Potato oxidized hydroxypropyl starch/pectin-based indicator film with Clitoria ternatea anthocyanin and silver nanoparticles for monitoring chilled beef freshness

Potato oxidized hydroxypropyl starch (POHS)/pectin (P) functional and smart beef freshness indicator films were prepared using butterfly pea (Clitoria ternatea) anthocyanin (BA) and silver nanoparticles (AgNPs). BA exhibited significant pH-responsive color changes. BA and AgNPs were evenly distributed within a polymer matrix to create a compatible film with POHS/P. The films containing BA and AgNPs had good UV resistance and maintained strong mechanical strength, barrier properties, and color stability. The color of the indicator film changed from purple to green when exposed to ammonia, with the 1 % POHS/P/BA/AgNPs film showing the most sensitive response. The films also demonstrated strong antibacterial and antioxidant properties. The freshness of beef was monitored using 1 % POHS/P/BA/AgNPs films and was identified as sub-fresh and spoiled on days 4 and 7, respectively. The relationship between the color change of the indicator label and the freshness of chilled beef was established: purple for fresh meat, blue for less fresh meat, and green for spoiled meat. Thus, the new POHS/P/BA/AgNPs film can serve as a smart packaging material to indicate food freshness and extend shelf life. These results suggest that POHS/P/BA/AgNPs films have significant potential as an active and smart food packaging material.

Recent Progress of Carrageenan-Based Composite Films in Active and Intelligent Food Packaging Applications

Recently, as concerns about petrochemical-derived polymers increase, interest in biopolymer-based materials is increasing. Undoubtedly, biopolymers are a better alternative to solve the problem of synthetic polymer-based plastics for packaging purposes. There are various types of biopolymers in nature, and mostly polysaccharides are used in this regard. Carrageenan is a hydrophilic polysaccharide extracted from red algae and has recently attracted great interest in the development of food packaging films. Carrageenan is known for its excellent film-forming properties, high compatibility and good carrier properties. Carrageenan is readily available and low cost, making it a good candidate as a polymer matrix base material for active and intelligent food packaging films. The carrageenan-based packaging film lacks mechanical, barrier, and functional properties. Thus, the physical and functional properties of carrageenan-based films can be enhanced by blending this biopolymer with functional compounds and nanofillers. Various types of bioactive ingredients, such as nanoparticles, natural extracts, colorants, and essential oils, have been incorporated into the carrageenan-based film. Carrageenan-based functional packaging film was found to be useful for extending the shelf life of packaged foods and tracking spoilage. Recently, there has been plenty of research work published on the potential of carrageenan-based packaging film. Therefore, this review discusses recent advances in carrageenan-based films for applications in food packaging. The preparation and properties of carrageenan-based packaging films were discussed, as well as their application in real-time food packaging. The latest discussion on the potential of carrageenan as an alternative to traditionally used synthetic plastics may be helpful for further research in this field.

Recent advances in reinforced bioplastics for food packaging - A critical review

Recently, diversifying the material, method, and application in food packaging has been massively developed to find more environment-friendly materials. However, the mechanical and barrier properties of the bioplastics are major hurdles to expansion in commercial realization. The compositional variation with the inclusion of different fillers could resolve the lacking performance of the bioplastic. This review summarizes the various reinforcement fillers and their effect on bioplastic development. In this review, we first discussed the status of bioplastics and their definition, advantages, and limitations regarding their performance in the food packaging application. Further, the overview of different fillers and development methods has been discussed thoroughly. The application of reinforced bioplastic for food packaging and its effect on food quality and shelf life are highlighted. The environmental issues, health concerns, and future perspectives of the reinforced bioplastic are also discussed at the end of the manuscript. Adding different fillers into the bioplastic improves physical, mechanical, barrier, and active properties, which render the required protective functions to replace conventional plastic for food packaging applications. Various fillers, such as natural and chemically synthesized, could be incorporated into the bioplastic, and their overall properties improve significantly for the food packaging application.

Designing of chitosan/gelatin based nanocomposite films integrated with Vachellia nilotica gum carbon dots for smart food packaging applications

Microbial growth and exposure to UV light is a persistent global concern resulting in food spoilage, therefore, smart packaging is crucial for the availability of safer and quality food. Present work describes fabrication of chitosan (CH) and gelatin (GL) based nanocomposite films by introducing green source, highly fluorescent Vachillia nilotica gum-derived carbon dots (VNG-CDs). The VNG-CDs and incorporated CH/GL nanocomposite films were characterized by UV-Visible, FTIR, XRD, SEM and TGA analysis. The FTIR and XRD data revealed that VNG-CDs, chitosan, gelatin, and glycerol are combined/interlinked to form homogeneous nanocomposite films. The inclusion of VNG-CDs to CS/GL-CDs nanocomposite film efficiently enhanced the thermal stability and improved mechanical properties. VNG-CDs added to films markedly blocked the ultraviolet light and their effectiveness improved as concentration of CDs increases, being >90 % in UVC (200-280 nm) region. The prepared CS/GL-CDs nanocomposite films manifested radical scavenging activity, reducing capability and also excellently inhibited growth of E. coli, K. pneumonia and S. aureus bacteria. The viability of CS/GL-CDs nanocomposite films examined using banana as a model fruit extending the storage time by two weeks. In conclusion, CH/GL films containing VNG-CDs can be developed into smart packaging materials with enhanced protection and antimicrobial properties.

Process-structure-property relationships of cellulose nanocrystals derived from Juncus effusus stems on ҡ-carrageenan-based bio-nanocomposite films

This study investigates the potential of Juncus plant fibers as a renewable source for producing cellulose nanocrystals (CNs) to reinforce polymers. Cellulose microfibers (CMFs) were extracted with a 0.43 ± 0.2 μm diameter and 69 % crystallinity through alkaline and bleaching treatments, then subjected to sulfuric acid hydrolysis, yielding four CN types (CN10, CN15, CN20 and CN30) with distinct physico-chemical properties and aspect ratios (47, 55, 57, and 60). The study assessed the influence of cellulose nanocrystals (CNs), incorporated at different weight percentages (3 %, 5 %, and 8 %), on thermal, transparency, and mechanical properties in k-carrageenan (CA) biocomposite films. The results indicate significant enhancements in these characteristics, highlighting good compatibility between CNs and CA matrix. Particularly noteworthy is the observed substantial improvement in tensile strength at an 8 wt% loading, with values of 23.43 ± 0.83 MPa for neat CA, 33.53 ± 0.83 MPa for CA-CN10, 36.67 ± 0.71 MPa for CA-CN15, 37.65 ± 0.56 MPa for CA-CN20, and 39.89 ± 0.77 MPa for CA-CN30 composites. Furthermore, the research explores the connection between the duration of hydrolysis and the properties of cellulose nanocrystals (CNs), unveiling their influence on the characteristics of nanocomposite films. Prolonged hydrolysis enhances CN crystallinity (CrI), aspect ratio, and surface charge content, consequently enhancing mechanical features like strength and flexibility in these films. These findings demonstrate the potential of Juncus plant fibers as a natural and eco-friendly resource for producing CNs that effectively reinforce polymers, making them an attractive option for diverse applications in the field.

Advanced technologies in biodegradable packaging using intelligent sensing to fight food waste

The limitation of conventional packaging in demonstrating accurate and real-time food expiration dates leads to food waste and foodborne diseases. Real-time food quality monitoring via intelligent packaging could be an effective solution to reduce food waste and foodborne illnesses. This review focuses on recent technological advances incorporated into food packaging for monitoring food spoilage, with a major focus on paper-based sensors and their combination with smartphone. This review paper offers a comprehensive exploration of advanced macromolecular technologies in biodegradable packaging, a general overview of paper-based probes and their incorporation into food packaging coupled with intelligent sensing mechanisms for monitoring food freshness. Given the escalating global concerns surrounding food waste, our manuscript serves as a pivotal resource, consolidating current research findings and highlighting the transformative potential of these innovative packaging solutions. We also highlight the current intelligent paper-based food freshness sensors and their various advantages and limitations. Examples of implementation of paper-based sensors/probes for food storage and their accuracy are presented. Finally, we examined how intelligent packaging can be an alternative to reduce food waste. Several technologies discussed here have good potential to be used in food packaging for real-time food monitoring, especially when combined with smartphone diagnosis.

Carrageenan-based active and intelligent packaging films integrated with anthocyanin and TiO2-doped carbon dots derived from sweet potato peels

Carrageenan-based sustainable active and pH-dependent color-changing composite films were fabricated by blending anthocyanin extracted from sweet potato peel (SPA) with TiO2-doped carbon dots (Ti-CDs) prepared using the biowaste of SPA extraction. The SPA and Ti-CDs were compatible with the carrageenan matrix and were uniformly dispersed in the used polymer to form a homogeneous film with increased mechanical properties. The composite film added with SPA and 3 wt% Ti-CD showed 100 % UV protection, superb antioxidant (100 % DPPH and ABTS scavenging assay), and potent antibacterial activity (complete eradication of foodborne L.monocytogenes and E. coli strains after 3 h incubation). Additionally, the composite films showed distinguishable colorimetric responses to pH 7-12 buffers and volatile ammonia. The intelligent sensing ability of the composite film was assessed through shrimp freshness monitoring, and the film's hue shifted from pink (fresh shrimp) to yellow/brown (inedible shrimp) during storage. Shrimp packaging studies have shown that composite films retard the rate of food quality change during storage and are a good indicator of shrimp spoilage. Therefore, the designed film is expected to have high applicability as a chip, and quick on-site sensor that detects seafood quality in real-time, and a highly effective multifunctional film for better product quality preservation.

Antibacterial, antioxidant and fruit packaging ability of biochar-based silver nanoparticles-polyvinyl alcohol-chitosan composite film

Silver nanoparticles were prepared by loading Ag+ into biochar of waste barley distillers' grains shell by reduction with trisodium citrate, and this silver-loaded biochar was introduced into polyvinyl alcohol-chitosan. Various analysis with Fourier Transform Infrared spectroscopy, X-ray diffraction, Thermogravimetric analysis, and water contact angle revealed that biochar-based silver nanoparticle was incorporated into the polyvinyl alcohol-chitosan film, the biochar-based silver nanoparticles-polyvinyl alcohol-chitosan (C-Ag-loaded PVA/CS) composite film had good thermostability and hydrophobicity. Through the analysis via disk diffusion method, the composite containing 3 % of biochar-based silver nanoparticles-polyvinyl alcohol-chitosan had high antibacterial activity (inhibition zone: 18 mm against E. coli and 15 mm against S. aureus), and the bacterial membrane permeability was measured, indicating that C-Ag-loaded PVA/CS composite film could destroy the cell membrane, release intracellular substances, and have high antioxidant activity. During the storage, the weight loss rate of the biochar-based silver nanoparticles-polyvinyl alcohol-chitosan plastic wrap group was 0.14 %, and the titratable acid content only decreased by 0.061 %, which had a good effect on extending the shelf life of blueberries. The C-Ag-loaded PVA/CS composite film could also delay deterioration of blueberries and prolong storage time. Overall, this composite film had potential in food packaging and extending food shelf-life aspects.

Ultraviolet blocking ability, antioxidant and antibacterial properties of newly prepared polyvinyl alcohol-nanocellulose‑silver nanoparticles-ChunJian peel extract composite film

In this work, nanocellulose (CNC) from waste water chestnut (WCT) shell was firstly used for preparing nanocomposite films, by using ChunJian peel extract (CJPE) as a green reducing agent to synthesize silver nanoparticles (AgNPs), and then loading them into polyvinyl alcohol-nanocellulose (PVA-CNC) matrix, a multifunctional nanocomposite material that could be used in food packaging was developed. The prepared films were tested for mechanical strength, barrier properties, thermal properties, antibacterial, antioxidant and biocompatibility through various characterizations. The PVA-CNC-AgNPs-CJPE film had good thermostability, mechanical strength, barrier properties, and biocompatibility. Compared with pure PVA film and PVA-CNC film, PVA-CNC-AgNPs-CJPE could shield over 95 % of the UVB (320-275 nm) spectrum and UVC (275-200 nm) spectrum and most of the UVA (400-320 nm). By disk diffusion analysis, the inhibition zones of PVA-CNC-AgNPs-CJPE film against E. coli, P. aeruginosa, S. aureus and E. faecalis were 22.3 mm, 25.0 mm, 22.0 mm and 19.3 mm, respectively. The milk antibacterial simulation test confirmed that PVA-CNC-AgNPs-CJPE film could effectively limit bacterial reproduction and prolong the shelf life of milk. PVA-CNC-AgNPs-CJPE film had excellent UV barrier properties, good antioxidant properties and high-efficiency antibacterial activity, which is expected to be widely used in sustainable nanocomposite food packaging.

Roles of polysaccharides-based nanomaterials in food preservation and extension of shelf-life of food products: A review

In food production sectors, food spoilage and contamination are major issues that threaten and negatively influence food standards and safety. Several physical, chemical, and biological methods are used to extend the shelf-life of food products, but they have their limitations. Henceforth, researchers and scientists resort to novel methods to resolve these existing issues. Nanomaterials-based extension of food shelf life has broad scope rendering a broad spectrum of activity including high antioxidant and antimicrobial activity. Numerous research investigations have been made to identify the possible roles of nanoparticles in food preservation. A wide range of nanomaterials via different approaches is ultimately applied for food preservation. Among them, chemically synthesized methods have several limitations, unlike biological synthesis. However, biological synthesis protocols are quite expensive and laborious. Predominant studies demonstrated that nanoparticles can protect fruits and vegetables by preventing microbial contamination. Though several nanomaterials designated for food preservation are available, detailed knowledge of the mechanism remains unclear. Hence, this review aims to highlight the various nanomaterials and their roles in increasing the shelf life of food products. Adding to the novel market trends, nano-packaging will open new frontiers and prospects for ensuring food safety and quality.

Nanotechnology-driven improvisation of red algae-derived carrageenan for industrial and bio-medical applications

Algae biomass has been recognized as feedstock with diverse application including production of biofuel, biofertilizer, animal feed, wastewater treatment and bioremediation. In addition, algae species are a potential reservoir of metabolites and polymers with potential to be utilized for biomedicine, healthcare and industrial purposes. Carrageenan is one such medicinally and industrially significant polysaccharide which is extracted from red algae species (Kappaphycus alvarezii and Eucheuma denticulatum, among the common species). The extraction process of carrageenan is affected by different environmental factors and the source of biomass, which can vary and significantly impact the yield. Diverse applications of carrageenan include hydrogel beads, bio-composites, pharmacological properties, application in cosmetics, food and related industries. Carrageenan biological activities including antioxidant, anti-inflammatory, antimicrobial, and antitumor activities are significantly influenced by sulfation pattern, yield percentage and molecular weight. In addition to natural biomedical potential of carrageenan, synergetic effect of carrageenan- nanocomposites exhibit potential for further improvisation of biomedical applications. Nanotechnology driven bio-composites of carrageenan remarkably improve the quality of films, food packaging, and drug delivery systems. Such nano bio-composites exhibit enhanced stability, biodegradability, and biocompatibility, making them suitable alternatives for drug delivery, wound-healing, and tissue engineering applications. The present work is a comprehensive study to analyze biomedical and other applications of Carrageenan along with underlying mechanism or mode of action along with synergetic application of nanotechnology.

Development of antioxidant and smart NH3 -sensing packaging film by incorporating bilirubin into κ-carrageenan matrix

BACKGROUND

Active and smart food packaging based on natural polymers and pH-sensitive dyes as indicators has attracted widespread attention. In the present study, an antioxidant and amine-response color indicator film was developed by incorporating bilirubin (BIL) into the κ-carrageenan (Carr) matrix.

RESULTS

It was found that the introduction of BIL had no effect on the crystal/chemical structure, water sensitivity and mechanical performance of the Carr-based films. However, the barrier properties to light and the thermal stability were significantly improved after the addition BIL. The Carr/BIL composite films exhibited excellent 1,1-diphenyl-2-picryl-hydrazyl (i.e. DPPH)/2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (i.e. ABTS) free radical scavenging abilities and color responsiveness to different concentrations of ammonia. The application assay reflected that the Carr/BIL0.0075 film was effective in delaying the oxidative deterioration of shrimp during storage and realizing the color response of its freshness through the change of b* value.

CONCLUSION

Active and smart packaging films were successfully prepared by incorporating different contents of BIL into the Carr matrix. The present study helps to further encourage the design and development of a multi-functional packaging material. © 2023 Society of Chemical Industry.

A review of physical, chemical and biological synthesis methods of bimetallic nanoparticles and applications in sensing, water treatment, biomedicine, catalysis and hydrogen storage

This article provides an in-depth analysis of various fabrication methods of bimetallic nanoparticles (BNP), including chemical, biological, and physical techniques. The review explores BNP's diverse uses, from well-known applications such as sensing water treatment and biomedical uses to less-studied areas like breath sensing for diabetes monitoring and hydrogen storage. It cites results from over 1000 researchers worldwide and >300 peer-reviewed articles. Additionally, the article discusses current trends, actionable recommendations, and the importance of synthetic analysis for industry players looking to optimize manufacturing techniques for specific applications. The article also evaluates the pros and cons of various fabrication methods, highlighting the potential of plant extract synthesis for mass production of capped BNPs. However, it warns that this method may not be suitable for certain applications requiring ligand-free surfaces. In contrast, physical methods like laser ablation offer better control and reactivity, especially for applications where ligand-free surfaces are critical. The report underscores the environmental benefits of plant extract synthesis compared to chemical methods that use hazardous chemicals and pose risks to extraction, production, and disposal. The article emphasizes the need for life cycle assessment (LCA) articles in the literature, given the growing volume of research on nanotechnology materials. This article caters to researchers at all stages and applies to various fields applying nanomaterials.

A Novel Indicator Based on Polyacrylamide Hydrogel and Bromocresol Green for Monitoring the Total Volatile Basic Nitrogen of Fish

An intelligent indicator was developed by immobilizing bromocresol green (BCG) within the polyacrylamide (PAAm) hydrogel matrix to monitor the total volatile basic nitrogen (TVB-N) content of fish. The FTIR analysis indicated that BCG was effectively incorporated into the PAAm through the formation of intermolecular hydrogen bonds. A thermogravimetric analysis (TGA) showed that the PAAm/BCG indicator had a mere 0.0074% acrylamide monomer residue, meanwhile, the addition of BCG improved the thermal stability of the indicator. In vapor tests with various concentrations of trimethylamine, the indicator performed similarly at both 4 °C and 25 °C. The total color difference values (ΔE) exhibited a significant linear response to TVB-N levels ranging from 4.29 to 30.80 mg/100 g at 4 °C (R2 = 0.98). Therefore, the PAAm/BCG indicator demonstrated stable and sensitive color changes based on pH variations and could be employed in smart packaging for real-time assessment of fish freshness.

Bimetallic hydrogels based on chitosan and carrageenan as promising materials for biological applications

In this study, novel crosslinked hydrogels based on chitosan (CS) and carrageenan (CRG) loaded with silver and/or copper nanoparticles (Ag/CuNPs) were prepared through a freeze-drying (thawing) process to be applied in biological applications comprising wound dressing. These hydrogels showed porous interconnected structures. The influence of the used nanoparticles (NPs) on the antibacterial properties of the CS/CRG hydrogels was explored. Antimicrobial results revealed that both CS/CRG/CuNPs, CS/CRG/AgNPs, and CS/CRG/Ag-CuNPs exhibited promising antibacterial and antifungal activity against Escherichia coli, Pseudomonas aeruginosa, Streptococcus mutans, Staphylococcus aureus, Bacillus subtilis, and Candida albicans. Moreover, CS/CRG/AgNPs, CS/CRG/CuNPs, and CS/CRG/Ag-CuNPs hydrogels showed potential antioxidant activity to be 57%, 78%, and 89%, respectively. Furthermore, cytotoxicity results against Vero normal cell line confirmed that all designed hydrogels are safe upon usage. The bimetallic CS/CRG hydrogels showed notably enhanced antibacterial properties among the as-prepared hydrogels allowing them to be a successful material upon being employed in wound dressing applications.

Melanin biopolymers from microbial world with future perspectives-a review

Melanin is an amorphous polymer made of heterogeneous functional groups synthesized by diverse organisms including fungi, bacteria, animals, and plants. It was widely acknowledged for its biological processes and its key role in the protection of organisms from environmental stress. Recently, melanin clutches attention in the field of nanobiotechnology, drug delivery, organic semiconductors and bioelectronics, environmental bioremediation, photoprotection, etc., Furthermore, melanin from natural sources like microbial community shows antimicrobial, fighting cancer, radical scavenging, cosmeceuticals, and many therapeutic areas as well. Though the multipotentiality nature of melanin has been put forth, real-world applications still flag fall behind, which might be anticipated to the inadequate and high price essence of natural melanin. However, current bioprocess technologies have paved for the large-scale or industrial production of microbial melanin, which could help in the replacement of synthetic melanin. Thus, this review emphasizes the various sources for melanin, i.e., types-based on its pathways and its chemical structures, functional efficiency, physical properties, and conventional and modern methods of both extraction and characterization. Moreover, an outlook on how it works in the field of medicine, bioremediation, and other related areas provides perspectives on the complete exploitation of melanin in practical applications of medicine and the environment.

Biodegradable Polymers and Polymer Composites with Antibacterial Properties

Antibiotic resistance is one of the greatest threats to global health and food security today. It becomes increasingly difficult to treat infectious disorders because antibiotics, even the newest ones, are becoming less and less effective. One of the ways taken in the Global Plan of Action announced at the World Health Assembly in May 2015 is to ensure the prevention and treatment of infectious diseases. In order to do so, attempts are made to develop new antimicrobial therapeutics, including biomaterials with antibacterial activity, such as polycationic polymers, polypeptides, and polymeric systems, to provide non-antibiotic therapeutic agents, such as selected biologically active nanoparticles and chemical compounds. Another key issue is preventing food from contamination by developing antibacterial packaging materials, particularly based on degradable polymers and biocomposites. This review, in a cross-sectional way, describes the most significant research activities conducted in recent years in the field of the development of polymeric materials and polymer composites with antibacterial properties. We particularly focus on natural polymers, i.e., polysaccharides and polypeptides, which present a mechanism for combating many highly pathogenic microorganisms. We also attempt to use this knowledge to obtain synthetic polymers with similar antibacterial activity.

Recent Advances and Progress on Melanin: From Source to Application

Melanin is a biological pigment formed by indoles and phenolic compounds. It is widely found in living organisms and has a variety of unique properties. Due to its diverse characteristics and good biocompatibility, melanin has become the focus in the fields of biomedicine, agriculture, the food industry, etc. However, due to the wide range of melanin sources, complex polymerization properties, and low solubility of specific solvents, the specific macromolecular structure and polymerization mechanism of melanin remain unclear, which significantly limits the further study and application of melanin. Its synthesis and degradation pathways are also controversial. In addition, new properties and applications of melanin are constantly being discovered. In this review, we focus on the recent advances in the research of melanin in all aspects. Firstly, the classification, source, and degradation of melanin are summarized. Secondly, a detailed description of the structure, characterization, and properties of melanin is followed. The novel biological activity of melanin and its application is described at the end.

Self-assembled surfactant-based nanoparticles as a platform for solubilization and enhancement of the photothermal activity of sepia melanin

Background

Sepia melanin (SM) is a natural photothermal biopolymer. Its biomedical applications are limited due to its poor solubility and bioavailability. This study aims to prepare a soluble formulation of sepia melanin to enhance its solubility, in turn, its bioavailability, and its use in photothermal therapy of cancer. SM was extracted from a sepia ink sac and prepared as insoluble powdered (SM) which is identified by FTIR, 1H-NMR, thermogravimetric analysis (TGA), and scanning electron microscope. SM was self-assembled using tween 80 into dispersed nanoparticles (SM-NP-Tw). The prepared SM-NP-Tw were fully characterized. The photothermal performance of SM-NP-Tw was assessed. Dark and photocytotoxicity of SM-NP-Tw was studied on HepG2 cells using two wavelengths (660 nm and 820 nm).

Results

The insoluble powdered (SM) exhibited a spherical nanoparticle-like shape as revealed by scanning electron microscope and was soluble only in an alkaline aqueous solution. TGA of SM showed high resistance to thermal degradation indicating good thermal stability. The prepared SM-NP-Tw exhibited a spherical shape with mean sizes of 308 ± 86 nm and a zeta potential of − 25 mv. The cell viability decreased significantly upon increasing the concentration and upon radiation at 820 nm. The results of UV–Vis spectroscopy and the photothermal performance revealed that melanin can absorb light in a wide range of wavelengths including near the IR region; thus, it can emit sufficient heat to kill cells through the photoheat conversion effects.

Conclusion

Sepia melanin nanoparticles self-assembled into tween-based nanostructures could be a promising natural platform for photothermal cancer therapy.

pH-Responsive strips integrated with resazurin and carbon dots for monitoring shrimp freshness

Carbon dots (CDs) were synthesized via a one-step hydrothermal approach using tangerine peel (Tan) and resazurin (Res) to fabricate biocompatible indicators for food freshness. The CDs' pH-responsive mechanism, morphology, zeta potential, XPS, and optical and fluorescence analysis were investigated. The as-prepared tangerine peel/resazurin carbon dots (Tan/Res CDs) exhibited pH-responsive emission that changed from yellow to orange as the pH value increased. The Tan/Res CDs showed the sensing ability of ammonia with a detection limit of 0.84 μM by proportionally losing fluorescence intensity as the concentration increased from 1 to 100 μM. The CDs were coated onto paper strips to impart biogenic amine (BAs) detection for pH-responsive intelligent monitoring of packaged foods. The Tan/Res CDs paper-based indicator exhibited an impressive color change from yellow to brown during the detection of ammonia vapor. The indicator also showed the ability to detect BAs through a color change, demonstrating the ability to monitor the freshness of shrimp in situ. Additionally, the efficacy of the Tan/Res CDs indicator is validated by total volatile basic nitrogen (TVB-N), providing customers and suppliers with a simple, inexpensive, and portable tool to monitor the freshness of seafood in real-time.

Ultrasound-assisted development and characterization of novel polyphenol-loaded pullulan/trehalose composite films for fruit preservation

A novel food packaging film was developed by incorporating a tea polyphenols-loaded pullulan/trehalose (TP@Pul/Tre) into a composite film with ultrasound-assisted treatment of dual-frequency (20/35 kHz, 40 W/L) for 15 min to assess the physicochemical and mechanical properties of a composite film. The optimized ultrasound-assisted significantly increases elongation at break, tensile strength, and improves the composite film's UV/water/oxygen barrier properties. Structure analysis using attenuated total reflectance-Fourier transform infrared, X-ray diffraction and thermal stability revealed that these improvements were achieved through ultrasound-enhanced H-bonds, more ordered molecular arrangements, and good intermolecular compatibility. Besides, the ultrasound-assisted TP@Pul/Tre film has proven to have good antibacterial performance against Escherichia coli and Staphylococcus aureus, with approximately 100 % lethality at 4 h and 8 h, respectively. Moreover, the ultrasound-assisted TP@Pul/Tre film effectively delayed moisture loss, oxidative browning, decay, and deterioration in fresh-cut apples and pears, thereby extending their shelf life. Thus, ultrasound has proved to be an effective tool for improving the quality of food packaging films, with a wide range of applications.

Macroalgae as biofactories of metal nanoparticles; biosynthesis and food applications

Nanotechnology has opened a new frontier in recent years, capable of providing new ways of controlling and structuring products with greater market value and offering significant opportunities for the development of innovative applications in food processing, preservation, and packaging. Macroalgae (MAG) are the major photoautotrophic group of living beings known as a potential source of secondary metabolites, namely phenolic compounds, pigments, and polysaccharides. Biosynthesis based on the abilities of MAG as "nanobiofactories" targets the use of algal secondary metabolites as reducing agents to stabilize nanoparticles (NPs). Nowadays, most of the studies are focused on the use of metal (Ag, Au) and metal-oxide (CuO, ZnO) NPs derived from algae. The eco-friendly biosynthesis of metal NPs reduces the cost and production time and increases their biocompatibility, due to the presence of bioactive compounds in MAG, making them suitable for a wide variety of applications. These compounds have been attributed to the antimicrobial and antioxidant properties responsible for their application through innovative technologies such as nanoencapsulation, nanocomposites, or biosensors in the food industry. Nevertheless, toxicity is a key factor that should be considered, so the applicable regulation needs to guarantee the safe use of metal NPs. Consequently, the aim of this review will be to compile the available information on MAG-mediated metal NPs, their biosynthesis, and potential food applications.

Active Food Packaging Made of Biopolymer-Based Composites

Food packaging plays a vital role in protecting food products from environmental damage and preventing contamination from microorganisms. Conventional food packaging made of plastics produced from unrenewable fossil resources is hard to degrade and poses a negative impact on environmental sustainability. Natural biopolymers are attracting interest for reducing environmental problems to achieve a sustainable society, because of their abundance, biocompatibility, biodegradability, chemical stability, and non-toxicity. Active packaging systems composed of these biopolymers and biopolymer-based composites go beyond simply acting as a barrier to maintain food quality. This review provides a comprehensive overview of natural biopolymer materials used as matrices for food packaging. The antioxidant, water barrier, and oxygen barrier properties of these composites are compared and discussed. Furthermore, biopolymer-based composites integrated with antimicrobial agents-such as inorganic nanostructures and natural products-are reviewed, and the related mechanisms are discussed in terms of antimicrobial function. In summary, composites used for active food packaging systems can inhibit microbial growth and maintain food quality.

Natural Gum-Based Functional Bioactive Films and Coatings: A Review

Edible films and coatings are a current and future food packaging trend. In the food and envi-ronmental sectors, there is a growing need to understand the role of edible packaging and sus-tainability. Gums are polysaccharides of natural origin that are frequently utilized as thickeners, clarifying agents, gelling agents, emulsifiers, and stabilizers in the food sector. Gums come in a variety of forms, including seed gums, mucilage gums, exudate gums, and so on. As a biodegradable and sustainable alternative to petrochemical-based film and coatings, gums could be a promising option. Natural plant gum-based edible packaging helps to ensure extension of shelf-life of fresh and processed foods while also reducing microbiological alteration and/or oxidation processes. In this review, the possible applications of gum-based polymers and their functional properties in development of edible films and coatings, were comprehensively dis-cussed. In the future, technology for developing natural gum-based edible films and coatings might be applied commercially to improve shelf life and preserve the quality of foods.

Pectin/carbon quantum dots fluorescent film with ultraviolet blocking property through light conversion

Carbon quantum dots (CQDs) were synthesized using glucose as a carbon source through a hydrothermal method. CQDs showed negligible cytotoxicity to L929 cells even after prolonged exposure of 72 h. The addition of CQD did not affect the pectin film's mechanical properties, water contact angle, and thermal stability. However, the CQD-added composite film generates reactive oxygen species (ROS), providing high antibacterial activity against pathogenic bacteria (L. monocytogenes and E. coli) and antifungal activity against mold (Aspergillus flavus), where a 100% eradication of bacteria and fungi population was observed. Also, the addition of CQD strengthens the antioxidant activity of the composite films by 95%. Further, the CQD-added pectin film converted ultraviolet rays into blue light, which improved the film's UV protection properties. Therefore, the pectin/CQD film has a high potential for a light conversion active packaging film that may prevent the deterioration of high-fat foods.

Retrospective analysis of the key molecules involved in the green synthesis of nanoparticles

Emerging nanotechnology leads to success in synthesizing and applying nanoparticles (NPs) using the green-chemistry approach. NPs synthesized using naturally derived materials are a potential alternative to chemical and physical methods because they are simple, cost-effective, eco-friendly, and lower the possibility of hazardous residues being released into the environment. Furthermore, NPs synthesized using the green synthesis approach are stable and biocompatible. However, because natural extracts contain a diverse spectrum of bioactive components, it is difficult to pinpoint the specific component involved in NP formation. Furthermore, the bioactive component contained in the extract changes based on a number of environmental factors; therefore, several studies began with the synthesis of NPs using a pure compound isolated from diverse natural sources. Hence, the present review paper makes an effort to retrospectively analyze the key compounds of the extracts which are responsible for the synthesis of the NPs. The analysis was carried out based on the physicochemical characteristics and biological activities of NPs synthesized from either the extract or the pure compounds. These pure-compound-based NPs were studied for their antimicrobial, antibiofilm, anti-inflammatory, anticancer, and antioxidant properties. In addition, the present review also describes progress in the study of pure compound-based numerous biological activities and the underlying mechanisms of action.

Biopolymer-based functional films for packaging applications: A review

Food packaging is a coordinated system comprising food processing, protection from contamination and adulteration, transportation and storage, and distribution and consumption at optimal cost with a minimum environmental impact to the packed food commodity. Active packaging involves deliberate addition of the functional ingredients either in the film or the package headspace to preserve the food quality, improve safety and nutrition aspects, and enhance the shelf-life. In this review, recent advances in the fabrication of biopolymer-based films, their classification (biodegradable-, active-, and intelligent packaging films), advanced fabrication strategies (composite-, multilayer-, and emulsified films), and special functions induced by the biopolymers to the film matrix (mechanical-, water resistance and gas barrier-, and optical properties, and bioactive compounds reservoir) were briefly discussed. A summary of conclusions and future perspectives of biopolymer-based packaging films as advanced biomaterial in preserving the food quality, improving safety and nutrition aspects, and enhancing shelf-life of the products was proposed.

Chitosan based film reinforced with EGCG loaded melanin-like nanocomposite (EGCG@MNPs) for active food packaging

In this study, EGCG loaded melanin-like nanoparticles (EGCG@MNPs) were incorporated into chitosan matrix to prepare an active nanocomposite food packaging film, chitosan-EGCG@MNPs (CH-EM). The influence of EGCG@MNPs on the physical and biological properties of the chitosan film was investigated. The EGCG@MNPs nanoparticles were cross-linked with chitosan through intermolecular hydrogen bonds and uniformly distributed in the matrix. Besides, the incorporation of EGCG@MNPs tremendously improved the solubility, swelling ratio and water vapor barrier properties of the film, and permitted superior ultraviolet rays blocking property. In addition, the mechanical properties, thermal stability and surface hydrophobicity have also been significantly improved. The CH-EM^2.0 nanocomposite films also showed excellent oxidation resistance (58.4 ± 4.4%, DPPH and 92.4 ± 1.3%, ABTS⁺), and strong inhibitory ability against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The experimental results comprehensively showed that the prepared chitosan-EGCG@MNPs nanocomposite film offering excellent potential for eco-friendly active food packaging.

The nano antibacterial composite film carboxymethyl chitosan/gelatin/nano ZnO improves the mechanical strength of food packaging

The carboxymethyl chitosan (CMCS)/fish skin gelatin (Gel) based novel nanocomposite film was developed with nano ZnO for potential food packaging applications. The SEM and FT-IR results indicated that the nano ZnO was success composited with CMCS/Gel film. The X-ray diffraction result revealed that the total crystallinity of the CMCS/Gel/nano ZnO achieved 94.92 %, improving the crystallinity of the original substrate. Compared with CMCS/nano ZnO and Gel/nano ZnO, the water solubility of CMCS/Gel/nano ZnO decreased to 23 %. Moreover, its contact angle reached 91°, representing that the composite film showed better solvent resistance and can be widely used in food packaging, especially in foods with high water content. After nano-ZnO was compounded with CMCS/Gel film, the physical properties were further improved. Furthermore, CMCS/Gel/nano ZnO has higher elasticity and ductility than CMCS/nano ZnO and Gel/nano ZnO. For food packages, CMCS/Gel films incorporated with nano ZnO depicted strong against Escherichia coli (99.20 %) and Staphylococcus aureus (84.70 %) for food packages. The CMCS/Gel film with the addition of ZnO was optimal for producing nanocomposite films with higher water-insolubility, elasticity and ductility, and higher antibacterial properties.

Van-mediated self-aggregating photothermal agents combined with multifunctional magnetic nickel oxide nanoparticles for precise elimination of bacterial infections

Building a novel and efficient photothermal antibacterial nanoplatform is a promising strategy for precise bacterial elimination. Herein, a nanocomposite NiO NPs@AuNPs@Van (NAV) for selective MRSA removal was constructed by electrostatic self-assembly of highly photothermal magnetic NiO NPs and vancomycin (Van)-modified gold nanoparticles (AuNPs). In the presence of MRSA and under NIR irradiation, Van-mediated AuNPs can self-aggregate on MRSA surface, generating photothermal effect in situ and killing 99.6% MRSA in conjunction with magnetic NiO NPs. Additionally, the photothermal efficiency can be improved by magnetic enrichment due to the excellent magnetism of NAV, thereby enhancing the bactericidal effect at a lower experimental dose. In vitro antibacterial experiments and full-thickness skin wound healing test demonstrated that this combination therapy could effectively accelerate wound healing in MRSA-infected mice, increase collagen coverage, reduce IL-6 and TNF-α content, and upregulate VEGF expression. Biological safety experiments confirmed that NAV has good biocompatibility in vivo and in vitro. Overall, this work reveals a new type of nanocomposite with enhanced photothermal antibacterial activity as a potential nano-antibacterial agent for treating bacteria-infected wounds.

Development of highly stable color indicator films based on κ-carrageenan, silver nanoparticle and red grape skin anthocyanin for marine fish freshness assessment

Color indicator films for fish freshness were fabricated by incorporating κ-carrageenan (CAR) polymer with red grape skin extract (GSE) as a pH-sensing agent and silver nanoparticles (AgNPs) as an antimicrobial agent. Anthocyanins in GSE exhibited distinguished pH responsive color changes. GSE and AgNPs were well compatible with CAR with intramolecular interactions, approved by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis, thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). GSE-containing films displayed distinguished color changes in response to pH variations and volatile ammonia. Enhanced UV blocking ability and strong antioxidant activity were revealed for GSE included films without sacrificing the physico-chemical properties of the CAR film. Films containing AgNPs showed improved mechanical strength and strong antimicrobial ability against both Escherichia coli and Staphylococcus aureus. The CAR/AgNPs/GSE film displayed a distinctive color change corresponding to changes in the total volatile basic nitrogen (TVB-N) of fish during storage. In addition, the CAR/AgNPs/GSE film showed excellent color stability to consecutive UV exposure and its storage time at 25 °C is expected to be at least 240 days, which indicates that it has high potential as an intelligent food freshness indicator film.

Polysaccharides: Sources, Characteristics, Properties, and Their Application in Biodegradable Films

Biodegradable films emerge as alternative biomaterials to conventional packaging from fossil sources, which, in addition to offering protection and increasing the shelf life of food products, are ecologically sustainable. The materials mostly used in their formulation are based on natural polysaccharides, plasticizing agents, and bioactive components (e.g., antimicrobial agents or antioxidants). The formulation of biodegradable films from polysaccharides and various plasticizers represents an alternative for primary packaging that can be assigned to specific food products, which opens the possibility of having multiple options of biodegradable films for the same product. This review describes the main characteristics of the most abundant polysaccharides in nature and highlights their role in the formulation of biodegradable films. The compilation and discussion emphasize studies that report on the mechanical and barrier properties of biodegradable films when made from pure polysaccharides and when mixed with other polysaccharides and plasticizing agents.

Preparation of sodium alginate/konjac glucomannan active films containing lycopene microcapsules and the effects of these films on sweet cherry preservation

In this study, lycopene microcapsules (LMs) were prepared using chitosan (CS) and carboxymethyl CS (CMCS) as the wall materials. Sodium alginate (SA) and konjac glucomannan (KGM) were used as substrates to fabricate LM/SA/KGM composite films. Results showed that when 2.0 % CMCS was employed, the resulting LMs had the maximum embedding rate of 83.17 %, smallest particle sizes, and stable zeta potentials. The LMs still had a high retention rate after 10 days of storage at 4 and 25 °C. When 2.0 % LMs were used, the corresponding composite film exhibited the best antibacterial properties, oxidation resistance, a high transparency (82.3 %), and a strong water vapor barrier (2.39 × 10^-10 g/m·s·Pa). Finally, the effects of the as-prepared composite films on the preservation of sweet cherries stored at 0 °C for 15 days were investigated. The results indicated that the LM/SA/KGM composite film effectively prolonged the shelf lives of sweet cherries and efficiently delayed the decline in the decay rate, pH, contents of soluble solids, and other indicators. The application of LM/SA/KGM composite films in fruit and vegetable preservation has development prospects and provides a reference for expanding the application range of lycopene and enhancing fruit and vegetable preservation.

Eryngo Extract-Mediated Green Synthesis of Silver Nanoparticles and its Antibacterial Activity against Resistance Strains

In the present study, a simple and fast approach was developed for the green synthesis of silver nanoparticles by using Eryngium campestre (Eryngo) extract prepared in boiling water. People have widely used the Eryngo plant as a vegetable, food, and medicine around the world. The dried leaves of Eryngo extracted in boiling water yielded approximately 67 mg/g (6.6%) solid residue. The extract had a high antioxidant activity of 71 %, which was rich in total phenolic and flavonoids as revealed through colorimetric assays. For preparing nanoparticles, silver nitrate was added to the plant extract diluents and kept until the solution color changed with a sharp indicative peak of AgNPs that appeared at 450 nm. In addition, UV/Vis, TEM, FESEM, DLS, EDS, and XRD analysis were used to characterize the as-synthesized AgNPs. The results confirmed the spherical shape and nano nature of AgNPs with an average size of 32 nm based on Fe-SEM and TEM observations. The prepared AgNPs also shown moderate free radical scavenging activity (60%) in DPPH test and exhibit antibacterial activity at low concentration (50 μg/mL) toward both gram-positive and gram-negative bacteria. In this respect, the inhibition zone was higher in gram-positive bacteria and the sensitivity order of S.aureus > MRSA > B.subtilis > P.aeruginosa > E.coli was achieved in response to Eryngo AgNPs. Interestingly, Eryngo AgNPs at low concentration were efficient on MRSA, as an antibiotic-resistant strain of S.aureus.

A Facile In Situ Synthesis of Resorcinol-Mediated Silver Nanoparticles and the Fabrication of Agar-Based Functional Nanocomposite Films

The in situ synthesis of silver nanoparticles (AgNPs) was performed using resorcinol and agar to produce agar-based antioxidant and antimicrobial films. AgNPs were regularly dispersed on the film matrix, and their presence improved the thermal stability of films. Additionally, the addition of AgNPs slightly increased the agar-based film’s tensile strength (~10%), hydrophobicity (~40%), and water vapor barrier properties (~20%) at 1.5 wt% of AgNP concentration. The resorcinol also imparted UV-barrier and antioxidant activity to the agar-based film. In particular, the agar-based film containing a higher quantity of AgNPs (>1.0 wt%) was highly effective against the foodborne pathogenic bacteria L. monocytogenes and E. coli. Therefore, agar-based composite films with improved physicochemical and functional properties may be promising for active packaging.

Simulation and Experimental Study of the Multisized Silver Nanoparticles Sintering Process Based on Molecular Dynamics

Multisized nanoparticles (MPs) are widely employed as electronic materials to form conductive patterns, benefitting from their excellent sintering properties and mechanical reliability. However, due to the lack of effective detection methods for the real-time sintering process, it is difficult to reveal the sintering behavior during the MPs sintering process. In this work, a molecular dynamics method is used to track the trajectory of silver atoms. The melting behavior of a single nanoparticle (SP) is first discussed. The structural evolution of equally sized nanoparticles (EPs) and unequally sized nanoparticles (UPs) during the sintering process is analyzed alongside morphology changes. It is proposed that the UPs sintering process benefits from the wetting behavior of small-sized nanoparticles on the surface of large-sized nanoparticles, and the sintering angle (θ) is proposed as an index to estimate the sintering result of UPs. Based on the works above, three basic sintering modes and one advanced sintering mode in the MP sintering process are analyzed emphatically in this paper, and the roles of different-sized nanoparticles in MPs are concluded from simulation and experimental results. This work provides theoretical support for conductive ink composition design and sintering process optimization.

Cellulose-based antimicrobial films incroporated with ZnO nanopillars on surface as biodegradable and antimicrobial packaging

Biodegradable and antimicrobial films without antibiotics are of great significance for the application associated with food packaging meanwhile minimizing the negative impact on environments. In this work, cellulose-based films with the surface tailor-constructed with ZnO nanopillars (ZnO NPs@Zn²⁺/Cel films) were prepared via chemical crosslinking in conjunction with a hydrothermal process for in-situ growth of ZnO NPs. As a packaging material, ZnO NPs@Zn²⁺/Cel films possess excellent mechanical properties, oxygen and water vapor barrier, food preservation, biodegradability and low Zn²⁺ migration. Moreover, ZnO NPs@Zn²⁺/Cel films show remarkable antimicrobial activity, especially for Staphylococcus aureus (gram-positive bacteria) and Escherichia coli (gram-negative bacteria). The antimicrobial mechanism of ZnO NPs@Zn²⁺/Cel films is studied using the controlled variable method, and results showed that the film without UV pretreatment killed bacterial cells mainly by mechanical rupture, while the film with UV pretreatment killed bacterial cells mainly via the synergistic effect of photocatalytic oxidation and mechanical rupture.

Applications of Inorganic Nanoparticles in Food Packaging: A Comprehensive Review

Nanoparticles (NPs) have acquired significance in technological breakthroughs due to their unique properties, such as size, shape, chemical composition, physiochemical stability, crystal structure, and larger surface area. There is a huge demand for packaging materials that can keep food fresher for extended periods of time. The incorporation of nanoscale fillers in the polymer matrix would assists in the alleviation of packaging material challenges while also improving functional qualities. Increased barrier properties, thermal properties like melting point and glass transition temperatures, and changed functionalities like surface wettability and hydrophobicity are all features of these polymers containing nanocomposites. Inorganic nanoparticles also have the potential to reduce the growth of bacteria within the packaging. By incorporating nano-sized components into biopolymer-based packaging materials, waste material generated during the packaging process may be reduced. The different inorganic nanoparticles such as titanium oxide, zinc oxide, copper oxide, silver, and gold are the most preferred inorganic nanoparticles used in food packaging. Food systems can benefit from using these packaging materials and improve physicochemical and functional properties. The compatibility of inorganic nanoparticles and their various forms with different polymers make them excellent components for package fortification. This review article describes the various aspects of developing and applying inorganic nanoparticles in food packaging. This study provides diverse uses of metals and metal oxides nanoparticles in food packaging films for the development of improved packaging films that can extend the shelf life of food products. These packaging solutions containing nanoparticles would effectively preserve, protect, and maintain the quality of the food material.