Effect of CuS reinforcement on the mechanical, water vapor barrier, UV-light barrier, and antibacterial properties of alginate-based composite films

Iron Nano Biocomposite-Infused Biopolymeric Films: A Multifunctional Approach for Robust Skin Repair

Sodium alginate (SA) biopolymeric films have various limitations such as poor mechanical properties, high vapor permeability, lack of antibacterial activity, excessive burst release, and weak cell adhesion. To overcome these limitations, a strategy involving the integration of nanofillers into an SA film matrix is explored. In this context, a cost-effective iron-containing carbon nano biocomposite (FeCNB) nanofiller is developed using a solvent-free technique. This nanocomposite is successfully incorporated into the alginate film matrix at varying concentrations (0.05, 0.1, and 0.15%) aimed at enhancing its physicochemical and biological properties for biomedical applications. Characterization through FESEM and BET analyses confirms the porous nature of the FeCNB. EDX shows the FeCNB's uniform distribution upon its integration into the film matrix, albeit without strong chemical interaction with SA. Instead, hydrogen bonding interactions become apparent in the FTIR spectra. By incorporating the FeCNB, the mechanical attributes of the films are improved and the water vapor permeability approaches the desired range (2000-2500 g/m2day). The film's swelling ratio reduction contributes to a decrease in water permeability. The antibacterial activity and sustained release property of the FeCNB-incorporated film are established using tetracycline hydrochloride (TCl), a model drug. The drug release profile resembled Korsmeyer-Peppas's release pattern. In vitro assessments via the MTT assay and scratch assay on NIH-3T3 cells reveal that FeCNB has no adverse effects on the biocompatibility of alginate films. The cell proliferation and adhesion to the SA film are significantly enhanced after infusion of the FeCNB. The in vivo study performed on the rat model demonstrates improved wound healing by FeCNB-impregnated films. Based on the comprehensive findings, the proposed FeCNB-incorporated alginate films prove to be a promising candidate for robust skin repair.

Modified polysaccharides for food packaging applications: A review

Development of new food packaging materials is crucial to reduce the use of single-use plastics and to limit their destructive impact on the environment. Polysaccharides provide an alternative solution to this problem. This paper summarizes and discusses recent research results on the potential of modifying polysaccharides as materials for film and coating applications. Modifications of polysaccharides significantly affect their properties, as well as their application usability. Although modifications of biopolymers for packaging applications have been widely studied, polysaccharides have attracted little attention despite being a prospective, environmentally friendly, and economically viable packaging alternative. Therefore, this paper discusses approaches to the development of biodegradable, polysaccharide-based food packaging materials and focuses on modifications of four polysaccharides, such as starch, chitosan, sodium alginate and cellulose. In addition, these modifications are presented not only in terms of the selected polysaccharide, but also in terms of specific properties, i.e. hydrophilic, barrier and mechanical properties, of polysaccharides. Such a presentation of results makes it much easier to select the modification method to improve the unsatisfactory properties of the material. Moreover, very often it happens that the applied modification improves one and worsens another property, which is also presented in this review.

Novel ammonia-sensitive sodium alginate-based films containing Co-Imd microcrystals for smart packaging application

Currently, there is an urgent requirement for the fabrication of smart packaging materials that can be applied for the real-time visual monitoring of food freshness. In this research, cubic Co-MOF (Co-Imd) microcrystal with ammonia-sensitivity and antibacterial activity was manufactured and then anchored within sodium alginate (NaAlg) matrix to construct smart packaging materials. The structure, physical and functional performances of NaAlg-based films with different content of Co-Imd (0.5, 1.0 and 2.0 wt% on NaAlg basis) were then evaluated in detail. Results reveal that the incorporated Co-Imd fillers are equally anchored within the NaAlg matrix due to the generation of new hydrogen-bonding interaction, which make an obvious improvement in mechanical strength, toughness, oxygen/water barrier, and UV-blocking ability of the NaAlg film. Moreover, the constructed NaAlg/Co-Imd blend films show superior antibacterial capability, ammonia-sensitivity function as well as color stability. Ultimately, the NaAlg/Co-Imd blend films were successfully utilized for indicating the deterioration of shrimp based on noticeable color alteration, suggesting their tremendous prospects for utilization in smart active packaging. This work offers a facile and efficient method for fabricating novel ammonia-sensitive and long-term color-stable NaAlg-based film materials with improved mechanical strength, toughness, oxygen/water barrier, UV-blocking, and antibacterial performances for smart active packaging application.

The reduce of water vapor permeability of polysaccharide-based films in food packaging: A comprehensive review

Polysaccharide-based films are favored in the food packaging industry because of their advantages of green and safe characters, as well as natural degradability, but due to the structural defects of polysaccharides, they also have the disadvantages of high water vapor permeability (WVP), which greatly limits their application in the food packaging industry. To break the limitation, numerous methods, e.g., physical and/or chemical methods, have been employed. This review mainly elaborates the up-to-date research status of the application of polysaccharide-based films (PBFs) in food packaging area, including various films from cellulose and its derivatives, starch, chitosan, pectin, alginate, pullulan and so on, while the methods of reducing the WVP of PBFs, mainly divided into physical and chemical methods, are summarized, as well as the discussions about the existing problems and development trends of PBFs. In the end, suggestions about the future development of WVP of PBFs are presented.

Polysaccharide-based films: from packaging materials to functional food

A wider application of naturally derived polysaccharides is of great interest as materials for food packaging industry. Biocompatibility and biodegradability of polysaccharide-based films and coatings ally with a shift from application of non-biodegradable petrochemical polymers to the more environmentally friendly ones. Due to a range of inherent features in chemical structure and bioactivity, the polysaccharide materials could bring additional functionality to food packaging. The chelating ability of the polysaccharides provides also their application as carriers of additional active components, such as nanoparticles, essential oils and polyphenols. The improved physicochemical, antibacterial and antioxidant properties of the filled films allows to consider the edible polysaccharide-based films as functional food products. This review is aimed at analysis of evolution of polysaccharide-based food packaging materials from inert one starting from cellophane to recent research works on development of multicomponent polysaccharide-based functional food films and coatings.

TiB2-Derived Nanosheets Enhance the Tensile Strength and Controlled Drug Release of Biopolymeric Films Used in Wound Healing

Wound healing using an alginate-based biopolymeric film is one of the most preferred treatments. However, these films lack mechanical strength (elasticity and tensile strength), show higher initial burst release, and exhibit high vapor permeability. The present study reports the development of nanosheets derived from titanium diboride (10 nm) (NTB)-incorporated biopolymeric films (0.025, 0.05, and 0.1% w/v) using sodium alginate (SA) and carboxymethyl cellulose (CMC) to overcome the shortfalls. The surface properties of the film, nanosheet distribution within the film, and possible interactions with the film are explored by using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Fourier transform infrared (FTIR), and X-ray diffraction (XRD). These analyses confirm that nanosheets are uniformly distributed in the film and introduce unevenness on the film's surface. The tensile strength of the nanosheet-incorporated film (0.1% NTB film) using UTM is found to be 24.30 MPa (six times higher compared to the blank film), equivalent to human skin. The water vapor transmission rate of the film is also found to be in the desired range (i.e., 2000-2500 g/m2 day). The biocompatibility of the NTB film is confirmed by the MTT assay test using NIH/3T3 cells and HEK 293 cells. Furthermore, the scratch assay shows that the developed films promote cell migration and proliferation. The antibacterial activity of the film is also demonstrated using a model drug, tetracycline hydrochloride (TCl). Besides, the film exhibits the sustained release of TCl and follows the Korsmeyer-Peppas model for drug release. Overall, the 0.1% w/v NTB film is easy to fabricate, biocompatible and shows superior mechanical properties.

Facile and eco-friendly fabrication of biocompatible hydrogel containing CuS@Ser NPs with mechanical flexibility and photothermal antibacterial activity to promote infected wound healing

Bacterial infections can significantly impede wound healing and pose a serious threat to the patient's life. The excessive use of antibiotics to combat bacterial infections has led to the emergence of multi-drug-resistant bacteria. Therefore, there is a pressing need for alternative approaches, such as photothermal therapy (PTT), to address this issue. In this study, for the first time, CuS NPs with photothermal properties were synthesized using sericin as a biological template, named CuS@Ser NPs. This method is simple, green, and does not produce toxic and harmful by-products. These nanoparticles were incorporated into a mixture (XK) of xanthan gum and konjac glucomannan (KGM) to obtain XK/CuS NPs composite hydrogel, which could overcome the limitations of current wound dressings. The composite hydrogel exhibited excellent mechanical flexibility, photothermal response, and biocompatibility. It also demonstrated potent antibacterial properties against both Gram-positive and negative bacteria via antibacterial experiments and accelerated wound healing in animal models. Additionally, it is proved that the hydrogel promoted tissue regeneration by stimulating collagen deposition, angiogenesis, and reducing inflammation. In summary, the XK/CuS NPs composite hydrogel presents a promising alternative for the clinical management of infected wounds, offering a new approach to promote infected wound healing.

Trends in Food Pathogens Risk Attenuation

Foodborne pathogens represent one of the most dangerous threats to public health along the food chain all over the world. Over time, many methods were studied for pathogen inhibition in food, such as the development of novel packaging materials with enhanced properties for microorganisms' growth inhibition (coatings, films) and the use of emerging technologies, like ultrasound, radio frequency or microwave. The aim of this study was to evaluate the current trends in the food industry for pathogenic microorganisms' inhibition and food preservation in two directions, namely technology used for food processing and novel packaging materials development. Five technologies were discussed in this study, namely high-voltage atmospheric cold plasma (HVACP), High-Pressure Processing (HPP), microwaves, radio frequency (RF) heating and ultrasound. These technologies proved to be efficient in the reduction of pathogenic microbial loads in different food products. Further, a series of studies were performed, related to novel packaging material development, by using a series of antimicrobial agents such as natural extracts, bacteriocins or antimicrobial nanoparticles. These materials proved to be efficient in the inhibition of a wide range of microorganisms, including Gram-negative and Gram-positive bacteria, fungi and yeasts.

Unveiling the Potential of Marine Biopolymers: Sources, Classification, and Diverse Food Applications

Environmental concerns regarding the usage of nonrenewable materials are driving up the demand for biodegradable marine biopolymers. Marine biopolymers are gaining increasing attention as sustainable alternatives in various industries, including the food sector. This review article aims to provide a comprehensive overview of marine biopolymers and their applications in the food industry. Marine sources are given attention as innovative resources for the production of sea-originated biopolymers, such as agar, alginate, chitin/chitosan, and carrageenan, which are safe, biodegradable, and are widely employed in a broad spectrum of industrial uses. This article begins by discussing the diverse source materials of marine biopolymers, which encompass biopolymers derived from seaweed and marine animals. It explores the unique characteristics and properties of these biopolymers, highlighting their potential for food applications. Furthermore, this review presents a classification of marine biopolymers, categorizing them based on their chemical composition and structural properties. This classification provides a framework for understanding the versatility and functionality of different marine biopolymers in food systems. This article also delves into the various food applications of marine biopolymers across different sectors, including meat, milk products, fruits, and vegetables. Thus, the motive of this review article is to offer a brief outline of (a) the source materials of marine biopolymers, which incorporates marine biopolymers derived from seaweed and marine animals, (b) a marine biopolymer classification, and (c) the various food applications in different food systems such as meat, milk products, fruits, and vegetables.

Development of Smart Films of a Chitosan Base and Robusta Coffee Peel Extract for Monitoring the Fermentation Process of Pickles

Smart film is widely used in the field of food packaging. The smart film was prepared by adding anthocyanin-rich Robusta coffee peel (RCP) extract into a chitosan (CS)-glycerol (GL) matrix by a solution-casting method. By changing the content of RCP (0, 10%, 15% and 20%) in the CS-GL film, the related performance indicators of CS-GL-RCP films were studied. The results showed that the CS-GL-RCP films had excellent mechanical properties, and CS-GL-RCP15 film maintained the tensile strength (TS) of 16.69 MPa and an elongation-at-break (EAB) of 18.68% with RCP extract. CS-GL-RCP films had the best UV-vis light barrier property at 200-350 nm and the UV transmittance was close to 0. The microstructure observation results showed that CS-GL-RCP films had a dense and uniform cross section, which proved that the RCP extract had good compatibility with the polymer. In addition, the CS-GL-RCP15 film was pH-sensitive and could exhibit different color changes with different pH solutions. So, the CS-GL-RCP15 film was used to detect the fermentation process of pickles at 20 ± 1 °C for 15 days. The pickles were stored in a round pickle container after the boiling water had cooled. The color of the CS-GL-RCP15 film changed significantly, which was consistent with the change of pickles from fresh to mature. The color of the smart film changed significantly with the maturity of pickles, and the difference of ΔE of film increased to 8.89 (15 Days), which can be seen by the naked eye. Therefore, CS-GL-RCP films prepared in this study provided a new strategy for the development of smart packaging materials.

Recent development of metal oxides and chalcogenides as antimicrobial agents

Pathogenic microbes are a major concern in hospitals and other healthcare facilities because they affect the proper performance of medical devices, surgical devices, etc. Due to the antimicrobial resistance or multidrug resistance, combatting these microbial infections has grown to be a significant research area in science and medicine as well as a critical health concern. Antibiotic resistance is where microbes acquire and innately exhibit resistance to antimicrobial agents. Therefore, the development of materials with promising antimicrobial strategy is a necessity. Amongst other available antimicrobial agents, metal oxide and chalcogenide-based materials have shown to be promising antimicrobial agents due to their inherent antimicrobial activity as well as their ability to kill and inhibit the growth of microbes effectively. Moreover, other features including the superior efficacy, low toxicity, tunable structure, and band gap energy has makes metal oxides (i.e. TiO₂, ZnO, SnO₂ and CeO₂ in particular) and chalcogenides (Ag₂S, MoS₂, and CuS) promising candidates for antimicrobial applications as illustrated by examples discussed in this review.

Essential characteristics improvement of metallic nanoparticles loaded carbohydrate polymeric films - A review

Petroleum-based films have contributed immensely to various environmental issues. Developing green-based films from carbohydrate polymers is crucial for addressing the harms encountered. However, some limitations exist on their property, processibility, and applicability that prohibit their processing for further developments. This review discusses the potential carbohydrate polymers and their sources, film preparation methods, such as solvent-casting, tape-casting, extrusion, and thermo-mechanical compressions for green-based films using various biological polymers with their merits and demerits. Research outcomes revealed that the essential characteristics improvement achieved by incorporating different metallic nanoparticles has significantly reformed the properties of biofilms, including crystallization, mechanical stability, thermal stability, barrier function, and antimicrobial activity. The property-enhanced bio-based films made with nanoparticles are potentially interested in replacing fossil-based films in various areas, including food-packaging applications. The review paves a new way for the commercial use of numerous carbohydrate polymers to help maintain a sustainable green environment.

Copper-based nanoparticles for biopolymer-based functional films in food packaging applications

This review summarizes the latest developments in the design, fabrication, and application of various Cu-based nanofillers to prepare biopolymer-based functional packaging films, focusing on the effects of inorganic nanoparticles on the optical, mechanical, gas barrier properties, moisture sensitivity, and functional properties of the films. In addition, the potential application of Cu-based nanoparticle-added biopolymer films for fresh food preservation and the effect of nanoparticle migration on food safety were discussed. The incorporation of Cu-based nanoparticles improved the film properties with enhanced functional performance. Cu-based nanoparticles such as copper oxide, copper sulfide, copper ions, and copper alloys affect biopolymer-based films differently. The properties of composite films containing Cu-based nanoparticles depend on the concentration of the filler, the state of dispersion, and the interaction of the nanoparticles with the biopolymer matrix in the film. The composite film filled with Cu-based nanoparticles effectively extended the shelf life by maintaining the quality of various fresh foods and securing safety. However, studies on the migration characteristics and safety of copper-based nanoparticle food packaging films are currently being conducted on plastic-based films such as polyethylene, and research on bio-based films is limited.

High performance biopolymeric packaging films containing zinc oxide nanoparticles for fresh food preservation: A review

Biodegradable food packaging films (FPFs) assembled from sustainable biopolymeric materials are of increasing interest to the food industry due to pollution and health risks resulting from the use of conventional plastic packaging. However, the functional performance of these FPFs is often poorer than that of plastic films, which limits their commercial application. This problem may be partly overcome by incorporating nano-additives like zinc oxide nanoparticles (ZNPs) into the films. The incorporation of ZNPs into FPFs can improve their functional performance. The properties of these films depends on the concentration, dispersion state, and interactions of ZNPs with the biopolymeric matrix in the films. ZNPs-loaded films and coatings are highly effective at preserving a variety of fresh foods. Studies of ZNPs migration through FPFs have shown that the zinc is mainly transported in an ionic form and the amount entering foods is below safety standards. This article reviews recent developments in the design, fabrication, and application of ZNPs-loaded FPFs based on biopolymers, focusing on the impacts of ZNPs on the optical, barrier, mechanical, water sensitivity, and antimicrobial properties of the films. The potential applications of ZNPs-loaded FPFs for fresh food preservation is also discussed.

High-performance carboxymethyl cellulose-based composite film tailored by versatile zeolitic imidazolate framework

Robust biopolymer-based composite film with multifunctional performances significantly contributes to the packaging field. Herein, we proposed a sort of carboxymethyl cellulose (CMC) based composite film via incorporating versatile zeolitic imidazolate framework (ZIF) materials. Compared to pristine CMC film, the OTR, WVTR, and tensile strength of CMC/ZIF composite film with 1 wt ‰ Zn/Co-ZIF were improved from 64.89 cm³*μm/(m²*d*kPa), 1579.21 g/(m²*24h) and 16.9 MPa to 20.79 cm³*μm/(m²*d*kPa), 1209.58 g/(m²*24h) and 70.1 MPa, respectively. Notably, owing to the reduced band gap and intrinsic chemical and thermal stability of Zn/Co-ZIF, the fabricated Zn/Co-ZIF/CMC composite film presented well UV protection capability within the whole UV region and excellent UV-blocking durability after being exposed to UV-light at 365 nm for 12 h. In practice, the photocatalytic degradation of RhB solutions under UV light could be effectively suppressed when using Zn/Co-ZIF/CMC film as UV protection layer. Our findings proposed the potential application of these versatile ZIF materials as functional nanofiller within biopolymer substances for UV protection and transparent packaging area.

Nanocatalytic Hydrogel with Rapid Photodisinfection and Robust Adhesion for Fortified Cutaneous Regeneration

Chronic inflammation caused by invasive bacterial infections severely interferes with the normal healing process of skin regeneration. Hypoxia of the infection microenvironment (IME) seriously affects the antibacterial effect of photodynamic therapy in phototherapy. To address this serious issue, a nanocatalytic hydrogel with an enhanced phototherapy effect consisting of a hydrogel polyvinyl alcohol (PVA) scaffold, MXene/CuS bio-heterojunction, and polydopamine (PDA) for photothermal antibacterial effects and promoting skin regeneration is designed. The MXene/CuS bio-heterojunction has a benign photothermal effect. Singlet oxygen (¹O₂) and hydroxyl radicals (·OH) were generated under near-infrared light, which made the hydrogel system have good antioxidant and antibacterial properties. The addition of PDA further improves the biocompatibility and endows the nanocatalytic hydrogel with adhesion. Additionally, in vivo assays display that the nanocatalytic hydrogel has good skin regeneration ability, including ability to kill bacteria, and promotes capillary angiogenesis and collagen deposition. This work proposes an approach for nanocatalyzed hydrogels with an activated IME response to treat wound infections by enhancing the phototherapeutic effects.

Physicochemical and Antibacterial Properties of Alginate Films Containing Tansy (Tanacetum vulgare L.) Essential Oil

Tansy (Tanacetum vulgare) is a common plant used in folk medicine for digestive problems, fevers, and migraines; against parasites; and as an insect repellent. The active substances in essential oil are responsible for its antimicrobial and antioxidant activity. Thus, tansy essential oil (TO) was added to alginate films to fabricate materials with antioxidant and antibacterial properties for food packaging. Sodium alginate films with glycerol and TO were tested in terms of structure, mechanical, thermal, antioxidant, and antibacterial properties. The structure of the films was examined using SEM and an ATR-FTIR spectrophotometer. The addition of TO to the alginate film significantly changed the films' microstructure, making them rougher and porous. A low-intensity band at 1739 cm^-1, indicative of the presence of TO, appeared in all spectra of alginate films with TO. Moreover, the studies revealed that essential oil acted as a plasticizer, slightly reducing tensile strength from about 7 MPa to 5 MPa and increasing elongation at break from 52% to 56% for the sample with 2% TO. The alginate films enriched in TO exhibited antioxidant properties (280 μmol Trolox/100 g of the sample with 2% TO) and antibacterial activity against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa.

Novel pectin-based nanocomposite film for active food packaging applications

Novel pectin-based films reinforced with crystalline nanocellulose (CNC) and activated with zinc oxide nanoparticles (ZnO NPs) were prepared by solvent-casting method. Film ingredients enhanced UV-blocking, thermal, and antibacterial properties of active films against well-known foodborne pathogens. Optimal active films exhibited higher mechanical, water vapor barrier properties compared to pristine pectin films. SEM confirmed the even distribution of CNC and ZnO NPs in pectin matrix and their interactions were proven using FTIR. Wrapping hard cheese samples artificially contaminated with Staphylococcus aureus and Salmonella enterica with the ternary nanocomposite film at 7 °C for 5 days significantly reduced the total population counts by at least 1.02 log CFU/g. Zn²⁺ migrating to wrapped cheese samples was below the specific limit (5 mg/kg), confirming their safety for food contact. Overall, ZnO/CNC/pectin nanocomposite films represent promising candidates for active food packaging as safe, eco-friendly alternatives for synthetic packaging materials.

Recent advances in metal sulfide nanoparticle-added bionanocomposite films for food packaging applications

Metal sulfide nanoparticles have recently attracted much attention due to their unique physical and functional properties. Metal sulfide nanoparticles used as optoelectronic and biomedical materials in the past decades are promising for making functional nanocomposite films due to their low toxicity and strong antibacterial activity. Recently, copper sulfide and zinc sulfide nanomaterials have been used to produce food packaging films for active packaging. Metal sulfide nanoparticles added as nanofillers are attracting attention in packaging applications due to their excellent potential to improve mechanical, barrier properties, and antibacterial activity. This review covers the fabrication process and important applications of metal sulfide nanoparticles. The development of metal sulfides reinforcing mainly copper sulfide and zinc sulfide nanomaterials as multifunctional nanofillers in bio-based films for active packaging applications has been comprehensively reviewed. As the recognition of metal sulfide nanoparticles as a functional filler increases, the development and application potential of active packaging films using them is expected to increase.

Alginate-based multifunctional films incorporated with sulfur quantum dots for active packaging applications

Sulfur quantum dots (SQDs) were fabricated using a facile hydrothermal method and used for the preparation of functional food packaging film and compared the properties with other sulfur-based fillers like elemental sulfur (ES) and sulfur nanoparticles (SNP). The SQDs have an average size of 5.3 nm and were very stable in aqueous suspension. Unlike other sulfur-based fillers, the SQD showed high antioxidant, antibacterial and antifungal activity, but no cytotoxicity was found for L929 mouse fibroblasts even after long-term exposure of 48 h. When sulfur-based fillers were added to the alginate film, SQD was more evenly dispersed in the polymer matrix than SNP and ES. The addition of SQD to the alginate film increased the film's UV barrier property by 82% and tensile strength by 18%. Also, the addition of SQDs to the films did not affect the stiffness (elastic modulus, EM) and water vapor barrier permeability (WVP) of the films. In addition, SQD-added films exhibited excellent antioxidant and strong antibacterial activity against bacterial (E. coli and L. monocytogenes) and fungal (A. niger and P. chrysogenum) food pathogens. When the film was applied as a bread packaging test, the SQD-added film prevented mold growth for 14 days, unlike the ES and SNP-added films.

Biopolymer-Based Films from Sodium Alginate and Citrus Pectin Reinforced with SiO2

Blend films based on sodium alginate (SA) and citrus pectin (P) reinforced with different concentrations of SiO₂ (0–10% w/w) were developed in this study. From the morphological (SEM) and structural (FT-IR) evaluation, it was verified that the incorporation of the reinforcing agent did not drastically modify the microstructure of the films, nor did new chemical bonds form. However, the XRD results suggested a slight reduction in the crystallinities of the blends by the incorporation of SiO₂. Among the formulations prepared, the addition of a 5% reinforcing agent was responsible for the simultaneous improvement of mechanical and barrier properties. Comparing the control sample (SA/P) with the SA/P/5.0%SiO₂ film, the tensile strength increased from 27.7 ± 3.7 to 40.6 ± 4.5 MPa, and the water-vapor transmission rate decreased from 319.8 ± 38.7 to 288.9 ± 23.5 g m⁻² day⁻¹. Therefore, SiO_2, as a reinforcing agent in SA/P blends, represents a simple and effective strategy for improving the properties of biopolymer-based films in applications, such as packaging.

Plant protein-based nanocomposite films: A review on the used nanomaterials, characteristics, and food packaging applications

Consumer demands to utilize environmentally friendly packaging have led researchers to develop packaging materials from naturally derived resources. In recent years, plant protein-based films as a replacement for synthetic plastics have attracted the attention of the global food packaging industry due to their biodegradability and unique properties. Biopolymer-based films need a filler to show improved packaging properties. One of the latest strategies introduced to food packaging technology is the production of nanocomposite films which are multiphase materials containing a filler with at least one dimension less than 100 nm. This review provides the recent findings on plant-based protein films as biodegradable materials that can be combined with nanoparticles that are applicable to food packaging. Moreover, it investigates the characterization of nanocomposite plant-based protein films/edible coatings. It also briefly describes the application of plant-based protein nanocomposite films/coating on fruits/vegetables, meat and seafood products, and some other foods. The results indicate that the functional performance, barrier, mechanical, optical, thermal and antimicrobial properties of plant protein-based materials can be extended by incorporating nanomaterials. Recent reports provide a better understanding of how incorporating nanomaterials into plant protein-based biopolymers leads to an increase in the shelf life of food products during storage time.

Alginate Biofunctional Films Modified with Melanin from Watermelon Seeds and Zinc Oxide/Silver Nanoparticles

Bioactive films find more and more applications in various industries, including packaging and biomedicine. This work describes the preparation, characterization and physicochemical, antioxidant and antimicrobial properties of alginate films modified with melanin from watermelon (Citrullus lanatus) seeds at concentrations of 0.10%, 0.25% and 0.50% w/w and with silver and zinc oxide nanoparticles (10 mM film casting solutions for both metal nanoparticles). Melanin served as the active ingredient of the film and as a nanoparticle stabilizer. The additives affected the color, antioxidant (~90% ABTS and DPPH radicals scavenging for all melanin modified films) and antimicrobial activity (up to 4 mm grow inhibition zones of E. coli and S. aureus for both zinc oxide and silver nanoparticles), mechanical (silver nanoparticles addition effected two-fold higher tensile strength), thermal and barrier properties for water and UV-vis radiation. The addition of ZnONP resulted in improved UV barrier properties while maintaining good visible light transmittance, whereas AgNP resulted in almost complete UV barrier and reduced visible light transmittance of the obtained films. What is more, the obtained films did not have an adverse effect on cell viability in cytotoxicity screening. These films may have potential applications in food packaging or biomedical applications.

Recent Advancements in Smart Biogenic Packaging: Reshaping the Future of the Food Packaging Industry

Due to their complete non-biodegradability, current food packages have resulted in major environmental issues. Today’s smart consumer is looking for alternatives that are environmentally friendly, durable, recyclable, and naturally rather than synthetically derived. It is a well-established fact that complete replacement with environmentally friendly packaging materials is unattainable, and bio-based plastics should be the future of the food packaging industry. Natural biopolymers and nanotechnological interventions allow the creation of new, high-performance, light-weight, and environmentally friendly composite materials, which can replace non-biodegradable plastic packaging materials. This review summarizes the recent advancements in smart biogenic packaging, focusing on the shift from conventional to natural packaging, properties of various biogenic packaging materials, and the amalgamation of technologies, such as nanotechnology and encapsulation; to develop active and intelligent biogenic systems, such as the use of biosensors in food packaging. Lastly, challenges and opportunities in biogenic packaging are described, for their application in sustainable food packing systems.

Recent advancement in improvement of properties of polysaccharides and proteins based packaging film with added nanoparticles: A review

Innovations and research on packaging materials are in a fast-growing stage to make them suitable for advanced packaging innovations and sustainability efforts. Biological macromolecules like algal polysaccharides, chitosan, gelatin and others like starch are explored for developing eco-friendly packaging alternatives. Compared to conventional synthetic polymers they have performance limitations that are tried to be overcome with added fillers. The unique properties of fillers in the nano range are explored for this. They can improve the overall property of polymer matrixes by improving barrier properties to oxygen and water vapour, increasing stability and mechanical strength. Exploring the possibilities of new nanoparticle-polymer combinations can bring novel properties in the packaging industry that can be used in smart and intelligent packaging areas. Thus studies on nanocomposite films from polysaccharides, protein compounds and nanoparticles can help to overcome the limitations of bio-polymers for novel packaging applications. This review covers the effect of nanoparticles on the optical, morphological, barrier, thermal and mechanical properties of polysaccharides and proteins based packaging film, along with the types of nanoparticles used in the composite films.

Advances in Functional Biopolymer-Based Nanocomposites for Active Food Packaging Applications

Polymeric nanocomposites have received significant attention in both scientific and industrial research in recent years. The demand for new methods of food preservation to ensure high-quality, healthy foods with an extended shelf life has increased. Packaging, a crucial feature of the food industry, plays a vital role in satisfying this demand. Polymeric nanocomposites exhibit remarkably improved packaging properties, including barrier properties, oxygen impermeability, solvent resistance, moisture permeability, thermal stability, and antimicrobial characteristics. Bio-based polymers have drawn considerable interest to mitigate the influence and application of petroleum-derived polymeric materials and related environmental concerns. The integration of nanotechnology in food packaging systems has shown promise for enhancing the quality and shelf life of food. This article provides a general overview of bio-based polymeric nanocomposites comprising polymer matrices and inorganic nanoparticles, and describes their classification, fabrication, properties, and applications for active food packaging systems with future perspectives.

Modification of Alginates to Modulate Their Physic-Chemical Properties and Obtain Biomaterials with Different Functional Properties

Modified alginates have a wide range of applications, including in the manufacture of dressings and scaffolds used for regenerative medicine, in systems for selective drug delivery, and as hydrogel materials. This literature review discusses the methods used to modify alginates and obtain materials with new or improved functional properties. It discusses the diverse biological and functional activity of alginates. It presents methods of modification that utilize both natural and synthetic peptides, and describes their influence on the biological properties of the alginates. The success of functionalization depends on the reaction conditions being sufficient to guarantee the desired transformations and provide modified alginates with new desirable properties, but mild enough to prevent degradation of the alginates. This review is a literature description of efficient methods of alginate functionalization using biologically active ligands. Particular attention was paid to methods of alginate functionalization with peptides, because the combination of the properties of alginates and peptides leads to the obtaining of conjugates with properties resulting from both components as well as a completely new, different functionality.

Carrageenan/agar-based functional film integrated with zinc sulfide nanoparticles and Pickering emulsion of tea tree essential oil for active packaging applications

A functional carrageenan/agar-based film was prepared by combining tea tree oil Pickering emulsion (PET) and zinc sulfide nanoparticles (ZnSNP). PET was formulated using tea tree essential oil stabilized with nanocellulose fibers. PET and ZnSNPs were uniformly dispersed in the binary polymer matrix and formed compatible films. The incorporation of ZnSNPs improved the mechanical strength, whereas PET slightly decreased the strength, but the combined addition of ZnSNP and PET maintained the mechanical strength with slightly improved flexibility. The addition of ZnSNP and PET, alone or in combination, slightly improved the water vapor barrier, water resistance, and thermal stability of the film. In addition, the carrageenan/agar-based composite membrane showed distinct antioxidant and antibacterial activity. The ZnSNP and PET incorporated binary composite films with enhanced physical and functional properties are likely to be used in active food packaging applications.

Copper sulfide with morphology-dependent photodynamic and photothermal antibacterial activities

Metal chalcogenides have been intensively investigated as antibacterial agents due to their unique structures and superior photoactivities. Herein, various structures of copper sulfide (CuS), a metal chalcogenide, such as microspheres (MSs), nanosheets (NSs), and nanoparticles (NPs), were developed in this work for antibacterial applications. A hydrothermal process was utilized to synthesize CuS MSs, CuS NSs, and CuS NPs. Under simulated solar light and near-infrared (NIR) light irradiation, the antibacterial behaviors, reactive oxygen species (ROS) production, and light-driven antibacterial mechanisms of CuS MSs, CuS NSs, and CuS NPs were demonstrated with the bacterium Escherichia coli (E. coli). Bacterial growth curves and ROS generation tests indicated that CuS NSs and CuS NPs had higher light-driven antibacterial activities than that of CuS MSs. ROS of hydroxyl (·OH) and superoxide anion radicals (O₂^-) were investigated via an electron spin resonance (ESR) spectroscopic analysis by respectively incubating CuS MSs, CuS NSs, and CuS NPs with E. coli under simulated solar light irradiation. Furthermore, E. coli incubated with CuS NPs and CuS NSs showed substantial bacterial degradation after NIR laser irradiation, which was attributed to their photothermal killing effects. Light-driven antibacterial mechanisms of CuS NSs and CuS NPs were investigated, and we discovered that under simulated solar and NIR light irradiation, CuS NSs and CuS NPs produced photoinduced electrons, and the copper ions and photoinduced electrons then reacted with atmospheric moisture to produce hydroxide and superoxide anion radicals and heat, resulting in bacterial mortality.

Preparation of pectin/agar-based functional films integrated with zinc sulfide nano petals for active packaging applications

Here we report on the robust synthesis of zinc sulfide nanoparticles (ZnSNP) using a simple one-pot reaction. The prepared ZnSNP was characterized and confirmed to be a petal-shaped nanoparticle. The ZnSNP was added to fabricate the pectin/agar-based functional composite film. The integration of ZnSNP has greatly improved the physical properties of the film, such as mechanical and UV protection properties, without significantly changing the transparency of the film. The addition of the nanofillers did not affect the film's hydrophobicity, water vapor barrier, and thermal properties. Moreover, the composite film showed intense antibacterial activity against foodborne pathogenic bacteria, E. coli and L. monocytogenes. The functional bio-nanocomposite films based on pectin/agar have high potential in active packaging applications.

NIR-triggered photocatalytic and photothermal performance for sterilization based on copper sulfide nanoparticles anchored on Ti3C2Tx MXene

Harmful bacterial flourish with the increase in environmental pollution and pose a great threat to human health. Thus, developing new and efficient antibacterial materials is imperative to reduce the pollution caused by traditional sterilization materials and improve sterilization efficiency. In this study, a new photocatalytic antibacterial material was developed to achieve an efficient antibacterial effect. Ti₃C₂T_x@CuS composites were synthesized by simple hydrothermal method, by which copper sulfide (CuS) nanoparticles were anchored on the surface of Ti₃C₂T_x to sharply improve the photocatalytic its antibacterial ability. Ti₃C₂T_x@CuS exhibits excellent antibacterial activity against Escherichia coli and Staphylococcus aureus with bactericidal rates of 99.6% and 99.1%, respectively. Photoluminescence spectroscopy (PL), decay time PL, photocurrent test, electrochemical impedance spectroscopy and finite element method showed that the formation of Ti₃C₂T_x@CuS heterojunction promoted the separation of electrons and holes, improved the electron transport efficiency, and elevated the generation of reactive oxygen species. Moreover, Ti₃C₂T_x@CuS has a stronger photothermal effect and causes more heat release than CuS to improve antibacterial performance. The Ti₃C₂T_x@CuS heterojunction has a broad application prospect in the disinfection and antibacterial fields.

Gelatin-Based Film Integrated with Copper Sulfide Nanoparticles for Active Packaging Applications

Gelatin-based multifunctional composite films were prepared by reinforcing various amounts of copper sulfide nanoparticles (CuSNP, 0.0, 0.5, 1.0, and 2.0 wt %), and the effect of CuSNP on the film was evaluated by analyzing its physical and antibacterial properties. CuSNP makes a compatible film with gelatin. The inclusion of CuSNP significantly enhanced the UV blocking, mechanical strength, and water vapor barrier properties of the gelatin film. The inclusion of CuSNP of 1.0 wt % or less did not affect the transparency of the gelatin film. When 2.0 wt % of CuSNP was mixed, the hydrophilicity of the gelatin film did not change noticeably, but its thermal properties slightly increased. Moreover, the gelatin/CuSNP composite film presented effective antibacterial activity against E. coli and some activity against L. monocytogenes. Gelatin/CuSNP composite films with better functional and physical properties can be used for food packaging or biomedical applications.

Architecting functionalized carbon microtube/carrollite nanocomposite demonstrating significant microwave characteristics

Biomass-derived materials have recently received considerable attention as lightweight, low-cost, and green microwave absorbers. On the other hand, sulfide nanostructures due to their narrow band gaps have demonstrated significant microwave characteristics. In this research, carbon microtubes were fabricated using a biowaste and then functionalized by a novel complementary solvothermal and sonochemistry method. The functionalized carbon microtubes (FCMT) were ornamented by CuCo2S4 nanoparticles as a novel spinel sulfide microwave absorber. The prepared structures illustrated narrow energy band gap and deposition of the sulfide structures augmented the polarizability, desirable for dielectric loss and microwave attenuation. Eventually, the architected structures were blended by polyacrylonitrile (PAN) to estimate their microwave absorbing and antibacterial characteristics. The antibacterial properties against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) were scrupulously assessed. Noteworthy, the maximum reflection loss (RL) of the CuCo2S4/PAN with a thickness of 1.75 mm was 61.88 dB at 11.60 GHz, while the architected FCMT/PAN composite gained a broadband efficient bandwidth as wide as 7.91 GHz (RL > 10 dB) and 3.25 GHz (RL > 20 dB) with a thickness of 2.00 mm. More significantly, FCMT/CuCo2S4/PAN demonstrated an efficient bandwidth of 2.04 GHz (RL > 20 dB) with only 1.75 mm in thickness. Interestingly, FCMT/CuCo2S4/PAN and CuCo2S4/PAN composites demonstrated an electromagnetic interference shielding efficiency of more than 90 and 97% at the entire x and ku-band frequencies, respectively.

Can Sustainable Packaging Help to Reduce Food Waste? A Status Quo Focusing Plant-Derived Polymers and Additives

The promotion of sustainable packaging is part of the European Green Deal and plays a key role in the EU’s social and political strategy. One option is the use of renewable resources and biomass waste as raw materials for polymer production. Lignocellulose biomass from annual and perennial industrial crops and agricultural residues are a major source of polysaccharides, proteins, and lignin and can also be used to obtain plant-based extracts and essential oils. Therefore, these biomasses are considered as potential substitute for fossil-based resources. Here, the status quo of bio-based polymers is discussed and evaluated in terms of properties related to packaging applications such as gas and water vapor permeability as well as mechanical properties. So far, their practical use is still restricted due to lower performance in fundamental packaging functions that directly influence food quality and safety, the length of shelf life, and thus the amount of food waste. Besides bio-based polymers, this review focuses on plant extracts as active packaging agents. Incorporating extracts of herbs, flowers, trees, and their fruits is inevitable to achieve desired material properties that are capable to prolong the food shelf life. Finally, the adoption potential of packaging based on polymers from renewable resources is discussed from a bioeconomy perspective.

Effect of low concentrations of SiO2 nanoparticles on the physical and chemical properties of sodium alginate-based films

This work investigated the effect of adding low concentrations of nano-SiO₂ (0.5, 1.0 and 1.5%) in the properties of films based on sodium alginate, to identify lower thresholds in the proportion of the reinforcing agent. It was found that, even in the smallest proportion, thermal stability of the nanocomposites improved significantly (with degradation onset increased by almost 15% compared with the control film). The surface morphology showed pronounced roughness at nano-SiO₂ concentrations greater than 1.0%, indicating agglomeration of part of the nanomaterial. Mechanical properties were reduced for the samples with concentrations equal to 1.0 and 1.5%, however, without significant differences between them. Conversely, water vapor and light barrier properties have not undergone significant changes in any formulation. Therefore, the use of 0.5% nano-SiO₂ in alginate films would be an easy and economically interesting way to improve thermal stability, without significantly reducing mechanical properties of the pure material.

Improved mechanical, water vapor barrier and UV-shielding properties of cellulose acetate films with flower-like metal-organic framework nanoparticles

Flower-like metal-organic frameworks (Cu-MOF) nanoparticles are successfully synthesized and incorporated into cellulose acetate (CA) matrix to prepare CA-based functional nanocomposite films via a simple solution-casting method. The effect of the incorporation of flower-like Cu-MOF on the morphological, mechanical, thermal, surface wettability, water vapor barrier, cytotoxicity, photostability and UV-shielding properties of CA films is fully investigated. Results reveal that the flower-like Cu-MOF has good compatibility with CA, providing uniform and compact nanocomposite films. The as-prepared nanocomposite films show improved mechanical properties, surface hydrophobicity, water vapor barrier ability compared to neat CA film, and exhibit super UV-shielding capability through the entire UV regions meanwhile retaining a high visible transparency. Moreover, the high transparency and UV-shielding ability of the nanocomposite films can be still maintained even after continuous UV-light (365 nm) irradiation for 12 h. In addition, MTT cytotoxicity assays towards normal human liver cells (HL-7702) reveal high cell viability (over 80%) and good biocompatibility for the CA/Cu-MOF nanocomposite films. These results indicate that the CA/Cu-MOF nanocomposite films with obviously improved physical and functional performances hold significant potential for transparent packaging and UV-protection applications.

Fabrication of Copper Sulfide Nanoparticles and Limonene Incorporated Pullulan/Carrageenan-Based Film with Improved Mechanical and Antibacterial Properties

Edible biopolymer (pullulan/carrageenan) based functional composite films were fabricated by the addition of copper sulfide nanoparticles (CuSNP) and D-limonene (DL). The DL and CuSNP were compatible with the pullulan/carrageenan biopolymer matrix. The addition of CuSNP significantly increased the UV-blocking properties without substantially reducing the transparency of the film. The addition of CuSNP improved the film's tensile strength by 10%; however, the DL addition did not significantly influence the strength, while the combined addition of CuSNP and DL increased the strength by 15%. The addition of the fillers did not significantly affect the thermal stability of the film, but the water vapor barrier property was slightly improved. There was no significant change in the moisture content and hydrophobicity of the composite film. Besides, the composite film showed some antimicrobial activity against food-borne pathogenic bacteria. The fabricated pullulan/carrageenan-based film with antimicrobial and UV-barrier properties is likely to be used in active food packaging applications.

Curcumin Incorporated Poly(Butylene Adipate-co-Terephthalate) Film with Improved Water Vapor Barrier and Antioxidant Properties

Curcumin incorporated poly(butylene adipate-co-terephthalate) (PBAT) based film was fabricated. Curcumin has uniformly distributed in the PBAT matrix to form a bright yellow PBAT/curcumin film. The PBAT/curcumin film has slightly reduced tensile strength and flexibility than the neat PBAT film, while the thermal stability of the film has not changed significantly. The blending of curcumin significantly decreased the water vapor permeability of the PBAT film. Additionally, the PBAT/curcumin film showed potent antioxidant activity with some antimicrobial activity. The PBAT/curcumin films with improved water vapor barrier and additional functions can be used for active packaging applications.