Transparent bionanocomposite films based on chitosan and TEMPO-oxidized cellulose nanofibers with enhanced mechanical and barrier properties

Cellulose nanofibers of oil palm fronds as a filler in nanocomposite coating for corrosion protection of copper

Cellulose nanofibers (CNF) create a physical barrier preventing contact with corrosive substances and improving corrosion prevention. Oil palm fronds (OPF), the primary source of underused biomass waste from plantations, were processed into CNF. The OPF-CNF, mixed with hydroxyethyl cellulose as the matrix, forms a nanocomposite. Corrosion analysis using electrochemical methods demonstrated that copper coated with cellulose-rich nanocomposite containing 5 % CNF had a significantly decreased corrosion rate with an efficiency of 97.92 %. This CNF-based coating, combining barrier and passivation mechanisms, enhances performance, providing a competitive, eco-friendly alternative to conventional coatings.

Nanocellulose-short peptide self-assembly for improved mechanical strength and barrier performance

Cellulose nanofibers (CNF) are the most abundant renewable nanoscale fibers on Earth, and their use in the design of hybrid materials is ever more acclaimed, although it has been mostly limited, to date, to CNF derivatives obtained via covalent functionalization. Herein, we propose a noncovalent approach employing a set of short peptides - DFNKF, DF(I)NKF, and DF(F5)NKF - as supramolecular additives to engineer hybrid hydrogels and films based on unfunctionalized CNF. Even at minimal concentrations (from 0.1% to 0.01% w/w), these peptides demonstrate a remarkable ability to enhance CNF rheological properties, increasing both dynamic moduli by more than an order of magnitude. Upon vacuum filtration of the hydrogels, we obtained CNF-peptide films with tailored hydrophobicity and surface wettability, modulated according to the peptide content and halogen type. Notably, the presence of fluorine in the CNF-DF(F5)NKF film, despite being minimal, strongly enhances CNF water vapor barrier properties and reduces the film water uptake. Overall, this approach offers a modular, straightforward method to create fully bio-based CNF-peptide materials, where the inclusion of DFNKF derivatives allows for facile functionalization and material property modulation, opening their potential use in the design of packaging solutions and biomedical devices.

TEMPO oxidized cellulose nanofiber-reinforced sodium alginate encapsulated poly(acrylamide) microcapsules and its releasing behaviours for enhancing oil recovery

Poly(acrylamide) (PAM) has excellent thickening ability as a conventional flooding agent. However, PAM confronts the problems of high injection pressure and high shear loss in the process of oil extraction, which have limited its application in this field. In this work, 2, 2, 6, 6-Tetramethylpiperidinooxy oxidized cellulose nanofibers (TOCNFs) enhanced sodium alginate (SA) shell was used to encapsulate PAM to form microcapsule. The composition, morphology, structure and the releasing behaviours of TOCNFs enhanced microcapsules was tested. Mechanical stirring was used to simulate the state of polymer subjected to shear during stratigraphic transport. The release performance of the microcapsules was characterized by measuring the change of viscosity with time. The ratio of the shell material with the best performance was explored, and the enhancement mechanism of the SA shell by TOCNFs was discussed. The experiments showed that the release time of PAM from the microcapsules was significantly prolonged with the addition of TOCNFs. The longest release time was observed when the ratio of SA and TOCNFs was 5: 1, with the release time of the microcapsules from the original 8 h to 16 h. The enhanced shear resistance of the microcapsules was attributed to the semi-interpenetrating network structure of SA and TOCNFs via Ca2+ cross-linking as well as hydrogen bonding. The prepared microcapsules have promising applications in enhancing oil recovery.

Nanocellulose@gallic Acid-Based MOFs: A Novel Material for Ecofriendly Food Packaging

The development of an effective food packaging material is essential for safeguarding against infections and preventing chemical, physical, and biological changes during food storage and transportation. In the present study, we successfully synthesized an innovative food packaging material by combining chitosan (CH), nanocellulose (NC), and a gallic acid-based metal-organic framework (MOF). The CH films were prepared using different concentrations of NC (5 and 10%) and MOFs (1.5, 2.5, and 5%). Various properties of prepared films, including water solubility (WS), moisture content (MC), swelling degree, oxygen permeability, water vapor permeability (WVP), mechanical property, color analysis, and light transmittance, were studied. The chitosan film with a 5% NC and 1.5% MOF (CH-5% NC-1.5% MOF) exhibited the least water solubility, moisture content, and water vapor permeability, indicating the overall stability of the film. Additionally, this film demonstrated low oxygen permeability, as indicated by a peroxide value of 18.911 ± 4.009, ensuring the effective preservation of packaged contents. Notably, this synthesized film exhibited high antioxidant activity, resulting in an extended duration of 52 days. This antioxidant activity was further validated by the preservation of apple slices for 9 days in a CH-5% NC-1.5% MOF film. The findings of the study suggest that the developed films can provide a promising and environmentally friendly solution for active food packaging.

Biodegradable gelatin/pectin films containing cellulose nanofibers and biguanide polymers: Characterization and application in sweet cherry packaging

To expand the utilization of gelatin and pectin derived from agricultural by-products, the composite films composed of gelatin, citrus pectin, cellulose nanofibers (CNF), and polyhexamethylene biguanide hydrochloride (PHMB) were prepared through the solvent casting method. Fourier infrared spectroscopy analysis verified the successful integration of CNF and PHMB into the gelatin-pectin matrix. The incorporation of CNF as a reinforcing agent substantially enhanced the barrier capabilities of the composite film. Moreover, the addition of PHMB, functioning as an antimicrobial agent, not only granted the film with antibacterial properties but also improved its physical characteristics and biodegradability. A water contact angle experiment revealed the film presented a certain degree of hydrophobicity. The optimal performances were attained with a composition in which CNF and PHMB constituted 8 % and 3 %, respectively, of the total weight of gelatin and pectin. As a packaging film, the composite film demonstrated its effectiveness by reducing the decay index and weight loss rate of sweet cherries during a 12-day storage period. In the soil degradation test, the composite film exhibited notable structural degradation by the 16th day. Consequently, the composite film will be used as an innovative and biodegradable packaging material to provide a sustainable solution for food packaging industries.

Dissolving-co-catalytic strategy for the preparation of flexible and wet-stable cellulose membrane towards biodegradable packaging

In the realization of the goal of circular economy, cellulose as one of sustainable biomass resources, have attracted much attention because of their abundant sources, biodegradability and renewability. However, the mechanical and waterproof performance of cellulose-based materials are usually not satisfying, which limits their high-value utilization. In this study, cellulose membrane with high-performance from the aspects of mechanical properties, water-resistance ability, oxygen barrier capacity and biodegradability, was prepared from bleached hardwood pulp (HBKP) in a AlCl3/ZnCl2/H2O solution. The AlCl3/ZnCl2/H2O acted as both solvent and catalyst to dissolve cellulose and facilitate the chemical crosslinking of epichlorohydrin (EPI) with cellulose, thus improved the overall performance of the obtained cellulose membrane. The addition sequence, amount and crosslinking time of EPI during chemical crosslinking had important effects on the properties of the membranes. When 7 wt% EPI was crosslinked for 24 h, the tensile stress reached 133 MPa and the strain reached 17 %. Moreover, the membrane had excellent oxygen insulation down to (1.1 ± 0.31) × 10-4 cm3/m2·d·Pa, and good water-resistance ability, no obvious swelling behavior after 450 days of immersion in distilled water. Furthermore, the membrane could be degraded by microorganisms in about 20 days. This cellulose-based membrane offers a sustainable and biodegradable packaging material.

Characterization of chitosan film incorporated pine bark extract and application in carp slices packaging

Active films based on chitosan incorporated with pine bark extract (PBE) were prepared and characterized. Subsequently, these films were utilized for packaging carp slices in refrigerated storage at 4 ± 1 °C. Analysis of the physicochemical properties and biological activity of the active films revealed that, except for water content, all assessed indices showed an increasing trend with an increase in the amount of supplemental PBE. As this trend progresses, scanning electron microscopy (SEM) analysis revealed deposition on the film surface accompanied by transverse lines and fractures, while the color of the film gradually changed from light yellow to reddish-brown. Fourier transform infrared spectroscopy (FTIR) indicated that the phenolic hydroxyl groups in PBE interacted with the hydrogen in the amino groups of chitosan molecules to form non-covalent bonds. X-ray diffraction analysis (XRD) showed that the reaction between PBE and chitosan altered the crystalline structure of chitosan molecules. Moreover, the analysis of the effects of active films on the pH, water-holding capacity, thiobarbituric acid values, and the total bacterial counts of carp slices revealed that in terms of preservation, films containing 30 % PBE were the most effective, using which the shelf life of carp slices could be extended by 50 %.

Ozone-activated lignocellulose films blended with chitosan for edible film production

This work focuses on the influence of ozone pretreatment on the fractionation and solubilization of sugarcane bagasse and soda bagasse pulp fibers in sodium hydroxide/urea solution, as well as the application of regenerated cellulose for producing edible films. The methodology involved pretreating lignocelluloses with ozone for 20 to 120 min before dissolving in sodium hydroxide/urea solution. The influence of the pretreatment conditions on cellulose dissolution yield was investigated. Regenerated cellulose films were then formed, with and without the addition of 2 % chitosan. Mechanical, physical, structural, thermal, and antimicrobial attributes were determined as a function of ozonation conditions of raw materials and chitosan content. The findings exhibited positive effects of short ozonation on enhancing mechanical strength, cohesion, and hydrophobicity. The prolonged ozonation of 120 min demonstrated optimal improvements in continuity, swelling, and antibacterial resistance of obtained films. Incorporating chitosan enhanced tensile performance, stiffness, and vapor barriers but increased moisture absorption. Tailoring the activation of biomass through ozone pretreatment and chitosan addition resulted in renewable films with adjustable properties to meet diverse packaging requirements, particularly for fruit protective coatings, ensuring the preservation of post-harvest quality.

Controlling the Magnetic Responsiveness of Cellulose Nanofiber Particles Embedded with Iron Oxide Nanoparticles

2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofiber (TOCN) particles, an innovative biobased material derived from wood biomass, have garnered significant interest, particularly in the biomedical field, for their distinctive properties as biocompatible particle adsorbents. However, their microscopic size complicates their separation in liquid media, thereby impeding their application in various domains. In this study, superparamagnetic magnetite nanoparticles (NPs), specifically iron oxide Fe3O4 NPs with an average size of 15 nm, were used to enhance the collection efficiency of TOCN-Fe3O4 composite particles synthesized through spray drying. These composite particles exhibited a remarkable ζ-potential (approximately -50 mV), indicating their high stability in water, as well as impressive magnetization properties (up to 47 emu/g), and rapid magnetic responsiveness within 60 s in water (3 wt % Fe3O4 to TOCN, 1 T magnet). Furthermore, the influence of Fe3O4 NP concentrations on the measurement of the speed of magnetic separation was quantitatively discussed. Additionally, the binding affinity of the synthesized particles for proteins was assessed on a streptavidin-biotin binding system, offering crucial insights into their binding capabilities with specific proteins and underscoring their significant potential as functionalized biomedical materials.

Electrospun fiber mats based on chitosan-carrageenan containing Malva sylvestris anthocyanins: Physic-mechanical, thermal, and barrier properties along with application as intelligent food packaging materials

This study aimed to encapsulate Malva sylvestris extract (MSE) into chitosan-carrageenan (CH-KC) fibers using the electrospinning technique and monitor the freshness of silver carp fillets during the refrigerated storage conditions for 8 days. The CH-KC + MSE 4 % fiber mats were red at pH values lower than 3, purple at pH 4-6, dark blue at pH 7, green at pH 8-10, and brown at pH 11-12. The tensile strength, elongation at break, water vapor permeability, oxygen transmission rate, moisture content, and water solubility of fabricated fiber mats were 7.71-11.02 MPa, 13.12 %-30.00 %, 7.35-20.01 × 10-4 g mm/m2 h Pa, 3.81-8.23 cm3/m2 h, 15.74 %-27.34 %, and 3.90 %-7.56 %, respectively. Regarding the potential application of a fabricated indicator for freshness monitoring of silver carp fillets, total viable count, psychrotrophic bacterial count, pH, and total volatile basic nitrogen reached 8.91 log CFU/g, 8.03 log CFU/g, 8.10, and 40.18 mg N/100 g at the end of the study, respectively. Meanwhile, the CH-KC + MSE 4 % fiber mat color changed from white to green. These findings suggest that CH-KC + MSE 4 % fiber mats can be further utilized in the food industry to control the freshness of refrigerated silver carp fillets.

Recent advances in TEMPO-oxidized cellulose nanofibers: Oxidation mechanism, characterization, properties and applications

Cellulose is the richest renewable polymer source on the earth. TEMPO-mediated oxidized cellulose nanofibers are deduced from enormously available wood biomass and functionalized with carboxyl groups. The preparation procedure of TOCNFs is more environmentally friendly compared to other cellulose, for example, MFC and CNCs. Due to the presence of functional carboxyl groups, TOCNF-based materials have been studied widely in different fields, including biomedicine, wastewater treatment, bioelectronics and others. In this review, the TEMPO oxidation mechanism, the properties and applications of TOCNFs are elaborated. Most importantly, the recent advanced applications and the beneficial role of TOCNFs in the various abovementioned fields are discussed. Furthermore, the performances and research progress on the fabrication of TOCNFs are summarized. It is expected that this timely review will help further research on the invention of novel material from TOCNFs and its applications in different advanced fields, including biomedicine, bioelectronics, wastewater treatment, and the energy sector.

Enhancement of the Physical and Functional Properties of Chitosan Films by Incorporating Galla chinensis Extract

Composite films based on chitosan (CS) incorporating Galla chinensis extract (GCNE) at different CS/GCNE weight ratios, which are both biodegradable and multifunctional, were fabricated using the solution-casting method. The FTIR analyses indicated that a good interaction was presented among the GCNE and CS through an intermolecular hydrogen bond. The incorporation of the GCNE improved the films' elongation at break, UV-light blocking, and decreased the moisture regain (from 16.68% to 10.69%) and water absorption (from 80.65% to 54.74%). Moreover, the CS/GCNE films exhibited a strong antioxidant activity (from 57.11% to 70.37% of DPPH and from 35.53% to 46.73% of ABTS scavenging activities) mainly due to the high content of phenolic compounds in the incorporated GCNE. The CS/GCNE film-forming solution coatings demonstrated their effectiveness in preserving the quality of postharvest mangoes, specifically by minimizing the change in the firmness, weight loss, titratable acidity, and total phenolic and ascorbic acids. These findings suggest that the multifunctional composite films possess a high application potential to preserve postharvest fruits.

High-strength hydrophilic N-halamines chitosan and cellulose nanofibers membranes with repeated bactericidal properties

Direct addition of disinfectants and membrane separation techniques have been common methods to address microbial contamination in water. However, disinfectants may generate toxic by-products, and even minor damage or biofilm formation on filtration membranes can lead to a heightened risk of microbial contamination. Consequently, how to quickly and safely disinfect microbial contaminated water sources remains a huge challenge. In this study, the high-strength broad-spectrum antibacterial CNF/CS composite membrane was fabricated by utilizing cellulose nanofibers (CNF) to reinforce the structure of chitosan (CS). The resulting CNF/CS composite membrane exhibits an impressive tensile strength of 148 MPa and boasts an active chlorine content of 5.29 %. Notably, even after undergoing 50 washing cycles and 10 repeated chlorination procedures, the structural integrity and high active chlorine content of the composite membrane remain preserved, validating its exceptional strength, stability, and chlorine rechargeability. Additionally, the CNF/CS antibacterial materials demonstrate remarkable attributes in terms of rapid sterilization, sustained and consistent release of active chlorine, and efficient inhibition of biofilm formation, demonstrating great potential in efficient, green, and safe sterilization.

ZnO Nanoparticles-Reinforced Chitosan-Xanthan Gum Blend Novel Film with Enhanced Properties and Degradability for Application in Food Packaging

Nations all over the world are imposing ban on single-use plastics, which are difficult to recycle and lead to creations of nonsustainable and nondegradable piles. To match the requirement in the market, suitable food packaging alternatives have to be developed that are biodegradable and environment-friendly. The current work is designed for the fabrication of a novel nanocomposite by blending xanthan gum in a chitosan matrix and reinforcing it with ZnO nanoparticles, through a solution casting method. Surface morphology of the film was investigated through field emission scanning electron microscopy, along with energy-dispersive X-ray spectroscopy mapping, and characterized through thermogravimetric analysis, Fourier transform infrared (FTIR) spectroscopy, mechanical testing, and ultraviolet spectroscopy. FTIR spectroscopy analysis corroborated the interaction between the components and the H-bond formation. Polyelectrolyte complex formation materializes between the oppositely charged chitosan and xanthan gum, and further nanoparticle incorporation significantly improves the mechanical properties. The synthesized nanocomposite was found to have increases in the tensile strength and elongation at break of pure chitosan by up to 6.65 and 3.57 times, respectively. The transmittance percentage of the bionanocomposite film was reduced compared to that of the pure chitosan film, which aids in lowering the oxidative damage brought on by UV radiation in packed food products. Moreover, the film also showed an enhanced barrier property against water vapor and oxygen gas. The film was totally biodegradable in soil burial at the end of the second month; it lost almost around 88% of its initial weight. The fabricated film does not pose a threat to the environment and hence has great potential for application in the future sustainable food packaging industry.

Thermoplastic starch (TPS)-based composite films for wastewater treatment: synthesis and fundamental characterization

Modification of starch is a potential basic research aiming to improve its water barrier properties. The general purpose of this study is to manufacture cross-linked iodinated starch citrate (ISC) with a degree of substitution (DS) ≈ 0.1 by modifying native corn starch with citric acid in the presence of iodine as an oxidizing agent. Thermoplastic starch (TPS) was generated with urea as a plasticizer and blended with various concentrations of ISC of (2, 4, 6%) (wt/wt) to obtain (UTPS/ISC₂, UTPS/ISC₄, and UTPS/ISC₆). Nanocomposite film was formed from UTPS/ISC₂ in presence of stabilized iodinated cellulose nanocrystals UTPS/ISC₂/SICNCs via gelatinization at a temperature of 80ºC. Water solubility and water vapor release were studied amongst the water barrier features. The fabricated starch-based composite films were evaluated utilizing Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electronic Microscope analysis (SEM), surface area, and tensile measurements. The adsorption of crystal violet (CV) dye onto produced samples was examined in an aqueous solution. The findings revealed that the UTPS/ISC₂/ISCNCs has 83% crystal violet elimination effectiveness. Moreover, the adsorption isotherms were assessed and figured out to vary in the order of Langmuir > Temkin > Freundlich > Dubinin-Radushkevich.

Exploring the Potential of Seaweed Derivatives for the Development of Biodegradable Plastics: A Comparative Study

Biodegradable films made from biopolymer materials have the potential to replace conventional plastics, which can reduce waste disposal problems. This study aims to explore the potential of different seaweed derivate films consisting of 2% (w/w) of kappaphycus alverezi (KA), kappa carrageenan (KC), refined carrageenan (RC) and semi-refined carrageenan (SRC) as bio-based materials with 0.9% (w/w) glycerol (G), and reinforced with different concentrations of cellulose nanofibers (CNFs) derived from palm waste. A characterization of the glycerol-plasticized seaweed derivatives containing 0, 5, 10, and 15% (v/w) cellulose nanofiber is carried out. The CNFs were studied based on their mechanical, physical and thermal properties including mechanical properties, thickness, moisture content, opacity, water solubility, water vapor permeability and thermal stability. The hydrogen bonding was determined using the DFT calculation generated by Gauss view software version 9.6. The KA + G + 10%CNF film exhibited a surface with slight cracks, roughness, and larger lumps and dents, resulting in inferior mechanical properties (18.50 Mpa), making it unsuitable for biofilm production. The KC + G + 10%CNF film exhibited mechanical properties 24.97 Mpa and water vapor permeability of 1.42311 × 10^-11 g s^-1 m^-1 Pa^-1. The RC/G/10%CNF film displayed the highest TS (48.23 MPa) and water vapor permeability (1.4168 × 10^-11 g s^-1 m^-1 Pa^-1), but it also had higher solubility in water (66%). In contrast, the SRC + G + 10%CNF film demonstrated excellent mechanical properties (45.98 MPa), low water solubility (42.59%), low water vapor permeability (1.3719 × 10^-11 g s^-1 m^-1 Pa^-1), and a high decomposition temperature (250.62 °C) compared to KA, KC and RC. These attributes develop films suitable for various applications, including food packaging with enhanced properties and stability.

High-performance bamboo composites based on the chemical bonding of active bamboo interface and chitosan

Nowadays, green, clean, and efficient sustainable development has become the world's mainstream industrial development. However, the bamboo/wood industry is still in the status quo with high fossil resource dependence and significant greenhouse gas emissions. Herein, a low-carbon and green strategy to produce bamboo composites is developed. The bamboo interface was modified directionally to a bamboo carboxy/aldehyde interface by using a TEMPO/NaIO₄ system, and then chemically cross-linked with chitosan to produce active bonding bamboo composite (ABBM). It was confirmed that the chemical bond cross-linking (CN, N-C-N, electrostatic interactions, hydrogen bonding) in the gluing region was helpful to obtain the excellent dry bonding strength (11.74 MPa), water resistance (5.44 MPa), and anti-aging properties (decreased by 20 %). This green production of ABBM solves the problem of poor water resistance and aging resistance of all-biomass-based chitosan adhesives. It can replace bamboo composites produced using fossil-based adhesives to meet the requirements of the construction, furniture, and packaging industries, changing the previous situation of composite materials requiring high temperature pressing and highly dependent on fossil-based adhesives. This provides a greener and cleaner production method for the bamboo industry, as well as more options for the global bamboo industry to achieve green and clean production goals.

Nanocomposites of cellulose nanofibers incorporated with carvacrol via stabilizing octenyl succinic anhydride-modified ɛ-polylysine

Food packaging plays an extremely important role in the global food chain, allowing for products to be shipped across long distances without spoiling. However, there is an increased need to both reduce plastic waste caused by traditional single-use plastic packaging and improve the overall functionality of packaging materials to extend shelf-life even further. Herein, we investigate composite mixtures based on cellulose nanofibers and carvacrol via stabilizing octenyl-succinic anhydride-modified epsilon polylysine (MɛPL-CNF) for active food packaging applications. The effects of epsilon polylysine (εPL) concentration and modification with octenyl-succinic anhydride (OSA) and carvacrol are evaluated with respect to composites morphology, mechanical, optical, antioxidant, and antimicrobial properties. We find that both increased εPL concentration and modification with OSA and carvacrol lead to films with increased antioxidant and antimicrobial properties, albeit at the expense of reduced mechanical performance. Importantly, when sprayed onto the surface of sliced apples, MεPL-CNF-mixtures are able to successfully delay/hinder enzymatic browning, suggesting the potential of such materials for a range of active food packaging applications.

Chitosan/snail slime films as multifunctional platforms for potential biomedical and cosmetic applications: physical and chemical characterization

Due to the pollution problem, the use of more sustainable materials with a reduced environmental impact, spanning across biocompatible and biodegradable polymers, is growing worldwide in many different fields, particularly when referring to applications in Life Sciences. Accordingly, with the aim of developing multifunctional materials for potential cosmetic/biomedical purposes, this work reports the physical and chemical characterization of chitosan-based films blended with snail slime, exhibiting antioxidant and sunscreen features. A suitable formulation for preparing free-standing chitosan platforms, mixing low molecular weight chitosan, lactic acid, glycerol, and snail slime into an appropriate ratio, is thus described. The results obtained by morphological analysis and ATR-FTIR spectroscopy, XRD, swelling analysis (also when varying pH, ionic strength, and temperature), and WVTR measurements evidence a uniform distribution of snail slime inside the chitosan network, forming more compacted structures. At first, the UV-Vis analysis is used to investigate the theoretical Sun Protection Factor, finding that these innovative platforms can be used for preventing sunburn. Then, the antioxidant features are investigated using the ABTS assay, displaying a snail slime-mediated and dose-dependent boosted activity.

Recent advances and future prospects of cellulose, starch, chitosan, polylactic acid and polyhydroxyalkanoates for sustainable food packaging applications

Cellulose, starch, chitosan, polylactic acid, and polyhydroxyalkanoates are seen as promising alternatives to conventional plastics in food packaging. However, the application of these biopolymers in the food packaging industry on a commercial scale is limited due to their poor performance and processing characteristics and high production cost. This review aims to provide an insight into the recent advances in research that address these limitations. Loading of nanofillers into polymer matrix could improve thermal, mechanical, and barrier properties of biopolymers. Blending of biopolymers also offers the possibility of acquiring newer materials with desired characteristics. However, nanofillers tend to agglomerate when loaded above an optimum level in the polymer matrix. This article throws light on different methods adopted by researchers to achieve uniform dispersion of nanofillers in bionanocomposites. Furthermore, different processing methods available for converting biopolymers into different packaging forms are discussed. In addition, the potential utilization of agricultural, brewery, and industrial wastes as feedstock for the production of biopolymers, and integrated biorefinery concept that not only keep the total production cost of biopolymers low but are also environment-friendly, are discussed. Finally, future research prospects in this field and the possible contribution of biopolymers to sustainable development are presented. This review will certainly be helpful to researchers working on sustainable food packaging, and companies exploring pilot projects to scale up biopolymer production for industrial applications.

Potential of chitosan/carbon nanoparticles and chitosan/lignocellulose nanofiber composite as growth media for peatland paddy seeds

Indonesia has committed to restoring degraded peatlands by revegetating them with paddy plants using paludiculture systems. Nanofertilizers derived from chitosan and oil palm biomass can be used to enhance paddy growth. This study analyzed the potential growth media of chitosan nanocomposite films for paddy seeds grown in tropical peatland. Chitosan nanocomposites were synthesized by reinforcing chitosan with activated carbon nanoparticles (ACNPs), nonactivated carbon nanoparticles (n-ACNPs), and lignocellulose nanofibers (LCNFs). All carbon nanoparticles were reversibly aggregated, whereas LCNFs did not have a tendency to aggregate but were entangled. The highest specific surface area and pore volume are on EFB ACNPs, followed by OPT LCNFs and EFB n-ACNPs. Both nanocomposites' tensile strength and elastic modulus value were reduced with an average of 45.77% and 34.00%, respectively, because of the lack of nano- and micro-aggregates formation, good dispersion, and incompatibility. In a germination test, chitosan nanocomposites provided the best growth patterns for the Dendang paddy variety, whereas, in a greenhouse test, the nanocomposites had the best growth patterns for the Indragiri paddy variety. Chitosan/empty fruit bunch ACNP nanocomposites grown in a germinator had the highest growth normality (100.00%), highest maximum growth potential (100.00%), and highest height average (11.27 cm). In the greenhouse test, chitosan/oil palm trunk n-ACNPs achieved the highest growth natality (16.44%) and growth rate (65.74%). All chitosan nanocomposites had a synergetic biofertilizing effect on fungi and mycorrhiza. Chitosan nanocomposites can be used as a growth regulator for peatland paddy varieties and can accelerate peatland restoration in tropical areas.

Fabrication and characterization of pullulan-based composite films incorporated with bacterial cellulose and ferulic acid

Pullulan-based composite films incorporated with bacterial cellulose (BC) and ferulic acid (FA) were prepared by solution casting method. The rheological, morphological, barrier, optical, anti-fogging, and antioxidant properties of pullulan-based composite films doped with BC and FA were investigated. The rheological results showed that all film-forming solution was pseudoplastic fluid and its viscosity increased with the increase of BC content. An appropriate BC (2 %) and FA were uniformly dispersed in pullulan to form uniform and dense composite films. With the increase of BC content, the roughness and opacity of composite films increased while their UV-vis barrier performance was improved by incorporating BC and FA. Fourier transform infrared spectrometer analysis demonstrated that hydrogen bond interactions among pullulan, BC, and FA were found, and incorporating BC could increase the crystallinity of the composite films, thus enhancing their mechanical, barrier, hydrophobic, and thermal stability properties. Pullulan-based composite films incorporated with 2 % BC and FA (P-BC2-FA) showed better mechanical properties, water, oxygen, and carbon dioxide barrier performances, and its water contact angle value also increased compared with control, respectively. P-BC2-FA film showed superior anti-fogging and antioxidant activities. These results indicate that the P-BC2-FA film are expected to be a potential target of bioactive packaging.

Functional Properties and Preservative Effect of P-Hydroxybenzoic Acid Grafted Chitosan Films on Fresh-Cut Jackfruit

In the present study, p-hydroxybenzoic acid-grafted chitosan (PA-g-CS) conjugates with different grafting degrees were synthesized by a free radical-regulated grafting approach. The conjugates were further developed into films by casting, and their characteristics and preservative effects on fresh-cut jackfruit were evaluated. Compared to the CS film, the PA-g-CS film showed comprehensive performance improvements, including enhancements of water solubility, anti-ultraviolet capacity, antioxidation, and antibacterial activity. Moreover, compared with CS film, some appreciable and favorable changes of physical properties were observed in the PA-g-CS films, which included water vapor permeability, oxygen permeability, surface morphology, moisture content, and mechanical intensity. Furthermore, compared to CS alone, the application of PA-g-CS films to fresh-cut jackfruit exerted a beneficial effect on the quality of products, as indicated by the inhibition of weight loss, softening, and membrane damage, the maintenance of soluble solids and ascorbic acids contents, as well as a reduced bacterial count and a higher sensory score. Among these PA-g-CS films, the best preservation effect was achieved with the highest degree of grafting (PA-g-CS III). The results suggested that the PA-g-CS film has the potential to be explored as a new type of packaging material for the preservation of fresh-cut fruits and vegetables.

Biohybrid Nanocellulose-Lysozyme Amyloid Aerogels via Electrostatic Complexation

Modern science is increasingly turning to nature for inspiration to design sustainable biomaterials in a smart and effective way. Herein, we describe biohybrid aerogels based on electrostatic complexation between cellulose and proteins-two of the most abundant natural polymers on Earth. The effects of both particle surface charge and particle size are investigated with respect to aerogel properties including the morphology, surface area, stability, and mechanical strength. Specifically, negatively charged nanocellulose (cellulose nanocrystals and cellulose nanofibers) and positively charged lysozyme amyloid fibers (full-length and shortened via sonication) are investigated in the preparation of fibrillar aerogels, whereby the nanocellulose component was found to have the largest effect on the resulting aerogel properties. Although electrostatic interactions between these two classes of charged nanoparticles allow us to avoid the use of any cross-linking agents, the resulting aerogels demonstrate a simple additive performance as compared to their respective single-component aerogels. This lack of synergy indicates that although electrostatic complexation certainly leads to the formation of local aggregates, these interactions alone may not be strong enough to synergistically improve bulk aerogel properties. Nevertheless, the results reported herein represent a critical step toward a broader understanding of biohybrid materials based on cellulose and proteins.

Regenerated Cellulose Products for Agricultural and Their Potential: A Review

Cellulose is one of the most abundant natural polymers with excellent biocompatibility, non-toxicity, flexibility, and renewable source. Regenerated cellulose (RC) products result from the dissolution-regeneration process risen from solvent and anti-solvent reagents, respectively. The regeneration process changes the cellulose chain conformation from cellulose I to cellulose II, leads the structure to have more amorphous regions with improved crystallinity, and inclines towards extensive modification on the RC products such as hydrogel, aerogel, cryogel, xerogel, fibers, membrane, and thin film. Recently, RC products are accentuated to be used in the agriculture field to develop future sustainable agriculture as alternatives to conventional agriculture systems. However, different solvent types and production techniques have great influences on the end properties of RC products. Besides, the fabrication of RC products from solely RC lacks excellent mechanical characteristics. Thus, the flexibility of RC has allowed it to be homogenously blended with other materials to enhance the final products' properties. This review will summarize the properties and preparation of potential RC-based products that reflect its application to replace soil the plantation medium, govern the release of the fertilizer, provide protection on crops and act as biosensors.

Sustainable Chitosan-Dialdehyde Cellulose Nanocrystal Film

In this study, we incorporated 2,3-dialdehyde nanocrystalline cellulose (DANC) into chitosan as a reinforcing agent and manufactured biodegradable films with enhanced gas barrier properties. DANC generated via periodate oxidation of cellulose nanocrystal (CNC) was blended at various concentrations with chitosan, and bionanocomposite films were prepared via casting and characterized systematically. The results showed that DANC developed Schiff based bond with chitosan that improved its properties significantly. The addition of DANC dramatically improved the gas barrier performance of the composite film, with water vapor permeability (WVP) value decreasing from 62.94 g·mm·m-2·atm-1·day-1 to 27.97 g·mm·m-2·atm-1·day-1 and oxygen permeability (OP) value decreasing from 0.14 cm3·mm·m-2·day-1·atm-1 to 0.026 cm3·mm·m-2·day-1·atm-1. Meanwhile, the maximum decomposition temperature (Tdmax) of the film increased from 286 °C to 354 °C, and the tensile strength of the film was increased from 23.60 MPa to 41.12 MPa when incorporating 25 wt.% of DANC. In addition, the chitosan/DANC (75/25, wt/wt) films exhibited superior thermal stability, gas barrier, and mechanical strength compared to the chitosan/CNC (75/25, wt/wt) film. These results confirm that the DANC and chitosan induced films with improved gas barrier, mechanical, and thermal properties for possible use in film packaging.

Influence of Charge and Heat on the Mechanical Properties of Scaffolds from Ionic Complexation of Chitosan and Carboxymethyl Cellulose

As one of the most abundant, multifunctional biological polymers, polysaccharides are considered promising materials to prepare tissue engineering scaffolds. When properly designed, wetted porous scaffolds can have biomechanics similar to living tissue and provide suitable fluid transport, both of which are key features for in vitro and in vivo tissue growth. They can further mimic the components and function of glycosaminoglycans found in the extracellular matrix of tissues. In this study, we investigate scaffolds formed by charge complexation between anionic carboxymethyl cellulose and cationic protonated chitosan under well-controlled conditions. Freeze-drying and dehydrothermal heat treatment were then used to obtain porous materials with exceptional, unprecendent mechanical properties and dimensional long-term stability in cell growth media. We investigated how complexation conditions, charge ratio, and heat treatment significantly influence the resulting fluid uptake and biomechanics. Surprisingly, materials with high compressive strength, high elastic modulus, and significant shape recovery are obtained under certain conditions. We address this mostly to a balanced charge ratio and the formation of covalent amide bonds between the polymers without the use of additional cross-linkers. The scaffolds promoted clustered cell adhesion and showed no cytotoxic effects as assessed by cell viability assay and live/dead staining with human adipose tissue-derived mesenchymal stem cells. We suggest that similar scaffolds or biomaterials comprising other polysaccharides have a large potential for cartilage tissue engineering and that elucidating the reason for the observed peculiar biomechanics can stimulate further research.

Functional Nanocellulose, Alginate and Chitosan Nanocomposites Designed as Active Film Packaging Materials

The aim of the study was to characterize and compare films made of cellulose nanocrystals (CNC), nano-fibrils (CNF), and bacterial nanocellulose (BNC) in combination with chitosan and alginate in terms of applicability for potential food packaging applications. In total, 25 different formulations were made and evaluated, and seven biopolymer films with the best mechanical performance (tensile strength, strain)—alginate, alginate with 5% CNC, chitosan, chitosan with 3% CNC, BNC with and without glycerol, and CNF with glycerol—were selected and investigated regarding morphology (SEM), density, contact angle, surface energy, water absorption, and oxygen and water barrier properties. Studies revealed that polysaccharide-based films with added CNC are the most suitable for packaging purposes, and better dispersing of nanocellulose in chitosan than in alginate was observed. Results showed an increase in hydrophobicity (increase of contact angle and reduced moisture absorption) of chitosan and alginate films with the addition of CNC, and chitosan with 3% CNC had the highest contact angle, 108 ± 2, and 15% lower moisture absorption compared to pure chitosan. Overall, the ability of nanocellulose additives to preserve the structure and function of chitosan and alginate materials in a humid environment was convincingly demonstrated. Barrier properties were improved by combining the biopolymers, and water vapor transmission rate (WVTR) was reduced by 15–45% and oxygen permeability (OTR) up to 45% by adding nanocellulose compared to single biopolymer formulations. It was concluded that with a good oxygen barrier, a water barrier that is comparable to PLA, and good mechanical properties, biopolymer films would be a good alternative to conventional plastic packaging used for ready-to-eat foods with short storage time.

Understanding the effects of copolymerized cellulose nanofibers and diatomite nanocomposite on blend chitosan films

Chitosan films lack various important physicochemical properties and need to be supplemented with reinforcing agents to bridge the gap. Herein, we have produced chitosan composite films supplemented with copolymerized (with polyacrylonitrile monomers) cellulose nanofibers and diatomite nanocomposite at different concentrations. The incorporation of CNFs and diatomite enhanced the physicochemical properties of the films. The mechanical characteristics and hydrophobicity of the films were observed to be improved after incorporating the copolymerized CNFs/diatomite composite at different concentrations (CNFs: 1%, 2% and 5%; diatomite: 10% and 30%). The antioxidant activity gradually increased with an increasing concentration (1-5% and 10-30%) of copolymerized CNFs/diatomite composite in the chitosan matrix. Moreover, the water solubility decreased from 30% for chitosan control film (CH-0) to 21.06% for films containing 30% diatomite and 5% CNFs (CNFs-D30-5). The scanning electron micrographs showed an overall uniform distribution of copolymerized CNFs/diatomite composite in the chitosan matrix with punctual agglomerations.

A review on chitosan and chitosan-based bionanocomposites: Promising material for combatting global issues and its applications

Over the last few years, several attempts have been made to replace petrochemical products with renewable and biodegradable components. The most challenging part of this approach is to obtain bio-based materials with properties and functions equivalent to those of synthetic products. Various naturally occurring polymers such as starch, collagen, alginate, cellulose, and chitin represent attractive candidates as they could reduce dependence on synthetic products and consequently positively impact the environment. Chitosan is also a unique bio-based polymer with excellent intrinsic properties. It is known for its anti-bacterial and film-forming properties, has high mechanical strength and good thermal stability. Nanotechnology has also applied chitosan-based materials in its most recent achievements. Therefore, numerous chitosan-based bionanocomposites with improved physical and chemical characteristics have been developed in an eco-friendly and cost-effective approach. This review discusses various sources of chitosan, its properties and methods of modification. Also, this work focuses on diverse preparation techniques of chitosan-based bionanocomposites and their emerging application in various sectors. Additionally, this review sheds light on future research scope with some drawbacks and challenges to motivate the researchers for future outstanding research works.

Visible light responsive, self-activated bionanocomposite films with sustained antimicrobial activity for food packaging

The research on a new type of low-cost, less-loss and adjustable sustained antibacterial activity food packaging films with self-activation ability and great industrialization potentiality is of great scientific and technological interest. Herein, a novel chitosan/negatively charged graphitic carbon nitride self-activation bionanocomposite films was prepared by one-step electrostatic self-assembly. First, the antibacterial efficiency of this film could reach to 99.8 ± 0.26% against E. coli and 99.9 ± 0.04% against S. aureus through self-activated under visible light. Second, this film can effectively extend the shelf life of tangerines to 24 days. Hemolysis and cell experiment test proved that this film was safe and nontoxic. Finally, negatively charged graphitic carbon nitride with low-cost can improve the mechanical, thermal and hydrophobic properties of neat chitosan films. This work can provide a new pathway for the preparation of low-cost packaging films with excellent visible light responsive property and sustainable antibacterial activity.

Highly dispersive Co3O4 nanoparticles incorporated into a cellulose nanofiber for a high-performance flexible supercapacitor

Transition metal oxides used as electrode materials for flexible supercapacitors have attracted huge attention due to their high specific capacitance and surface-to-volume ratio, specifically for cobalt oxide (Co₃O₄) nanoparticles. However, the low intrinsic electronic conductivity and aggregation of Co₃O₄ nanoparticles restrict their electrochemical performance and prevent these electrode materials from being commercialized. Herein, a facile, advantageous, and cost effective sol-gel synthetic route for growing Co₃O₄ nanoparticles uniformly over a low cost and eco-friendly one-dimensional (1D) hydrophilic cellulose nanofiber (CNF) surface has been reported. This exhibits high conductivity, which enables the symmetric electrode to deliver a high specific capacitance of ∼214 F g^-1 at 1 A g^-1 with remarkable cycling behavior (∼94% even after 5000 cycles) compared to that of pristine CNF and Co₃O₄ electrodes in an aqueous electrolyte. Furthermore, the binder-free nature of 1D Co₃O₄@CNF (which was carbonized at 200 °C for about 20 min under a H₂/Ar atmosphere) shows great potential as a hybrid flexible paper-like electrode and provides a high specific capacitance of 80 F g^-1 at 1 A g^-1 with a superior energy density of 10 W h kg^-1 in the gel electrolyte. This study provides a novel pathway, using a hydrophilic 1D CNF, for realizing the full potential of Co₃O₄ nanoparticles as advanced electrode materials for next generation flexible electronic devices.

Development of an active packaging system containing zinc oxide nanoparticles for the extension of chicken fillet shelf life

The casting method was employed to prepare gelatin-based nanocomposite films containing different concentrations of cellulose nanofiber (CNF) as a reinforcement filler (2.5%, 5%, and 7.5% w/w of gelatin) as well as zinc oxide nanoparticles (ZnO NPs) as an antimicrobial agent (1%, 3%, 5%, and 7% w/w of gelatin). The results showed that the incorporation of 5% CNFs (optimum concentration) significantly boosted the films' stiffness (YM; by 47%) and strength (TS; by 72%) but decreased its flexibility (EAB; by 28%), water vapor permeability, and moisture absorption. The best G/CNF film antibacterial activity was provided by the 5% concentration of ZnO NPs according to the disk diffusion assay; Gram-positive bacteria were inhibited significantly more than Gram-negative bacteria. The antimicrobial efficacy of the G/CNF/ZnO NPs film as a food packaging material was assessed via counts of Staphylococcus aureus and Pseudomonas fluorescens inoculated on chicken fillets (as a food model) in the treatment (G/5% CNF/5% ZnO) and control groups (plastic bag). The antibacterial film led to a significant reduction in the bacterial load of the chicken fillets (p < .05), especially against the Gram-positive strain. This study illustrated that G/CNF/ZnO NPs films can be utilized as active packaging to prolong the shelf life of different perishable foods such as meat.

Developed Chitosan/Oregano Essential Oil Biocomposite Packaging Film Enhanced by Cellulose Nanofibril

The use of advanced and eco-friendly materials has become a trend in the field of food packaging. Cellulose nanofibrils (CNFs) were prepared from bleached bagasse pulp board by a mechanical grinding method and were used to enhance the properties of a chitosan/oregano essential oil (OEO) biocomposite packaging film. The growth inhibition rate of the developed films with 2% (w/w) OEO against E. coli and L. monocytogenes reached 99%. With the increased levels of added CNFs, the fibrous network structure of the films became more obvious, as was determined by SEM and the formation of strong hydrogen bonds between CNFs and chitosan was observed in FTIR spectra, while the XRD pattern suggested that the strength of diffraction peaks and crystallinity of the films slightly increased. The addition of 20% CNFs contributed to an oxygen-transmission rate reduction of 5.96 cc/m2·day and water vapor transmission rate reduction of 741.49 g/m2·day. However, the increase in CNFs contents did not significantly improve the barrier properties of the film. The addition of 60% CNFs significantly improved the barrier properties of the film to light and exhibited the lowest light transmittance (28.53%) at 600 nm. Addition of CNFs to the chitosan/OEO film significantly improved tensile strength and the addition of 60% CNFs contributed to an increase of 16.80 MPa in tensile strength. The developed chitosan/oregano essential oil/CNFs biocomposite film with favorable properties and antibacterial activity can be used as a green, functional material in the food-packaging field. It has the potential to improve food quality and extend food shelf life.