Konjac glucomannan-based composite materials: Construction, biomedical applications, and prospects

Konjac glucomannan (KGM) as an emerging natural polymer has attracted increasing interests owing to its film-forming properties, excellent gelation, non-toxic characteristics, strong adhesion, good biocompatibility, and easy biodegradability. Benefiting from these superior performances, KGM has been widely applied in the construction of multiple composite materials to further improve their intrinsic performances (e.g., mechanical strength and properties). Up to now, KGM-based composite materials have obtained widespread applications in diverse fields, especially in the field of biomedical. Therefore, a timely review of relevant research progresses is important for promoting the development of KGM-based composite materials. Innovatively, firstly, this review briefly introduced the structure properties and functions of KGMs based on the unique perspective of the biomedical field. Then, the latest advances on the preparation and properties of KGM-based composite materials (i.e., gels, microspheres, films, nanofibers, nanoparticles, etc.) were comprehensively summarized. Finally, the promising applications of KGM-based composite materials in the field of biomedical are comprehensively summarized and discussed, involving drug delivery, wound healing, tissue engineering, antibacterial, tumor treatment, etc. Impressively, the remaining challenges and opportunities in this promising field were put forward. This review can provide a reference for guiding and promoting the design and biomedical applications of KGM-based composites.

Development of Slow-Release Fertilizers with Function of Water Retention Using Eco-Friendly Starch Hydrogels

Over the past two decades, the development and commercialization of slow-release fertilizers (SRFs) have significantly advanced, with the primary aim of mitigating environmental issues associated with excessive fertilizer use. A range of methodologies, including chemical and physical reactions, incorporation into carriers with porous and layered structures, and coating techniques, have been explored and refined. On the other hand, global challenges such as drought and desertification further underscore the need for SRFs that not only control nutrient release but also improve soil moisture retention. This paper reviews the development and application of eco-friendly starch hydrogels as fertilizer carriers and water retention for SRFs, particularly starch-based superabsorbent polymers (SAPs) produced through grafting copolymerization with acrylamide. This review explores both scientific issues, such as the microstructures and releasing mechanisms of SAPs, and technical development, involving copolymerization technologies, multi-initialization processes, methods of loading fertilizer into hydrogel, etc. Starch, as both a biodegradable and renewable carbohydrate polymer, offers distinct advantages due to its excellent chemical stability and high reactivity. The fabrication techniques of SAPs have been developed from traditional batch polymerization in aqueous solutions to more efficient, solvent-free reactive extrusion. The benefits of SRFs based on SAPs encompass enhanced soil aeration, the prevention of soil deterioration, the minimization of water evaporation, environmental pollution control, reduction in plant mortality, and prolonged nutrient retention within soil. In this review, we summarize the current progress, identify limitations in existing technologies, and propose future research directions to further enhance the performance of starch-based SRFs.

Chemically tailored graphite oxide nanoparticles for improving material properties of canola protein-based films

Canola protein obtained from canola meal, a byproduct of the canola industry, is an economical biopolymer with promising film-forming properties. It has significant potential for use as a food packaging material, though it possesses some functional limitations that need improvement. Incorporating nanomaterials is an option to enhance functional properties. This study aims to produce canola protein films by integrating GO exfoliated at several oxidation times and weight ratios to optimize mechanical, thermal, and barrier properties. Oxidation alters the C/O ratio and adds functional groups that bond with the amino/carboxyl groups of protein, enhancing the film properties. Significant improvement was obtained in GO at 60 and 120 min oxidation time and 3% addition level. Tensile strength and elastic modulus increased 200% and 481.72%, respectively, compared to control. Control films showed a 37.57 × 10-3 cm3m/m2/day/Pa oxygen permeability, and it was significantly reduced to 5.65 × 10-3 cm3m/m2/day/Pa representing a 665% reduction.

Design and Evaluation of Inorganic/Organic Hybrid Bio-composite for Site-Specific Oral Delivery of Darifenacin

Benign hyperplasia (BHP) is a common disorder that affects men over the age of 60 years. Transurethral resection of the prostate (TURP) is the gold standard for operative treatment, but a range of drugs are also available to improve quality of life and to reduce BHP-associated urinary tract infections and complications. Darifenacin, an anti-muscarinic agent, has been found effective for relieving symptoms of overactive bladder associated with BHP, but the drug has poor solubility and bioavailability, which are major challenges in product development. An inorganic/organic bio-composite with gastric pH-resistant property was synthesized for the targeted oral delivery of Darifenacin to the lower gastrointestinal tract (GIT). This development was accomplished through co-precipitation of calcium carbonate in quince seed-based mucilage. The FTIR, XRD, DSC, and TGA results showed good drug-polymer compatibility, and the SEM images showed calcite formation in the quince hydrogel system. After 72 h, the drug release of 34% and 75% were observed in acidic (0.1N HCl) and 6.8 pH phosphate buffer, respectively. A restricted/less drug was permeated through gastric membrane (21.8%) as compared to permeation through intestinal membrane (65%.) The developed composite showed significant reduction in testosterone-induced prostatic hyperplasia (2.39 ± 0.12***) as compared to untreated diseased animal group. No sign of organ toxicity was observed against all the developed composites. In this study, we developed an inorganic-organic composite system that is highly biocompatible and effective for targeting the lower GIT, thereby avoiding the first-pass metabolism of darifenacin.

Various Morphologies of Graphitic Carbon Nitride (g-C3N4) and Their Effect on the Thermomechanical Properties of Thermoset Epoxy Resin Composites

This research aims to highlight the importance of diverse forms of graphitic carbon nitride (g-C3N4) as strengthening elements in epoxy composites. It explores the influence of three different forms of g-C3N4 and their concentrations on the mechanical properties of the epoxy composites. Various characterization techniques, such as scanning electron microscopy (SEM), dynamic light scattering (DLS), thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR), were utilized to comprehend the effects of g-C3N4 morphology and particle size on the physical and chemical characteristics of epoxy resin. Mechanical properties, such as tensile strength, strain, modulus, and fracture toughness, were determined for the composite samples. SEM analysis was performed to examine crack morphology in samples with different reinforcements. Findings indicate that optimal mechanical properties were achieved with a 0.5 wt% bulk g-C3N4 filler, enhancing tensile strength by 14%. SEM micrographs of fracture surfaces revealed a transition from brittle to rough morphology, suggesting increased toughness in the composites. While the TGA results showed no significant impact on degradation temperature, dynamic mechanical analysis demonstrated a 17% increase in glass transition temperature. Furthermore, the improvement in thermal breakdown up to 600 °C was attributed to reinforced covalent bonds between carbon and nitrogen, supported by FTIR results.

Development of biodegradable film from cactus (Opuntia Ficus Indica) mucilage loaded with acid-leached kaolin as filler

Nowadays, substituting petroleum-based plastics with biodegradable polymers made from polysaccharides loaded with various reinforcing materials has recently gained attention due to the impact of conventional plastics wastes. In this study, polysaccharidic mucilage from Ethiopian cactus (Opuntia Ficus Indica) was derived using microwave-assisted extraction technique to develop biodegradable polymers that were inexpensive, readily available, simple to make, and ecofriendly. The effect of microwave power 300-800 W, solid-liquid (cactus-sodium hydroxide solution) ratio 1:5-1:25, sodium hydroxide concentration 0.1-0.8 mol/L, and extraction time 2-10 min on mucilage extraction were studied and the maximum yield of mucilage was attained at optimized parameters of 506 W, 1:20, 0.606 mol/L, and 9.5 min, respectively. Biodegradable polymers made with mucilage alone have poor mechanical characteristics and are thermally unstable. Thus, to overcome the stated problems, glycerol as a plasticizer and acid-leached kaolin crosslinked with urea as a reinforcing material were used. Moreover, the effect of acid-leached kaolin and glycerol on the physico-chemical properties of the films was studied, and a maximum tensile strength of 6.74 MPa with 18.45 % elongation at break, thermally improved biodegradability of 26 %, were attained at 10 % acid-leached kaolin and 20 % glycerol crosslinking with 2 % urea. But the maximum degradability of 53.5 % was attained at 30 % glycerol content. The control and reinforced biodegradable films were characterized using TGA, FTIR, SEM, and XRD to determine the thermal, functional group, morphology, and crystallinity of the bioplastics, respectively. These biodegradable plastics may be used for packaging application.

Processing of Thin Films Based on Cellulose Nanocrystals and Biodegradable Polymers by Space-Confined Solvent Vapor Annealing and Morphological Characteristics

L-poly(lactic acid), poly(3-hydroxybutyrate), and poly-hydroxybutyrate-co-hydroxyvalerate are biodegradable polymers that can be obtained from renewable biomass sources. The aim of this study was to develop three types of environmentally friendly film biocomposites of altered microstructure by combining each of the above-mentioned polymers with cellulose nanocrystal fillers and further processing the resulting materials via space-confined solvent vapor annealing. Cellulose was previously obtained from renewable biomass and further converted to cellulose nanocrystals by hydrolysis with the lactic acid. The solutions of biodegradable polymers were spin-coated onto solid substrates before and after the addition of cellulose nanocrystals. The obtained thin film composites were further processed via space-confined solvent vapor annealing to eventually favor their crystallization and, thus, to alter the final microstructure. Indeed, atomic force microscopy studies have revealed that the presence of cellulose nanocrystals within a biodegradable polymer matrix promoted the formation of large crystalline structures exhibiting fractal-, spherulitic- or needle-like morphologies.

A Review on Barrier Properties of Cellulose/Clay Nanocomposite Polymers for Packaging Applications

Packaging materials are used to protect consumer goods, such as food, drinks, cosmetics, healthcare items, and more, from harmful gases and physical and chemical damage during storage, distribution, and handling. Synthetic plastics are commonly used because they exhibit sufficient characteristics for packaging requirements, but their end lives result in environmental pollution, the depletion of landfill space, rising sea pollution, and more. These exist because of their poor biodegradability, limited recyclability, etc. There has been an increasing demand for replacing these polymers with bio-based biodegradable materials for a sustainable environment. Cellulosic nanomaterials have been proposed as a potential substitute in the preparation of packaging films. Nevertheless, their application is limited due to their poor properties, such as their barrier, thermal, and mechanical properties, to name a few. The barrier properties of materials play a pivotal role in extending and determining the shelf lives of packaged foods. Nanofillers have been used to enhance the barrier properties. This article reviews the literature on the barrier properties of cellulose/clay nanocomposite polymers. Cellulose extraction stages such as pretreatment, bleaching, and nanoparticle isolation are outlined, followed by cellulose modification methods. Finally, a brief discussion on nanofillers is provided, followed by an extensive literature review on the barrier properties of cellulose/clay nanocomposite polymers. Although similar reviews have been presented, the use of modification processes applied to cellulose, clay, and final nanocomposites to enhance the barrier properties has not been reviewed. Therefore, this article focuses on this scope.

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.

Biodegradable composite films based on mucilage from Opuntia ficus-indica (Cactaceae): Microstructural, functional and thermal properties

This study evaluated the feasibility of using cactus mucilage (CM) to elaborate biobased composite films blended with styrene-butadiene rubber latex (SBL). The CM was extracted and precipitated with ethanol (CMET) and isopropanol (CMIS). Mucilage-based films were formulated using three levels of mucilage (4, 6, and 8 wt%). The microstructure, thickness, moisture content, density, water contact angle, water vapor permeability, film solubility, thermal stability, and toughness of mucilage films blended with SBL (SBL/CMET and SBL/CMIS) were measured. The properties of mucilage-based films varied systematically, depending on the concentration of mucilage. The addition of SBL to CM film produces compatible, hydrophobic, flexible, and stiffer films with low moisture contents and good barrier properties. The mucilage film incorporated with 6 wt% CMET and CMIS reached the highest Young's modulus of 1512 ± 21 and 1988 ± 55 MPa, respectively. The DSC of produced films reveals that the Tg of SBL/CMIS is lower than that of SBL/CMIS. The synthesized films were structurally stable at high temperatures. The biodegradability of the composite films buried in the ground shows that the produced films are 100 % biodegradable after 40 days. Thus, CM blended with SBL can benefit specific applications, especially food packaging.

Seaweed polysaccharide nanocomposite films: A review

A million tonnes of plastic produced each year are disposed of after single use. Biodegradable polymers have become a promising material as an alternative to petroleum-based polymers. Utilising biodegradable polymers will promote environmental sustainability which has emerged with potential features and performances for various applications in different sectors. Seaweed-derived polysaccharides-based composites have been the focus of numerous studies due to the composites' renewability and sustainability for industries (food packaging and medical fields like tissue engineering and drug delivery). Due to their biocompatibility, abundance, and gelling ability, seaweed derivatives such as alginate, carrageenan, and agar are commonly used for this purpose. Seaweed has distinct film-forming characteristics, but its mechanical and water vapour barrier qualities are weak. Thus, modifications are necessary to enhance the seaweed properties. This review article summarises and discusses the effect of incorporating seaweed films with different types of nanoparticles on their mechanical, thermal, and water barrier properties.

Combined Effect of Citric Acid and Polyphenol-Rich Grape Seed Extract towards Bioactive Smart Food Packaging Systems

Alginate films (2% w·v^-1) were prepared with varying concentrations (5-20% w/w) of citric acid and aqueous grape seed extract (GSE) filtrate (11.66 ± 1.32 g GAE/L) using the solvent-evaporation method. Crosslinking alginate via ester bonds (FTIR analysis) with citric acid up to 10% (w/w) led to a 33% increase in tensile strength, a 34% reduction in water vapor transmission rate (WVTR), and had no impact on elongation at break. Crosslinking alginate with citric acid in the presence of GSE increased the tensile strength by 17%, decreased WVTR by 21%, and significantly improved DPPH scavenging activity. Moreover, after incubation for 24 h at 37 °C, the film-forming solutions exhibited increased antimicrobial activity, resulting in 0.5- and 2.5-log reductions for Escherichia coli and Staphylococcus aureus, respectively, compared to the values obtained without the addition of GSE. The stronger inhibitory effect observed against Gram-positive bacteria can be attributed to the unique composition and structure of their cell walls, which creates a barrier that restricts the penetration of polyphenols into the cells. The pH adjustment of the GSE film-forming solution from 2.0 to 10.0 shifted the UV/VIS absorption spectra, resulting in a colour change from yellow to red. The findings of this study have showcased the potential of combining GSE and citric acid to enhance the functionality and bioactivity of alginate films for applications in smart food packaging.

Host-guest drug delivery by β-cyclodextrin assisted polysaccharide vehicles: A review

Among different form of cyclodextrin (CD), β-CD has been taken a special attraction in pharmaceutical science due to lowest aqueous solubility and adequate cavity size. When β-CD forms inclusion complex with drugs then biopolymers such as polysaccharides in combination plays a vital role as a vehicle for safe release of drugs. It is noticed that, β-CD assisted polysaccharide-based composite achieves better drug release rate through host-guest mechanism. Present review is a critical analysis of this host-guest mechanism for release of drugs from polysaccharide supported β-CD inclusion complex. Various important polysaccharides such as cellulose, alginate, chitosan, dextran, etc. in relevant to drug delivery are logically compared in present review by their association with β-CD. Efficacy of mechanism of drug delivery by different polysaccharides with β-CD is analytically examined in schematic form. Drug release capacity at different pH conditions, mode of drug release, along with characterization techniques adopted by individual polysaccharide-based CD complexes are comparatively established in tabular form. This review may explore better visibility for researchers those are working in the area of controlled release of drugs by vehicle consist of β-CD associated polysaccharide composite through host-guest mechanism.

Mechanical, Barrier, Antioxidant and Antimicrobial Properties of Alginate Films: Effect of Seaweed Powder and Plasma-Activated Water

The incorporation of natural fillers such as seaweed may potentially enhance the properties of biopolymer films. In this study, we investigated the effect of seaweed powder as a bio-filler in alginate-based films at different concentrations (10, 30, and 50%, w/w alginate) and particle sizes (100 and 200 μm) on the mechanical, barrier, antioxidant, and antimicrobial properties of alginate which are essential for food packaging applications. Initially, mechanical properties of the alginate films prepared at different temperatures were evaluated to find the optimal temperature for preparing alginate solution. The addition of seaweed powder did not have any positive effect on the mechanical properties of the alginate films. However, the barrier (water vapor transmission rate) and antioxidant properties were improved with the addition of seaweed filler regardless of concentration. In addition, selected films were prepared in plasma-activated water (PAW). The mechanical properties (tensile strength, but not elongation at break) of the films prepared with PAW improved compared to the films prepared in distilled water, while a significant decrease was observed when incorporated with the seaweed filler. The films prepared in PAW also showed improved barrier properties compared to those prepared in distilled water. The antimicrobial activity of the alginate-seaweed film-forming solution was in general more pronounced when prepared with PAW and stored at 10 °C, particularly at the highest concentration of the film-forming solution (83.3% v/v). A more pronounced inhibitory effect was observed on the Gram-positive S. aureus than on the Gram-negative E. coli, which has been attributed to the different composition and structure of the respective cell walls. This study has demonstrated the potential of seaweed filler in combination with PAW towards enhanced functionality and bioactivity of alginate films for potential food packaging applications.

Hybrid Graphenene Oxide/Cellulose Nanofillers to Enhance Mechanical and Barrier Properties of Chitosan-Based Composites

Chitosan-based hybrid nanocomposites, containing cellulose nanocrystals (CNCs), graphene oxide (GO), and borate as crosslinking agents, were successfully prepared by solution-casting technique. The synergistic effect of the two fillers, and the role of the cross-linker, in enhancing the structural and functional properties of the chitosan polymer, was investigated. XPS results confirm the chemical interaction between borate ions and hydroxyl groups of chitosan, GO, and CNCs. The morphological characterization shows that the GO sheets are oriented along the casting surface, whereas the CNC particles are homogenously distributed in the sample. Results of tensile tests reveal that the presence of graphene oxide enhances the elastic modulus, tensile strength, elongation at break, and toughness of chitosan, while cellulose and borate induce an increase in the elastic modulus and stress at the yield point. In particular, the borate-crosslinked chitosan-based sample containing 0.5 wt% of GO and 0.5 wt% of CNCs shows an elongation at a break value of 30.2% and a toughness value of 988 J*m⁻³ which are improved by 124% and 216%, respectively, compared with the pristine chitosan. Moreover, the water permeability results show that the presence of graphene oxide slightly increases the water barrier properties, whereas the borate and cellulose nanocrystals significantly reduce the water vapor permeability of the polymer by about 50%. Thus, by modulating the content of the two reinforcing fillers, it is possible to obtain chitosan-based nanocomposites with enhanced mechanical and water barrier properties which can be potentially used in various applications such as food and electronic packaging.

Polymeric Coatings and Antimicrobial Peptides as Efficient Systems for Treating Implantable Medical Devices Associated-Infections

Many infections are associated with the use of implantable medical devices. The excessive utilization of antibiotic treatment has resulted in the development of antimicrobial resistance. Consequently, scientists have recently focused on conceiving new ways for treating infections with a longer duration of action and minimum environmental toxicity. One approach in infection control is based on the development of antimicrobial coatings based on polymers and antimicrobial peptides, also termed as “natural antibiotics”.

Effect of Cold Plasma Treatment on the Packaging Properties of Biopolymer-Based Films: A Review

Biopolymers, like polysaccharides and proteins, are sustainable and green materials with excellent film-forming potential. Bio-based films have gained a lot of attention and are believed to be an alternative to plastics in next-generation food packaging. Compared to conventional plastics, biopolymers inherently have certain limitations like hydrophilicity, poor thermo-mechanical, and barrier properties. Therefore, the modification of biopolymers or their films provide an opportunity to develop packaging materials with desired characteristics. Among different modification approaches, the application of cold plasma has been a very efficient technology to enhance the functionality and interfacial characteristics of biopolymers. Cold plasma is biocompatible, shows uniformity in treatment, and is suitable for heat-sensitive components. This review provides information on different plasma generating equipment used for the modification of films and critically analyses the impact of cold plasma on packaging properties of films prepared from protein, polysaccharides, and their combinations. Most studies to date have shown that plasma treatment effectively enhances surface characteristics, mechanical, and thermal properties, while its impact on the improvement of barrier properties is limited. Plasma treatment increases surface roughness that enables surface adhesion, ink printability, and reduces the contact angle. Plasma-treated films loaded with antimicrobial compounds demonstrate strong antimicrobial efficacy, mainly due to the increase in their diffusion rate and the non-thermal nature of cold plasma that protects the functionality of bioactive compounds. This review also elaborates on the existing challenges and future needs. Overall, it can be concluded that the application of cold plasma is an effective strategy to modify the inherent limitations of biopolymer-based packaging materials for food packaging applications.

Biobased composites from agro-industrial wastes and by-products

The greater awareness of non-renewable natural resources preservation needs has led to the development of more ecological high-performance polymeric materials with new functionalities. In this regard, biobased composites are considered interesting options, especially those obtained from agro-industrial wastes and by-products. These are low-cost raw materials derived from renewable sources, which are mostly biodegradable and would otherwise typically be discarded. In this review, recent and innovative academic studies on composites obtained from biopolymers, natural fillers and active agents, as well as green-synthesized nanoparticles are presented. An in-depth discussion of biobased composites structures, properties, manufacture, and life-cycle assessment (LCA) is provided along with a wide up-to-date overview of the most recent works in the field with appropriate references. Potential uses of biobased composites from agri-food residues such as active and intelligent food packaging, agricultural inputs, tissue engineering, among others are described, considering that the specific characteristics of these materials should match the proposed application.

Gum Arabic-Magnetite Nanocomposite as an Eco-Friendly Adsorbent for Removal of Lead(II) Ions from Aqueous Solutions: Equilibrium, Kinetic and Thermodynamic Studies

In this study, a gum Arabic-magnetite nanocomposite (GA/MNPs) was synthesized using the solution method. The prepared nanocomposite was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and thermogravimetric analysis (TGA). The prepared composite was evaluated for the adsorption of lead(II) ions from aqueous solutions. The controlling factors such as pH, contact time, adsorbent dose, initial ion concentration, and temperature were investigated. The optimum adsorption conditions were found to be 0.3 g/50 mL, pH = 6.00, and contact time of 30 min. The experimental data well fitted the pseudo-second-order kinetic model and the Langmuir isotherm model. The maximum adsorption capacity was determined as 50.5 mg/g. Thermodynamic parameters were calculated postulating an endothermic and spontaneous process and a physio-sorption pathway.

Pectin-cellulose nanocrystal biocomposites: Tuning of physical properties and biodegradability

The fabrication of pectin-cellulose nanocrystal (CNC) biocomposites has been systematically investigated by blending both polysaccharides at different relative concentrations. Circular free-standing films with a diameter of 9 cm were prepared by simple solution of these carbohydrates in water followed by drop-casting and solvent evaporation. The addition of pectin allows to finely tune the properties of the biocomposites. Textural characterization by AFM showed fibrous morphology and an increase in fiber diameter with pectin content. XRD analysis demonstrated that pectin incorporation also reduced the degree of crystallinity though no specific interaction between both polysaccharides was detected, by ATR-FTIR spectroscopy. The optical properties of these biocomposites were characterized for the first time and it was found that pectin in the blend reduced the reflectance of visible light and increased UV absorbance. Thermal stability, analyzed by TGA, was improved with the incorporation of pectin. Finally, pectin-cellulose nanocrystal biocomposites showed a good biodegradability in seawater, comparable to other common bioplastics such as cellulose and low-molecular weight polylactide, among others.

Preparation and Characterization of TPP-Chitosan Crosslinked Scaffolds for Tissue Engineering

Scaffolds are three-dimensional porous structures that must have specific requirements to be applied in tissue engineering. Therefore, the study of factors affecting scaffold performance is of great importance. In this work, the optimal conditions for cross-linking preformed chitosan (CS) scaffolds by the tripolyphosphate polyanion (TPP) were investigated. The effect on scaffold physico-chemical properties of different concentrations of chitosan (1 and 2% w/v) and tripolyphosphate (1 and 2% w/v) as well as of cross-linking reaction times (2, 4, or 8 h) were studied. It was evidenced that a low CS concentration favored the formation of three-dimensional porous structures with a good pore interconnection while the use of more severe conditions in the cross-linking reaction (high TPP concentration and crosslinking reaction time) led to scaffolds with a suitable pore homogeneity, thermal stability, swelling behavior, and mechanical properties, but having a low pore interconnectivity. Preliminary biocompatibility tests showed a good osteoblasts’ viability when cultured on the scaffold obtained by CS 1%, TPP 1%, and an 8-h crosslinking time. These findings suggest how modulation of scaffold cross-linking conditions may permit to obtain chitosan scaffold with properly tuned morphological, mechanical and biological properties for application in the tissue regeneration field.

Extracted Compounds from Neem Leaves as Antimicrobial Agent on the Physico-Chemical Properties of Seaweed-Based Biopolymer Films

Neem leaves extract was incorporated into the matrix of seaweed biopolymer, and the seaweed-neem biocomposite films were irradiated with various doses of gamma irradiation (0.5, 1.5, 2.5, 3.5, and 4.5 kGy). The physical, barrier, antimicrobial, and mechanical properties of the films were studied. The incorporation of 5% w/w neem leaves extract into a seaweed-based film, and gamma irradiation dose of 2.5 kGy was most effective for improved properties of the film. The results showed that the interfacial interaction of the seaweed-neem improved with physical changes in colour and opacity. The water solubility, moisture content, and water vapour permeability and biodegradability rate of the film reduced. The contact angle values increased, which was interpreted as improved hydrophobicity. The tensile strength and modulus of the films increased, while the elongation of the composite films decreased compared to the control film. The film’s antimicrobial activities against bacteria were improved. Thus, neem leaves extract in combination with the application of gamma irradiation enhanced the performance properties of the film that has potential as packaging material.

Nanocellulose: From Fundamentals to Advanced Applications

Over the past few years, nanocellulose (NC), cellulose in the form of nanostructures, has been proved to be one of the most prominent green materials of modern times. NC materials have gained growing interests owing to their attractive and excellent characteristics such as abundance, high aspect ratio, better mechanical properties, renewability, and biocompatibility. The abundant hydroxyl functional groups allow a wide range of functionalizations via chemical reactions, leading to developing various materials with tunable features. In this review, recent advances in the preparation, modification, and emerging application of nanocellulose, especially cellulose nanocrystals (CNCs), are described and discussed based on the analysis of the latest investigations (particularly for the reports of the past 3 years). We start with a concise background of cellulose, its structural organization as well as the nomenclature of cellulose nanomaterials for beginners in this field. Then, different experimental procedures for the production of nanocelluloses, their properties, and functionalization approaches were elaborated. Furthermore, a number of recent and emerging uses of nanocellulose in nanocomposites, Pickering emulsifiers, wood adhesives, wastewater treatment, as well as in new evolving biomedical applications are presented. Finally, the challenges and opportunities of NC-based emerging materials are discussed.

The Role of Two-Step Blending in the Properties of Starch/Chitin/Polylactic Acid Biodegradable Composites for Biomedical Applications

The current research trend for excellent miscibility in polymer mixing is the use of plasticizers. The use of most plasticizers usually has some negative effects on the mechanical properties of the resulting composite and can sometimes make it toxic, which makes such polymers unsuitable for biomedical applications. This research focuses on the improvement of the miscibility of polymer composites using two-step mixing with a rheomixer and a mix extruder. Polylactic acid (PLA), chitin, and starch were produced after two-step mixing, using a compression molding method with decreasing composition variation (between 8% to 2%) of chitin and increasing starch content. A dynamic mechanical analysis (DMA) was used to study the mechanical behavior of the composite at various temperatures. The tensile strength, yield, elastic modulus, impact, morphology, and compatibility properties were also studied. The DMA results showed a glass transition temperature range of 50 °C to 100 °C for all samples, with a distinct peak value for the loss modulus and factor. The single distinct peak value meant the polymer blend was compatible. The storage and loss modulus increased with an increase in blending, while the loss factor decreased, indicating excellent compatibility and miscibility of the composite components. The mechanical properties of the samples improved compared to neat PLA. Small voids and immiscibility were noticed in the scanning electron microscopy images, and this was corroborated by X-ray diffraction graphs that showed an improvement in the crystalline nature of PLA with starch. Bioabsorption and toxicity tests showed compatibility with the rat system, which is similar to the human system.

Biodegradable Carbon-based Ashes/Maize Starch Composite Films for Agricultural Applications

The aim of this work is the development and characterization of biodegradable thermoplastic recycled carbon ashes/maize starch (TPAS) composite films for agricultural applications. A proper plasticizer, that is, glycerol, was added to a commercial maize starch in an amount of 35 wt.%. Carbon-based ashes were produced by the biomass pyro-gasification plant CMD ECO 20, starting from lignocellulosic wastes. The ashes were added to glycerol and maize native starch at different amounts ranging from 7 wt. % to 21 wt.%. The composite was mixed at 130 °C for 10 min and then molded. The effect of the different amounts of carbon based ashes on the thermal and physical-mechanical properties of the composite was assessed by using several techniques, such as rheology, wide- angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), moisture absorption, degradation and mechanical tests. The presence of the carbon waste ashes allows to improve thermal and durability performances of the thermoplastic starch (TPS) films. It reduces the water absorption of starch matrix and strongly decreases the deterioration of starch, independently from fillers amount, enhancing the lifetime of the TPS films in outdoor conditions. In addition, the waste carbon ashes/maize starch films present an advantage in comparison to those of neat starch; it can biodegrade, releasing the plant nutrients contained in the ashes into the soil. In conclusion, this approach for recycling carbon waste ashes increases the efficiency of industrial waste management, along with a reduction of its impact on the environment.

Recent Trends in the Use of Pectin from Agro-Waste Residues as a Natural-Based Biopolymer for Food Packaging Applications

Regardless of the considerable progress in properties and versatility of synthetic polymers, their low biodegradability and lack of environmentally-friendly character remains a critical issue. Pectin is a natural-based polysaccharide contained in the cell walls of many plants allowing their growth and cell extension. This biopolymer can be extracted from plants and isolated as a bioplastic material with different applications, including food packaging. This review aims to present the latest research results regarding pectin, including the structure, different types, natural sources and potential use in several sectors, particularly in food packaging materials. Many researchers are currently working on a multitude of food and beverage industry applications related to pectin as well as combinations with other biopolymers to improve some key properties, such as antioxidant/antimicrobial performance and flexibility to obtain films. All these advances are covered in this review.

Biomass-Derived Dialdehyde Cellulose Cross-linked Chitosan-Based Nanocomposite Hydrogel with Phytosynthesized Zinc Oxide Nanoparticles for Enhanced Curcumin Delivery and Bioactivity

A sustainable biomass-based nanocomposite hydrogel was formulated, characterized, and applied for curcumin delivery. Phytosynthesized zinc oxide nanoparticles (ZnO NPs) employing musk melon (Cucumis melo) seed extract was embedded in the hydrogel matrices and cross-linked using Dialdehyde cellulose prepared from sugarcane (Saccharum officinarum) bagasse (SCB). Nanoparticle incorporation enhanced the hydrogel's swelling degree to 4048% at pH 4.0. Also, an improved tensile strength of 14.1 ± 0.32 MPa was exhibited by the nanocomposite hydrogel compared to 9.79 ± 0.76 MPa for the pure chitosan cellulose hydrogel. A curcumin loading efficiency of 89.68% with around 30% increased loading was exhibited for the nanocomposite hydrogel. A Fickian diffusion-controlled curcumin release mechanism with maximum release at pH 7.4 was obtained. The synergistic effect on the antimicrobial activity was exhibited against Staphylococcus aureus and Trichophyton rubrum. The in vitro cytotoxicity studies employing L929 cells and A431 cells demonstrated good biocompatibility and enhanced anticancer activity of the curcumin-loaded green nanocomposite hydrogel compared to pure curcumin.