Natural-Fiber-Reinforced Chitosan, Chitosan Blends and Their Nanocomposites for Various Advanced Applications

Native Silk Fibers: Protein Sequence and Structure Influences on Thermal and Mechanical Properties

Silk fibers produced by arthropods have inspired an array of materials with applications in healthcare, medical devices, textiles, and sustainability. Silks exhibit biodiversity with distinct variations in primary protein constituent sequences (fibroins, spidroins) and structures across taxonomic classifications, specifically the Lepidopteran and Araneae orders. Leveraging the biodiversity in arthropod silks offers advantages due to the diverse mechanical properties and thermal stabilities achievable, primarily attributed to variations in fiber crystallinity and repeating amino acid motifs. In this review, we aim to delineate known properties of silk fibers and correlate them with predicted protein sequences and secondary structures, informed by newly annotated genomes. We will discuss established patterns in repeat motifs governing specific properties and underscore the biological diversity within silk fibroin and spidroin sequences. Elucidating the relationship between protein sequences and properties of natural silk fibers will identify strategies for designing new materials through rational silk-based fiber design.

Biodegradable chitosan-based films decorated with biosynthetic copper oxide nanoparticle for post-harvest tomato preservation

Postharvest fruit decay caused by pathogens is an important factor leading to product waste and economic losses, and fruit coating is considered an effective strategy to solve this problem due to its simple operation and effectiveness. In this study, nano modified chitosan film (CSC) was created by mixing chitosan (CS) and copper oxide nanoparticles (CuO NPs) synthesized using abandoned Ficus carica fruit. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectra indicated the formation of intermolecular interactions between CS and CuO NPs in the composite film. Compared with CS film, the water vapor permeability (WVP), oxygen permeability (OP) and carbon dioxide permeability (CDP) of CSC film were decreased by 71.78 %, 38.03 % and 43.12 %, respectively, while the opacity, tensile strength (TS) and elongation at break (EB) of CSC film were improved by 8.42, 3.42 and 1.89 times, respectively. The in vitro antifungal activity of CSC film against Alternaria alternata was improved by 78.27 %, compared with CS film. Furthermore, CSC coating significantly delayed the development of tomato fruit diseases during storage, reduced respiration rate, ethylene production and weight loss. After 24 d of storage, the decay index and the weight loss rates of fruits in the CS and CSC groups decreased by 25.00 % and 48.54 %, 35.72 % and 54.08 % compared to the control, respectively. CSC coating effectively maintained the contents of ascorbic acid, titratable acid, soluble sugars, total phenols and flavonoids, while increasing copper content in the peel of tomato fruits. Complete degradation of CSC film in soil was extended by 56 d compared to CS film. To sum up, CSC coating can be a potential choice for extending the shelf life of tomato fruits, improving their edible quality and commercialization, and having better environmental friendliness.

Modulating Treg cell activity in prostate cancer via chitosan nanoparticles loaded with si-BATF/PRDM1

Prostate cancer is a significant health issue, with regulatory T (Treg) cells playing a crucial role in its progression. This study explores the potential of chitosan-modified magnetic nanoparticles loaded with si-BATF/PRDM1 to target Treg cell activity in impeding prostate cancer development. By understanding the function of BATF and PRDM1 in Treg cells, the research demonstrates their central involvement in prostate cancer progression. Through experiments in vitro and in vivo, including single-cell sequencing and gene silencing assays, chitosan nanoparticles efficiently deliver siRNA, inhibiting BATF and PRDM1 expression. This inhibition leads to suppressed tumor growth and metastasis in prostate cancer models. The findings highlight the promise of nanoparticle-based approaches in modulating Treg cell activity for prostate cancer therapy, offering a potential avenue for precision medicine interventions in combating this prevalent malignancy.

Synthesis and characterization of modified chitosan as a promising material for enterosorption of heavy metal ions

Currently, an important ecological problem is environmental pollution and its negative impact on living organisms, the consequences of which are deterioration in general health and the manifestation of various diseases, poisoning, endo- and exotoxicosis. Enterosorption method was proposed as a promising method for removing toxic substances from the living organisms using enterosorbents which can absorb various toxic substances of endogenous and exogenous nature in the lumen of the gastrointestinal tract. It has been proposed to use polymer-containing enterosorbents for eliminating of heavy metals from the organism. The purpose of this research was to synthesize a quaternized derivative of chitosan, specifically N-(2-hydroxybenzyl)-N-ethyl-N-methyl chitosan chloride (Q-CHS). The synthesis of Q-CHS involved the formation of a Schiff base, followed by the quaternization of the amino group of chitosan (CHS). The structures of both pure CHS and quaternized CHS were studied using various physico-chemical methods, including FTIR, NMR, XRD, SEM, DSC and TGA analyses in order to determine the structure and confirm the formation of the final product.

Elaboration of chitosan nanoparticles loaded with star anise extract as a therapeutic system for lung cancer: Physicochemical and biological evaluation

The research study aimed to maximize the important medical role of star anise extract (SAE) through its loading on a widely available natural polymer (chitosan, Cs). Thus, SAE loaded chitosan nanoparticles (CsNPs) was prepared. The finding illustrated the formation of spherical particles of SAE loaded CsNPs as proved by transmission electron microscope (TEM). In addition, the average particle size of CsNPs and SAE loaded CsNPs are 131.8 ± 24.63 and 318.5 ± 73.94 nm, respectively. Scanning electron microscope (SEM) showed the presence of many spherical particles deposited on the surface of CsNPs owing to the deposition of SAE on the surface and encapsulated into pores of CsNPs. It also showed the presence of elements such as sodium, potassium, copper, magnesium, zinc, calcium, and iron, as well as the elements that accompanied with CsNPs: carbon, oxygen, nitrogen, and phosphorus. The extract was rich in bioactive components, such as anethole, shikimic acid, and different flavonoids, contributing to its medicinal qualities. The bioactive molecules in SAE were assessed by chromatographic analysis. Using the agar well diffusion test, the antibacterial qualities of CsNPs and SAE loaded CsNPs were evaluated against pathogenic bacteria linked to lung illnesses. The most significant inhibition zones showed that the SAE loaded CsNPs had the most antibacterial activity. The anticancer activity using MTT assay was used in the biological assessments to determine the cytotoxicity against the NCl-H460 lung cancer cell line. The results showed that CsNPs loaded with SAE considerably decreased cell viability in a dose-dependent manner, with the most significant anticancer impact by SAE loaded CsNPs. Furthermore, in vivo tests on lung cancer therapy revealed that when compared to other treatment groups, the SAE loaded CsNPs group showed the greatest reduction in tumor biomarkers and inflammation, as seen by decreased levels of Plasma malondialdehyde (MDA), tumor protein 53 (p53), Tumor necrosis factor-alpha (TNF- alpha), and fibronectin. Results concluded that these thorough characterizations, biological assessments, and antibacterial tests have confirmed the effective integration of SAE into CsNPs. Further, SAE loaded CsNPs could be a suitable option for various biomedical applications in tackling lung cancer and the inactivation of bacterial infection.

The Properties of Thin Films Based on Chitosan/Konjac Glucomannan Blends

In this work, blend films were prepared by blending 2% chitosan (CS) and 0.5% konjac glucomannan (KGM) solutions. Five ratios of the blend mixture were implemented (95:5, 80:20, 50:50, 20:80, and 5:95), and a pure CS film and a pure KGM film were also obtained. All the polymeric films were evaluated using FTIR spectroscopy, mechanical testing, SEM and AFM imaging, thermogravimetric analyses, swelling and degradation analyses, and contact angle measurements. The CS/KGM blends were assessed for their miscibility. Additionally, the blend films' properties were evaluated after six months of storage. The proposed blends had good miscibility in a full range of composition proportions. The blend samples, compared to the pure CS film, indicated better structural integrity. The surface structure of the blend films was rather uniform and smooth. The sample CS/KGM 20:80 had the highest roughness value (Rq = 12.60 nm). The KGM addition increased the thermal stability of films. The blend sample CS/KGM 5:95 exhibited the greatest swelling ability, reaching a swelling degree of 946% in the first fifteen minutes of the analysis. Furthermore, the addition of KGM to CS improved the wettability of the film samples. As a result of their good mechanical properties, surface characteristics, and miscibility, the proposed CS/KGM blends are promising materials for topical biomedical and cosmetic applications.

Melt-Processed Polybutylene-Succinate Biocomposites with Chitosan: Development and Characterization of Rheological, Thermal, Mechanical and Antimicrobial Properties

The current research is devoted to the development and characterization of green antimicrobial polymer biocomposites for food packaging applications. The biocomposites were developed by melt compounding on the basis of two different succinate polymer matrices with varying chain stiffness-polybutylene succinate (PBS) or its copolymer with 20 mol.% of polybutylene adipate (PBSA). Fungi chitosan oligosaccharide (C98) and crustacean chitosan (C95) were used as antimicrobial additives. The rheological properties of the developed biocomposites were determined to clear out the most suitable temperature for melt processing. In addition, mechanical, thermal, barrier and antimicrobial properties of the developed biocomposites were determined. The results of the investigation revealed that PBSA composites with 7 wt% and 10 wt% of the C98 additive were more suitable for the development of green packaging films because of their higher ultimate elongation values, better damping properties as well as their superior anti-microbial behavior. However, due to the lower thermal stability of the C98 additive as well as PBSA, the melt processing temperatures of the composites desirably should not exceed 120 °C. Additionally, by considering decreased moisture vapor barrier properties, it is recommended to perform further modifications of the PBSA-C98 composites through an addition of a nanoclay additive due to its excellent barrier properties and thermal stability.

Optimization on overall performance of Modified Ultrafine Cementitious Grout Materials (MUCG) and hydration mechanism analysis

Given the challenges encountered in injecting grout into micro-cracked rock masses, a modified ultrafine cementitious grout material (MUCG) was developed using ultrafine cement, polyvinyl alcohol (PVA) fibers, and a high-efficiency superplasticizer. To identify the optimal ratio of constituents for grouting these rock masses, extreme difference and multiple linear regression analyses were conducted based on test results of flowability and mechanical properties. A mix comprising 9% silica fume, 0.2% bentonite, 0.3% PVA fibers, 0.15% superplasticizer, and 2% setting accelerator was identified as the optimal mix. The microstructure characteristics of the optimal MUCG (MUCGop) grout cemented body were analyzed using XRD, FTIR, BET, and SEM. XRD and FTIR analyses indicated that a substantial amount of C-(A)S-H gel, CH, and AFt were formed within the first 3 days, highlighting the early strength characteristics of MUCGop. Over time, the content of C-A-H stabilized at 22%, the amount of CH decreased from 19% to 14%, whereas the amount of AFt increased to 15.9% by Day 28. Unexpectedly, CaCO3 content increased due to carbonation, reaching 37.3% by Day 28. BET and SEM analyses demonstrated that the specific surface area and porosity (most probable pore size) gradually decreased over time. At various ages, mesopores (cumulative pore diameter, median pore diameter) initially increased and then decreased. Micro-cracks appeared in the cemented body by Day 7, resulting in a slight decrease in strength (3.92%) from Day 3 to Day 7. The formation of well-developed needle-like AFt, C-(A)S-H gel, and small-volume plate-like CH contributed to uniform cementation and a denser structure. From Day 7 to Day 28, there was a slight increase in strength, by an amount of 10.66%. These findings have significant scientific implications for understanding the mechanisms of grouting reinforcement in micro-cracked rock masses.

Sources and Extraction of Biopolymers and Manufacturing of Bio-Based Nanocomposites for Different Applications

In the recent era, bio-nanocomposites represent an emerging group of nanostructured hybrid materials and have been included in a new field at the frontier of materials science, life sciences, and nanotechnology. These biohybrid materials reveal developed structural and functional features of great attention for diverse uses. These materials take advantage of the synergistic assembling of biopolymers with nanometer-sized reinforcements. Conversely, polysaccharides have received great attention due to their several biological properties like antimicrobial and antioxidant performance. They mainly originated in different parts of plants, animals, seaweed, and microorganisms (bacteria, fungi, and yeasts). Polysaccharide-based nanocomposites have great features, like developed physical, structural, and functional features; affordability; biodegradability; and biocompatibility. These bio-based nanocomposites have been applied in biomedical, water treatment, food industries, etc. This paper will focus on the very recent trends in bio-nanocomposite based on polysaccharides for diverse applications. Sources and extraction methods of polysaccharides and preparation methods of their nanocomposites will be discussed.

Materials based on biodegradable polymers chitosan/gelatin: a review of potential applications

Increased mass manufacturing and the pervasive use of plastics in many facets of daily life have had detrimental effects on the environment. As a result, these worries heighten the possibility of climate change due to the carbon dioxide emissions from burning conventional, non-biodegradable polymers. Accordingly, biodegradable gelatin and chitosan polymers are being created as a sustainable substitute for non-biodegradable polymeric materials in various applications. Chitosan is the only naturally occurring cationic alkaline polysaccharide, a well-known edible polymer derived from chitin. The biological activities of chitosan, such as its antioxidant, anticancer, and antimicrobial qualities, have recently piqued the interest of researchers. Similarly, gelatin is a naturally occurring polymer derived from the hydrolytic breakdown of collagen protein and offers various medicinal advantages owing to its unique amino acid composition. In this review, we present an overview of recent studies focusing on applying chitosan and gelatin polymers in various fields. These include using gelatin and chitosan as food packaging, antioxidants and antimicrobial properties, properties encapsulating biologically active substances, tissue engineering, microencapsulation technology, water treatment, and drug delivery. This review emphasizes the significance of investigating sustainable options for non-biodegradable plastics. It showcases the diverse uses of gelatin and chitosan polymers in tackling environmental issues and driving progress across different industries.

Synthesis and characterization of Co(II) porphyrin complex supported on chitosan/graphene oxide nanocomposite for efficient green oxidation and removal of Acid Orange 7 dye

Catalytic degradation of Acid Orange 7 (AO7) by hydrogen peroxide in an aqueous solution has been investigated using cobalt(II) complex of 5, 10, 15, 20 Tetrakis [4-(hydroxy)phenyl] porphyrin [Co(II) TPHPP] covalently supported chitosan/Graphene Oxide nanocomposite [Co(II) TPHPP]-Cs/GO, as highly efficient and recoverable heterogeneous catalyst. The structures and properties of [Co(II) TPHPP]-Cs/GO nanocomposite were characterized by techniques such as UV-Vis, FT-IR, SEM, EDX, TEM, and XRD. The oxidation reaction was followed by recording the UV-Vis spectra of the reaction mixture with time at λmax = 485 nm. [Co(II) TPHPP]-Cs/GO nanocomposite demonstrated high catalytic activity and could decompose 94% of AO7 within 60 min. The factors that may influence the oxidation of Acid Orange 7, such as the effect of reaction temperature, pH, concentration of catalyst, Acid Orange 7, and hydrogen peroxide, have been studied. The results of total organic carbon analysis (TOC) showed 50% of dye mineralization under mild reaction conditions of AO7 (1.42 × 10-4M) with H2O2 (8 × 10-2M) in the presence of [Co(II) TPHPP]-Cs/GO nanocomposite (15 × 10-3 g/ml) and pH = 9 at 40 °C. The reuse and stability of the nanocomposite were examined and remarkably, even after six cycles of reuse, there was no significant degradation or deactivation of the recycled catalyst. Residual organic compounds in the reaction mixture were identified by using GC-MS analyses. The radical scavenging measurements and photoluminescence probing technology of disodium salt of terephthalic acid indicated the formation of the hydroxyl radical as the reactive oxygen species in the [Co(II) TPHPP]-Cs/GO nanocomposite/H2O2 system. A mechanism for the oxidation reaction has been discussed.

Polymer-Based Wound Dressings Loaded with Essential Oil for the Treatment of Wounds: A Review

Wound healing can result in complex problems, and discovering an effective method to improve the healing process is essential. Polymeric biomaterials have structures similar to those identified in the extracellular matrix of the tissue to be regenerated and also avoid chronic inflammation, and immunological reactions. To obtain smart and effective dressings, bioactive agents, such as essential oils, are also used to promote a wide range of biological properties, which can accelerate the healing process. Therefore, we intend to explore advances in the potential for applying hybrid materials in wound healing. For this, fifty scientific articles dated from 2010 to 2023 were investigated using the Web of Science, Scopus, Science Direct, and PubMed databases. The principles of the healing process, use of polymers, type and properties of essential oils and processing techniques, and characteristics of dressings were identified. Thus, the plants Syzygium romanticum or Eugenia caryophyllata, Origanum vulgare, and Cinnamomum zeylanicum present prospects for application in clinical trials due to their proven effects on wound healing and reducing the incidence of inflammatory cells in the site of injury. The antimicrobial effect of essential oils is mainly due to polyphenols and terpenes such as eugenol, cinnamaldehyde, carvacrol, and thymol.

Advances in chitosan-based blends as potential drug delivery systems: A review

During the last decades, the ever-increasing incidence of diseases has led to high rates of mortality throughout the world. On the other hand, the inability and deficiencies of conventional approaches (such as chemotherapy) in the suppression of diseases remain challenging issues. As a result, there is a fundamental requirement to develop novel, biocompatible, bioavailable, and practical nanomaterials to prevent the incidence and mortality of diseases. Chitosan (CS) derivatives and their blends are outstandingly employed as promising drug delivery systems for disease therapy. These biopolymers are indicated more efficient performance against diseases compared with conventional modalities. The CS blends possess improved physicochemical properties, ease of preparation, high affordability, etc. characteristics compared with other biopolymers and even pure CS which result in efficient thermal, mechanical, biochemical, and biomedical features. Also, these blends can be administrated through different routes without a long-term treatment period. Due to the mentioned properties, numerous formulations of CS blends are developed for pharmaceutical sciences to treat diseases. This review article highlights the progressions in the development of CS-based blends as potential drug delivery systems against diseases.

Fabrication and characterization of unique sustain modified chitosan nanoparticles for biomedical applications

Chitosan (CS) is a biopolymer that offers a wide range in biomedical applications due to its biocompatibility, biodegradability, low toxicity and antimicrobial activity. Syringaldehyde (1) is a naturally occurring organic compound characterized by its use in multiple fields such as pharmaceuticals, food, cosmetics, textiles and biological applications. Herein, development of chitosan derivative with physicochemical and anticancer properties via Schiff base formation from the reaction of chitosan with sustainable eco-friendly syringaldehyde yielded the (CS-1) derivative. Moreover, in the presence of polyethylene glycol diglycidyl ether (PEGDGE) or sodium tripolyphosphate (TPP) as crosslinkers gave chitosan derivatives (CS-2) and (CS-3NPs) respectively. The chemical structures of the new chitosan derivatives were confirmed using different tools. (CS-3NPs) nanoparticle showed improvement in crystallinity, and (CS-2) derivative revealed the highest thermal stability compared to virgin chitosan. The cytotoxicity activity of chitosan and its derivatives were evaluated against HeLa (human cervical carcinoma) and HEp-2 (Human Larynx carcinoma) cell lines. The highest cytotoxicity activity was exhibited by (CS-3NPs) compared to virgin chitosan against HeLa cell growth inhibition and apoptosis of 90.38 ± 1.46% and 30.3% respectively and IC50 of 108.01 ± 3.94 µg/ml. From the above results, it can be concluded that chitosan nanoparticle (CS-3NPs) has good therapeutic value as a potential antitumor agent against the HeLa cancer cell line.

One-step fabrication of millimeter-scale hollow vesicles with chitosan /DADMAC/ sodium alginate graft copolymer for enhanced anionic dye adsorption

Hollow vesicles are promising in water treatment due to their unique structure of the membrane and inner cavity. However, the adsorption capacity needs to be improved for targeted pollutants. Herein, millimeter-scale hollow vesicles were prepared with a one-step process of sequential stirring and grafting using chitosan, diallyldimethylammonium chloride, and sodium alginate as raw materials with the purpose of efficient removal of anionic dyes from wastewater. The composite vesicles were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The hollow vesicles showed the structure of the cationic membrane and the inner cavity, facilitating the dye adsorption. The adsorption capacity for the anionic dye Reactive Black 5 reached 698.1 mg/g, more than twice that of the binary composite vesicles without graft. The adsorption kinetics and isotherm data coincided with the pseudo-second-order and Langmuir models, respectively, and the adsorption mechanism was monolayer chemisorption. Moreover, the vesicles worked well in wide ranges of environment pH, temperature, and co-existing pollutants. They also possessed excellent cyclic regeneration performance, in which 93 % of the initial adsorption capacity was maintained after four cycles. These results indicate that the millimeter-scale hollow vesicles exhibit broad application prospects for wastewater purification.

Machine intelligence-accelerated discovery of all-natural plastic substitutes

One possible solution against the accumulation of petrochemical plastics in natural environments is to develop biodegradable plastic substitutes using natural components. However, discovering all-natural alternatives that meet specific properties, such as optical transparency, fire retardancy and mechanical resilience, which have made petrochemical plastics successful, remains challenging. Current approaches still rely on iterative optimization experiments. Here we show an integrated workflow that combines robotics and machine learning to accelerate the discovery of all-natural plastic substitutes with programmable optical, thermal and mechanical properties. First, an automated pipetting robot is commanded to prepare 286 nanocomposite films with various properties to train a support-vector machine classifier. Next, through 14 active learning loops with data augmentation, 135 all-natural nanocomposites are fabricated stagewise, establishing an artificial neural network prediction model. We demonstrate that the prediction model can conduct a two-way design task: (1) predicting the physicochemical properties of an all-natural nanocomposite from its composition and (2) automating the inverse design of biodegradable plastic substitutes that fulfils various user-specific requirements. By harnessing the model's prediction capabilities, we prepare several all-natural substitutes, that could replace non-biodegradable counterparts as exhibiting analogous properties. Our methodology integrates robot-assisted experiments, machine intelligence and simulation tools to accelerate the discovery and design of eco-friendly plastic substitutes starting from building blocks taken from the generally-recognized-as-safe database.

Influence of chitosan protonation degree in nanofibrillated cellulose/chitosan composite films and their morphological, mechanical, and surface properties

Composite films of nanofibrillated cellulose (NFC) and chitosan (CS) were prepared by spray deposition method, and the influence of polymers ratio and protonation degree (α) of chitosan was evaluated. Films were characterized using morphological, mechanical, and surface techniques. Higher NFC content increased Young's modulus of film composites and reduced air permeability, while higher CS content increased water contact angle. Variations in the degree of protonation of chitosan from non-protonated (α = 0) to fully protonated (α = 1) in the NFC/CS composite film with a fixed composition allowed to modulate surface, mechanical, and structural properties, such as water contact angle (31.3-109.2°), Young's modulus (1.7-5.3 GPa), elongation at break (3.1-1.2 %), oxygen transmission rate (9.0-5.5 cm3/m2day) and air permeability (2074-426 s). Highly protonated chitosan composite films showed similar contact angles to pure chitosan films, while low protonated chitosan composite films presented contact angles similar to pure NFC films, suggesting a possible coating effect of NFC by CS through electrostatic interactions, evidenced by microscopy and spectroscopy analysis. By mixing both polymers and adjusting composition and protonation degree it was possible to enhance their properties, making pH adjustment a useful tool for NFC/CS composite films formation.

Advancements in Hybrid Cellulose-Based Films: Innovations and Applications in 2D Nano-Delivery Systems

This review paper delves into the realm of hybrid cellulose-based materials and their applications in 2D nano-delivery systems. Cellulose, recognized for its biocompatibility, versatility, and renewability, serves as the core matrix for these nanomaterials. The paper offers a comprehensive overview of the latest advancements in the creation, analysis, and application of these materials, emphasizing their significance in nanotechnology and biomedical domains. It further illuminates the integration of nanomaterials and advanced synthesis techniques that have significantly improved the mechanical, chemical, and biological properties of hybrid cellulose-based materials.

The Controlled Release of Abscisic Acid (ABA) Utilizing Alginate-Chitosan Gel Blends: A Synergistic Approach for an Enhanced Small-Molecule Delivery Controller

The integration of abscisic acid (ABA) into a chitosan-alginate gel blend unveils crucial insights into the formation and stability of these two substances. ABA, a key phytohormone in plant growth and stress responses, is strategically targeted for controlled release within these complexes. This study investigates the design and characterization of this novel controlled-release system, showcasing the potential of alginate-chitosan gel blends in ABA delivery. Computational methods, including molecular dynamics simulations, are employed to analyze the structural effects of microencapsulation, offering valuable insights into complex behavior under varying conditions. This paper focuses on the controlled release of ABA from these complexes, highlighting its strategic importance in drug delivery systems and beyond. This controlled release enables targeted and regulated ABA delivery, with far-reaching implications for pharmaceuticals, agriculture, and plant stress response studies. While acknowledging context dependency, the paper suggests that the liberation or controlled release of ABA holds promise in applications, urging further research and experimentation to validate its utility across diverse fields. Overall, this work significantly contributes to understanding the characteristics and potential applications of chitosan-alginate complexes, marking a noteworthy advancement in the field of controlled-release systems.

Nanomicrosphere sustained-release urokinase systems with antioxidant properties for deep vein thrombosis therapy

Deep vein thrombosis (DVT) is a venous return disorder caused by abnormal clotting of blood in deep veins. After thrombosis, most of the thrombus will spread to the deep vein trunk throughout the limb. If DVT is not treated in time, most of them will develop into thrombosis sequelae and even threaten life. Intravenous thrombolytic drugs are the most promising strategy for treating DVT, but current drugs used for thrombolysis suffer from short half-lives and narrow therapeutic indexes. To effectively manage DVT, it is necessary to develop a novel multifunctional drug-loading system to effectively prolong the treatment time and improve the therapeutic efficacy. In this study, a urokinase-loaded protocatechuic aldehyde-modified chitosan microsphere drug-loading platform was constructed for the treatment of DVT. This microsphere adsorbed urokinase well through electrostatic interaction, and the introduction of bovine serum albumin conferred stability to the microspheres. Therefore, the microsphere drug delivery system could achieve slow drug release to effectively dissolve blood fibrin. In addition, chitosan grafted with protocatechuic aldehyde imparted excellent antioxidant activity to the system to reduce free radicals in the blood vessels. Effective management of oxidative stress could avoid abnormal platelet activation and new thrombus formation. The experimental results showed that this microsphere had good biocompatibility, anti-inflammatory properties, and considerable thrombolytic activity. In conclusion, this study provided a new direction and developed a novel multi-functional nano microsphere drug delivery platform for the treatment of DVT.

Extraction of lignocellulosic fiber and cellulose microfibrils from agro waste-palmyra fruit peduncle: Water retting, chlorine-free chemical treatments, physio-chemical, morphological, and thermal characterization

In this paper, lignocellulosic fibers and cellulose microfibrils (CMFs) were extracted from palmyra fruit peduncle waste and investigated as naturally derived cellulosic materials for their potential use as reinforcement materials in composite applications. The physicochemical, mechanical, and thermal properties of the extracted fiber were studied. Physical and morphological analysis results revealed an extracted fiber diameter of 82.5 μm with a very rough surface, providing excellent interfacial bonding performance with the polymer matrix. Chemical, mechanical, and thermal results showed that the fibers consist mainly of cellulose as their crystallized phase, with a cellulose content of 56.5 wt% and a tensile strength of 693.3 MPa, along with thermal stability up to 252 °C. The chemically extracted CMFs exhibit a short, rough-surfaced, cylindrical cellulose structure with a diameter range of 10-15 μm. These CMFs demonstrate excellent thermal stability, withstanding temperatures up to 330 °C. Furthermore, the formation of CMFs is evident from a substantial increase in the crystallinity index, which increased from 58.2 % in the raw fibers to 78.2 % in the CMFs. FT-IR analysis further confirms the successful removal of non-cellulosic materials through chlorine-free chemical treatments. These findings strongly support the potential use of extracted fibers and CMFs as reinforcement materials in polymers.

A Review of the Preparation of Porous Fibers and Porous Parts by a Novel Micro-Extrusion Foaming Technique

This review introduces an innovative technology termed "Micro-Extrusion Foaming (MEF)", which amalgamates the merits of physical foaming and 3D printing. It presents a groundbreaking approach to producing porous polymer fibers and parts. Conventional methods for creating porous materials often encounter obstacles such as the extensive use of organic solvents, intricate processing, and suboptimal production efficiency. The MEF technique surmounts these challenges by initially saturating a polymer filament with compressed CO2 or N2, followed by cell nucleation and growth during the molten extrusion process. This technology offers manifold advantages, encompassing an adjustable pore size and porosity, environmental friendliness, high processing efficiency, and compatibility with diverse polymer materials. The review meticulously elucidates the principles and fabrication process integral to MEF, encompassing the creation of porous fibers through the elongational behavior of foamed melts and the generation of porous parts through the stacking of foamed melts. Furthermore, the review explores the varied applications of this technology across diverse fields and imparts insights for future directions and challenges. These include augmenting material performance, refining fabrication processes, and broadening the scope of applications. MEF technology holds immense potential in the realm of porous material preparation, heralding noteworthy advancements and innovations in manufacturing and materials science.

Research progress on chitin/chitosan-based emulsion delivery systems and their application in lipid digestion regulation

Excessive lipid intake is linked to an elevated risk of health problems. However, reducing lipid contents may influence food structure and flavor. Some alternatives are needed to control the lipid absorption. Emulsions are common carriers for lipids, which can control the hydrolysis and absorption of lipids. Chitin (Ch) and chitosan (CS) are natural polysaccharides with good biodegradability, biocompatibility, and unique cationic properties. They have been reported to be able to delay lipolysis, which can be regarded as one of the most promising agents that regulates lipid digestion (LiD). The application of Ch/CS and their derivatives in emulsions are summarized in this review with a focus on their performances and mechanisms for LiD regulation, aiming to provide theoretical guidance for the development of novel Ch/CS emulsions, and the regulation of LiD. A reasonable design of emulsion interface can provide its resistance to the external environment and then control LiD. The properties of emulsion interface are the key factors affecting LiD. Therefore, systematic study on the relationship between Ch/CS-based emulsion structure and LiD can not only instruct the reasonable design of emulsion interface to accurately regulate LiD, but also provide scientific guidelines for applying Ch/CS in functional food, medicine and other fields.

Luminescent Hybrid BPA.DA-NVP@Eu2L3 Materials: In Situ Synthesis, Spectroscopic, Thermal, and Mechanical Characterization

A series of homogeneous hybrid BPA.DA-NVP@Eu2L3 materials were obtained through an in situ approach where the luminescent dopant was formed at the molecular level with different contents (0.1; 0.2; 0.5; 1; and 2% by weight). A Europium(III) complex (Eu2L3) with quinoline-2,4-dicarboxylic acid was applied as a luminescence additive while a polymer matrix consisted of a combination of bisphenol A diacrylate (BPA.DA) and N-vinylpyrrolidone (NVP) monomers. Synthesis steps and the final materials were monitored by NMR and Fourier transform infrared spectroscopy (FTIR). The emission, excitation spectra, lifetime, and quantum yield measurements were applied for the determination of the photophysical characteristics. The thermal and mechanical properties of the obtained materials were tested via thermal analysis methods (TG/DTG/DSC and TG-FTIR) in air and nitrogen atmospheres, dynamic mechanical analysis (DMA), and hardness and bending measurements. Generally, even a small addition of the metal complex component causes changes in the thermal, mechanical, and luminescent properties. Hybrid materials with a greater europium complex content are characterized by a lower stiffness and hardness while the heterogeneity and the flexibility of the samples increase. A very small amount of an Eu2L3 admixture (0.1% wt.) in a hybrid material causes an emission in the red spectral range and the luminescence intensity was reached for the BPA-DA-NVP@1%Eu2L3 material. These materials may be potentially used in chemical sensing, security systems, and protective coatings against UV.

Polysaccharide-based antibacterial coating technologies

To tackle antimicrobial resistance, a global threat identified by the United Nations, is a common cause of healthcare-associated infections (HAI) and is responsible for significant costs on healthcare systems, a substantial amount of research has been devoted to developing polysaccharide-based strategies that prevent bacterial attachment and biofilm formation on surfaces. Polysaccharides are essential building blocks for life and an abundant renewable resource that have attracted much attention due to their intrinsic remarkable biological potential antibacterial activities. If converted into efficient antibacterial coatings that could be applied to a broad range of surfaces and applications, polysaccharide-based coatings could have a significant potential global impact. However, the ultimate success of polysaccharide-based antibacterial materials will be determined by their potential for use in manufacturing processes that are scalable, versatile, and affordable. Therefore, in this review we focus on recent advances in polysaccharide-based antibacterial coatings from the perspective of fabrication methods. We first provide an overview of strategies for designing polysaccharide-based antimicrobial formulations and methods to assess the antibacterial properties of coatings. Recent advances on manufacturing polysaccharide-based coatings using some of the most common polysaccharides and fabrication methods are then detailed, followed by a critical comparative overview of associated challenges and opportunities for future developments. STATEMENT OF SIGNIFICANCE: Our review presents a timely perspective by being the first review in the field to focus on advances on polysaccharide-based antibacterial coatings from the perspective of fabrication methods along with an overview of strategies for designing polysaccharide-based antimicrobial formulations, methods to assess the antibacterial properties of coatings as well as a critical comparative overview of associated challenges and opportunities for future developments. Meanwhile this work is specifically targeted at an audience focused on featuring critical information and guidelines for developing polysaccharide-based coatings. Including such a complementary work in the journal could lead to further developments on polysaccharide antibacterial applications.

Development and Evaluation of Cross-Linked Alginate-Chitosan-Abscisic Acid Blend Gel

Abscisic acid (ABA) has been proposed to play a significant role in the ripening of nonclimacteric fruit, stomatal opening, and response to abiotic stresses in plants, which can adversely affect crop growth and productivity. The biological effects of ABA are dependent on its concentration and signal transduction pathways. However, due to its susceptibility to the environment, it is essential to find a suitable biotechnological approach to coat ABA for its application. One promising approach is to utilize alginate and chitosan, two natural polysaccharides known for their strong affinity for water and their ability to act as coating agents. In this study, an alginate-chitosan blend was employed to develop an ABA cover. To achieve this, an alginate-chitosan-abscisic acid (ALG-CS-ABA) blend was prepared by forming ionic bonds or complexes with calcium ions, or through dual cross-linking. This was done by dripping a homogeneous solution of alginate-chitosan and ABA into a calcium chloride solution, resulting in the formation of the blend. By combining the unique properties of alginate, chitosan, and ABA, the resulting ALG-CS-ABA blend can potentially offer enhanced stability, controlled release, and improved protection of ABA. These characteristics make it a promising biotechnological approach for various applications, including the targeted delivery of ABA in agricultural practices or in the development of innovative plant-based products. Further evaluation and characterization of the ALG-CS-ABA blend will provide valuable insights into its potential applications in the fields of biomedicine, agriculture, and tissue engineering.

Influence of Woven Glass-Fibre Prepreg Orientation on the Flexural Properties of a Sustainable Composite Honeycomb Sandwich Panel for Structural Applications

Owing to the high potential application need in the aerospace and structural industry for honeycomb sandwich composite, the study on the flexural behaviour of sandwich composite structure has attracted attention in recent decades. The excellent bending behaviour of sandwich composite structures is based on their facesheet (FS) and core materials. This research studied the effect of woven glass-fibre prepreg orientation on the honeycomb sandwich panel. A three-point bending flexural test was done as per ASTM C393 standard by applying a 5 kN load on different orientation angles of woven glass-fibre prepreg honeycomb sandwich panel: α = 0°, 45° and 90°. The results show that most of the sandwich panel has almost the same failure mode during the three-point bending test. Additionally, the α = 0° orientation angle shows a higher maximum load prior to the first failure occurrence compared to others due to higher flexibility but lower stiffness. In addition, the woven glass-fibre prepreg orientation angle, α = 0°, has the maximum stress and flexural modulus, which directly depend upon the maximum load value obtained during the flexural test. In addition, the experimental results and analytical prediction for honeycomb sandwich deflection show good agreement. According to the result obtained, it is revealed that woven glass-fibre honeycomb sandwich panels with an α = 0° orientation is a good alternative compared to 45° and 90°, especially when better bending application is the main purpose. The final result of this research can be applied to enhance the properties of glass-fibre-reinforced polymer composite (GFRPC) cross-arm and enhance the existing cross-arm used in high transmission towers.

A Blend Consisting of Agaran from Seaweed Gracilaria birdiae and Chromium Picolinate Is a Better Antioxidant Agent than These Two Compounds Alone

A blend refers to the combination of two or more components to achieve properties that are superior to those found in the individual products used for their production. Gracilaria birdiae agaran (SPGb) and chromium picolinate (ChrPic) are both antioxidant agents. However, there is no documentation of blends that incorporate agarans and ChrPic. Hence, the objective of this study was to generate blends containing SPGb and ChrPic that exhibit enhanced antioxidant activity compared to SPGb or ChrPic alone. ChrPic was commercially acquired, while SPGb was extracted from the seaweed. Five blends (B1; B2; B3; B4; B5) were produced, and tests indicated B5 as the best antioxidant blend. B5 was not cytotoxic or genotoxic. H₂O₂ (0.6 mM) induced toxicity in fibroblasts (3T3), and this effect was abolished by B5 (0.05 mg·mL^-1); neither ChrPic nor SPGb showed this effect. The cells also showed no signs of toxicity when exposed to H₂O₂ after being incubated with B5 and ChrPic for 24 h. In another experiment, cells were incubated with H₂O₂ and later exposed to SPGb, ChrPic, or B5. Again, SPGb was not effective, while cells exposed to ChrPic and B5 reduced MTT by 100%. The data demonstrated that B5 has activity superior to SPGb and ChrPic and points to B5 as a product to be used in future in vivo tests to confirm its antioxidant action. It may also be indicated as a possible nutraceutical agent.

Development of Chitosan Green Composites Reinforced with Hemp Fibers: Study of Mechanical and Barrier Properties for Packaging Application

The use of bioresourced packaging materials is an interesting solution for ecological issues. This work aimed to develop novel chitosan-based packaging materials reinforced with hemp fibers (HF). For this purpose, chitosan (CH) films were filled with 15%, 30%, and 50% (w/w) of two kinds of HF: Untreated fibers cut to 1 mm (UHF) and steam exploded fibers (SEHF). The effect of HF addition and HF treatments on chitosan composites was studied in terms of mechanical properties (tensile strength (TS), elongation at break (EB), and Young's modulus (YM)), barrier properties (water vapor (WVP) and oxygen permeabilities), and thermal properties (glass transition (Tg) and melting temperatures (Tm)). The addition of HF, whether untreated or steam exploded, increased the TS of chitosan composites by 34-65%. WVP was significantly reduced by the addition of HF but no significant change was observed for O2 barrier property, which was in the range between 0.44 and 0.68 cm3·mm/m2·d. Tm of the composite films increased from 133 °C for CH films to 171 °C for films filled with 15% SEHF. However, no significant modification was observed for Tg (105-107 °C). The present study showed that the developed biocomposites had improved properties, mainly the mechanical resistance. Their use in food packaging will help industrials the move toward a sustainable development and circular economy.

The Unique Morphology of Coconut Petiole Fibers Facilitates the Fabrication of Plant Composites with High Impact Performance

The present work explored alkali-treated coconut petiole fibers (ACPFs) characterization and the effect of fiber loadings on the mechanical properties of poly (lactic acid) (PLA)/ACPF composites for the first time. The physical, mechanical, and interfacial properties, as well as the morphology of the ACPFs were reported. It was found that ACPFs with a density of 0.92 g/cm³ have average tensile strength and tensile modulus equal to 355.77 MPa and 5212.36 MPa. The interfacial strength between ACPFs and PLA was high (14.06 MPa), attributed to the micro-sized holes on the fibers, as established from SEM micrographs. Then composites with varying fiber loadings were fabricated by melt-blending and compression molding. The mechanical (tensile, flexural, and impact) performance of composites was reported. Based on the high interfacial strength between fibers and PLA and the unique "spiral" structure of fibers, the composites reached a high impact strength of 8.2 kJ/m² and flexural modulus of 6959.70 MPa at 50 wt.%, representing 150% and 50% improvement relative to pure PLA.

Alginate Based Core-Shell Capsules Production through Coextrusion Methods: Recent Applications

Encapsulation is used in various industries to protect active molecules and control the release of the encapsulated materials. One of the structures that can be obtained using coextrusion encapsulation methods is the core-shell capsule. This review focuses on coextrusion encapsulation applications for the preservation of oils and essential oils, probiotics, and other bioactives. This technology isolates actives from the external environment, enhances their stability, and allows their controlled release. Coextrusion offers a valuable means of preserving active molecules by reducing oxidation processes, limiting the evaporation of volatile compounds, isolating some nutrients or drugs with undesired taste, or stabilizing probiotics to increase their shelf life. Being environmentally friendly, coextrusion offers significant application opportunities for the pharmaceutical, food, and agriculture sectors.

Flexible self-healing nanocomposite based gelatin/tannic acid/acrylic acid reinforced with zinc oxide nanoparticles and hollow silver nanoparticles based on porous silica for rapid wound healing

In this research, gelatin (Ge), tannic acid (TA), acrylic acid (AA) as a matrix are used. Zinc oxide (ZnO) nanoparticles (10, 20, 30, 40 and 50 wt%) and hollow silver nanoparticles along with ascorbic acid (1, 3, and 5 wt%) are considered as reinforcement. In order to prove the functional groups of nanoparticles made from Fourier-transform infrared spectroscopy (FTIR), and determine the existing phases of the powders in the hydrogel, X-ray diffraction (XRD) is used, also to investigate the morphology, size, and porosity of the holes and in the scaffolds, scanning electron microscope analysis is used (FESEM). Then, mechanical tests such as tension and compression test are performed to determine the most optimal state of the composite. Also, the antibacterial test is performed for the manufactured powders and hydrogel, as well as the toxicity test for the fabricated hydrogel. The results show that the sample (30 wt% of zinc oxide and 5 wt% of hollow nanoparticles) is the most optimal hydrogel based on mechanical tests and biological properties.

Effect of corn husk fibre loading on thermal and biodegradable properties of kenaf/cornhusk fibre reinforced corn starch-based hybrid composites

This paper documents the thermal and biodegradation behaviour of kenaf/cornhusk fiber reinforced corn starch-based hybrid composites film (CS/K-CH) produced by solution casting method. To develop both components as biodegradable hybrid composite, this research used corn starch as matrix, kenaf fiber and cornhusk fibre as a filler. Changes in physical structure and weight from the soil burial test were measured using Mettler Toledo digital balance ME. Films produced from physically blended corn starch reinforced kenaf biocomposites films (CS/K) biocomposite film had faster biodegradation and lost 96.18% of weight within 10 days compared with corn starch hybrid composites that only lost 83.82% of total weight. It was observed that the control film, CS/K biocomposite film was completely degraded after 10 days, meanwhile it took 12 days for hybrid composite films to be fully degrade. The thermal properties such as TGA and DTG were also measured. Addition of corn husk fiber significantly improve the film's thermal properties. Glass transition temperatures of corn starch hybrid films were significantly lowered when cornhusk compositions were increased from 0.2% wt to 0.8% wt. Importantly, the current work has demonstrated that hybrid films made of corn starch can be a suitable biodegradable material for substitute synthetic plastic.

Natural Polymeric Composites Derived from Animals, Plants, and Microbes for Vaccine Delivery and Adjuvant Applications: A Review

A key element in ensuring successful immunization is the efficient delivery of vaccines. However, poor immunogenicity and adverse inflammatory immunogenic reactions make the establishment of an efficient vaccine delivery method a challenging task. The delivery of vaccines has been performed via a variety of delivery methods, including natural-polymer-based carriers that are relatively biocompatible and have low toxicity. The incorporation of adjuvants or antigens into biomaterial-based immunizations has demonstrated better immune response than formulations that just contain the antigen. This system may enable antigen-mediated immunogenicity and shelter and transport the cargo vaccine or antigen to the appropriate target organ. In this regard, this work reviews the recent applications of natural polymer composites from different sources, such as animals, plants, and microbes, in vaccine delivery systems.

Recent progressions in biomedical and pharmaceutical applications of chitosan nanoparticles: A comprehensive review

Nowadays, the most common approaches in the prognosis, diagnosis, and treatment of diseases are along with undeniable limitations. Thus, the ever-increasing need for using biocompatible natural materials and novel practical modalities is required. Applying biomaterials, such as chitosan nanoparticles (CS NPs: FDA-approved long-chain polymer of N-acetyl-glucosamine and D-glucosamine for some pharmaceutical applications), can serve as an appropriate alternative to overcome these limitations. Recently, the biomedical applications of CS NPs have extensively been investigated. These NPs and their derivatives can not only prepare through different physical and chemical approaches but also modify with various molecules and bioactive materials. The potential properties of CS NPs, such as biocompatibility, biodegradability, serum stability, solubility, non-immunogenicity, anti-inflammatory properties, appropriate pharmacokinetics and pharmacodynamics, and so forth, have made them excellent candidates for biomedical applications. Therefore, CS NPs have efficiently applied for various biomedical applications, like regenerative medicine and tissue engineering, biosensors for the detection of microorganisms, and drug delivery systems (DDS) for the suppression of diseases. These NPs possess a high level of biosafety. In summary, CS NPs have the potential ability for biomedical and clinical applications, and it would be remarkably beneficial to develop new generations of CS-based material for the future of medicine.

Rice thermoplastic starch nanocomposite films reinforced with nanocellulose

Rice starch is a raw material with proven potential in obtaining biodegradable polymers. Plasticization improves the flexibility characteristics of starch-based films, although they still tend to have low tensile strength and high hydrophilicity. The addition of nanocellulosic materials is an alternative to improve these characteristics. In this chapter, the effects of adding different sources and concentrations of nanocellulose (NC) on the properties of thermoplastic rice starch films (TRSF) are addressed. One can highlight as main effects the increase of tensile strength and transparency of the films, the reduction of water vapor permeability and water solubility. The type of NC used, the way it is obtained, as well as its interaction with starch molecules are factors that influence the effects. Further studies involving the interaction of TRSF and NC should be conducted in order to overcome the lack of information.

Silane treated starch dispersed PBAT/PHBV-based composites: Improved barrier performance for single-use plastic alternatives

The objective of this study is to include 5 wt% silane-treated starch (S-t-Starch) into biodegradable flexible poly(butylene adipate-co-terephthalate) (PBAT)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) blend matrix, which can facilitate superior barrier and balanced mechanical properties. With the intension of improving compatibilization between matrix and filler, starch (biological macromolecule) was efficiently treated with 15 wt% of 3-glycidoxypropyl trimethoxy silane (GPTMS), a coupling agent. Various analyses such as barrier, mechanical, thermal, surface morphology and rheological were performed using cast extruded PBAT/PHBV-based composite films. Comprehensive characterizations suggested that cast extruded PBAT/PHBV with 5 wt% S-t-Starch composites exhibited 91 and 82 % improvement in oxygen and water vapor barrier, respectively, compared to PBAT film. The increment in % crystallinity (as supported by DSC analysis) of PBAT/PHBV/5%S-t-Starch composite due to the silane component was one of the reasons for barrier improvement. The other reason was the improved interfacial adhesion between matrix and S-t-Starch particles (as supported by SEM analysis), which restricted the mobility of the polymer chains. The elongation at break (%EB) of the cast extruded PBAT/PHBV/5%Starch film was slightly improved from 536 to 542 % after silane treatment. Hence, the developed polymer composite in this research work can contribute to flexible packaging applications that require improved barrier properties.

Green synthesis of chitosan/erythritol/graphene oxide composites for simultaneous removal of some toxic species from simulated solution

In this study, chitosan (Ch) is adapted via green methodology including sonication induced crosslinking with different weight ratios of erythritol (Er) from (Ch-Er)1 to (Ch-Er)4. The products were casted in the form of thin films. The chemical modification was proved via FTIR spectroscopy. Then, the modified products were verified via an atomic force microscopy (AFM) investigation for their topography and surface properties. The data revealed that the optimized sample was (Ch-Er)3. This sample was further modified by different weight ratios of graphene oxide 0.1, 0.2, 0.4, and 0.8 wt./wt. (symbolized as (Ch-Er)3GO1, (Ch-Er)3GO2, (Ch-Er)3GO4, and (Ch-Er)3GO8 respectively). The prepared samples were investigated by different analytical tools. Then, the adjusted sample (Ch-Er)3GO2 was irradiated by electron beam (e-beam) at 10 and 20 kGy of irradiation doses to give samples (Ch-Er)3GO2R10 and (Ch-Er)3GO2R20, respectively. The AFM data of the irradiated samples showed that the pore size decreases, and surface roughness increases at higher energy e-beam due to the formation of more crosslinking points. The optimum samples of the prepared formulations were tested as sorbent materials for simultaneous elimination of methylene blue (MB) dye and mercury cation (Hg2+) from simulated solutions. The maximum removal of both MB dye and Hg2+ cation was achieved by (Ch-Er)3GO2R10 (186.23 mg g-1 and 205 mg g-1) respectively.

Biodegradable Electrospun Nanofiber Membranes as Promising Candidates for the Development of Face Masks

Aerosol particles, such as the widespread COVID-19 recently, have posed a great threat to humans. Combat experience has proven that masks can protect against viruses; however, the epidemic in recent years has caused serious environmental pollution from plastic medical supplies, especially masks. Degradable filters are promising candidates to alleviate this problem. Degradable nanofiber filters, which are developed by the electrospinning technique, can achieve superior filtration performance. This review focuses on the basic introduction to air filtration, the general aspects of face masks, and nanofibers. Furthermore, the progress of the state of art degradable electrospun nanofiber filters have been summarized, such as silk fibroin (SF), polylactic acid (PLA), chitosan, cellulose, and zein. Finally, the challenges and future development are highlighted.

Effect of Wood Dust Fibre Treatments Reinforcement on the Properties of Recycled Polypropylene Composite (r-WoPPC) Filament for Fused Deposition Modelling (FDM)

The efficacy of wood dust fibre treatment on the property of wood dust reinforced recycled polypropylene composite (r-WoPPC) filament was investigated. The wood dust fibre was treated using alkali, silane, and NaOH-silane. The treated wood fibre was incorporated with r-PP using a twin-screw extruder to produce filament. The silane treatment on wood dust fibre enhances interfacial bonding between wood fibre and recycled PP; hence, a filament has the highest wire pull strength, which is 35.2% higher compared to untreated and alkaline-treated wood dust filament. It is because silanol in silane forms a siloxane bond that acts as a coupling agent that improves interfacial bonding between wood dust fibre and recycled PP. The SEM micrograph of the fracture structure reveals that treated silane has strong interfacial bonding between wood dust fibre and recycled PP, having minimal void, gap, and good fibre adhesion. The water absorption test results indicate that filament with treated wood dust absorbs less water than filament with untreated wood because the treatment minimizes the gap between wood fibres and recycled PP. The FTIR analysis identified the presence of silane on the wood dust surface for silane-treated wood dust. The DSC studies suggest that the temperature range 167-170 °C be used in the extrusion machine to produce r-WoPPC filament. As a result, r-WoPPc filaments containing silane-treated wood dust have better mechanical properties and have a greater potential for usage in FDM applications.

PVA/Chitosan Thin Films Containing Silver Nanoparticles and Ibuprofen for the Treatment of Periodontal Disease

Local delivery of drugs or antimicrobial agents is a suitable approach in the management of periodontitis when the infection is localized deep in the pockets and does not adequately respond to mechanical debridement and/or systemic antibiotic treatment. In this context, the objective of this study was to prepare new biocomposite films with antimicrobial, anti-inflammatory, and good mechanical properties to be applied in periodontal pockets. The composite film is eco-friendly synthesized from poly(vinyl alcohol) (PVA) cross-linked with oxidized chitosan (OxCS). Silver nanoparticles (AgNps) were inserted during film synthesis by adding freshly chitosan-capped AgNps colloidal solution to the polymer mixture; the addition of AgNps up to 1.44 wt.% improves the physico-chemical properties of the film. The characterization of the films was performed by FT-IR, atomic mass spectrometry, X-ray spectroscopy, and SEM. The films displayed a high swelling ratio (162%), suitable strength (1.46 MPa), and excellent mucoadhesive properties (0.6 N). Then, ibuprofen (IBF) was incorporated within the best film formulation, and the IBF-loaded PVA/OxCS-Ag films could deliver the drug in a sustained manner up to 72 h. The biocomposite films have good antimicrobial properties against representative pathogens for oral cavities. Moreover, the films are biocompatible, as demonstrated by in vitro tests on HDFa cell lines.

Effect of Agar on the Mechanical, Thermal, and Moisture Absorption Properties of Thermoplastic Sago Starch Composites

Thermoplastic starch is a material that has the potential to be environmentally friendly and biodegradable. However, it has certain drawbacks concerning its mechanical performance and is sensitive to the presence of moisture. The current study assessed agar-containing thermoplastic sago starch (TPSS) properties at various loadings. Variable proportions of agar (5%, 10%, and 15% wt%) were used to produce TPSS by the hot-pressing method. Then, the samples were subjected to characterisation using scanning electron microscopy (SEM), mechanical analysis, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and moisture absorption tests. The results demonstrated that adding agar to starch-based thermoplastic blends significantly improved their tensile, flexural, and impact properties. The samples' morphology showed that the fracture had become more erratic and uneven after adding agar. FT-IR revealed that intermolecular hydrogen bonds formed between TPSS and agar. Moreover, with an increase in agar content, TPSS's thermal stability was also increased. However, the moisture absorption values among the samples increased slightly as the amount of agar increased. Overall, the proposed TPSS/agar blend has the potential to be employed as biodegradable material due to its improved mechanical characteristics.

Effect of Chemical Treatment of Sugar Palm Fibre on Rheological and Thermal Properties of the PLA Composites Filament for FDM 3D Printing

The thermal and rheological properties of bio-composite filament materials are crucial characteristics in the development of a bio-composite Fused Deposition Modeling (FDM) filament since the printing mechanism of FDM strongly depends on the heating and extrusion process. The effect of chemical treatment on the thermal and rheological properties was investigated to develop composite filaments for FDM using natural fibres such as sugar palm fibre (SPF). SPF underwent alkaline and silane treatment processes before being reinforced with PLA for improving adhesion and removing impurities. Thermogravimetric Analysis (TGA), Differential Scanning Calorimetric (DSC), and Melt Flow Index (MFI) analyses were conducted to identify the differences in thermal properties. Meanwhile, a rheological test was conducted to investigate the shear stress and its viscosity. The TGA test shows that the SPF/PLA composite treated with NaOH and silane showed good thermal stability at 789.5 °C with 0.4% final residue. The DSC results indicate that the melting temperature of all samples is slightly the same at 155 °C (in the range of 1 °C), showing that the treatment does not interfere with the melting temperature of the SPF/PLA composite. Thus, the untreated SPF/PLA composite showed the highest degradation temperature, which was 383.2 °C. The SPF/PLA composite treated with NaOH and silane demonstrated the highest melt flow index of 17.6 g/min. In conclusion, these findings offer a reference point for determining the filament extrusion and printability of SPF/PLA composite filaments.

Friction and wear characteristics of synthetic diamond and graphene-filled polyether ether ketone composites

Modifying tribo films using filler particles is a significant area of research in developing polymer-based tribo components to minimize material loss during the sliding process. This study focused on altering the wear characteristics of a polyetheretherketone (PEEK)/graphene high-performance polymer composite to strengthen the tribo film by adding synthetic diamond particles. The hot-pressed PEEK composite reinforced by graphene and diamond particles increased the hardness and thermal stability of the composite. Compared with pure PEEK, composites containing 1% graphene and 1% diamond particles showed an increment of 25% and 23% in hardness and thermal stability, respectively. Fourier-transform infrared spectroscopy and X-ray diffraction analysis verified the compatibility and intactness of the fillers in the PEEK matrix. The tribo properties of PEEK composites were characterized by a pin-on-disc tribometer on a counter steel surface. A PEEK composite containing 0.75 wt% graphene and 0.5 wt% diamond particles exhibited the lowest friction of 0.17 at a pressure of 1.5 MPa. The specific wear rate was low (1.78 × 10−6 mm3/Nm) for the composite containing 1 wt% graphene and 1 wt% diamond particles at a pressure of 1.5 MPa. Varying synthetic diamond and graphene filler concentrations in the PEEK matrix change the wear process by modifying the tribo film characteristics, revealing the lowest friction and wear rate. X-ray photoelectron and Raman spectroscopy show that the polymer film was transferred to the steel countersurface, and the tribo-chemical products of the tribo film contribute to a stable tribo film. The ferric oxide film and the tribo film improve the composite’s self-lubricating properties and load-bearing ability. Hence, the composite containing 0.75% of graphene and 0.5% of a synthetic diamond can be employed in the sliding bearing application of continuous conveyors used in mass production systems.

Application of the Composite Fibers Based on Chitosan and Chitin Nanofibrils in Cosmetology

Chitosan and composite fibers containing chitin nanofibrils have been developed for use in cosmetology. The tensile strength of the chitosan multifilaments is 160.6 ± 19.0 MPa, and of the composite multifilaments containing chitin, nanofibrils are 198.0 ± 18.4 MPa. Chitin nanofibrils introduced into the chitosan solution contribute to the creation of a new spatial arrangement of chitosan chains and their denser packing. The studies carried out by optical, scanning electron, and atomic force microscopy has shown that the serum, consisting of a mixture of lactic acid and sodium lactate, contains extended oriented structures—“liquid filaments”. It has been also shown that a mixture of serum and composite fibers based on chitosan and chitin nanofibrils has mucoadhesive, film-forming properties. The introduction of composite fibers containing chitin nanofibrils into the serum promotes the reinforcing effect of liquid filaments, the lifting effect of the film. The obtained composition can be used in cosmetology as a skin care product.

Recent Developments in Cassava (Manihot esculenta) Based Biocomposites and Their Potential Industrial Applications: A Comprehensive Review

The rapid use of petroleum resources coupled with increased awareness of global environmental problems associated with the use of petroleum-based plastics is a major driving force in the acceptance of natural fibers and biopolymers as green materials. Because of their environmentally friendly and sustainable nature, natural fibers and biopolymers have gained significant attention from scientists and industries. Cassava (Manihot esculenta) is a plant that has various purposes for use. It is the primary source of food in many countries and is also used in the production of biocomposites, biopolymers, and biofibers. Starch from cassava can be plasticized, reinforced with fibers, or blended with other polymers to strengthen their properties. Besides that, it is currently used as a raw material for bioethanol and renewable energy production. This comprehensive review paper explains the latest developments in bioethanol compounds from cassava and gives a detailed report on macro and nano-sized cassava fibers and starch, and their fabrication as blend polymers, biocomposites, and hybrid composites. The review also highlights the potential utilization of cassava fibers and biopolymers for industrial applications such as food, bioenergy, packaging, automotive, and others.