Improving the thermal stability of different types of xylan by acetylation

3D-Printed Polymeric Biomaterials for Health Applications

3D printing, also known as additive manufacturing, holds immense potential for rapid prototyping and customized production of functional health-related devices. With advancements in polymer chemistry and biomedical engineering, polymeric biomaterials have become integral to 3D-printed biomedical applications. However, there still exists a bottleneck in the compatibility of polymeric biomaterials with different 3D printing methods, as well as intrinsic challenges such as limited printing resolution and rates. Therefore, this review aims to introduce the current state-of-the-art in 3D-printed functional polymeric health-related devices. It begins with an overview of the landscape of 3D printing techniques, followed by an examination of commonly used polymeric biomaterials. Subsequently, examples of 3D-printed biomedical devices are provided and classified into categories such as biosensors, bioactuators, soft robotics, energy storage systems, self-powered devices, and data science in bioplotting. The emphasis is on exploring the current capabilities of 3D printing in manufacturing polymeric biomaterials into desired geometries that facilitate device functionality and studying the reasons for material choice. Finally, an outlook with challenges and possible improvements in the near future is presented, projecting the contribution of general 3D printing and polymeric biomaterials in the field of healthcare.

Chemical structures and immunomodulatory activities of polysaccharides from Polygonatum kingianum

The physicochemical properties of the polysaccharides in Polygonatum kingianum, a Chinese medicinal herb used for both medicine and food, have not been fully studied. This study isolated three polysaccharides (PKP-1, PKP-2, and PKP-3) from the dry rhizomes of P. kingianum, with an average molecular weight of approximately 3137 Da, 5341 Da and 3755 Da, respectively. Structural analysis showed that all the three polysaccharides are fructans with β-D-Fruf-(2→, →6)-β-D-Fruf-(2→, →1)-β-D-Fruf-(2→, →1,6)-β-D-Fruf-(2→ and →6)-α-D-Glcp-(1→ glycosidic bond type. Notably, PKP-2 contains both acetyl groups and trace amounts of mannose residues. Scanning electron microscopy indicated that each polysaccharide possesses unique surface morphology. Thermal analysis showed that the three polysaccharides have good thermal stability. Rheological studies further revealed that all the three polysaccharides are typical shear thinning fluids. In vitro experiments showed that PKP-1 and PKP-2 significantly promote the secretion of NO and cytokines (TNF-α, IL-6) in macrophages by activating the NF-κB signaling pathway, thereby demonstrating potential immunomodulatory activity. These findings lay a theoretical foundation for the potential application of Polygonatum polysaccharides in the food industry.

Advancing plant cell wall modelling: Atomistic insights into cellulose, disordered cellulose, and hemicelluloses - A review

The complexity of plant cell walls on different hierarchical levels still impedes the detailed understanding of biosynthetic pathways, interferes with processing in industry and finally limits applicability of cellulose materials. While there exist many challenges to readily accessing these hierarchies at (sub-) angström resolution, the development of advanced computational methods has the potential to unravel important questions in this field. Here, we summarize the contributions of molecular dynamics simulations in advancing the understanding of the physico-chemical properties of natural fibres. We aim to present a comprehensive view of the advancements and insights gained from molecular dynamics simulations in the field of carbohydrate polymers research. The review holds immense value as a vital reference for researchers seeking to undertake atomistic simulations of plant cell wall constituents. Its significance extends beyond the realm of molecular modeling and chemistry, as it offers a pathway to develop a more profound comprehension of plant cell wall chemistry, interactions, and behavior. By delving into these fundamental aspects, the review provides invaluable insights into future perspectives for exploration. Researchers within the molecular modeling and carbohydrates community can greatly benefit from this resource, enabling them to make significant strides in unraveling the intricacies of plant cell wall dynamics.

Acetylated nanocellulose reinforced hydroxypropyl starch acetate realizing polypropylene replacement for green packaging application

The use of natural starch as a replacement for petroleum-based packaging materials is limited due to its poor processability, weak mechanical properties, and strong moisture sensitivity. To address these limitations, this study adopts molecular design of hydroxypropylation and acetylation to sequentially modify natural starch, and material design of introducing acetylated cellulose nanofibers (ACNF) into the starch matrix to reinforce the material. Hydroxypropylation decreased the interaction force between the starch molecular chains, thereby reducing the glass transition temperature. Subsequent acetylation introduced hydrophobic acetyl groups that disrupted intermolecular hydrogen bonds, enhancing the mobility of the starch molecular chain, and endowed the hydroxypropyl starch acetate (HPSA) with excellent thermoplastic processability (melt index of 7.12 g/10 min) without the need for plasticizers and notable water resistance (water absorption rate of 3.0 %). The introduction of ACNF generated a strong interaction between HPSA chains, promoting the derived ACNF-HPSA to exhibit excellent mechanical strength, such as high impact strength of 2.1 kJ/m2, tensile strength of 22.89 MPa, elasticity modulus of 813.22 MPa, flexural strength of 24.18 MPa and flexural modulus of 1367.88 MPa. Its overall performance even surpassed that of polypropylene (PP) plastic, making it a potential alternative material for PP-based packaging materials.

New blend of renewable bioplastic based on starch and acetylated xylan with high resistance to oil and water vapor

Renewable materials of biological origin exhibit attractive properties in relation to traditional plastics, as they can be partially or completely replaced, thereby reducing environmental impacts. Hemicelluloses are a group of polysaccharides that have expanded applications when acetylated. Acetylation can improve the mechanical strength and water vapor barrier properties of xylan-based bioplastics. By partially acetylating xylan in the present study, it was possible to use water as a solvent for the film-forming solution and starch as a second polysaccharide in the formation of bioplastics. Xylan was modified via partial chemical acetylation by varying the reaction time, solvent, and catalyst content. The bioplastics were formed by non-acetylated xylan and acetylated xylan with degrees of substitution (DS) of 0.45 and 0.9, respectively, with starch to form blends using glycerol as a plasticizer. Acetylation with DS 0.45 showed better results in increasing the hydrophilicity of the bioplastic. On the other hand, acetylation influenced the thermal stability of bioplastics, increasing the maximum temperature of the degradation rate from 302 °C to 329 °C and 315 °C, owing to changes in the crystallinity of the polymers. In addition to the modulus of elasticity 2.99 to 290.61 and 274.67 MPa for the non-acetylated bioplastic and the bioplastic with DS of 0.45 and 0.90, respectively. Thus, the films obtained presented suitable physicochemical properties for use in various industrial applications, such as active and intelligent packaging in the food sector.

Significantly improve film formability of acetylated xylans by structure optimization and solvent screening

Acetylated xylans have great potential in fabricating functional film and coating materials, which need a good solubility/dispersibility and film formability in an easily evaporable solvent. However, the changes of film formability with degree of substitution by acetyls (DSAc) in different solvent systems for xylans have not been extensively studied, which limit the application of acetylated xylans in film materials. In this study, acetylated xylans with DSAc of 0-2 were prepared and the effects of acetyl groups on solubility/dispersibility, crystallinity and film formability of xylans in water and chloroform solvent systems were investigated. Due to the change of polarity, xylans with DSAc of 0-0.62 are only soluble in water solvents, while xylans with DSAc of 1.13-2 are only soluble in chloroform/ethanol (70/30 v/v) organic solvents. We have found that the film formability of acetylated xylans is highly related to their solubility and crystallization. Film formable xylans all had good solubility in the cast solvents. However, although with good solubility, xylans with DSAc of 0-0.3 and DSAc of 1.76-2 cannot form intact films, which is due to the forming of xylan hydrate crystals and xylan diacetate crystals. With the increase of DSAc, the mechanical property of xylan film increases initially at low DSAc and decreases at high DSAc. This study provides theoretical basis for applying xylans and their derivatives in advanced functional film and coating materials with great biocompatibility and biodegradability.

Green Approaches on Modification of Xylan Hemicellulose to Enhance the Functional Properties for Food Packaging Materials-A Review

Based on the environmental concerns, the utilisation of hemicelluloses in food packaging has become a sustainable alternative to synthetic polymers and an important method for the efficient utilisation of biomass resources. After cellulose, hemicellulose is a second component of agricultural and forestry biomass that is being taken advantage of given its abundant source, biodegradability, nontoxicity and good biocompatibility. However, due to its special molecular structure and physical and chemical characteristics, the mechanical and barrier properties of hemicellulose films and coatings are not sufficient for food packaging applications and modification for performance enhancement is needed. Even though there are many studies on improving the hydrophobic properties of hemicelluloses, most do not meet environmental requirements and the chemical modification of these biopolymers is still a challenge. The present review examines emerging and green alternatives to acetylation for xylan hemicellulose in order to improve its performance, especially when it is used as biopolymer in paper coatings or films for food packaging. Ionic liquids (ILs) and enzymatic modification are environmentally friendly methods used to obtain xylan derivatives with improved thermal and mechanical properties as well as hydrophobic performances that are very important for food packaging materials. Once these novel and green methodologies of hemicellulose modifications become well understood and with validated results, their production on an industrial scale could be implemented. This paper will extend the area of hemicellulose applications and lead to the implementation of a sustainable alternative to petroleum-based products that will decrease the environmental impact of packaging materials.

Wood hemicelluloses as effective wall materials for spray-dried microcapsulation of polyunsaturated fatty acid-rich oils

The most commonly-used and effective wall materials (WMs) for spray-dried microencapsulation of bioactive compounds are either costly, or derived from unsustainable sources, which lead to an increasing demand for alternatives derived from sustainable and natural sources, with low calories and low cost. Wood hemicelluloses obtained from by-products of forest industries appear to be attractive alternatives as they have been reported to have good emulsifying properties, low viscosity at high concentrations, high heat stability and low heat transfer. Here, we investigated the applicability of spruce galactoglucomannans (GGM) and birch glucuronoxylans (GX), to encapsulate flaxseed oil (FO, polyunsaturated fatty acid-rich plant based oil) by spray drying; and the results were compared to those of the highly effective WM, gum Arabic (GA). It was found that depending on solid ratios of WM:FO (1:1, 3:1 and 5:1), encapsulation efficiency of GGM was 88-96%, and GX was 63-98%. At the same encapsulation ratio, both GGM and GX had higher encapsulation efficiency than GA (49-92%) due to their ability to produce feed emulsions with a smaller oil droplet size and higher physical stability. In addition, the presence of phenolic residues in GGM and GX powders enabled them to have a greater ability to protect oil from oxidation during spray drying than GA. Physiochemical properties of encapsulated powders including thermal properties, morphology, molecular structure, particle size and water adsorption intake are also investigated. The study has explored a new value-added proposition for wood hemicelluloses which can be used as effective WMs in the production of microcapsules of polyunsaturated fatty acid-rich oils for healthy and functional products in food, pharmaceutical and cosmetic industries.

Naturally and chemically acetylated polysaccharides: Structural characteristics, synthesis, activities, and applications in the delivery system: A review

Acetylated polysaccharides refer to polysaccharides containing acetyl groups on sugar units. In the past, the acetylation modification of wall polysaccharides has been a hot research topic for scientists. However, in recent years, many studies have reported that acetylation-modified plant, animal, and microbial polysaccharide show great potential in delivery systems. From the latest perspective, this review systematically presents the different sources of naturally acetylated polysaccharides, the regularity of their modification, the chemical preparation of acetylation modifications, the biological activities and functions of acetylated polysaccharides, and the application in the delivery system. In nature, acetylated polysaccharides are extensively distributed in plants, microorganism, and animals. The level of acetylation modification, the distribution of chains, and the locations of acetylation modification sites differ between species. An increasing number of acetylated polysaccharides were prepared in the aqueous medium, which is safe, environment friendly, and low-cost. In addition to being necessary for plant growth and development, acetylated polysaccharides have immunomodulatory, antioxidant, and anticancer properties. The above-mentioned multiple sources, multifunctional and multi-active acetylated polysaccharides, make them an increasingly important part of delivery systems. We conclude by discussing the future directions for research and development and the potential uses for acetylated polysaccharides.

Acetylation modification improved the physicochemical properties of xyloglucan from tamarind seeds

Acetylation modification was conducted to improve the water-solubility and solution properties of xyloglucan from tamarind seeds (TSX). Three acetylated TSX with different degree of substitution (DS) were successfully prepared, and their structure and molecular parameters were investigated by FT-IR, NMR, and high-performance size exclusion chromatography (HPSEC). Further, the effects of acetylation on the thermal stability, solubility, and rheological properties of TSX were studied. Results showed that acetyl groups were mainly substituted at the O-6 position of terminal galactose with DS of 0.2, 0.47, and 0.36 for AC-2, AC-5, and AC-10, respectively. HPSEC analysis indicated that molecular weight of acetylated derivatives decreased slightly, and the solution conformation became more flexible as the DS increase. By comparing with TSX, the thermal stability, water-solubility, solution transmittance, and ζ-potential of acetylated TSX were significantly improved as the DS increase. In addition, rheological studies demonstrated that acetylation reduced the shear viscosity, but high DS of acetylation could induce the weak gelling property of TSX. In conclusion, acetylation modification could be applied to improve the physicochemical properties of TSX and promote its further application in food and pharmaceutical industries.

Fungal xylanolytic enzymes: Diversity and applications

As important polysaccharide degraders in nature, fungi can diversify their extensive set of carbohydrate-active enzymes to survive in ecological habitats of various composition. Among these enzymes, xylanolytic ones can efficiently and sustainably degrade xylans into (fermentable) monosaccharides to produce valuable chemicals or fuels from, for example relevant for upgrading agro-food industrial side streams. Moreover, xylanolytic enzymes are being used in various industrial applications beyond biomass saccharification, e.g. food, animal feed, biofuel, pulp and paper. As a reference for researchers working in related areas, this review summarized the current knowledge on substrate specificity of xylanolytic enzymes from different families of the Carbohydrate-Active enZyme database. Additionally, the diversity of enzyme sets in fungi were discussed by comparing the number of genes encoding xylanolytic enzymes in selected fungal genomes. Finally, to support bio-economy, the current applications of fungal xylanolytic enzymes in industry were reviewed.

Effects of ultrasound on the degradation kinetics, physicochemical properties and prebiotic activity of Flammulina velutipes polysaccharide

The controllable ultrasonic modification was hindered due to the uncertainty of the relationship between ultrasonic parameters and polysaccharide quality. In this study, the ultrasonic degradation process was established with kinetics. The physicochemical properties and prebiotic activity of ultrasonic degraded Flammulina velutipes polysaccharides (U-FVPs) were investigated. The results showed that the ultrasonic degradation kinetic models were fitted to 1/Mt-1/M0 = kt. When the ultrasonic intensity increased from 531 to 3185 W/cm2, the degradation proceeded faster. The decrease of polysaccharide concentration contributed to the degradation of FVP, and the fastest degradation rate was at 60 °C. Ultrasound changed the solution conformation of FVP, and partially destroyed the stability of the triple helix structure of FVP. Additionally, the viscosity and gel strength of FVP decreased, but its thermal stability was improved by ultrasound. Higher ultrasonic intensity led to larger variations in physicochemical properties. Compared with FVP, U-FVPs could be more easily utilized by gut microbiota. U-FVPs displayed better prebiotic activity by promoting the growth of Bifidobacterium and Brautella and inhibiting the growth of harmful bacteria. Ultrasound could be effectively applied to the degradation of FVP to improve its physicochemical properties and bioactivities.

Cellulose-hemicellulose interactions - A nanoscale view

In this work, we study interactions of five different hemicellulose models, i.e. Galactoglucomannan, O-Acetyl-Galactoglucomannan, Fuco-Galacto-Xyloglucan, 4-O-Methylglucuronoxylan, and 4-O-Methylglucuronoarabinoxylan, and their respective binding strength to cellulose nanocrystals by molecular dynamics simulations. Glucuronoarabinoxylan showed the highest free energy of binding, whereas Xyloglucan had the lowest interaction energies amongst the five models. We further performed simulated shear tests and concluded that failure mostly happens at the inter-molecular interaction level within the hemicellulose fraction, rather than at the interface with cellulose. The presence of water molecules seems to have a weakening effect on the interactions of hemicellulose and cellulose, taking up the available hydroxyl groups on the surface of the cellulose for hydrogen bonding. We believe that these studies can shed light on better understanding of plant cell walls, as well as providing evidence on variability of the structures of different plant sources for extractions, purification, and operation of biorefineries.

Balanced Xylan Acetylation is the Key Regulator of Plant Growth and Development, and Cell Wall Structure and for Industrial Utilization

Xylan is the most abundant hemicellulose, constitutes about 25–35% of the dry biomass of woody and lignified tissues, and occurs up to 50% in some cereal grains. The accurate degree and position of xylan acetylation is necessary for xylan function and for plant growth and development. The post synthetic acetylation of cell wall xylan, mainly regulated by Reduced Wall Acetylation (RWA), Trichome Birefringence-Like (TBL), and Altered Xyloglucan 9 (AXY9) genes, is essential for effective bonding of xylan with cellulose. Recent studies have proven that not only xylan acetylation but also its deacetylation is vital for various plant functions. Thus, the present review focuses on the latest advances in understanding xylan acetylation and deacetylation and explores their effects on plant growth and development. Baseline knowledge about precise regulation of xylan acetylation and deacetylation is pivotal to developing plant biomass better suited for second-generation liquid biofuel production.

Xylan-based hydrogels for potential skin care application

Skin care biomaterials from natural compounds are increasingly needed in recent. We demonstrate a simple strategy to fabricate the dialdehyde xylan (DAX) crosslinked hydrogel with skin care potential. The hydrogel mainly consists of dialdehyde xylan, which is used as crosslinker for gelatin (G). Glycerol (Gly) and nicotinamide (NCA) are introduced here for improving the texture, antibacterial property as well as skin care functionality. The in vitro release results demonstrate that NCA can be released smoothly from the xylan-based gel, whereby the xylan-based fabricated gel can be utilized as an ideal matrix gel in skin care with loading and release function. The antibacterial ability is in the following order: Yeast > Bacillus subtilis > Staphylococcus aureus. The cytocompatibility experiments confirm the excellent viability of the gel. These merits demonstrate the fabricated hydrogel as a potential material in skin care.