Carbohydrate Polymers最新文献

In this study, a chitosan derivative with strong iron (III) chelating capabilities was developed by grafting the Deferoxamine (DFO) chelator to achieve a substitution degree of 3.8 ± 0.2 %. Through blending with ungrafted chitosan of low degree of acetylation (DA), a formulation able to form a physical hydrogels was formed in aqueous media, without the requirement of a cross-linking agent. The functionalization of chitosan with DFO led to xerogels exhibiting superior iron (III) chelation capacity and higher swelling when exposed to aqueous solutions, in comparison with to an unmodified chitosan xerogel. Notably, this material extracts iron (III) even against the strong iron chelator deferiprone. Furthermore, the material demonstrates selectivity for iron (III) chelation even in the presence of competing cations like copper (II) and zinc (II).

Concerns about food safety and environmental impact from chemical surfactants have prompted interest in natural lignocellulosic materials as alternatives. In this study, we combined hydrated deep eutectic solvent (DES) pretreatment with ultrasound treatment to prepare lignocellulosic nanofibrils (LCNF) from bamboo shoot shells with appropriate surface properties for stabilizing Pickering emulsions. The pretreatment intensity effectively modulated the surface characteristics of LCNF, achieving desirable wettability through lignin retention and in-situ esterification. The resulting LCNF/curcumin Pickering emulsion (CPE) demonstrated curcumin protection and pH-responsive color changes, while the ensuing CPE/PVA composite film exhibited ultraviolet shielding, mechanical strength, oxygen barrier, and antioxidant properties. Furthermore, the CPE/PVA film showed promise as a real-time indicator for monitoring shrimp freshness, maintaining sensitivity to spoilage even after six months of storage. These findings advance the advancement of green LCNF technologies, providing eco-friendly solutions for valorizing bamboo shoot shells and enhancing the application of LCNF in Pickering emulsions.

Cellulose-binding domains (CBDs) play a vital role in cellulose degradation by enzymes. Despite the strong ability of brown-rot fungi to degrade cellulose in wood, they have been considered to lack or have a low number of enzymes with CBD. Here, we report the C-terminal domain of a lytic polysaccharide monooxygenase from the brown-rot fungus Gloeophyllum trabeum (GtLPMO9A-2) functions as a CBD, classified as a new family of carbohydrate-binding module, CBM104. The amino acid sequence of GtCBM104 shows no similarity to any known CBDs. A BLAST search identified 84 homologous sequences at the C-terminus of some CAZymes, mainly LPMO9, in basidiomycetous genomes. Binding experiments revealed GtCBM104 binds selectively to native crystalline cellulose (cellulose I), but not to artificially modified crystalline or amorphous cellulose, while the typical fungal CBD (CBM1) bound to all cellulosic materials tested. The adsorption efficiency of GtCBM104 to cellulose I was >20-times higher than that of CBM1. Adsorption tests and microscopic observations strongly suggested that GtCBM104 binds to the hydrophilic regions of cellulose microfibrils, while CBM1 recognizes the hydrophobic surface. The discovery of GtCBM104 strongly suggests that the contribution of CBD to the cellulose enzymatic degradation mechanism of brown-rot fungi is much larger than previously thought.

This study aims to investigate the effects of levan on the progression of hyperuricemia (HUA) rats and elucidate its underlying mechanisms. After levan intervention, both low and high-dose groups exhibited a significant decrease in serum uric acid (UA) levels, reaching 71.0 % and 77.5 %, respectively, compared to the model group. Furthermore, levan could alleviate renal pathological damage caused by glomerular cell vacuolation, inflammatory infiltration and collagen deposition. The results of enzyme activity assay and real-time fluorescence quantitative PCR showed that levan decreased UA production by inhibiting adenosine deaminase (ADA) activity and gene expression in liver; it upregulated ATP-binding cassette subfamily G member 2 protein (ABCG2) and organic anion transporter 1 (OAT1) transporter gene expression in the kidney, promoting UA excretion. Gut microbiome analysis indicated that levan regulated gut flora dysbiosis induced by HUA, resulting in up-regulated the abundance of beneficial bacteria (Muribaculaceae, Faecalibaculum, Bifidobacterium, and Lactobacillus) and decreased conditioned pathogenic bacteria (Escherichia_Shigella and Proteus). Non-targeted metabolomics showed changes in various serum metabolites associated with glycerophospholipid metabolism, lipid metabolism, and inflammation following oral administration of levan. Therefore, levan may be a promising functional dietary supplement for regulating the gut flora and remodeling of metabolic disorders in individuals with HUA.

Chitosan materials are much important in adsorption, separation and water treatment due to their hydrophilicity, biodegradability and easy functionalization. However, they were difficult to form structural materials, which limited its application in engineering. In this paper, a new type of chitosan porous materials was prepared with two-step strategy involving the freezing crosslinking of chitosan with glutaraldehyde to form cryogels, and their subsequent reduction with NaBH₄ to transform CN bonds into CN bonds, resulting in remarkable improvement of mechanical property. That is, the strength remained almost unchanged after 80 % deformation. The abundant -NH₂ and -OH on the surface of materials, as well as the unique pore structure from cryogels, gave relatively high adsorption capacity for metals and dyes (88.73 ± 4.25 mg·g⁻¹ for Cu(II) and 3261.05 ± 36.10 mg·g⁻¹ for Congo red). The surface hydrophilicity of materials made it possible for selective water permeation with over 95 % separation efficiency for oil-water mixtures. In addition, simple hydrophobic modification using bromotetradecane achieved selective oil permeation with over 96 % separation efficiency for oil-water mixtures. This study not only provides a new strategy to endow chitosan materials with excellent mechanical property, large adsorption capacity and good oil-water separation performance, but also offers environmentally friendly materials for sewage treatment applications.

Implant-associated infection (IAI) is a prevalent and potentially fatal complication of orthopaedic surgery. Boosting antibacterial immunity, particularly the macrophage-mediated response, presents a promising therapeutic approach for managing persistent infections. In this study, we successfully isolated and purified a homogeneous and neutral water-soluble polysaccharide, designated as AM-1, from the edible fungus Agaricus blazei Murrill. Structure analysis revealed that AM-1 (Mw = 3.87 kDa) was a low-molecular-weight glucan characterized by a primary chain of →4)-α-D-Glcp-(1 → and side chains that were linked at the O-6 and O-3 positions. In vivo assays showed that AM-1 effectively attenuated the progression of infection and mitigated infectious bone destruction in IAI mouse models. Mechanistically, AM-1 promotes intracellular autophagy-lysosomal biogenesis by inducing the nuclear translocation of transcription factor EB, finally enhancing the bactericidal capabilities and immune-modulatory functions of macrophages. These findings demonstrate that AM-1 significantly alleviates the progression of challenging IAIs as a presurgical immunoenhancer. Our research introduces a novel therapeutic strategy that employs natural polysaccharides to combat refractory infections.

Raffinose family oligosaccharides (RFOs) have diverse structures and exhibit various biological activities. When using RFOs as prebiotics, their structures need to be identified. If we first knew whether an RFO was classical or non-classical, structural identification would become much easier. Here, we cloned and expressed an α-galactosidase (BF0224) from Bacteroides fragilis which showed strict specificity for hydrolyzing α-Gal-(1 → 6)-Gal linkages in RFOs. BF0224 efficiently distinguished classical from non-classical RFOs by identifying the resulting hydrolyzed oligo- and mono-saccharides with HPAEC-PAD-MS. Using this strategy, we identified a non-classical RFO from Pseudostellaria heterophylla (Miquel) Pax with DP6 (termed PHO-6), as well as a classical RFO from Lycopus lucidus Turcz. with DP7 (termed LTO-7). To characterize these RFO structures, we employed four other commercial or reported α-galactosidases in combination with NMR and methylation analysis. Using this approach, we elucidated the accurate chemical structure of PHO-6 and LTO-7. Our study provides an efficient analytical approach to structurally analyze RFOs. This enzyme-based strategy also can be applied to structural analysis of other glycans.

The microenvironment of wound healing is susceptible to bacterial infection, chronic inflammation, oxidative stress, and inadequate angiogenesis, requiring the development of innovative wound dressings with antibacterial, anti-inflammatory, antioxidant, and angiogenic capabilities. This research crafted a new multifunctional bacterial cellulose composite membrane infused with copper-doped carbon dots (BC/Cu(II)-RCDs). Findings validated the successful loading of copper-doped carbon dots onto the BC membrane via hydrogen bonding interactions. Compared to the pure BC membrane, the BC/Cu(II)-RCDs composite membrane exhibited significantly enhanced hydrophilicity, tensile properties, and thermal stability. Diverse in vitro assays demonstrated excellent biocompatibility and antibacterial activity of BC/Cu(II)-RCDs composite membranes, alongside their ability to expedite the inflammatory phase and stimulate angiogenesis. In vivo trials corroborated the membrane's ability to foster epithelial regeneration, collagen deposition, and tissue regrowth in full-thickness skin wounds in rats while also curbing inflammation in infected full-thickness skin wounds. More importantly, the treatment of the BC/Cu(II)-RCDs composite membrane may result in the activation of VEGF and MAPK signaling proteins, which are key players in cell migration, angiogenesis, and skin tissue development. In essence, the developed BC/Cu(II)-RCDs composite membrane shows promise for treating infected wounds and serves as a viable alternative material for medicinal bandages.

Licorice is not only a widely used food, but also a classic tonic Chinese medicine, which mainly contains glycyrrhiza polysaccharides (GP) and flavonoids with excellent anti-inflammatory and antioxidant pharmacological activities. In this study, a neutral homogeneous polysaccharide (GP1–2) was isolated from Glycyrrhiza uralensis Fisch. However, its gelation behavior and properties have yet to be comprehensively studied. In this study, a Ca²⁺ cross-linked physical hydrogel based on neutral GP1–2 (GP1–2-Ca²⁺) is fabricated. The ability of metal ions to cross-linked gelation with GP1–2 is explored with respect to the polysaccharide concentrations, ion species, and pH environments. The pH range of Ca²⁺ cross-linked with GP1–2 to form hydrogel is 8 to 10, and the gelation concentration ranges from 20.0 % to 50.0 % w/v. Subsequently, the properties of the GP1–2-Ca²⁺ hydrogels are investigated using rheological measurements, scanning electron microscopy, free radical scavenging, MTT assays, healing capability, and enzyme-linked immunosorbent assays. The results reveal that the structure of GP1–2 presents an irregular porous structure, however, the physical gel formed after cross-linking with Ca²⁺ microscopically showed a globular porous structure with uniform distribution, suggesting that this structure characteristic may be used as a carrier material for drug delivery. Meanwhile, the GP1–2-Ca²⁺ hydrogel also possessed extraordinary viscoelasticity, cytocompatibility, antioxidant properties, anti-inflammatory activity, and ability to promote wound healing. Furthermore, the potential of GP1–2-Ca²⁺ hydrogels as drug delivery materials was validated by using rhein as a model drug for encapsulation, it is demonstrated that its cumulative release behavior of GP1–2-Ca²⁺ is pH-dependent. All in all, this study reveals the potential application of natural polysaccharides in drug delivery, highlighting its dual roles as carrier materials and bioactive ingredients.

Despite the significant amount of denim waste and its potential as a cellulose source, its use has been neglected. This study uses N-methyl morpholine-N-oxide, an eco-friendly solvent, to dissolve denim (including 100 % cotton) and create a denim film. Achieving a 10 % denim record solubility, a cellulosic film was also fabricated for comparison. Characterisation techniques were applied, and molecular dynamics simulations explored intramolecular interactions and the influence of indigo dye on dissolution process. FTIR spectra indicated no chemical reactions during dissolution and regeneration, though a shift in OH stretching suggested a change in crystallinity, confirmed by XRD results showing decreased crystallinity and a structural shift from cellulose I to cellulose II. ¹³C NMR analysis revealed disruptions in interchain hydrogen bonds after regeneration. TGA results showed lower decomposition temperatures for both films compared to the powders. Testing mechanical properties showed the denim film had higher elongation at break but lower tensile strength than the cellulose film. MD simulations indicated indigo dye did not significantly affect fundamental interactions but decreased denim solubility by reducing the diffusion coefficient. Rheological tests supported the simulation results, showing higher viscosity and molecular weight for the denim solution compared to cellulose.