Search Results (815)

Limnospira platensis is a promising sustainable biomass for functional food production. During cultivation, it secretes extracellular polysaccharides (EPS) with underutilized potential as food ingredients. This study aimed to strategically fractionate Spirulina EPS (SEPS) by molecular weight (MW: <30, 30–100, >100 kDa) to elucidate their structure-function relationships for targeted food applications. We found distinct functional diversification: The mid-MW fraction (SEPS-2, 30–100 kDa) was an amphiphilic glycoprotein complex with potential interfacial activity. The high-MW fraction (SEPS-3, >100 kDa) formed a dense, glucose-rich glucan network, suggesting utility as a natural thickener or texturizer. In contrast, the low-MW fraction (SEPS-1, <30 kDa), rich in deoxy-sugars, exhibited superior antioxidant capacity, indicating potential as a bioactive preservative or nutraceutical. Spectroscopic and morphological analyses linked these structural differences to their physicochemical properties. Notably, the 30–100 kDa fraction transitions from a cultivation byproduct to a functional food architect, where its interfacial properties can be leveraged to engineer stable, clean-label emulsion-based food products. This work provides a foundation for the valorization of L. platensis EPS, demonstrating how MW-directed fractionation can unlock tailored functionalities-from bioactive agents to structural polymers-for the development of next-generation foods from circular bioeconomy streams. Full article

Selenium (Se) biofortification is considered an effective approach to enhance the nutritional and functional properties of fungal polysaccharides. In this study, Pleurotus geesteranus was biofortified with different Se sources including sodium selenite [Se(IV)], sodium selenate [Se(VI)], potassium 2-selenocyanatoacetate (PSeCA), and selenium ore powder (SeOP) to obtain Se-enriched polysaccharides by ultrasound-assisted extraction (UAE). UAE parameters were optimized via a Box–Behnken design; the optimized UAE model exhibited high predictability (R² = 0.9886, CV = 1.71%), enabling reliable scale-up for industrial extraction, with the PSeCA group achieving the highest polysaccharide content (75.12 mg/g) and Se level (13.85 mg/kg) compared to the control and other Se-fortified groups. The monosaccharide composition analysis on polysaccharides revealed that Se(IV) and Se(VI) primarily increased mannose and fructose contents, whereas PSeCA and SeOP exhibited characteristic glucose-dominant profiles. Furthermore, the molecular weight (Mw) distribution of fungal polysaccharides could be altered under biofortification conditions. In addition, polysaccharides of each group revealed different antioxidant bioactivities among tested free radicals. The result indicated that PSeCA as an organic Se source, rarely studied, has promising potential in P. geesteranus biofortification for obtaining antioxidant Se-polysaccharides. Full article

Owing to the pronounced compositional heterogeneity of waste cooking oil (WCO), WCO-rejuvenated asphalt often exhibits unstable performance. To improve the compositional controllability of WCO-based rejuvenators, WCO was fractionated according to molecular weight differences into three characteristic fractions: light, medium, and heavy components. Nine rejuvenator formulations with different component ratios were prepared to investigate the synergistic mechanism among WCO fractions with different molecular weights and to propose an optimal blending range. Thermal stability tests, dynamic shear rheometer (DSR) tests, multiple stress creep recovery (MSCR) tests, and bending beam rheometer (BBR) tests were conducted to evaluate the performance of the rejuvenators and rejuvenated asphalts. Gas chromatography (GC) and gel permeation chromatography (GPC) were further used to analyze the chemical composition and molecular-weight distribution. The results show that increasing the proportions of light and medium WCO components improves the low-temperature performance of rejuvenated asphalt; however, when the combined content of light and medium components exceeds 40%, the high-temperature performance is adversely affected. The heavy component improves the rutting factor, creep recovery capacity, and thermal oxidative aging resistance of rejuvenated asphalt, and the coefficient of determination between the long-term aging CAI and heavy-component content reaches 0.959. Thermal stability tests show that the mass loss rate of the nine rejuvenators after 1.5 h of heating ranges from 2.8% to 4.3%, with greater mass loss for formulations containing higher light-component contents. GPC results show that the Mn and Mw of R-4 (492 g/mol and 641 g/mol) are higher than those of R-8 (463 g/mol and 600 g/mol), indicating that a higher macromolecular fraction contributes to improved thermal stability. Considering high-temperature, low-temperature, and aging performance together, rejuvenated asphalt achieves the closest overall performance to the base binder when the heavy component is controlled at 50–60% and the medium component is approximately 30%. Full article

Petrochemical-based plastics are widely used due to their convenience and low cost, with polyethylene (PE) being the most produced globally. However, the lack of efficient and sustainable treatment methods for conventional plastic wastes has led to severe environmental pollution. A new fungus strain capable of degrading PE was isolated from soil samples collected at a waste disposal site in Henan province and identified as Aspergillus sydowii W144. After 30 days of incubation under solid-state culture conditions, the strain demonstrated significant oxidative depolymerization of low-density polyethylene (LDPE). FTIR results revealed a substantial increase in the carbonyl index of the LDPE film, while differential scanning calorimetry (DSC) analysis detected an enhanced crystallinity in the LDPE film. Notably, distinct pitting and erosion marks were observed on the surface of LDPE film using scanning electron microscopy (SEM). Quantitative analysis showed a weight loss rate of 6.39% and a reduction in Weight-Average Molecular Weight (Mw) by 50.93%. Among currently identified PE-degrading strains polyethylene, A. sydowii W144 exhibits particularly outstanding depolymerization efficiency, especially on untreated PE. Based on the whole-genome data of A. sydowii W144, a preliminary model of the putative polyethylene degradation pathway in A. sydowii W144 was constructed through homology-based sequence analysis and by referencing previously reported polyethylene degradation pathways. Laccase/multicopper oxidase plays a key role in the initial oxidation of PE. Heterologous expression of the candidate gene laccase4 in Pichia pastoris yielded an active enzyme (~56 kDa) with a laccase activity of 460 U/L, confirming its functionality. This study provides a novel microbial resource and potential enzymatic tools for PE biodegradation. The strain exhibits a promising application in complex ecosystems for PE pollution. IMPORTANCE: The polyethylene-degrading strain A. sydowii W144 isolated in this study exhibits highly efficient depolymerization capabilities, particularly under solid-state culture conditions. Genomic sequencing analysis enabled the construction of a potential polyethylene (PE) degradation pathway and facilitated the identification of key laccase and multicopper oxidase genes involved in this process. The isolation of this novel strain enriches the microbial resources available for PE waste treatment and offers new insights into the mechanisms of plastic biodegradation. Full article

The ionotropic γ-aminobutyric acid receptor (iGABAR) is an important insecticidal molecular target. However, the native iGABARs composition remains unknown in insect. Here, CsRdl1, truncated transcripts of CsRdl2 and CsLcch3 were obtained in the rice stem borer (RSB), Chilo suppressalis Walker. The N-terminal-truncated CsRDL2 (∆N-CsRDL2) and N-terminal-truncated CsLCCH3 (∆N-CsLCCH3) were deduced and studied in vivo, and desmethyl-broflanilide (DMBF) binding characteristics were simulated in silico. Genome and transcriptome analyses revealed truncated transcripts of CsRdl2 and CsLcch3 encoded 48 kDa of ∆N-CsRDL2 and 37 kDa of ∆N-CsLCCH3, respectively. The CsRDL1, CsRDL2 and CsLCCH3 were detected respectively from native iGABARs at molecular weights (Mws) ≥ 440 kDa in BN-PAGE. In BN/SDS-PAGE, three CsRDL1 bands (~54, ~55 and ~70 kDa), one CsRDL2 band (~48 kDa) and one CsLCCH3 band (~37 kDa) were identified in native iGABARs at Mws ≥ 669 kDa, and corresponded to CsRDL1ad, CsRDL1bd, post-translationally modified CsRDL1, ∆N-CsRDL2 and ∆N-CsLCCH3, respectively. Immunofluorescence confirmed these three subunits distributed in the same region of adult heads. Finally, DMBF displayed higher binding affinities for heteromeric iGABARs than for homomeric CsRDL1 iGABAR in silico. These findings confirm that ∆N-CsRDL2 and ∆N-CsLCCH3 in native iGABARs might support the rational design of novel insecticides. Full article

Aging has a significant influence on the rheological behavior and service performance of asphalt binders. In this study, base asphalt binder (BAB) and rubberized asphalt binder (RAB) with different aging levels were investigated to clarify their aging evolution and performance correlations. Rheological tests were conducted to evaluate high-temperature rutting resistance, intermediate-temperature fatigue performance, and low-temperature cracking resistance. The 2S2P1D viscoelastic model was used to analyze the evolution of viscoelastic parameters, while gel permeation chromatography (GPC) was adopted to characterize molecular weight changes during aging. The results showed that aging increased the rutting resistance of both binders, but reduced fatigue performance and low-temperature cracking resistance. Among the 2S2P1D viscoelastic model parameters, G_∞, δ, and β were more sensitive to aging than the other parameters and exhibited relatively clear variation trends. Selected viscoelastic parameters also showed significant correlations with rheological performance indices. GPC results indicated that both binder systems progressively evolved toward higher molecular weight during aging, with the molecular weight distribution curves shifting toward the high-molecular-weight region. For RAB, M_w was more sensitive to aging than M_n and showed some fluctuation at intermediate aging stages, reflecting a more complex molecular evolution. Overall, the results indicate that selected 2S2P1D viscoelastic parameters can serve as sensitive indicators of aging evolution and provide a useful basis for interpreting the performance correlations and rheological changes of asphalt binders from a viscoelastic perspective. Full article

Valorization of abundant agricultural residues, particularly lignin, provides the opportunity to divert waste streams while enabling materials to inherently exhibit durable functionalities, including UV-blocking, antioxidant properties and water repellency. This study reports the side-by-side valorization of hemp hurd (HL) and corn stover lignin (CL), extracted using the CELF process, into electrospun lignin/nylon 6 nanofiber membranes, establishing how lignin botanical origin, molecular weight (M_w), and blend ratio govern multifunctional performance relevant to protective membranes in textiles. Lignin–nylon 6 hydrogen bonding was regulated by the OH content and accessibility, M_w, and purity, and influenced the functional properties of the fibers. While stronger in low-M_w nanofibers, these interactions were weakest in low-M_w HL samples due to the lowest purity, despite the highest OH content. Fibers with low-M_w lignin yielded finer, brittle fibers with higher UV blocking, whereas high-M_w fractions showed higher antioxidant performance due to decreased interactions with nylon 6. Overall, lignin/nylon 6 nanofiber membranes delivered biobased UPF 50+ performance, 55–61% antioxidant activity at the optimal concentration, and exhibited tunable water repellency via fraction selection and the blend ratio. In combination with a nanofiber architecture, these membranes can impart durable inherent functionality onto textile substrates without affecting their existing properties, including water vapor permeability, without the use of chemical finishing, while utilizing renewable resources from agricultural residues. Full article

Hyaluronan (HA) is a ubiquitous extracellular matrix (ECM) component that is gaining significant attention for its diverse roles in cell signalling and disease. The biological functions of HA are dependent on its molecular weight (M_w): low M_w polysaccharide chains drive stimulatory processes such as inflammation and angiogenesis, whereas high M_w HA is stabilising and anti-inflammatory. Growing evidence indicates that HA is integral to brain function. The composition of HA in the brain is regulated by the balance of enzymatic synthesis and degradation, mediated by different isoforms of hyaluronan synthase (HAS) and hyaluronidase (HYAL) respectively. Fluctuating expression of the genes encoding the HAS and HYAL enzymes has been implicated in neuropathology and ageing, with some studies providing evidence towards epigenetic regulation of these genes. The regulatory environment of the brain confers a unique balance of enhanced protection alongside the requirement for maximum flexibility. This scoping review focuses on summarising current knowledge regarding epigenetic regulation of HAS and HYAL genes in neural contexts, as well as identifying gaps in knowledge against which future research can be directed. Understanding how these genes are regulated, particularly through epigenetic mechanisms, provides insight into how HA is regulated in the brain, facilitating understanding regarding its function in brain health and disease. Full article

This study aimed to investigate the wound-healing mechanisms of chitosan with a defined molecular weight (MW) and degree of deacetylation (DD), and to explore its potential in hydrogel formulations, optimized for enhanced antibacterial performance. An active molecular chitosan (AMC) was prepared via enzymatic treatment to target a specific MW range with excellent biological activity. The antibacterial, anti-inflammatory, and wound-healing effects of AMC-based hydrogels were evaluated. Given AMC’s antibacterial activity against vancomycin-resistant Staphylococcus aureus (VRSA), its anti-inflammatory effects were also evaluated in full-thickness wounds in BALB/c nude mice. Anti-inflammatory effects were assessed using ELISA and immunohistochemical staining to measure levels of IL-1β, IL-4, IL-6, IL-10, and TNF-α. AMC treatment significantly reduced wound size and suppressed inflammatory cytokine production. These results suggest that hydrogels containing AMC may enhance both antibacterial and anti-inflammatory properties, potentially promoting wound healing. Full article

Hyaluronic acid (HA) is a glycosaminoglycan commonly administered orally, and its molecular weight (MW) influences its physicochemical behavior and potential interactions with the gut microbiota. However, MW-dependent effects on community assembly and fermentation-derived metabolites within the low-molecular-weight (LMW) range remain insufficiently resolved. In this study, five HA samples (6.9–35 kDa) were evaluated using an in vitro human fecal fermentation model. Microbial composition was profiled by 16S rRNA gene sequencing, and SCFAs were quantified by UPLC. Compared with the control under the same basal medium, HA supplementation was associated with shifts in community structure and higher alpha diversity. The 6.9 and 9.5 kDa groups were associated with significantly higher total SCFA concentrations, particularly butyrate, than the 13, 17, and 35 kDa groups under the same basal medium. Because soluble starch was present in the fermentation medium, these differences should be interpreted as modulation effects rather than direct evidence of HA-specific fermentation. 16S-based functional prediction suggested MW-dependent differences in predicted central carbohydrate metabolism potential, which were consistent with the observed SCFA patterns but should be interpreted as inferred functional potential rather than direct evidence of pathway activity. These findings indicate that HA molecular weight is associated with differential microbial and SCFA response patterns under the present in vitro conditions. Lower-MW HA within the tested range was associated with higher SCFA output, particularly butyrate, under a shared starch-containing basal medium, highlighting molecular weight as a potential formulation parameter in HA microbiota-centered applications. Full article

The immunomodulatory potential of natural polysaccharides is often limited by their structural complexity and high molecular weight. In this study, DFIP-A3-1 (M_w = 8.68 × 10³ g/mol) was obtained from the leaves of Isatis indigotica Fort. by ultrafiltration, DEAE-650M, and Sephadex G-100 chromatography, followed by acid degradation. Fortunately, DFIP-A3-1 exhibited the most potent immunostimulatory activity in vitro. HPGPC, HPSEC-MALLS-RID, GC-MS, FT-IR, Congo red tests, SEM, and AFM were used to characterize their structure, and 1D/2D NMR was used for further investigation of DFIP-A3-1 for in-depth structural clarification. DFIP-A3-1 was primarily composed of Rha and Gal. Based on methylation and NMR analyses, the structure of DFIP-A3-1 was elucidated as follows: →1)-β-Galp-(4→1,4)-α-Rhap-(2→1,4)-α-Rhap-(2→1)-β-Galp-(6→1)-β-Galp-(6→1,6)-β-Galp-(3→1,6)-β-Galp-(3→. Furthermore, DFIP-A3-1 was found to exhibit a triple-helix conformation. DFIP-A3-1 markedly upregulated the secretion of NO, IL-6, and TNF-α and enhanced the mRNA expression levels of their related genes in RAW 264.7 cells. Moreover, DFIP-A3-1 activated p-IκBα, p-p65, and TLR4, while co-treatment with TAK-242 markedly suppressed the expression of these pathway-related proteins. All of the aforementioned findings suggested that DFIP-A3-1 is a promising natural immunomodulatory drug deserving of additional research and use. Full article

Binding affinity prediction in computational drug discovery is confounded by trivial correlations between molecular size and measured potency. We introduce cellular sheaf Laplacians as descriptors of ligand molecular geometry that quantify geometric frustration independent of system size. Sheaves are constructed over molecular graphs by assigning three-dimensional coordinate spaces to atoms and projection operators encoding ideal bonding geometry to edges; eigendecomposition of the resulting Laplacian yields spectral features measuring inconsistencies between local geometric constraints and global topology. Applied to 14,050 protein-ligand complexes from the PDBbind v2020 refined set, MW-residualized Sheaf features capture a statistically significant geometric signal ($r_{\mathrm{partial}} = 0.171$, $p<{10}^{-70}$) that is orthogonal to the Wiener index ($r=0.013$) and persists after controlling for both molecular weight and classical graph-theoretic descriptors ($r_{\mathrm{partial}} = 0.390$, $p<{10}^{-9}$). Sheaf spectral features alone achieve predictive performance ($R^2=0.403$) approaching that of fourteen classical cheminformatics descriptors ($R^2=0.446$), and their combination yields consistent improvements across the binding affinity spectrum (RMSE $=1.43$$p{K}_d$). Permutation importance analysis confirms the Sheaf Frobenius norm as the second most influential descriptor after molecular weight. We introduce Topological Binding Efficiency as a size-normalized quality metric identifying ligands that achieve potent binding through geometric complementarity rather than molecular bulk. Gaussian mixture analysis of the maximum eigenvalue distribution among strong binders reveals two distinct spectral modes corresponding to planar aromatic and three-dimensional sp3-rich scaffolds, confirmed by significant differences in fraction of sp3 carbons and aromatic ring counts ($p<{10}^{-8}$). As an intentionally ligand-centric framework, our approach complements rather than replaces protein-aware co-modelling architectures. This work establishes cellular sheaf theory as a principled framework for encoding molecular topology with statistically significant associations with binding affinity, providing interpretable geometric insights that are inaccessible to conventional molecular descriptors. Full article

This study investigates the impacts of algogenic organic matter (AOM) distribution characteristics, specifically molecular weight (MW) and hydrophobicity, on the formation of disinfection byproducts (DBPs) derived from Microcystis aeruginosa. This study focuses on both extracellular organic matter (EOM) and intracellular organic matter (IOM) and their contributions to DBP formation. AOM was divided into 12 fractions based on MW and hydrophobicity (transphilic, hydrophilic, and hydrophobic fractions). The results reveal that the hydrophobic fraction (HPO) contributes the most to IOM, while low-MW (<1 kDa) and high-MW (>100 kDa) organic matter are the main components of AOM. An analysis of fluorescent species indicates that humic acid-like and fulvic acid-like compounds derived from the hydrophilic fraction (HPI) of EOM and the hydrophobic fraction (HPO) of IOM are the dominant low-MW (<1 kDa) species. Additionally, aromatic proteins derived from HPO in both EOM and IOM are the dominant high-MW (>100 kDa) fluorescent species. This suggests that proteins or polysaccharides are the primary adsorbents on the membrane during ultrafiltration (UF), while the humic acid component is not significantly deposited. Furthermore, this study identifies that the >100 kDa HPO in IOM serves as the main precursor for trichloromethane (TCM), trichloroacetic acid (TCAA), and dichloroacetic acid (DCAA). In EOM, the precursor for the highest TCMFP (63.6 µg/mg-C) is the >100 kDa HPI, while the highest contribution to TCM (21%) is from the >100 kDa HPO. These findings provide crucial information for controlling DBPs derived from AOM through membrane filtration, particularly in eutrophic water environments. Full article

This paper presents a method for the measurement of absolute molecular weight of cellulose using a multi-angle light scattering (MALS) detector in 99% dimethyl sulfoxide/1% 1-Ethyl-3-methylimidazolium acetate (DMSO/EmimOAc). The paper also delivers a suitable dn/dc value for cellulose in this solvent. It discusses the pros and cons of using absolute molecular weight measurements versus traditional column calibration in this solvent. The conclusion is that the dn/dc for cellulose in this solvent is 0.049 ± 0.003 mL/g. Absolute molecular weight measurements in this solvent are somewhat beneficial for celluloses with Mw > 250 kg/mol. However, for low-Mw celluloses (e.g., Avicel), it has severe limitations. Herein, it is confirmed that the DMSO/EmimOAc system can be used to replace the traditional DMAc/LiCl system for cellulose molecular weight analysis of some cellulose materials. However, the former is more costly and time-consuming than the latter. Full article

The occurrence of shear creep in polyethylene under applied stress results in deformation, which restricts the service life of the final product. However, the factors influencing shear creep and its underlying mechanisms remain unclear. This article investigates the effects of average molecular weight and comonomer on the shear creep behavior and underlying mechanisms of high-density polyethylene (HDPE). The materials chosen were HDPE with weight-average molecular weights (Mw) of 148,100, 191,800, 226,500, 252,700 and 325,100 g/mol, as well as copolymers incorporating propylene or octene as comonomers. The results indicate that creep deformation decreases with increasing Mw, and that polyethylene copolymers incorporating propylene and octene cause increased creep deformation compared to homopolymers. Dynamic mechanical analysis (DMA) and rheological testing were used to investigate the influence of Mw and comonomer on shear creep behavior. The experimental results demonstrate that increasing the weight-average molecular weight enhances molecular chain entanglement, thereby improving creep resistance. The incorporation of comonomers introduces branches into the polyethylene structure, reducing entanglement density and leading to diminished creep resistance. This study provides valuable insights and references for the development of polyethylene materials that resist shear creep. Full article