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1.
Food Chem ; 462: 140949, 2025 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-39213976

RESUMO

Hydrogels based on natural polymers have aroused interest from the scientific community. The aim of this investigation was to obtain natural extracts from mango peels and to evaluate their addition (1, 3, and 5%) on the rheological behavior of mango starch hydrogels. The total phenolic content, antioxidant activities, and phenolic acid profile of the natural extracts were evaluated. The viscoelastic and thixotropic behavior of hydrogels with the addition of natural extracts was evaluated. The total phenol content and antioxidant activity of the extracts increased significantly (p<0.05) with the variation of the ethanol-water ratio; the phenolic acid profile showed the contain of p-coumaric, ellagic, ferulic, chlorogenic acids, epicatechein, catechin, querecetin, and mangiferin. The viscoelastic behavior of the hydrogels showed that the storage modulus G' is larger than the loss modulus G'' indicating a viscoelastic solid behavior. The addition of extract improved the thermal stability of the hydrogels. 1% of the extracts increase viscoelastic and thixotropic properties, while concentrations of 3 to 5% decreased. The recovery percentage (%Re) decreases at concentrations from 0% to 1% of natural extracts, however, at concentrations from 3% to 5% increased.


Assuntos
Antioxidantes , Hidrogéis , Mangifera , Extratos Vegetais , Reologia , Amido , Mangifera/química , Hidrogéis/química , Extratos Vegetais/química , Amido/química , Antioxidantes/química , Viscosidade , Frutas/química , Fenóis/química
2.
Food Chem ; 462: 140974, 2025 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-39197239

RESUMO

Total starch granule-associated proteins (tGAP), including granule-channel (GCP) and granule-surface proteins (GSP), alter the physicochemical properties of starches. Quinoa starch (QS) acts as an effective emulsifier in Pickering emulsion. However, the correlation between the tGAP and the emulsifying capacity of QS at different scales remains unclear. Herein, GCP and tGAP were selectively removed from QS, namely QS-C and QS-A. Results indicated that the loss of tGAP increased the water permeability and hydrophilicity of the starch particles. Mesoscopically, removing tGAP decreased the diffusion rate and interfacial viscous modulus. Particularly, GSP had a more profound impact on the interfacial modulus than GCP. Microscopically and macroscopically, the loss of tGAP endowed QS with weakened emulsifying ability in terms of emulsions with larger droplet size and diminished rheological properties. Collectively, this work demonstrated that tGAP played an important role in the structural and interfacial properties of QS molecules and the stability of QS-stabilized emulsions.


Assuntos
Chenopodium quinoa , Emulsificantes , Emulsões , Interações Hidrofóbicas e Hidrofílicas , Proteínas de Plantas , Amido , Chenopodium quinoa/química , Amido/química , Emulsões/química , Emulsificantes/química , Proteínas de Plantas/química , Tamanho da Partícula , Reologia
3.
Braz Oral Res ; 38: e097, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39356904

RESUMO

The aim of this study was to develop a mixture of dimethacrylate isomers (PG6EMA) as a potential monomer for dental adhesives and composites. PG6EMA was synthesized de novo and characterized in the presence of ethanol (3%, 6% or 9%). BisGMA/TEGDMA (BTEG, 50/50 wt.%) was used as the resin control. Composites were formulated with 60 wt.% of either PG6EMA or BisGMA (40 wt.% TEGDMA and 70 wt.% filler). DMPA (0.2 wt.%) and DPI-PF6 (0.4 wt.%) were added as photoinitiators, irradiated with a mercury arc lamp (320-500 nm, 500 mW/cm2; Acticure). All materials were tested for polymerization kinetics (near-infrared), viscosity (η) and storage modulus (G', oscillatory rheometry). The composites were further characterized for water sorption/solubility, wet/dry flexural strength/modulus and polymerization stress. Data were analyzed with one-way ANOVA/Tukey's test (α = 0.05). The PG6EMA resins showed lower rates of polymerization compared with BTEG (p = 0.001) but high degrees of conversion (p = 0.002). Solvent concentration did not affect RPMAX but the 6% and 9% mixtures showed higher final DC, likely due to reduced viscosity. PG6EMA had much higher viscosity than BTEG (p <0.001) and lower G' (p = 0.003). Composites modified with PG6EMA have slower polymerization rates (p = 0.001) but higher final DC (p = 0.04) than the control. PG6EMA/TEGDMA showed lower dry/wet flexural strength and comparable dry modulus. The PG6EMA/TEGDMA composite showed a 18.4% polymerization stress reduction compared to the BTEG composite. Both base monomers had similar WS/SL and G'. Within its limitations, this study demonstrated that the newly synthesized PG6EMA was a viable alternative to BisGMA in dental composites.


Assuntos
Bis-Fenol A-Glicidil Metacrilato , Resinas Compostas , Teste de Materiais , Metacrilatos , Polimerização , Ácidos Polimetacrílicos , Resinas Compostas/química , Resinas Compostas/efeitos da radiação , Bis-Fenol A-Glicidil Metacrilato/química , Metacrilatos/química , Viscosidade , Ácidos Polimetacrílicos/química , Análise de Variância , Fatores de Tempo , Reprodutibilidade dos Testes , Valores de Referência , Resistência à Flexão , Polietilenoglicóis/química , Propriedades de Superfície , Solubilidade , Cinética , Reologia , Cimentos Dentários/química , Cura Luminosa de Adesivos Dentários/métodos
4.
NPJ Biofilms Microbiomes ; 10(1): 98, 2024 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-39358392

RESUMO

Extracellular polysaccharides are crucial components for biofilm development. Although Bacillus subtilis is one of the most characterized Gram-positive biofilm model system, the structure-function of its exopolysaccharide, EpsA-O, remains to be elucidated. By combining chemical analysis, NMR spectroscopy, rheology, and molecular modeling, high-resolution data of EpsA-O structure from atom to supramolecular scale was obtained. The repeating unit is composed of the trisaccharide backbone [→3)-ß-D-QuipNAc4NAc-(1→3)-ß-D-GalpNAc-(1→3)-α-D-GlcpNAc-(1]n, and the side chain ß-D-Galp(3,4-S-Pyr)-(1→6)-ß-D-Galp(3,4-S-Pyr)-(1→6)-α-D-Galp-(1→ linked to C4 of GalNAc. Close agreement between the primary structure and rheological behavior allowed us to model EpsA-O macromolecular and supramolecular solution structure, which can span the intercellular space forming a gel that leads to a complex 3D biofilm network as corroborated by a mutant strain with impaired ability to produce EpsA-O. This is a comprehensive structure-function investigation of the essential biofilm adhesive exopolysaccharide that will serve as a useful guide for future studies in biofilm architecture formation.


Assuntos
Bacillus subtilis , Biofilmes , Espectroscopia de Ressonância Magnética , Polissacarídeos Bacterianos , Biofilmes/crescimento & desenvolvimento , Polissacarídeos Bacterianos/química , Polissacarídeos Bacterianos/metabolismo , Bacillus subtilis/química , Reologia , Modelos Moleculares , Aderência Bacteriana , Sequência de Carboidratos
5.
Sci Rep ; 14(1): 22773, 2024 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-39354037

RESUMO

In this work, a novel tool for small-scale filament production is presented. Unlike traditional methods such as hot melt extrusion (HME), the device (i) allows filament manufacturing from small material amounts as low as three grams, (ii) ensures high diameter stability almost independent of the viscoelastic behavior of the polymer melt, and (iii) enables processing of materials with rheological profiles specifically tailored toward fused filament fabrication (FFF). Hence, novel materials, previously difficult to process due to HME limitations, become easily accessible for FFF for the first time. Here, we showcase the production of highly flexible drug-free, and drug-loaded filaments based on ethylene-vinyl acetate polymers with a vinyl acetate content of 28 w% (EVA28) and unprecedented high melt flow rates of up to 400 g/10 min. Owing to their low viscosity, FFF with low print nozzle sizes of 250 µm was achieved for the first time for EVA28. These small nozzle diameters facilitate 3D-printing of high-resolution structures in small-dimensional dosage forms such as subcutaneous implantable drug delivery systems, which can later be used for personalization. Consequently, the material portfolio for FFF is tremendously broadened, allowing material and formulation optimization toward FFF, independent of a preliminary extrusion process.


Assuntos
Polivinil , Impressão Tridimensional , Polivinil/química , Viscosidade , Sistemas de Liberação de Medicamentos , Reologia , Próteses e Implantes , Elasticidade , Medicina de Precisão , Humanos
6.
Carbohydr Polym ; 345: 122581, 2024 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-39227110

RESUMO

High methyl-esterified citrus pectin (HMCP) is often used as a thickness in food products and is considered a poor emulsifier, especially in neutral pH solutions. Our previous findings show that the emulsifying capacity of HMCP could be significantly enhanced by calcium cations. Besides, the pH of the solution decreased in the presence of calcium cations. However, the impact of solution pH on HMCP emulsifying capacity in the presence of calcium cations is unclear. In this study, the pH of the HMCP solution was adjusted from 3.00 to 8.00 before adding calcium cations. The solution properties and emulsifying properties were analyzed in light of the existence of calcium cations. The results showed that the pH of the HMCP solutions decreased after bringing calcium cations into them. Calcium cations could change the solution rheological properties, particle size distributions and morphologies, and the particle microenvironmental hydrophobic areas in HMCP solutions while increasing the pH of HMCP solutions, contributing to improving the emulsifying capacity of HMCP. HMCP had the best emulsifying ability when the pH of the HMCP solutions was kept at a neutral level. This research gives us new ideas to adjust the emulsifying property of HMCP.


Assuntos
Cálcio , Emulsificantes , Pectinas , Pectinas/química , Concentração de Íons de Hidrogênio , Cálcio/química , Emulsificantes/química , Reologia , Emulsões/química , Tamanho da Partícula , Cátions/química , Interações Hidrofóbicas e Hidrofílicas , Esterificação , Citrus/química
7.
Ultrason Sonochem ; 110: 107059, 2024 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-39250863

RESUMO

The aim of the present study was to evaluate the effects of ultrasound-assisted intermittent tumbling (UT) at 300 W, 20 kHz and 40 min on the conformation, intermolecular interactions and aggregation of myofibrillar proteins (MPs) and its induced gelation properties at various tumbling times (4 and 6 h). Raman results showed that all tumbling treatments led the helical structure of MPs to unfold. In comparison to the single intermittent tumbling treatment (ST), UT treatment exerted more pronounced effects on strengthening the intermolecular hydrogen bonds and facilitating the formation of an ordered ß-sheet structure. When the tumbling time was the same, UT treatment caused higher surface hydrophobicity, fluorescence intensity and disulfide bond content in the MPs, inducing the occurrence of hydrophobic interaction and disulfide cross-linking between MPs molecules, thus forming the MPs aggregates. Additionally, results from the solubility, particle size, atomic force microscopy and SDS-PAGE further indicated that, relative to the ST treatment, UT treatment was more potent in promoting the polymerization of myosin heavy chain. The MPs aggregates in the UT group were more uniform than those in the ST group. During the gelation process, the pre-formed MPs aggregates in the UT treatment increased the thermal stability of myosin, rendering it more resistant to heat-induced unfolding of the myosin rod region. Furthermore, they improved the protein tail-tail interaction, resulting in the formation of a well-structured gel network with higher gel strength and cooking yield compared to the ST treatment.


Assuntos
Géis , Miofibrilas , Reologia , Géis/química , Miofibrilas/química , Ondas Ultrassônicas , Proteínas Musculares/química , Conformação Proteica , Interações Hidrofóbicas e Hidrofílicas , Animais , Agregados Proteicos
8.
Food Res Int ; 195: 114988, 2024 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-39277259

RESUMO

This study investigated the effect of gellan gum (GG) and glucono-δ-lactone (GDL) on the acid-induced gel properties of pea protein isolate (PPI) pretreated with media milling. The inclusion of GG substantially enhanced the gel hardness of PPI gel from 18.69 g to 792.47 g though slightly reduced its water holding capacity (WHC). Rheological analysis showed that GG increased storage modulus (G') and decreased damping factor of gels in the small amplitude oscillatory shear region and transformed its strain thinning behavior into weak strain overshoot behavior in the large amplitude oscillatory shear region. SEM revealed that GG transformed the microstructure of gel from a uniform particle aggregate structure to a chain-like architecture composed of filaments with small protein particles attached. Turbidity and zeta potential analysis showed that GG promoted the transformation of PPI from a soluble polymer system to an insoluble coagulant during acidification. When GG content was relatively high (0.2 %-0.3 %), high GDL content increased the electrostatic interaction between PPI and GG molecules, causing their rapid aggregation into a dense irregular aggregate structure, further enhancing gel strength and WHC. Overall, GG and GDL can offer the opportunity to modulate the microstructure and gel properties of acid-induced PPI gels, presenting potential for diversifying food gel design strategies through PPI-GG hybrid systems.


Assuntos
Géis , Gluconatos , Lactonas , Proteínas de Ervilha , Polissacarídeos Bacterianos , Reologia , Polissacarídeos Bacterianos/química , Lactonas/química , Géis/química , Gluconatos/química , Proteínas de Ervilha/química , Concentração de Íons de Hidrogênio
9.
Int J Pharm ; 664: 124651, 2024 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-39218326

RESUMO

Hot melt extrusion (HME) has been widely used as a continuous and highly flexible pharmaceutical manufacturing process for the production of a variety of dosage forms. In particular, HME enables preparation of amorphous solid dispersions (ASDs) which can improve bioavailability of poorly water-soluble drugs. The rheological properties of drug-polymer mixtures can significantly influence the processability of drug formulations via HME and eventually the end-use product properties such as physical stability and drug release. The objective of this review is to provide an overview of various rheological techniques and properties that can be used to evaluate the flow behavior and processability of the drug-polymer mixtures as well as formulation characteristics such as drug-polymer interactions, miscibility/solubility, and plasticization to improve the HME processability. An overview of the thermodynamics and kinetics of ASD processing by HME is also provided, as well as aspects of scale-up and process modeling, highlighting rheological properties on formulation design and process development. Overall, this review provides valuable insights into critical rheological properties which can be used as a predictive tool to optimize the HME processing conditions.


Assuntos
Composição de Medicamentos , Tecnologia de Extrusão por Fusão a Quente , Reologia , Tecnologia de Extrusão por Fusão a Quente/métodos , Composição de Medicamentos/métodos , Solubilidade , Polímeros/química , Liberação Controlada de Fármacos , Preparações Farmacêuticas/química , Química Farmacêutica/métodos , Estabilidade de Medicamentos , Temperatura Alta
10.
PLoS One ; 19(9): e0309727, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39321189

RESUMO

Landslides are common geological hazards that cause significant losses. Anti-slide piles are commonly used in landslide engineering, and model testing is one of the means to study pile-supported structures. However, model tests face several challenges, including difficulty in controlling the experimental process, challenges in repeated tests, and difficulty in monitoring soil deformation around piles. To address these issues, this study presents a model test method using particle image velocimetry (PIV), transparent soil, and 3D printing technology. Using this method, a series of model tests were conducted, including single-row and double-row anti-slide piles. The experimental results indicate that, compared with single-row piles, double-row piles exhibit better supporting effects. In the pile‒soil interaction, the displacement of the extrusion of soil between piles was controlled under the combined action of the front and back rows of piles. The inclination angle of a single-row pile after the test was 8°, whereas that of a double-row pile was reduced by 62.5%. With respect to the displacement of the soil behind the piles, the phenomenon of a "displacement triangle" behind the piles was observed. An analysis of the change process in this area revealed that the relative displacement caused by pile‒soil interactions is mainly distributed in the surface layer of the soil. The experiments demonstrate that this system is suitable for pile-supported structure model tests.


Assuntos
Impressão Tridimensional , Solo , Solo/química , Deslizamentos de Terra , Reologia , Modelos Teóricos
11.
ACS Appl Mater Interfaces ; 16(39): 51916-51931, 2024 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-39302428

RESUMO

Hydrogels, due to their excellent microstructure and mechanical strength, have become a novel biomaterial in wound dressing. However, plant proteins have never been considered because of their poor original gelling performances and insufficient rheological properties. Here, we reported the fabrication of a plant protein-based thermal-reversible gel using a reverse micelle-extracted hemp protein isolate (HPI). A systematic study was conducted to fully reveal their microstructure, rheological properties, and anti-inflammatory effect to lay a foundation for this newly developed plant protein hydrogel as a potential natural wound dressing. By modulating protein concentration (4% HPI) and temperature (85 °C), a thermal-reversible HPI gel appeared as a filament structure with the major molecular driving force of hydrophobic interactions and hydrogen bonds. By characterizing the rheological properties, lower gel strength and wider linear viscoelastic regime were determined in the thermal-reversible HPI gel compared with a thermal-irreversible HPI gel. Besides, large amplitude oscillatory shear data identified the thermal-reversible gel as a soft gel which demonstrated intracycle strain stiffening and shear thinning behavior. Moreover, the thermal-reversible HPI gel is nontoxic and has benefits in neutrophil growth with injectability and perfect wound coverage. This study opens a novel means to form a natural thermal-reversible hydrogel that can be a new material source for wound dressing.


Assuntos
Bandagens , Cannabis , Hidrogéis , Reologia , Cannabis/química , Hidrogéis/química , Hidrogéis/farmacologia , Proteínas de Plantas/química , Humanos , Cicatrização/efeitos dos fármacos , Temperatura , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia
12.
PLoS One ; 19(9): e0309176, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39325769

RESUMO

This study uses numerical methods (ANSYS-Fluent) to investigate the viscous fingering of the displaced phase as a shear-thinning fluid in the classic three-dimensional Hele-Shaw cell. Comparing the behavior of fingerings with different properties on the upper and lower surfaces of a three-dimensional model, it was found that when the upper and lower surfaces are walls, under the combined action of moving contact lines and Saffman-Taylor instability, fingering splitting occurs at the tip, resulting in the appearance of two fingers at the interface. In addition, we have found that interfacial tension has a suppressive effect on short waves. As the interfacial tension increases, the velocity at the advancing tip decreases. Therefore, when the interface tension is 0, viscous fingering displacement reaches the farthest distance. We have also conducted research on the viscous fingering at different temperatures. The results indicate that increasing the temperature leads to a decrease in the viscosity of the displaced phase, making the flow more stable. As the temperature rises, the pressure gradient inside the flow path increases, pushing the viscous fingering further.


Assuntos
Modelos Teóricos , Viscosidade , Temperatura , Tensão Superficial , Hidrodinâmica , Reologia
13.
Sci Rep ; 14(1): 22193, 2024 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-39333772

RESUMO

Okara is a by-product obtained from soybean milk containing high dietary fiber. This study focused on how to add value to okara by converting it into okara cellulose powder. The feasibility of using mechanical energy from the extrusion process to produce cellulose powder from okara was compared with the traditional mechanical method, hydrothermal and untreated okara powder (SBM). The extrusion process was carried out at different screw speeds (350-450 rpm), amount of water (0.5-1 L per hour), and number of treatment cycles. The physicochemical and functional properties of the okara cellulose powder and specific mechanical energy were analyzed. Results showed that the particle size of samples treated by 6 cycles of extrusion reduced to three times lower than SBM. The sample subjected to hydrothermal and extrusion showed significantly increased swelling ratio, water solubility index (WSI), and antioxidant capacity. However, only the extrusion treatment could improve the rheological properties. Increasing the cycles of extrusion treatment increased the swelling ratio and WSI values. Extrusion altered the color and chemical composition by decreasing the lightness and total dietary fiber. Extrusion treatment was proved to be an effective mechanical method for improving okara properties and converting the by-product into a potentially value-added ingredient for use in future food applications.


Assuntos
Celulose , Pós , Celulose/química , Pós/química , Alimentos de Soja/análise , Tamanho da Partícula , Solubilidade , Fibras na Dieta/análise , Antioxidantes/química , Antioxidantes/farmacologia , Reologia , Proteínas de Plantas , Polissacarídeos
14.
Int J Biol Macromol ; 278(Pt 4): 135281, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39256126

RESUMO

Particle concentrations (w) and oil content (Φ) are crucial factors influencing the gel stability of Pickering emulsions. To understand the stabilization mechanism comprehensively, we prepared emulsion gels stabilized by CNF/DMY composite particles at various w (0.5-1.5 wt%) and Φ (0.2-0.6, v/v). The microstructure revealed the adsorption of these particles at the oil-water interface, with excess particles forming a three-dimensional network structure in the continuous phase. Rheological studies showed that the network structure of Pickering emulsions was significantly influenced by w and Φ, resulting in improved emulsion gel strength that hindered the movement of oil droplets and oxygen in the continuous phase, thereby enhancing emulsion stability. Three scenarios for the critical strain (γco) were observed: at Φ = 0.2, γco decreased with increasing w, while at Φ = 0.4, γco increased with increasing w. At Φ = 0.6, γco remained relatively constant regardless of w. In conclusion, adjusting particle concentration and oil content enabled the control of microstructure, rheological properties, and antioxidant capacity of emulsion gels. These findings could be a valuable resource for formulating and ensuring the quality of emulsion gel-based products in the food industry.


Assuntos
Celulose , Emulsões , Géis , Nanofibras , Oxirredução , Reologia , Emulsões/química , Nanofibras/química , Géis/química , Celulose/química , Flavonóis/química , Antioxidantes/química
15.
Sci Rep ; 14(1): 21646, 2024 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-39284856

RESUMO

Two cystic fibrosis (CF) rat models, one carrying the common Phe508del mutation and the other a nonsense cystic fibrosis transmembrane conductance regulator (CFTR) mutation (knockout) were previously characterised. Although relevant CFTR mRNA reductions were present in the lung, no overt CF lung disease was observed. This study used flexiVent lung mechanic assessment and regional ventilation assessment via X-ray velocimetry (XV) functional imaging to assess the lung phenotype in both models. To determine the sensitivity of XV regional ventilation imaging, the effect of a localised physical obstruction (delivery of agar beads to part of the lungs) on lung ventilation was examined. At baseline, Phe508del and knockout CF rats had a lower inspiratory capacity, total respiratory system compliance, and static compliance than wildtype rats. Following agar bead delivery all XV ventilation parameters were altered, with substantial increases in poorly ventilated regions and ventilation heterogeneity. XV ventilation maps accurately identified locations of bead-induced airflow changes. Despite unremarkable lung histopathology, this study indicated that CF rats display altered respiratory mechanics, with CF rats needing to exert additional effort to expand and deflate their lungs due to increased stiffness. This study demonstrated the utility of XV imaging providing spatial lung ventilation information.


Assuntos
Regulador de Condutância Transmembrana em Fibrose Cística , Fibrose Cística , Modelos Animais de Doenças , Pulmão , Mecânica Respiratória , Animais , Fibrose Cística/diagnóstico por imagem , Fibrose Cística/genética , Fibrose Cística/fisiopatologia , Ratos , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Regulador de Condutância Transmembrana em Fibrose Cística/metabolismo , Pulmão/diagnóstico por imagem , Pulmão/metabolismo , Pulmão/patologia , Pulmão/fisiopatologia , Reologia , Masculino , Ratos Sprague-Dawley
16.
Soft Matter ; 20(36): 7321-7332, 2024 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-39248497

RESUMO

Lung surfactant is inactivated in acute respiratory distress syndrome (ARDS) by a mechanism that remains unclear. Phospholipase (PLA2) plays an essential role in the normal lipid recycling processes, but is present in elevated levels in ARDS, suggesting it plays a role in ARDS pathophysiology. PLA2 hydrolyzes lipids such as DPPC-the primary component of lung surfactant-into palmitic acid (PA) and lyso-PC (LPC). Because PA co-crystallizes with DPPC to form rigid, elastic domains, we hypothesize that PLA2-catalyzed degradation establishes a stiff, heterogeneous rheology in the monolayer, and suggests a potential mechanical role in disrupting lung surfactant function during ARDS. Here we study the morphological and rheological changes of DPPC monolayers as they are degraded by PLA2 using interfacial microbutton microrheometry coupled with fluorescence microscopy. While degrading, domain morphology passes through qualitatively distinct transitions: compactification, coarsening, solidification, aggregation, network percolation, network erosion, and nucleation of PLA2-rich domains. Initially, condensed domains relax to more compact shapes, and coarsen via Ostwald ripening and coalescence up until the domains solidify, marked by a distinct roughening of domain boundaries that does not relax. Domains aggregate and eventually form a percolated network, whose elements then erode and whose connections are broken as degradation continues. The relative enzymatic activity of PLA2, set by the age of the sample, impacts the order and the duration of morphology transitions. The fresher the PLA2, the faster the overall degradation, and the earlier the onset of domain solidification: domains solidify before aggregating with fresh PLA2 samples, but aggregate and percolate before solidification with aged PLA2. Irrespective of the activity of the PLA2, all measured linear viscoelastic surface shear moduli obey the same dependence on condensed phase area fraction (log|G*| ∝ ϕ) throughout monolayer degradation. Moreover, the onset of domain solidification coincides with the time when the relative surface elasticity begins to increase.


Assuntos
Fosfolipases A2 , Surfactantes Pulmonares , Reologia , Fosfolipases A2/metabolismo , Fosfolipases A2/química , Surfactantes Pulmonares/metabolismo , Surfactantes Pulmonares/química , 1,2-Dipalmitoilfosfatidilcolina/química , 1,2-Dipalmitoilfosfatidilcolina/metabolismo
17.
Bioinspir Biomim ; 19(6)2024 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-39255824

RESUMO

A remarkable variety of organisms use metachronal coordination (i.e. numerous neighboring appendages beating sequentially with a fixed phase lag) to swim or pump fluid. This coordination strategy is used by microorganisms to break symmetry at small scales where viscous effects dominate and flow is time-reversible. Some larger organisms use this swimming strategy at intermediate scales, where viscosity and inertia both play important roles. However, the role of individual propulsor kinematics-especially across hydrodynamic scales-is not well-understood, though the details of propulsor motion can be crucial for the efficient generation of flow. To investigate this behavior, we developed a new soft robotic platform using magnetoactive silicone elastomers to mimic the metachronally coordinated propulsors found in swimming organisms. Furthermore, we present a method to passively encode spatially asymmetric beating patterns in our artificial propulsors. We investigated the kinematics and hydrodynamics of three propulsor types, with varying degrees of asymmetry, using Particle Image Velocimetry and high-speed videography. We find that asymmetric beating patterns can move considerably more fluid relative to symmetric beating at the same frequency and phase lag, and that asymmetry can be passively encoded into propulsors via the interplay between elastic and magnetic torques. Our results demonstrate that nuanced differences in propulsor kinematics can substantially impact fluid pumping performance. Our soft robotic platform also provides an avenue to explore metachronal coordination at the meso-scale, which in turn can inform the design of future bioinspired pumping devices and swimming robots.


Assuntos
Materiais Biomiméticos , Cílios , Hidrodinâmica , Robótica , Natação , Robótica/instrumentação , Animais , Natação/fisiologia , Cílios/fisiologia , Fenômenos Biomecânicos , Ctenóforos/fisiologia , Biomimética/métodos , Biomimética/instrumentação , Desenho de Equipamento , Reologia , Elastômeros de Silicone/química , Viscosidade
18.
Carbohydr Polym ; 346: 122570, 2024 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-39245477

RESUMO

This study investigated the influence of Konjac Glucomannan (KGM) with varying degrees of polymerization (DKGMx) on the gelatinization and retrogradation characteristics of wheat starch, providing new insights into starch-polysaccharide interactions. This research uniquely focuses on the effects of DKGMx, utilizing multidisciplinary approaches including Rapid Visco Analysis (RVA), Differential Scanning Calorimetry (DSC), rheological testing, Low-Field Nuclear Magnetic Resonance (LF-NMR), and molecular simulations to assess the effects of DKGMx on gelatinization temperature, viscosity, structural changes post-retrogradation, and molecular interactions. Our findings revealed that higher degrees of polymerization (DP) of DKGMx significantly enhanced starch's pasting viscosity and stability, whereas lower DP reduced viscosity and interfered with retrogradation. High DP DKGMx promoted retrogradation by modifying moisture distribution. Molecular simulations revealed the interplay between low DP DKGMx and starch molecules. These interactions, characterized by increased hydrogen bonds and tighter binding to more starch chains, inhibited starch molecular rearrangement. Specifically, low DP DKGMx established a dense hydrogen bond network with starch, significantly restricting molecular mobility and rearrangement. This study provides new insights into the role of the DP of DKGMx in modulating wheat starch's properties, offering valuable implications for the functional improvement of starch-based foods and advancing starch science.


Assuntos
Mananas , Polimerização , Amido , Triticum , Triticum/química , Amido/química , Viscosidade , Mananas/química , Ligação de Hidrogênio , Reologia , Simulação de Dinâmica Molecular , Varredura Diferencial de Calorimetria
19.
Carbohydr Polym ; 346: 122615, 2024 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-39245495

RESUMO

This study investigates the complexation between tea seed starch (TSS) and tea polyphenols (TPs) at varying concentrations (2.5, 5.0, 7.5, and 10.0 %). The objectives can expand the knowledge of TSS, which is a novel starch, and to examine how TPs influence the structure and physicochemical properties of the complexes. Results indicate that TPs interact with TSS through hydrogen bonding, altering granule morphology and disrupting ordered structure of starch. Depending on the concentration, TPs induce either V-type or non-V-type crystal structures within TSS, which had bearing on iodine binding capacity, swelling, pasting, gelatinization, retrogradation, rheology, and gel structure. In vitro digestibility analysis reveals that TSS-TPs complexes tend to reduce readily digestible starch while increasing resistant starch fractions with higher TP concentrations. Thus, TSS-TPs complexes physicochemical and digestibility properties can be modulated, providing a wide range of potential applications in the food industry.


Assuntos
Polifenóis , Sementes , Amido , Chá , Polifenóis/química , Amido/química , Sementes/química , Chá/química , Ligação de Hidrogênio , Reologia
20.
Carbohydr Polym ; 346: 122644, 2024 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-39245531

RESUMO

A complex heteropolysaccharide SCP-2 named schisanan B (Mw = 1.005 × 105 g/mol) was obtained from water extracts of Schisandra chinensis fruits, and its planar structure was finally deduced as a galacturonoglucan by a combination of monosaccharide compositions, methylation analysis, partial acid hydrolysis, enzymatic hydrolysis and 1D/2D-nuclear magnetic resonance spectroscopy. The conformation of SCP-2 exhibited a globular shape with branching in ammonium formate aqueous solutions. The rheological properties of SCP-2 were investigated on concentrations, temperature, pH and salts. The in vitro immunomodulatory activity assay demonstrated that SCP-2 significantly enhanced the production of nitric oxide (NO) and stimulated the secretion of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in macrophages. Through a combination of high-resolution live-cell imaging, surface plasmon resonance, and molecular docking techniques, SCP-2 exhibited a strong binding affinity with the Toll-like receptor 4 (TLR4). Moreover, western blot analysis revealed that SCP-2 effectively induced downstream signaling proteins associated with TLR4 activation, thereby promoting macrophage activation. The evidence strongly indicates that TLR4 functions as a membrane protein target in the activation of macrophages and immune regulation induced by SCP-2.


Assuntos
Frutas , Reologia , Schisandra , Receptor 4 Toll-Like , Schisandra/química , Camundongos , Frutas/química , Células RAW 264.7 , Animais , Receptor 4 Toll-Like/metabolismo , Simulação de Acoplamento Molecular , Óxido Nítrico/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Pectinas/química , Fator de Necrose Tumoral alfa/metabolismo , Glucanos/química , Interleucina-6/metabolismo
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