Main Chain Structure Research Articles

1H and 13C NMR Study of Oligosuccinimide Prepared by Thermal Condensation and Evaluation of Its Scale Inhibition

<p>The presence of scale is a serious problem in the petroleum industry, and some efforts should be made to control scale formation. Oligosuccinimide (OSI) is an oligomer with several repeating units of succinimide. The structure of the OSI main chain and end groups has never been comprehensively analyzed. Meanwhile, OSI is potentially a scale inhibitor due to chelating properties, high polarity, and high solubility. This study investigates the molecular structure of oligosuccinimide, focusing on the main chain and end groups. Synthesis was carried out by thermal condensation between maleic anhydride and ammonium carbonate using a <sup>1</sup>H and <sup>13</sup>C NMR spectroscope equipped with Distortionless Enhancement by Polarization Transfer 135, Heteronuclear Multiple Quantum Coherence, and Single Quantum Coherence. The NMR analysis results detected the presence of the main chain and several synthesized OSI end groups, such as the amino, succinimide, and maleimide end groups. However, the dicarboxylic acid end group and other irregular structures, as in polysuccinimide (various synthesis methods), were not identified. It confirmed that our thermal condensation method produced OSI with less irregular structures than previous methods. Evaluation of OSI as CaCO<sub>3</sub> and CaSO<sub>4</sub> scales inhibitor showed reasonably good performance in very small concentrations. The inhibition efficiency was 73.20% for the CaCO<sub>3</sub> scale with 10 mg.L<sup>-1</sup> and 55.29% for the CaSO<sub>4</sub> scale with 10 mg.L<sup>-1</sup> inhibitor concentration. Analysis of thermal stability informed OSI has good thermal stability because it started to be degraded at 353.38 °C.</p>

SOBA: Development and testing of a soluble oligomer binding assay for detection of amyloidogenic toxic oligomers

The formation of toxic Amyloid β-peptide (Aβ) oligomers is one of the earliest events in the molecular pathology of Alzheimer's Disease (AD). These oligomers lead to a variety of downstream effects, including impaired neuronal signaling, neuroinflammation, tau phosphorylation, and neurodegeneration, and it is estimated that these events begin 10 to 20 y before the presentation of symptoms. Toxic Aβ oligomers contain a nonstandard protein structure, termed α-sheet, and designed α-sheet peptides target this main-chain structure in toxic oligomers independent of sequence. Here we show that a designed α-sheet peptide inhibits the deleterious effects on neuronal signaling and also serves as a capture agent in our soluble oligomer binding assay (SOBA). Pre-incubated synthetic α-sheet-containing Aβ oligomers produce strong SOBA signals, while monomeric and β-sheet protofibrillar Aβ do not. α-sheet containing oligomers were also present in cerebrospinal fluid (CSF) from an AD patient versus a noncognitively impaired control. For the detection of toxic oligomers in plasma, we developed a plate coating to increase the density of the capture peptide. The proof of concept was achieved by testing 379 banked human plasma samples. SOBA detected Aβ oligomers in patients on the AD continuum, including controls who later progressed to mild cognitive impairment. In addition, SOBA discriminated AD from other forms of dementia, yielding sensitivity and specificity of 99% relative to clinical and neuropathological diagnoses. To explore the broader potential of SOBA, we adapted the assay for a-synuclein oligomers and confirmed their presence in CSF from patients with Parkinson's disease and Lewy body dementia.

Structural Characterization of Polysaccharide Derived from Gastrodia elata and Its Immunostimulatory Effect on RAW264.7 Cells.

A polysaccharide from Gastrodia elata (named GEP-1) was isolated with a DEAE-52 column and Sephadex G-100 column. The structural characteristics showed that GEP-1 was mainly composed of glucose (92.04%), galactose (4.79%) and arabinose (2.19%) with a molecular weight of 76.444 kDa. The polydispersity (Mw/Mn) of GEP-1 was 1.25, indicating that the distribution of molar mass (Mw) was relatively narrow, which suggested that GEP-1 was a homogeneous polysaccharide. Moreover, the molecular conformation plot of the root mean square (RMS) radius (<rg2> 1/2) versus Mw yielded a line with a slope less than 0.33 (0.15 ± 0.02), displaying that GEP-1 is a compact and curly spherical molecule in NaNO3 aqueous solution. NMR and methylation analyses revealed that the main chain structure of GEP-1 was α-(1→4)-glucans. Furthermore, it was proven that GEP-1 possessed cytoproliferative and enhancing phagocytic activities and induced cytokine (TNF-α, IL1-β) and nitric oxide (NO) release in macrophages by upregulating the related gene expression. In addition, the RNA-seq results suggested that the GEP-1-induced immunomodulatory effect was mainly caused by activation of the NF-κB signaling pathway, which was further verified by NF-κB ELISA and pathway inhibition assays. As a result, GEP-1 exhibits the potential to be developed as a novel cheap immunostimulant without obvious toxicity.

A Facile Method for Thermally, Light, and Mechanically Stable Organic Solar Cells Using Ultraviolet‐Initiated Crosslinkable Additive

AbstractCrosslinkable additive in organic solar cells has great potential to fix metastable bulk heterojunction, supplying solutions for burn‐in loss and long‐term instability. New roles of crosslinkable additive as a solvent additive, radical scavenger, and stretchability enhancer beyond its well‐known role as a crosslinker with morphology frozen effect are reported. According to the main chain structure between Br in end groups, crosslinkable additive is divided into two types of alkyl and siloxane main chain, expecting different roles. First, the alkyl moiety molecule, 1,8‐dibromooctane (DBr‐octane), provides the effects of improved thermal and light stability without any loss in efficiency. The DBr‐octane device shows remarkable enhanced results in burn‐in‐free, maintaining 90% of its initial efficiency after 600 min at 85 °C, and light stability, maintaining 90% of its initial efficiency after 360 min under 1 SUN, in a fullerene system. Second, crosslinkable additive is treated with siloxane main chain molecule, bis(3‐bromopropyl)‐terminated poly(dimethyl siloxane) (DBr‐siloxane), in an active layer to secure stretchability. As a result, the DBr‐siloxane‐treated film stretches up to 70% and the flexible device of the fullerene system maintains an initial efficiency of over 60% after 1000 bending cycles at a bending radius of 1.8 mm.

Preparation, characterization and bioactivities of selenized polysaccharides from Lonicera caerulea L. fruits

Native polysaccharide was obtained from Lonicera caerulea L. fruits (PLP). Two selenized polysaccharides (PSLP-1 and PSLP-2) were synthesized by the microwave-assisted HNO3-Na2SeO3 method, where the selenium (Se) contents were 228 ± 24 and 353 ± 36 μg/g, respectively. The molecular weights of PLP, PSLP-1, and PSLP-2 were 5.9 × 104, 5.6 × 104, and 5.1 × 104 kDa, respectively. PSLP-1 and PSLP-2 contained the same type of monosaccharides as PLP but with different molar ratios. The main chain structure of the native polysaccharide was not changed after selenization. PLP, PSLP-1, and PSLP-2 contained the same six types of glycosidic bonds. Bioactivity assays revealed that the two selenized polysaccharides possessed better antioxidant activities than PLP, but their bile acid-binding abilities and inhibitory activities on acetylcholinesterase (AChE) had weakened. In summary, PLP, PSLP-1, and PSLP-2 may be promising Se supplements in functional foods and inhibitors for the treatment of AChE.

Preparation of All Amorphous PMMA Resins Based on the Graft Architecture with a Flexible Main Chain for Simultaneous Enhancement of Thermal and Mechanical Toughness

AbstractThis study shows the design of poly(methyl methacrylate) (PMMA)‐based glassy polymers with simultaneous improvement of thermal resistance and mechanical toughness, based on the graft architecture with a low glass transition (Tg) flexible main chain. The microphase‐separated structure of the flexible main chain and the glassy graft chains in this design may be key to these improved properties. Notably, the graft copolymer depicts the ductile fracture, and the microscopy observation for the fractured sample exhibits the presence of abundant void formation with relatively homogenous size and interval throughout the sample. The void formation could originate from the preferential fracture of aggregated flexible components distributed throughout the sample, indicating the effective role of the flexible main chain on the suppression of the internal stress. The novelty of the present study is on the use of simple graft architecture for enhancing the toughness of glassy resins. This idea is indeed distinct from the conventional approach to improve toughness by adding plasticizer or rubber particles, therefore opening a new method for the creation of high‐functional glassy polymers.

Controlling the microphase morphology and performance of cross-linked highly sulfonated polyimide membranes by varying the molecular structure and volume of the hydrophobic cross-linkable diamine monomers

Morphological control is essential for tuning the performance of polymer electrolyte membranes (PEMs). Block copolymerization is an effective but complicated way to control the morphology of PEMs. It is urgent to explore a simple alternative method to achieve this target. Herein, the molecular engineering strategy that changes the molecular structure and volume of hydrophobic cross-linkable diamine and introduces a hydrophobic network structure was used to optimize the microphase morphology of sulfonated polyimides (SPIs). Three diamine monomers containing tetrafluorostyrol pendant groups have been synthesized (4-(2,3,5,6-tetrafluoro-4-vinylphenoxy)benzene-1,3-diamine (TFVPDM), 1,3-bis(2-trifluoromethyl-4-amino-phenoxy)-5-(2,3,5,6-tetrafluoro-4-vinylphenoxy)benzene (6FTFPB), 2,2-bis(3-amino-4-(2,3,5,6-tetrafluoro-4-vinylphenoxy)phenyl)hexafluoropropane (6FATFVP)). Based on these monomers, 4,4′-diaminostilbene-2,2′-disulfonic acid (DASDSA) and 1,4,5,8-naphthalenetetracarboxylicdianhydride (NTDA), three cross-linked SPIs (CSPIs: CSPI-T-10, CSPI-TP-10, CSPI-AP-10) with similar ion-exchange capacity (IEC) value of 2.29–2.46 meq. g−1 but different main-chain structures were prepared through polycondensation and thermal cross-linking process. The introduced hydrophobic cross-linked structure improves the oxidative stability and methanol resistance of CSPI membranes. The CSPI membranes prepared from cross-linkable hydrophobic diamine with larger molecular volume and containing hydrophobic structural units in the main chain exhibit more pronounced phase separation morphology and higher proton conductivity. Moreover, the methanol resistance of CSPI membranes is dependent on the combined effect of IEC, degree of crosslinking (DC), and main-chain structure. The higher DC and main-chain containing hydrophobic structure are beneficial for enhancing the methanol resistance. The CSPI-AP-10, which was prepared from the 6FATFVP with the largest molecular volume, more hydrophobic cross-linkable pendant groups and hydrophobic linkages, exhibits the best performance. The CSPI-AP-10 membranes showed high proton conductivity and excellent methanol resistance. The direct methanol fuel cells (DMFCs) assembled from CSPI-AP-10 have a high max power density (PDmax) of 106.2 mW cm−2 in 2 M methanol and 75.1 mW cm−2 in 10 M methanol. The results indicated that the CSPI-AP-10 was a promising candidate as a PEM in DMFC application.

Experimental and application of continuous regeneration of waste rubber

AbstractCombined with the Serial Rubber Continuous Mixing Device (SRCMD) and custom‐built rotors, the real continuous regeneration of waste rubber was realized. The upstream mixer effectively solves the problem of pretreatment of waste rubber and realizes its preliminary regeneration. The downstream twin‐screw extruder realizes supplementary regeneration and plasticized extrusion of waste rubber. The optimal process parameters for preparing SRCMD‐reclaimed rubber were explored through orthogonal experiments. Compared to the commercially‐reclaimed rubber produced by the traditional vulcanization tank high‐temperature regeneration method, the SRCMD‐reclaimed rubber well retains the main chain structure of waste rubber and has obvious advantages in various properties. The conveyor belt coverings made by partially replacing styrene butadiene rubber with SRCMD‐reclaimed rubber fully meet the requirements of the national standard in all properties and are better than commercially‐reclaimed rubber, which has good application prospects and provides a guide for promoting the industrial transformation of recycled rubber.

New Degradable Semiconducting Polymers for Photoacoustic Imaging of λ-Carrageenan-Induced Arthritis Mouse Model.

Semiconducting polymer has a high extinction coefficient and a long band absorption and can be used as a photoacoustic imaging contrast agent. However, nonbiodegradable semiconducting polymers may cause biosafety issues due to being retained in the body. Therefore, developing degradable semiconducting polymers is necessary for in vivo imaging. Herein, we developed three degradable semiconducting polymers with unique optical properties. We adjusted the optical properties of semiconducting polymers by designing the molecular structure of semiconducting polymers. Polymers with a donor-π-acceptor structure could easily improve the optical properties through adjusting the donor or acceptor units. Through adjusting the electron-donor and -acceptor units, three diketopyrrolopyrrole derivative polymers (DPPTz, DPPQu, and DPPWu) were synthesized and converted into nanosize particles. By introducing the degradable chemical groups in the main chain structure of semiconducting polymers, diketopyrrolopyrrole polymers could be degraded by ClO-. Among these nanosize particles, DPPTz NPs and DPPQu NPs were used to achieve the in vivo photoacoustic imaging of λ-carrageenan-induced arthritis mouse model. This work provides a novel design idea for the designing of red-shifted semiconducting polymer with degradable properties.

Controllable synthesis and structural design of novel all-organic polymers toward high energy storage dielectrics.

As the core unit of energy storage equipment, high voltage pulse capacitor plays an indispensable role in the field of electric power system and electromagnetic energy related equipment. The mostly utilized polymer materials are metallized polymer thin films, which are represented by biaxially oriented polypropylene (BOPP) films, possessing the advantages including low cost, high breakdown strength, excellent processing ability, and self-healing performance. However, the low dielectric constant (ε r < 3) of traditional BOPP films makes it impossible to meet the demand for increased high energy density. Controlled/living radical polymerization (CRP) and related techniques have become a powerful approach to tailor the chemical and physical properties of materials and have given rise to great advances in tuning the properties of polymer dielectrics. Although organic-inorganic composite dielectrics have received much attention in previous studies, all-organic polymer dielectrics have been proven to be the most promising choice because of its light weight and easy large-scale continuous processing. In this short review, we begin with some basic theory of polymer dielectrics and some theoretical considerations for the rational design of dielectric polymers with high performance. In the guidance of these theoretical considerations, we review recent progress toward all-organic polymer dielectrics based on two major approaches, one is to control the polymer chain structure, containing microscopic main-chain and side-chain structures, by the method of CRP and the other is macroscopic structure design of all-organic polymer dielectric films. And various chemistry and compositions are discussed within each approach.

Molecular design and experiment of ion transport inhibitors towards concrete sustainability

Regulating the transmission of chloride medium in concrete is the primary research work to improve the durability and sustainability of concrete, effectively saving offshore buildings' maintenance costs. Inspired by the molecular design of drug delivery, this study designed an erosive solution-responsive ion transport inhibitors (ITI) to restrain the transport of erosive solution in calcium silicate hydrates (C–S–H) gel pores, which is expected to reduce the water absorption and chloride diffusion coefficient of concrete efficiently. In this investigation, molecular dynamics was applied to reveal the mechanism of ITI with different main-chain structures on the atomic scale, and an evaluation system of such polymers was proposed. When the main chain is the carboxylic group, the ITI is similar to the hinge of the door. Once the corrosion solution invades the gel channel, the hydrophobic group will be perpendicular to the surface of calcium silicate hydrates to prevent the transmission of the solution. However, when the main chain is alcohol amine, the ITI can gather at the front of the erosion solution to form a water plugging medium and complex with the eroded ions to inhibit the diffusion of ions. On this basis, the optimal ITI is evaluated through water adsorption and chloride ion diffusion tests and further applied in offshore engineering. The results show that they can effectively alleviate chloride ion erosion without sacrificing mechanical properties.

One-pot treatment with maleic anhydride vs. the interfacial compatibility of polycaprolactone-microcrystalline cellulose composites

Polycaprolactone (PCL) is an eco-friendly and biodegradable synthetic polyester encouraged by various government authorities. These biodegradable bioplastics and lignocellulose composites have attracted people’s attention. Usually, neat PCL has poor interfacial compatibility with potential reinforcing particles and poor mechanical properties, which limit its application. The drawbacks can be effectively solved with maleic anhydride (MA) and microcrystalline cellulose (MCC). In this study, PCL composites were prepared by the one-pot synthesis method. The roughness of the PCL-MA/MCC film was reduced 66.7%, the contact angle (CA) reached a maximum of 87.5°, and its tensile strength was effectively improved by 77.8%. The thermodynamic properties of PCL-MA were similar to PCL. In contrast to PCL, the thermodynamic properties of PCL-MA were minimally affected, and the main chain structure of PCL was not broken despite the formation of new chemical groups. Its interfacial compatibility and mechanical properties were effectively improved.

Analysis of Serum from Acute Leukemia Patients Using Surface-Enhanced Raman Spectroscopy (SERS)

In this paper, we show surface-enhanced Raman spectroscopy (SERS) of serum from acute leukemia and analyze the SERS through the multivariate statistical method of principal component analysis (PCA). First, the changes in the structure of proteins, lipids, carbohydrates, and other substances in the serum of patients with acute leukemia are analyzed from the molecular perspective. The results showed that the ordered structure of the protein main chain and the side chain conformation was weakened, the main chain structure was almost broken, and the protein became loose and disordered. In addition, the content of esters, amino acids, glycoproteins, and carbohydrate-related substances decreases, indicating a change in the environment. Finally, the PCA method was used to analyze the SERS signal of the serum of healthy people and patients with acute leukemia to accurately distinguish the two serum samples. The above conclusions can provide a favorable experimental basis for diagnosing leukemia and the study of the biochemical mechanism involved.

Disulfide Dichloride: A High Efficiency Vulcanizing Agent for Sulfurized Polyacrylonitrile

Sulfurized polyacrylonitrile (SPAN) cathodes have shown great prospects in commercial applications due to the high discharge capacity, good cycle stability, and low self-discharge rate. However, high sulfurization temperature results in loss of nitrogen atoms, which leads to imperfect SPAN structure and is not conducive to fast electron transfer. A high efficiency vulcanizing agent of S2Cl2 was used to reduce the reaction temperature in this work. We found that S2Cl2 promotes PAN cyclization, reduces the cyclization reaction temperature, and avoids the loss of nitrogen atoms and the agglomeration of SPAN primary particles in high-temperature reactions. The SPAN cathode material prepared using S2Cl2 has a more regular structure six-membered ring main chain structure and a smaller primary particle size, which is beneficial to the rapid conduction of electrons and lithium ions in the electrode material. The electrochemical test results confirmed that the SPAN cathode material prepared by S2Cl2 has higher active material utilization, better cycle stability, and better rate performance.

Thermoresponsive Properties of Poly[oligo(ethylene glycol) sorbate]s Prepared by Organocatalyzed Group Transfer Polymerization

The current contribution presents the synthesis of poly[oligo(ethylene glycol) sorbate]s (PREGmSs) by the t-Bu-P4-catalyzed group transfer polymerization (GTP) method, their postpolymerization modification at the backbone double bond, and thermoresponsive properties in aqueous solution. Four oligo(ethylene glycol) sorbate monomers (REGmSs), including 2-(2-methoxyethoxy)ethyl sorbate (MeEG2S), 2-(2-(2-methoxyethoxy)ethoxy)ethyl sorbate (MeEG3S), 2-(2-(2-ethoxyethoxy)ethoxy)ethyl sorbate (EtEG3S), and 2-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)ethyl sorbate (MeEG4S), are newly designed to study the thermoresponsive properties of their related polymers. The t-Bu-P4-catalyzed GTP of REGmS only proceeds in a 1,4-regioselective addition manner to quantitatively produce the backbone trans-rich (ca. 80%) PREGmS. The complete hydrogenation and epoxidation of the backbone double bonds result in hydrogenated and epoxidized polymers (PREGmS-H2 and PREGmS-epoxy, respectively), which have different main-chain structures and rigidity from their parent PREGmS. Given the 1,4-substituted structure of a sorbate monomer, the chemical structure determination of PREGmS-H2 by 13C NMR spectra demonstrates that the above polymers have an erythro-rich (ca. 60%) structure in diastereochemistry and a diisotactic/disyndiotactic ratio around 1:1 in stereoregularity. The thermoresponsive properties of PREGmS, PREGmS-H2, and PREGmS-epoxy in aqueous solutions are studied in detail from various aspects in terms of polymer mass concentration, molecular weight, length and end group of the oligo(ethylene glycol) side chain, and main-chain structure by turbidity, 1H NMR spectroscopy, and dynamic light scattering (DLS) methods, which are discussed below.

Enantioseparation on helical poly(diphenylacetylene)s bearing optically-active pendants: Effects of differences in higher-order structures of kinetically-trapped and thermodynamically-stable states on chiral recognition ability

An optically-active poly(diphenylacetylene) (PDPA) bearing carboxy pendant groups with left-handed helicity memory (M-h-poly-1), synthesized using the noncovalent helicity-induction-and-memory strategy, was converted into a PDPA bearing optically-active pendant groups through an amide bonding (M-hKT-poly-2S), while maintaining the left-handed helicity memory, by reaction with (S)-1-phenylethylamine ((S)-2) using a condensing reagent at room temperature. Its chiral recognition ability was investigated as a chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC). M-hKT-poly-2S exhibited significantly different chiral recognition ability towards racemates compared to the previously reported corresponding helical PDPA bearing the same optically-active pendant groups (M-hTS-poly-2S) (prepared by the reaction of an optically-inactive PDPA bearing carboxy pendants with (S)-2, followed by thermal annealing, to induce a left-handed helical structure in the polymer main chain). Although the main chains of both M-hKT-poly-2S and M-hTS-poly-2S formed almost completely left-handed helical structures, their higher-order structures varied slightly, as confirmed by various spectroscopic methods (UV-Vis, circular dichroism (CD), IR, and vibrational CD). M-hKT-TS-poly-2S, the PDPA formed on the thermal annealing of M-hKT-poly-2S, exhibited the same higher-order structure and chiral discrimination ability as M-hTS-poly-2S. Therefore, slight differences in the higher-order structures of the kinetically-trapped metastable state (M-hKT-poly-2S) and the thermodynamically-stable state (M-hTS-poly-2S), due to differences in synthetic procedures, significantly impact their chiral recognition abilities as CSPs, even with identical primary structures and helix-sense of the polymer main chain.

A novel exopolysaccharide produced by Zygosaccharomyces rouxii with cryoprotective and freeze-drying protective activities

In the present work, a novel exopolysaccharide EPS-3791 was extracted and purified from a salt-tolerant yeast, Zygosaccharomyces rouxii. Structural analyses showed that EPS-3791 was composed of galactose, glucose and mannose in a molar ration of 1.00: 4.25: 13.30 with a molecular weight of 64.412 kDa. Fourier transform infrared spectroscopy manifested the main functional groups, α- and β- configurations. Methylated analysis indicated T-Manp-(1→, →2)-Glcp-(1 → and → 2,6)-Manp-(1 → were the main linkages. 800 MHz nuclear magnetic resonance spectroscopy demonstrated the EPS-3791 structure of a novel main chain and branched chain. Atomic force microscope and scanning electron microscope revealed a homogeneous and uniform porous structure. In addition, EPS-3791 was proven to have cryoprotective and freeze-drying protective effects on Lactococcus lactis, and exhibited better protective performance than that of trelahose during freeze-drying of L. lactis, suggesting that EPS-3791 could be developed into cryoprotectant or lyoprotectant applied in food industry.

Biopolymers Produced by Sphingomonas Strains and Their Potential Applications in Petroleum Production.

The genus Sphingomonas was established by Yabuuchi et al. in 1990, and has attracted much attention in recent years due to its unique ability to degrade environmental pollutants. Some Sphingomonas species can secrete high-molecular-weight extracellular polymers called sphingans, most of which are acidic heteropolysaccharides. Typical sphingans include welan gum, gellan gum, and diutan gum. Most sphingans have a typical, conserved main chain structure, and differences of side chain groups lead to different rheological characteristics, such as shear thinning, temperature or salt resistance, and viscoelasticity. In petroleum production applications, sphingans, and their structurally modified derivatives can replace partially hydrolyzed polyacrylamide (HPAM) for enhanced oil recovery (EOR) in high-temperature and high-salt reservoirs, while also being able to replace guar gum as a fracturing fluid thickener. This paper focuses on the applications of sphingans and their derivatives in EOR.

The copolymerization of SO2with propylene oxide mediated by organic ammonium salts: a comprehensive study of the main-chain structure, living polymerization character and regioselectivity

The copolymerization of SO2with PO mediated by PPNCl was comprehensively studied with reference to main-chain structure analysis, living polymerization character, regioselectivity, and cyclic byproducts.

Structural characterization and rheological properties of an alkali-extracted β-glucan from Hypsizygus marmoreus

A homogeneous β-glucan (JHMP-70) was obtained from Hypsizygus marmoreus by alkali extraction and ethanol precipitation, and had an apparent molecular weight of 394 kDa. Its fine structure was investigated by FT-IR, methylation combined with GC-MS and 1D and 2D NMR analysis. Results indicated JHMP-70 was a branched β-(1 → 6)-glucan substituted at O-3 by the non-reducing β-Glcp and/or β-(1 → 3)-linked β-Glcp side chains at a ratio of 1:1. SEM observation revealed that there were micro-spherical shapes intertwined with randomly distributed fibrous filaments. Rheological measurements showed that its flow behavior was highly dependent on the concentration. Newtonian behavior was evident at low concentration, whereas pseudoplastic behavior was observed at high concentration. Besides, the addition of salt ions (Na + or Ca2+) significantly decreased the apparent viscosity of JHMP-70 solution. The low viscosity of JHMP-70 was probably attributed to its structural features, including main chain structure, branching degree and side chain length. This work can provide a basis theory to expand the application of the polysaccharides from H. marmoreus in food industry, because their lower viscosity and superior fluidity are desired in beverage products to impart stability against phase separation without compromising other sensorial properties.