Different Degrees Of Polymerization Research Articles

The influence of the poly(ethylene glycol) on the mean activity coefficients of NaCl aqueous solutions. The application of the MSA and HNC method

A primitive model electrolyte in mixture with uncharged hard spheres was used to model the concentration dependence of the mean activity coefficient of sodium chloride in aqueous solutions of poly(ethylene glycol) (PEG) of different degree of polymerization and concentration. Ornstein-Zernike integral equation was numerically solved using the hypernetted chain (HNC) closure and the results were compared with the results of an analytical solution valid within the mean spherical approximation (MSA) closure. Good agreement between the HNC and MSA activity coefficients was obtained. However, at higher NaCl concentrations the convergence of the numerical solution was not satisfied for large model PEG molecules. The presence of the neutral component in the solution increases the mean activity coefficients in the whole concentration range due to the confinement. For a given NaCl and PEG concentration, decreasing the dielectric constant of the solution diminishes the activity coefficient due to stringer interaction between the ions. Mean activity coefficients of NaCl in two aqueous solutions differing in the concentrations of PEG (molecular weight of 12,000gmol−1) were determined also experimentally and compared with MSA results. The agreement was semi-qualitative, mainly due to difficulties in estimating good model parameters for the PEG molecules and the potential decrease of the dielectric constant of the solvent.

A novel structural fucosylated chondroitin sulfate from Holothuria Mexicana and its effects on growth factors binding and anticoagulation

Fucosylated chondroitin sulfate (FCS), a structurally distinct glycosaminoglycan from the body wall of sea cucumber, possesses many biological properties and pharmacology functions. The refined structure of FCS isolated from sea cucumber Holothuria Mexicana (FCShm) was characterized by NMR spectra and HILIC-FTMS, which demonstrated four types of branches in FCShm. Among these, two branches were α-L-Fuc-2S4S (where Fuc is fucose and S is sulfo) and α-L-Fuc-4S linked to O-3 of glucuronic acid residues, while others were identified as α-L-Fuc-4S and α-L-Fuc-3S4S attached to O-6 of N-acetylgalactosamine residue. Furthermore, the fucosyl branches were α-1,3-linked with different degree of polymerization from 1 to 5. FCShm exhibited high affinity to fibroblast growth factor 1 and 2, growth factors involved in neovascularization. Moreover, FCShm displayed intrinsic anticoagulant activity and inhibited thrombin and factor Xa activation by antithrombin III. Our results proposed a novel structural FCS and demonstrated its favorable application prospects in anti-angiogenesis and anticoagulation.

Novel coal and siloxane based surfactants: Bola polysiloxanes modified with butynediol-ethoxylate and their properties

Novel polysiloxane amphiphiles obtained by introducing coal-based amphiphiles (butynediol ethoxylate) into polysiloxanes based on hydrosilylation reaction by two steps: first, synthesizing hydride terminated polysiloxane with different degree of polymerization (HTP); second, butynediol-ethoxylate was grafted on hydride terminated polysiloxane at terminals to get bola coal-based polysiloxane amphiphiles (EO-PSi-EO). In our work, EO-PSi-EO were compared together to investigate the impacts of different ratios of hydrophilic and hydrophobic groups on its properties. A conclusion was obtained from the work that EO-PSi-EO with various hydrophobic backbones have low surface tension, rich aggregate behavior, excellent wetting property and low foam.

Evaluation of supercritical CO2 dried cellulose aerogels as nano-biomaterials

Cellulose is the renewable, biodegradable and abundant resource and is suggested as an alternative material to silica due to the high price and environmental load of silica. The first step for cellulose aerogel production is to dissolve cellulose, and hydrated calcium thiocyanate molten salt is one of the most effective solvents for preparing porous material. Cellulose aerogels were prepared from dissolved cellulose samples of different degree of polymerization (DP) and drying methods, and tested with shrinkage, density and mechanical strength. Supercritical CO2 dried cellulose aerogels shrank less compared to freeze-dried cellulose aerogels, whereas the densities were increased according to the DP increases in both cellulose aerogels. Furthermore, scanning electron microscope (SEM) images showed that the higher DP cellulose aerogels were more uniform with micro-porous structure. Regarding the mechanical strength of cellulose aerogels, supercritical CO2 dried cellulose aerogels with higher molecular weight were much more solid.

Characterization of Lipophilized Monomeric and Oligomeric Grape Seed Flavan-3-ol Derivatives.

Grape seed proanthocyanidins, composed of flavan-3-ols of different degrees of polymerization, are natural food antioxidants. Flavan-3-ols in grape seed are usually polyhydroxy derivatives which exhibit hydrophilic character. Monomeric and oligomeric flavan-3-ols were modified structurally to improve their lipophilicity, expand their application in lipophilic media, and enhance their cellular absorption in the body. The esterification of the water-soluble flavan-3-ols was prepared by Lipozyme TL IM with lauric acid, and their enhanced lipophilicity was confirmed by a 1-octanol/water partition coefficient. The chemical structures of monomeric and oligomeric flavan-3-ol derivatives, identified by HPLC-MS-MS and 1H and 13C NMR, were 3'-O-lauroyl catechin, 3'-O-lauroyl epicatechin, 3',5'-2-O-lauroyl epigallocatechin, 3',3″,5″-3-O-lauroyl epicatechin gallate, 3',3″-2-O-lauroyl procyanidin A2, 3',3″-2-O-lauroyl procyanidin B1, and 3',3″,3‴-3-O-lauroyl procyanidin C1. Flavan-3-ol derivatives exhibited the highest 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activities compared to that of parent flavan-3-ols, butylated hydroxytoluene and tert-butyl hydroquinone. The results suggest that flavan-3-ol derivatives may be used as potential lipophilic antioxidants in the food industry.

Microencapsulation of Eugenia uniflora L. juice by spray drying using fructans with different degrees of polymerisation

The objective of this work was to microencapsulate pitanga (Eugenia uniflora L.) juice by spray drying, using High Performance Agave Fructans (HPAF) and High Degree of Polymerisation Agave Fructans (HDPAF) and maltodextrin (MD), respectively, as the wall materials. The physicochemical and antioxidant properties of the capsules during storage at various temperatures were evaluated. The microparticles developed using fructans HPAF and HDPAF, exhibited similar physicochemical and flow properties to those presented by the microparticles prepared with MD. The highest yield and concentration of anthocyanins after drying and during storage were found for a 1:6 core:wall material ratio. The total color change was a good indicator of the microcapsule stability. This study showed that both fructans fraction possess similar encapsulating properties to MD and that the HDPAF were more efficacious than MD at protecting the antioxidants during drying and storage.

Obtaining orange juice–maltodextrin powders without structure collapse based on the glass transition temperature and degree of polymerization

ABSTRACTA set of four maltodextrins (MXs) with different degree of polymerization were employed as carrying agents for the spray drying of liquid orange juice (OJ) without collapse in the microstructure; this was visually observed as fine powders non-agglomerated were obtained with a characteristic color. The powders were subjected to water adsorption and characterized. The effect of the MX added was the increase in the adsorption of water and the subsequent depression in the glass transition temperature (Tg). The microstructure did not crystalize at any water activity, but the phase changed from an amorphous solid to a solid covered by saturated liquid. Additionally, a simple mathematical model based on the molar fractions and the Tg of the individual components was proposed for predicting the overall Tg of the ternary system water–OJ–MX. The results presented herein may contribute to the processing of sugar-rich systems and in the stability of food products.

Effect of inulin with different degree of polymerization on water redistribution of steamed bread

The aim of this work was to study the influences of three types of inulin with different degree of polymerization on the water state of steamed bread during production and storage. The addition of inulin reduced the moisture content of the dough and facilitated the migration of free water to bound water. In the fermentation process, inulin had little impact on the bound water content in the dough, but could speed up the fermentation process. During the storage time, the freezable water content in steamed bread crumb decreased faster in the presence of inulin. The weaker interaction of freezable water with starch and protein chains became stronger, while the stronger interaction of tightly bound water with starch and protein chains decreased compared to the control. The changes of melting and vaporization enthalpies suggested that inulin could accelerate water migration of steamed bread from the inside to the outside.

Enzymatic Hydrolysis of Water Extractable Polysaccharides from Leaves of Plantago major L.

Plantago major L. leaves have been used for centuries by the traditional medicine in the treatment of infectious disorders of the respiratory, urinary and digestive tracts. Researchers have reported that hot water extracts of Plantago major possess a broad-spectrum of anticancer, antioxidant and antiviral activities, as well as activities which modulate cell-mediated immunity. Their beneficial properties may be due to the significant content of polysaccharides. The polysaccharides that have been isolated from the leaves of Plantago major L. have different structures - pectic substances, galactans, arabinogalactans, glucomannans. The aim of this paper was to study the correlation between the structure of the water extractable polysaccharides isolated from Plantago major L. leaves and their enzymatic hydrolysis with different carbohydrate hydrolases. The hydrolysis reactions were performed with the enzymes hemicellulase and mannanase. Spectrophotometric total reducing sugars assay was used to examine the hydrolysis yield. The monosaccharide and oligosaccharide compositions were determined using HPLC analysis. The highest hydrolysis yield of the water extractable polysaccharides from Plantago major leaves was obtained by treatment with hemicellulase. The hydrolysis yield increased with the augmentation of the ratio of enzyme to polysaccharide. Galactose was the prevalent monosaccharide identified in the composition of the isolated polysaccharides. Oligosaccharides with different degree of polymerization were also detected. The enzymatic hydrolysis of water extractable polysaccharides from Plantago major leaves allows us to obtain different types of oligosaccharides with beneficial effects on both human health and industry.

Characterizing amorphous silicates in extraterrestrial materials: Polymerization effects on Raman and mid‐IR spectral features of alkali and alkali earth silicate glasses

AbstractAmorphous silicates are common in extraterrestrial materials, especially in carbonaceous chondrites of petrologic types 1 and 2. In addition, high percentage of amorphous components and poorly crystalline phyllosilicates were found in the mudstones at Gale Crater by the CheMin instruments on board of Mar Curiosity rover, which illustrates the importance of characterizing amorphous silicates in future planetary surface explorations. The structure of an amorphous silicate can vary in two aspects: the degree of polymerization and the degree of crystallinity. Here we present the first phase study on characterizing synthetic alkali and alkali earth silicate glasses with different degrees of polymerization by using vibration spectroscopy. Compared with crystalline silicates, their Raman and mid‐IR spectra show broad spectral peaks but have the similar peak positions. We find that a change in the degree of polymerization of these silicate glasses affects their Raman band positions, especially the ratio of Raman band intensities, as well as the positions of the Christiansen feature and reststrahlen bands in their mid‐IR absorbance spectra. Based on these observations, we establish a calibration curve that could enable semiquantification of the polymerization degree of silicate glasses in planetary surface/subsurface materials during future robotic planetary surface exploration missions.

Effect of inulin with different degree of polymerization on plain wheat dough rheology and the quality of steamed bread

The aim of this study was to evaluate the effect of different polymerization degree of inulin on plain wheat dough rheology and quality of steamed bread. It was found the water absorption of dough decreased with the increasing of short-chain (FS) and natural inulin (FI) and increased with the increasing of long-chain inulin (FXL) higher than 7.5%. Three kinds of inulin all increased the development time, stability and farinograph quality number and decreased softening degree of the dough. When proof time was less than 90min, the extensibility increased with the substitution of 5% of FS, 5% of FI and 2.5% of FXL. The resistance to extension, ratio number of resistance to extensibility and energy all increased with the increasing of FS and FI as well as the time. While the energy increased with FXL substation at 45min and dropped thereafter, regardless of the concentration. The addition of inulin all enhanced the brightness, specific volume and hardness of steamed bread and decreased the water content, vaporization enthalpy, springiness, recovery, and cohesiveness. During the storage, inulin reduced the change rates of relative hardness, recovery, and cohesiveness and increased the change rate of relative enthalpy, which restrained the staling rate of steamed bread.

Inulin with different degrees of polymerization modulates composition of intestinal microbiota in mice.

The study aimed to analyze the global influences of dietary inulin with different degrees of polymerization (DP) on intestinal microbial communities. Six-week-old male C57BL/6J mice were treated with fructo-oligosaccharides and inulin for 6 weeks. Fecal samples were obtained at time point 0 and 6th week. 16S rRNA sequence analysis was used to measure intestinal microbiota performed on the Illumina MiSeq platform. Influences of dietary inulin on intestinal microbiota were more complex effects than bifidogenic effects, relative abundance of butyrate-producing bacteria increased after interventions. Akkermansia muciniphila, belonging to mucin-degrading species, became a dominant species in Verrucomicrobia phylum after treatment with fructo-oligosaccharides and inulin. Modulation effects of intestinal microbiota were positively correlated with DP. Lower DP interventions exhibited better effects than higher DP treatment on stimulation of probiotics. We hypothesized that Akkermansia muciniphila played an important role on maintaining balance between mucin and short chain fatty acids.

3D high-resolution two-photon crosslinked hydrogel structures for biological studies

The design and development of high resolution 3D gelatin hydrogel woodpile structures by two-photon crosslinking is reported. Significantly, topological and mechanical conditions of polymerized gelatin structures were suitable for cell accommodation in the volume of the woodpiles, leading to a cell density per unit area comparable to the bare substrate. The fabricated structures, presenting micrometric features of high resolution, are actively deformed by cells, both in terms of cell invasion within rods and of cell attachment in-between contiguous woodpiles. Possible biological targets for this 3D approach are customized 3D tissue models, or studies of cell adhesion, deformation and migration.

Cytotoxicity of Light-Cured Dental Materials according to Different Sample Preparation Methods.

Dental light-cured resins can undergo different degrees of polymerization when applied in vivo. When polymerization is incomplete, toxic monomers may be released into the oral cavity. The present study assessed the cytotoxicity of different materials, using sample preparation methods that mirror clinical conditions. Composite and bonding resins were used and divided into four groups according to sample preparation method: uncured; directly cured samples, which were cured after being placed on solidified agar; post-cured samples were polymerized before being placed on agar; and “removed unreacted layer” samples had their oxygen-inhibition layer removed after polymerization. Cytotoxicity was evaluated using an agar diffusion test, MTT assay, and confocal microscopy. Uncured samples were the most cytotoxic, while removed unreacted layer samples were the least cytotoxic (p < 0.05). In the MTT assay, cell viability increased significantly in every group as the concentration of the extracts decreased (p < 0.05). Extracts from post-cured and removed unreacted layer samples of bonding resin were less toxic than post-cured and removed unreacted layer samples of composite resin. Removal of the oxygen-inhibition layer resulted in the lowest cytotoxicity. Clinicians should remove unreacted monomers on the resin surface immediately after restoring teeth with light-curing resin to improve the restoration biocompatibility.

Protein-polyelectrolyte complexes: Molecular dynamics simulations and experimental study

Despite use of polyelectrolytes is considered to be a prospective approach of protein aggregation suppression, owing to formation of soluble protein-polyelectrolyte complexes, the structure of the complexes and mechanism of their formation are not sufficiently understood. The aim of this work was to study the influence of degree of polymerization on the structure and properties of formed complexes. We carried out molecular dynamics simulations of complexes of cationic protein lysozyme with highly charged polyanions – poly(styrene sulfonate) and polyphosphate – of different degree of polymerization. It has been shown that the short charged chains are bound with the protein via a great majority of repeat units, while the long chains have unbound fragments that form charged loops and tails around the protein surface. These loops were earlier suggested to provide stability of the complex. Furthermore, the charge of the complex increased with increasing length of chain. These findings are consistent with the experimentally measured zeta potential. The obtained results help to explain why polyanion protective efficiency against protein aggregation increases with increase of the degree of polymerization.

Effects of inulin with different degree of polymerization on gelatinization and retrogradation of wheat starch.

The effects of three types of inulin, including FS (DP≤10), FI (DP of 2-60) and FXL (DP≥23), on the gelatinization and retrogradation characteristics of wheat starch were investigated. As the concentration of inulin added into starch increased, the gelatinization temperature increased whereas the breakdown value decreased, and the value of setback first decreased and then increased slightly. The three types of inulin with lower concentrations (<15%) all showed obvious suppression effects on the short-term retrogradation of wheat starch. After 7days of storage, the three types of inulin showed a significant suppression of starch retrogradation in the addition range of 5-7.5%. They can all inhibit amylose retrogradation, but accelerate amylopectin retrogradation. Inulin with lower DP has stronger effects on the starch retrogradation. Generally, the three types of inulin can all retard the retrogradation performance of wheat starch to some extent in the long-term storage.

Physicochemical and catalytic properties of SAPO-31 materials prepared from the silica sources characterized by a different degree of polymerization

Two series of microporous silicoaluminophosphates SAPO-31 with different Si content (Si/Al = 0—0.5) were synthesized using silica sources characterized by various degree of polymerization (fumed silica and tetraethoxysilane). Physicochemical properties of the resulted materials were studied by X-ray diffraction, XPS, scanning (SEM) and transmission (TEM) electron microscopy. The nature of the silicon species was identified by 29Si NMR method and the acidity was measured by IR-spectroscopy of adsorbed pyridine. The activity and selectivity of Pd modified SAPO-31 samples from both series were evaluated in the isomerization of n-decane. It was found that the use of the monomer as a silicon source ensured more efficient silicon incorporation, which resulted in the higher activity of Pd/SAPO-31 catalysts. Moreover, the selectivity of these samples for isomerization was found to be independent of the silicon content and its distribution.

The Solubility of Microcrystalline Cellulose in Sodium Hydroxide Solution Is Inconsistent with International Specifications.

Microcrystalline cellulose (MCC) is used globally as an inactive ingredient in food and nutraceutical products and is commonly used as a food additive. To confirm the conformity of MCC to the solubility requirements stipulated in international specifications, the solubilities of commercially available MCC products were tested in sodium hydroxide (NaOH) solution. All of the samples were insoluble in NaOH solution, which is inconsistent with the descriptions provided in international specifications. We also prepared celluloses with different degree of polymerization (DP) values by acid hydrolysis. Celluloses with lower DP were prepared using a three-step process, and their solubilities were tested in NaOH solution. These celluloses were found to be insoluble, which is inconsistent with the descriptions provided in international specifications. The present study suggests that the descriptions of the solubility of the celluloses in NaOH solution found in the current international specifications should be revised.

Bioglass implant-coating interactions in synthetic physiological fluids with varying degrees of biomimicry.

Synthetic physiological fluids are currently used as a first in vitro bioactivity assessment for bone grafts. Our understanding about the interactions taking place at the fluid–implant interface has evolved remarkably during the last decade, and does not comply with the traditional International Organization for Standardization/final draft International Standard 23317 protocol in purely inorganic simulated body fluid. The advances in our knowledge point to the need of a true paradigm shift toward testing physiological fluids with enhanced biomimicry and a better understanding of the materials’ structure-dissolution behavior. This will contribute to “upgrade” our vision of entire cascades of events taking place at the implant surfaces upon immersion in the testing media or after implantation. Starting from an osteoinductive bioglass composition with the ability to alleviate the oxidative stress, thin bioglass films with different degrees of polymerization were deposited onto titanium substrates. Their biomineralization activity in simulated body fluid and in a series of new inorganic–organic media with increasing biomimicry that more closely simulated the human intercellular environment was compared. A comprehensive range of advanced characterization tools (scanning electron microscopy; grazing-incidence X-ray diffraction; Fourier-transform infrared, micro-Raman, energy-dispersive, X-ray photoelectron, and surface-enhanced laser desorption/ionization time-of-flight mass spectroscopies; and cytocompatibility assays using mesenchymal stem cells) were used. The information gathered is very useful to biologists, biophysicists, clinicians, and material scientists with special interest in teaching and research. By combining all the analyses, we propose herein a step forward toward establishing an improved unified protocol for testing the bioactivity of implant materials.

Size effects of chitooligomers with certain degrees of polymerization on the chilling tolerance of wheat seedlings

In this study, six fully deacetylated single chitooligomers (COSs, chitobiose to chitoheptaose) and one fully deacetylated COS mixture were applied to wheat seedlings to investigate their effects on the plants’ defence response under chilling stress. The results showed that exogenous COS with different degrees of polymerization (DPs) could promote the growth of plants, decrease the concentration of malondialdehyde (MDA), increase the content of chlorophyll and modulate the activities of antioxidant enzymes. The analysis of genes expression suggested that COS could alleviate the damage of chilling stress by effectively regulating the expression of antioxidant enzyme genes. Furthermore, chitohexaose and chitoheptaose had the most effective activities of alleviating chilling stress to wheat seedlings, which suggested the DP played important roles in the activities of COS. The close relationship between the activities of COSs and their DPs reveals that the activities of COSs are dependent upon a specific structure to interact with elicitor receptors on plant cell membrane.