High Molecular Weight Polymers Research Articles

Synthesis and Secretion of Microbial Extracellular Polysaccharides

Complex carbohydrates are frequently deposited on the cell surface to form cell walls, capsules, or 3-dimensional matrices called biofilms. Often, the high molecular weight polymers are synthesized intracellularly and transported across at least one biological membrane by dedicated translocation machineries. We are interested in how polysaccharides are assembled and deposited on the cell surface. In particular, bacterial cellulose is a major biofilm component of many enterobacteria and secreted during its synthesis by the membrane-embedded cellulose synthase, a processive glycosyltransferase. Using the tools of structural and molecular biology, we delineated the mechanism by which the enzyme elongates a cellulose polymer and translocates it across the membrane through a pore formed by its own transmembrane region. We have also examined O antigens, which constitute the variable region of lipopolysaccharides in the outer membrane of Gram-negative bacteria. The polymers are synthesized inside the cell on a lipid anchor and transported to the periplasm by the WzmWzt ABC transporter. Crystal structures of the transporter in nucleotide-free and ATP-bound states suggest a processive translocation mechanism through a channel formed by the transporter. Molecular dynamics simulations suggest that membrane lipids are a fundamental part of the transporter's function by sealing its channel in a resting state.

INFLUENCE OF PHYTOLYTIC AND PROTEOLYTIC ENZYMES ON CONVERSION OF WHEAT AND CORN GRAIN POLYMERS

Grain, in addition to starch, hemicelluloses and protein, is known to be phytic acid and its salts. It has been shown that the use of phytolytic enzymes promotes the release of phosphorus, improves the digestibility of feed nutrients and increases the meat productivity of livestock and poultry. However, the catalytic effect of phytases and their combinations with proteases on degradation of polysaccharides and protein polymers in grain raw materials, on the release of cations and anions, especially in grain wort for the production of alcohol, has been little studied. This work shows for the first time that phytolytic enzymes improve qualitative estimates, rheological properties and change the ionic composition of grain wort by not only releasing phosphates and metal cations, but also by increasing the concentration of organic salt anions. The combined action of phytolytic and proteolytic enzymes on polymers of grain raw materials provides their catalytic degradation to soluble carbohydrates, nitrogenous substances, cations and anions to produce the enriched grain wort. This work aimed to assess the degree of phytolytic and proteolytic conversion of high-molecular-weight polymers in grain wort. For grain wort, 50 g portions of wheat (Triticum sp.) or corn (Zea mays) grain flour put into Erlenmeyer flasks were added with 150 cm3 of water and incubated in a water bath. At grain batching for starch dextrinization, a thermo-stable a-amylase was added (0.6 units/g starch). For starch conversion to sugars and hydrolysis of non-starch polysaccharides in the control, we used glucoamylase (9.0 units/g starch) and xylanase (0.15 units/g raw material). Phytase (from 1.0 to 2.5 units/g raw material) and a proteolytic enzyme preparation (0.1 units/g raw material) were also added. The control was added neither with phytase, nor the proteolytic enzyme. The profiles of the main polymers of grain raw materials, the grain wort concentration, the content of reducing carbohydrates (RС) were determined according to the techno-chemical instructions for the control of alcohol production, the amine nitrogen (NH2+) concentration was measured by a method based on the ability of amino acids to form soluble copper compounds with a suspension of copper phosphate. The dynamic viscosity of the grain wort was evaluated by vibrational viscometry. The study of the ionic composition of the grain mix and wort was carried out using a PrinCE-560 series capillary electrophoresis system (PrinCE Technologies B.V., Netherlands) equipped with a conductometric detector. The optimal dosage of phytase was 1.5 units/g raw material which ensures the maximum release of ions identified by capillary electrophoresis and the effective conversion of polysaccharides, protein and phytin substances of the grain. It was found that the phytolytic enzymes contributed to a decrease in the viscosity of wheat and corn wort of more than 20 %, a 9.5-11.3 % increase in the concentration of reducing carbohydrates, and a 2.1-2.4-fold increase in the concentrations of released ions. The concentration of amino nitrogen in the wort did not change significantly. It was shown that as a result of the phytolytic action, the concentration of not only metal phosphates and cations, but also anions of organic salts, such as oxalates, malates, citrates, and succinates (in wheat wort) and oxalates, malates, citrates, and lactates (in corn wort) increased. A more significant effect of phytase for corn wort was revealed: the concentration of phosphates in the nutrient medium increased 3.9 times vs. 1.6 times for wheat wort, the levels of potassium and magnesium ions were 12 % and 22 % higher, respectively, as compared to the control in which the phytase was not used. The optimal composition of the enzyme complex is proposed which ensures the effective hydrolysis of polysaccharides, phytin and protein substances of processed raw materials. The synergistic effect of phytolytic and proteolytic enzymes enhances the catalytic hydrolysis of high molecular weight polymers of plant origin and enriches the grain wort with carbohydrates, nitrogenous substances, phosphates, and minerals in bioavailable form. Biocatalytic treatment of grain with the developed enzyme complex which, along with amylases and xylanase, contains phytase and proteases, provides a 16.8 % and 18.8 % increase in the concentration of reducing carbohydrates in wheat and corn wort, a 1.7- and 1.9-fold increase in amine nitrogen and a decrease in wort viscosity by 41.7 % and 44.7 %, respectively.

КОНВЕРСИЯ ПОЛИМЕРОВ ЗЕРНА ПШЕНИЦЫ И КУКУРУЗЫ ПОД ВЛИЯНИЕМ ФИТОЛИТИЧЕСКИХ И ПРОТЕОЛИТИЧЕСКИХ ФЕРМЕНТОВ

Grain, in addition to starch, hemicelluloses and protein, is known to be phytic acid and its salts. It has been shown that the use of phytolytic enzymes promotes the release of phosphorus, improves the digestibility of feed nutrients and increases the meat productivity of livestock and poultry. However, the catalytic effect of phytases and their combinations with proteases on degradation of polysaccharides and protein polymers in grain raw materials, on the release of cations and anions, especially in grain wort for the production of alcohol, has been little studied. This work shows for the first time that phytolytic enzymes improve qualitative estimates, rheological properties and change the ionic composition of grain wort by not only releasing phosphates and metal cations, but also by increasing the concentration of organic salt anions. The combined action of phytolytic and proteolytic enzymes on polymers of grain raw materials provides their catalytic degradation to soluble carbohydrates, nitrogenous substances, cations and anions to produce the enriched grain wort. This work aimed to assess the degree of phytolytic and proteolytic conversion of high-molecular-weight polymers in grain wort. For grain wort, 50 g portions of wheat (Triticum sp.) or corn (Zea mays) grain flour put into Erlenmeyer flasks were added with 150 cm3 of water and incubated in a water bath. At grain batching for starch dextrinization, a thermo-stable a-amylase was added (0.6 units/g starch). For starch conversion to sugars and hydrolysis of non-starch polysaccharides in the control, we used glucoamylase (9.0 units/g starch) and xylanase (0.15 units/g raw material). Phytase (from 1.0 to 2.5 units/g raw material) and a proteolytic enzyme preparation (0.1 units/g raw material) were also added. The control was added neither with phytase, nor the proteolytic enzyme. The profiles of the main polymers of grain raw materials, the grain wort concentration, the content of reducing carbohydrates (RС) were determined according to the techno-chemical instructions for the control of alcohol production, the amine nitrogen (NH2+) concentration was measured by a method based on the ability of amino acids to form soluble copper compounds with a suspension of copper phosphate. The dynamic viscosity of the grain wort was evaluated by vibrational viscometry. The study of the ionic composition of the grain mix and wort was carried out using a PrinCE-560 series capillary electrophoresis system (PrinCE Technologies B.V., Netherlands) equipped with a conductometric detector. The optimal dosage of phytase was 1.5 units/g raw material which ensures the maximum release of ions identified by capillary electrophoresis and the effective conversion of polysaccharides, protein and phytin substances of the grain. It was found that the phytolytic enzymes contributed to a decrease in the viscosity of wheat and corn wort of more than 20 %, a 9.5-11.3 % increase in the concentration of reducing carbohydrates, and a 2.1-2.4-fold increase in the concentrations of released ions. The concentration of amino nitrogen in the wort did not change significantly. It was shown that as a result of the phytolytic action, the concentration of not only metal phosphates and cations, but also anions of organic salts, such as oxalates, malates, citrates, and succinates (in wheat wort) and oxalates, malates, citrates, and lactates (in corn wort) increased. A more significant effect of phytase for corn wort was revealed: the concentration of phosphates in the nutrient medium increased 3.9 times vs. 1.6 times for wheat wort, the levels of potassium and magnesium ions were 12 % and 22 % higher, respectively, as compared to the control in which the phytase was not used. The optimal composition of the enzyme complex is proposed which ensures the effective hydrolysis of polysaccharides, phytin and protein substances of processed raw materials. The synergistic effect of phytolytic and proteolytic enzymes enhances the catalytic hydrolysis of high molecular weight polymers of plant origin and enriches the grain wort with carbohydrates, nitrogenous substances, phosphates, and minerals in bioavailable form. Biocatalytic treatment of grain with the developed enzyme complex which, along with amylases and xylanase, contains phytase and proteases, provides a 16.8 % and 18.8 % increase in the concentration of reducing carbohydrates in wheat and corn wort, a 1.7- and 1.9-fold increase in amine nitrogen and a decrease in wort viscosity by 41.7 % and 44.7 %, respectively.

Probing the Release of Bupropion and Naltrexone Hydrochloride Salts from Biopolymeric Matrices of Diverse Chemical Structures.

In the last decades, the notion of including excipients in the formulations, as inert substances aiding production processes, has changed and they are recently viewed as multifunctional discrete entities. It is now well documented that excipients serve several roles, spreading from the stabilization and modified release, to providing biocompatible properties and targeting moieties. The aim of this study was to develop matrix-based oral drug delivery systems of bupropion hydrochloride (BUP·HCl) and naltrexone hydrochloride (NTX·HCl), suitable for releasing these active substances in a modified manner, providing a stable level of drug release, which is simultaneously therapeutically effective and non-toxic, thus reducing side effects, after a single dose administration, throughout the gastrointestinal tract. The new formulations, employing hydroxypropylmethycellulose (HPMC K15M) (a cellulosic polymer, which, generally hydrates to form a gelatinous layer that is critical to prevent wetting and rapid drug release from the matrices), poly(methacylic acid-co-ethyl acrylate) 1:1 (Eudragit® L100-55: effective for site specific drug delivery in intestine), poly(ethylene oxide) (PEO) (7 × 106: a high molecular weight polymer, water-soluble, in micro-granular powder form), as the rate controlling polymers, were chosen to lead to a “soothing out” release pattern of these drugs, at 0 ≤ t ≤ 120 min. Moreover, the release of the two drugs from the ulvan-based tablets, was found to follow the desired profile, throughout the entire course of the dissolution experiments.

A Weight-of-the-Evidence Approach for Evaluating, in Lieu of Animal Studies, the Potential of a Novel Polysaccharide Polymer to Produce Lung Overload.

The United States Environmental Protection Agency (EPA) is concerned about the respiratory effects caused by respirable particles of water-insoluble high molecular weight polymers. The EPA has proposed a tiered approach to evaluate polymer lung overload, a kinetic event. Kinetic polymer lung overload in itself is not necessarily adverse, however, inhalation of respirable particulate matter can have adverse effects (i.e., inflammation, fibrosis, etc.). If Tier I testing demonstrates that particles may reach the distal lung (i.e., a non-negligible amount of respirable particles/droplets ≤10 μm in diameter and lack of biosolubility), then animal inhalation testing in Tiers II-IV would be requested. In silico, in chemico, and in vitro alternatives should be considered versus in vivo testing for animal welfare purposes. An in chemico measure of biosolubility was used to demonstrate that a novel α-1,3-glucan polysaccharide, made by enzymatic polymerization of glucose from sucrose, is biosoluble and fits a simple exponential decay model with a half-life on the order of 66 days. The multiple-path particle dosimetry (MPPD) in silico model was used to predict lung burden for the novel α-1,3-glucan polysaccharide. MPPD was validated with measurements in rats exposed to a toner particulate and showed good agreement with lung burden measurements. A simulated 24 month rat exposure yielded 10-20 times less lung burden for the polysaccharide compared to the toner at equivalent exposure concentrations. The MPPD model was refined to include biosolubility data for the polysaccharide polymer. Data for amorphous silica were used to validate the clearance model, and the model incorporating dissolution predicted the amorphous silica lung burden within 20% of measured values. Human equivalent concentrations (HECs) were calculated for each toner rat exposure concentration. HECs were also determined for the polysaccharide at exposure concentrations yielding the same predicted internal doses as the toner. The in vitro, in chemico and in silico studies described here for the novel polysaccharide provide a useful weight of evidence approach in the absence of animal studies for the evaluation of polymer substances where polymer lung overload may be a concern.

Nanometer-scale capillary-driven flow and molecular weight govern polymer nanostructure deposition from a heated tip

This paper investigates the physical process of polymer nanostructure deposition from a heated atomic force microscope (AFM) tip and focuses on the role of capillary-driven flow on deposited feature sizes during thermal dip-pen nanolithography. We used a heated AFM tip to deposit 50–350 nm wide poly(methyl methacrylate) nanoribbons by varying tip temperature, tip speed, and polymer molecular weight. For polymers of different molecular weights, the width of the deposited polymer nanoribbons decreases with capillary number (Ca), independent of tip temperature, tip speed, and polymer molecular weight. These results indicate that the capillary-driven flow governs polymer nanostructure deposition from a heated tip. For high molecular weight polymers deposited with feature size close to the polymer radius of gyration Rg, the molecular weight also influences the size of the deposited polymer ribbon. Using scaling arguments, we show that the feature size can be predicted by Ca and Rg. Uniform and continuous deposition occurs only when Ca << 1, confirming that the polymer flow is driven by the capillary force. The results of this study enable better control of speed and resolution at which polymer nanostructures can be fabricated using AFM.

The alkaline stability and fuel cell performance of poly(N-spirocyclic quaternary ammonium) ionenes as anion exchange membrane

A series of polymer based on spirocyclic quaternary ammonium (QA) cations having 5-/6- and 6-/6- membered rings were designed and prepared from tetrakis(bromomethyl) monomers to investigate the alkaline and fuel cell stability of spirocyclic ionenes. The alkaline stability testing of model compounds and DFT calculations showed that the spirocyclic QA having 5-/6-membered rings based on phenyl and biphenyl showed a better stability than that of the spirocyclic QA with naphthalene 6-/6-membered rings probably due to the strong electro-withdrawing effect of naphthalene rings. Although the high molecular weight polymer with naphthalene rings could not be obtained, the spirocyclic ionenes based on phenyl or biphenyl showed high molecular weight. Thus, the blending membrane with rigid NPBI have been fabricated to mitigate the water solubility of spirocyclic ionenes due to their high IEC values. The blending membrane showed a high ionic conductivity even at elevated temperature without any excessive swelling in spite of its high IEC value. Employing the spirocyclic ionenes as membrane, the H2/O2 single cell at 60 °C was firstly demonstrated. A peak power density of 135 mW cm−2 was achieved for PP80N20 membrane. Surprisingly, the fuel cell device durability provided a counterintuitive data that showed that spirocyclic ionenes with excellent alkaline stability were not superior in device function assessment. A rapid ring-opening degradation as confirmed by NMR technique for the spirocyclic ionenes was observed in device testing. These results that stability investigation gives us new directions for polymer and cations designs for highly durable devices.

Research on the gelling process of cement slurries for sealing boreholes drilling through shallow gas-bearing levels

The article presents issues related to the sealing slurry technology concerning gelling processes (i.e., static built-up of gel strength of cement slurries). Based on research conducted around the world, it can be concluded that the rate of gelling of the cement slurry has an important role in the process of preventing possible gas exhalations from the annular space. After the cement slurry is pumped into the borehole (especially in zones with shallow gas horizons), the so-called migration (exhalation) of the formation medium (i.e. uncontrolled outflow of e.g. gas from the annular space) may occur. The most important caused of gas migration from the shallow horizons after casings cementation are the inability to maintain a certain overpressure by the column of the binding cement slurry and too long binding of the cement slurry after pumping into the borehole. The initially liquid cement slurry, when pumped out of the casing, acts as a liquid, creating a certain hydrostatic pressure on the deposit. e.g. gas. However, after some time, the period of building the static gel strength (SGS) starts until the cement sets. The SGS building process, i.e. gelling of the cement slurry, reduces the ability to transmit hydrostatic pressure to the reservoir. The Oil and Gas Institute – National Research Institute has tested a number of cement slurry formulations characterized by different gelling and bonding times. Slurries were made on the basis of three typed of latex with the symbols L1, L2, L3, two types of water glass with symbols S1, S2, amorphous silica with the symbol CB, nano-components based on n-SiO2 and n-Al2O3 with the symbols NS and NA as well as high-molecular weight polymer with the symbol GS. Different amounts of setting accelerator were used with the tested slurries. Tests were carried out for eighteen cement recipes, which made it possible to select the optimal compositions of slurries with short gelling and setting times. The samples containing one of the types of latex in the appropriate concentration, the GS polymer, as well as those containing n-SiO2 and n-Al2O3, showed a very advantageous course of the gelation plot (static build-up of gel strength). Their TT transition times, reflecting the course of gelation, ranged from several to several tens of minutes (which is a proof of high ability to prevent gas migration from shallow gas accumulations). The cement slurries developed at the Oil and Gas Institute – National Research Institute, due to their good technological parameters, could be used in the process of cementing casing strings.

A new approach for modeling viscoelastic thin film lubrication

Lubricants can exhibit significant viscoelastic effects due to the addition of high molecular weight polymers. The overall behavior of the mixture is vastly different from a simpler Newtonian fluid. Therefore, understating the influence of viscoelasticity on the load carrying capacity of the film is essential for lubricated contacts. A new modeling technique based on lubrication theory is proposed to take into account viscoelastic effects. As a result, we obtain a modified equation for the pressure, i.e. the viscoelastic Reynolds (VR) equation. We have first examined a parabolic slider to mimic a roller bearing configuration. An increase of the load carrying capacity is observed when polymers are added to the lubricant. Furthermore, our results are compared with existing models based on the lubrication approximation and direct numerical simulations (DNS). For small Weissenberg number (Wi), i.e. the ratio between the polymer relaxation time and the residence time scale, VR predicts the same pressure of the linearized model, in which ϵWi is the perturbation parameter (ϵ is the ratio between the vertical length scale and the horizontal length scale). However, the difference grows rapidly as viscoelastic effects become stronger. Excellent quantitative and qualitative agreement is observed between DNS and our model over small to moderate Weissenberg number. While DNS is numerically unstable at high values of the Weissenberg number, VR does not have the same issue allowing to capture the evolution of the stress and pressure also when the viscoelastic effects are strong. It is shown that even in high shear flows, normal stresses have the largest impact on load carrying capacity and thus cannot be neglected. Furthermore, the additional pressure due to viscoelasticity comprises two components, the first one due to the normal stress and the second one due to the shear stress. Afterwards, the methodology used for the parabolic slider is extended to a plane slider where, instead, the load decreases by adding polymers to the fluid. In particular, under the effect of the polymers surface slopes enhance the rate at which pressure gradients increase, whereas curvature opposes this along the contact. Therefore, the increase of the load carrying capacity observed for viscoelastic lubricants is due to its shape close to the inlet, which is steeper than the plane slider.

Enhancement of filtration efficacy for particulate matters using β-glucan coated commercial masks

Ambient air pollution, in particular, particulate matter (PM) pollution imposes serious health concerns such as hospitalization and premature deaths, worldwide. While commercial breathing masks are in use for protection against this hazardous issue, yet their efficiency in filtering PM was not up to the par, besides several other discomforts such as poor breathability due to reduced air flow, sweat production etc. In this study, commercial face mask coated with β-glucan, a high molecular weight polymer is tested for its efficacy in filtering PM. Quantification of PM before and after filtration and microscopic observation (using scanning electron microscopy (SEM)) of the fabric used in filtering the dust pollutants (generated from wood chips and cigarette) showed that β-glucan coated fabric were significantly efficient in capturing PM (size of 10 and 2.5 μm in diameter) than that of the untreated control fabric, wherein the former had filtration efficacy with fold increase of 11.6 and 2.6 towards capturing PM2.5 and PM10 respectively than the latter. Thus, β- glucan coated fabric was found to be effective in filtering PM.

A Computational Fluid Dynamics Study of Liquid–Solid Nano-fluid Flow in Horizontal Pipe

A regular phenomenon in the petroleum industry is the challenges being faced with a multiphase flow system. Recovering only the oil often results in static pressure losses which often leads to a multiphase mixture being pumped to a separation or processing terminal. The rate of micellar aggregates breakup of surfactants is usually faster when compared to their rate of formation. Polymers of high molecular weights are capable of reducing drag even at minute concentrations degrades under shear stress and at high temperatures, this mechanical degradation could be improved upon with the combination of these duos, thereby making use of the physicochemical interactions between polymers molecules and surfactants micellar aggregates, In this study, ionic polymers such as polyacrylic acid (PAA), Tween 20 (non-ionic surfactant) and Carbon Nanotubes (CNT) particle were tested individually and the complexes examined in the pipeline at varied concentrations. A drag reduction of about 50% was obtained with 1000 ppm of polymer, 300 ppm of the surfactant and 500 ppm of the nanofluid CNT. An increase in concentration with increased Torque was also observed regardless of the sample tested. It was realized that these combinations could be a better drag reduction method as results were obtained and analyzed by comparing the individual performances of these substances, with the complexes where the complexes have a better performance, and this could be as a result of the critical role played by the complex mixtures. The effect of the various additives was simulated using computational fluid dynamics.

Direct Arylation Polycondensation toward Water/Alcohol-Soluble Conjugated Polymers: Influence of Side Chain Functional Groups.

Direct arylation of 2,7-dibromofluorene with n-octyl, 6-diethoxylphosphorylhexyl, 6-(N,N-diethylamino)hexyl or 6-bromohexyl side chains and 1,2,4,5-tetrafluorobenzene (TFB) were conducted to investigate the effect of side chain functional groups on the coupling, and the resulting TFB-substituted fluorene derivatives were used as C-H monomers for the synthesis of water/alcohol soluble conjugated polymers (WSCPs) by direct arylation polycondensation (DArP). The direct arylation and DArP of the monomers carrying phosphonate and amino groups went on smoothly in typical DArP conditions, that is, Pd(OAc)2/PtBu2Me-HBF4/base/DMAc and Pd2(dba)3·CHCl3/P(o-MeOPh)3/pivalic acid/base/THF, and high molecular weight polymers with these groups were successfully synthesized. However, for fluorene-monomers with bromohexyl side chains, the target products could not be obtained from the above conditions but could be prepared in the absence of carboxylic acid additives in low polar solvents. With the above DArP-made polymers as cathode interfacial layers, high performance organic solar cells (OSCs) were successfully fabricated.

Encapsulation of fruit peel proanthocyanidins in biopolymer microgels: Relationship between structural characteristics and encapsulation/release properties

Sodium alginate was used to fabricate biopolymer microgels to encapsulate two proanthocyanidins (PAs) fractions (F1 and F2) isolated from Choerospondias axillaris (C. axillaris) fruit peels. The impact of the molecular mass of the PAs on their entrapment efficiency and release profile was then established. Additionally, the antioxidant and prebiotic activities of the two PA fractions were investigated. The F1 fraction mainly contained oligomers, while the F2 fraction contained higher molecular weight polymers. Both F1 and F2 fractions exhibited strong antioxidant and prebiotic activities at certain concentrations. The entrapment efficiency of F1 and F2 fractions in alginate beads were 43.4 ± 3.2% and 62.2 ± 4.1%, respectively. The entrapment of the F2 fraction was significantly higher than that of the F1 fraction (p < 0.05), which was attributed to its higher molecular weight. The release of the F2 fraction from the alginate beads was marked slower than the F1 fraction, in both water and simulated gastrointestinal conditions, indicating that PAs with higher molecular weight have the potential for creating prolonged release systems. This study highlights the importance of selecting nutraceuticals with appropriate molecular characteristics to obtain good entrapment efficiency and release properties.

Extraction of ingredients from tea leaves using oxidative enzymatic reaction and optimization of extraction conditions

Peroxidase (POD) and polyphenol oxidase (PPO) are used as biocatalyst in many processes such as oxidization reactions, wastewater treatment, phenol synthesis and so on. The purpose of current study is enzymes extraction from biomass (tea leaves) as well as evaluation of their activation. Different parameters including temperature, buffer concentration, buffer type, buffer/tea leaves ratio, addition of high molecular weight polymers and emulsifiers, and pH were optimized in order to obtain the highest enzymes activity. Response Surface Methodology (RSM) procedure is employed for statistical analysis of enzymes extraction. It is understood from the result that PPO and POD possess the highest activity at temperatures of 25 °C and 50 °C, pH 7 and 5, buffer molarity of 0.1, and 0.05, buffer/tea leaves ratio = 5 for both, contact time = 20 min and 10 min, and presence of 6% and 3% PVP, 5% and 0% Tween 80 for PPO and POD, respectively. Amounts of highest activity for PPO and POD biocatalysts were calculated 0.42 U/mL and 0.025493 U/mL, respectively. Moreover, the entire inactivation of PPO took place after 30 min at 40 °C and 60 °C and 20 min at 80 °C. However, POD lost 35% of its activity after 30 min at 40 °C and 60 °C. The amount of 6% POD activity was kept after 45 min at 80 °C. Generally, it was indicated that POD was more resistant to thermal treatment than PPO.

Achieving highly efficient gene transfer to the bladder by increasing the molecular weight of polymer-based nanoparticles

Short dwell-time and poor penetration of the bladder permeability barrier (BPB) are the main obstacles to intravesical treatments for bladder diseases, and is evidenced by the lack of such therapeutic options on the market. Herein, we demonstrate that by finely tuning the molecular weight of our cationic polymer mucoadhesive nanoparticles, we enhanced our gene transfer, leading to improved adherence and penetrance through the BPB in a safe and efficient manner. Specifically, increasing the polymer molecular weight from 45 kDa to 83 kDa enhanced luciferase plasmid transfer to the healthy murine bladder, leading to 1.35 ng/g luciferase protein expression in the urothelium and lamina propria regions. The relatively higher molecular weight polymer (83 kDa) did not induce morphologic changes or inflammatory responses in the bladder. This approach of altering polymer molecular weight for prolonging gene transfer residence time and deeper penetration through the BPB could be the basis for the design of future gene therapies for bladder diseases.

Manufacturing technology of low-molecular-weight chitosan based on enzymatic hydrolysis

Chitosan is natural high molecular weight polymer of D-glucosamine and N-acetyl - D - glucosamine connected by 1,4 - b - glycoside bond with a molecular mass of 1000 kDa (and above), practical use is difficult because of high viscosity of its aqueous solutions even at low concentrations, and lack of solubility at neutral pH and, consequently, low biological activity. To reduce viscosity, improve the solubility and enhance biological activity of high molecular weight chitosan subjected to depolymerization. Chitosan, like other polysaccharides, is characterized by a hydrolysis reaction, which is due to the presence of glycoside bonds in the molecule that are lable to hydrolyzing agents, for example, aqueous solutions of acids, alkalis, as well as to the effect of some hydrolases. During hydrolysis, glycoside bonds are broken and, as a result, the molecular weight of chitosan decreases. However, these processes are accompanied by the formation of significant amounts of toxic products and require very costly disposal of waste before it is discharged into the environment. Chitin and chitosan are natural biopolymers and their synthesis, modification and degradation are associated with enzymatic transformations. It is the biodegradability to the usual substances for the body that is one of the main advantages of chitosan. It is obvious that the most appropriate method is the enzymatic hydrolysis of chitosan. As enzyme preparations for the degradation of chitin and chitosan, enzyme complexes of various origins are used. These can be enzymes from crab or krill hepatopancreas complexes, as well as pancreatin from the pancreas of cattle. But more often for this purpose, enzymes complexes with chitinolytic activity of microbiological origin are used. In this study, low-molecular-weight chitosan was obtained by enzymatic hydrolysis using the extracellular chitinolytic complex of Streptomyces kurssanovii. The resulting chitosan had a medium-viscosity molecular weight of 25-40 kDa. Carrying out two stages of fractionation (stepwise acidification and separation on membranes) made it possible to obtain chitosan fractions with a narrow distribution by molecular weight.

The inhibitory effect of in situ extracellular polymeric substances on trimethoprim adsorption by activated sludge

The extracellular polymeric substances (EPS) of activated sludge are a mixture of high molecular weight polymers secreted by microorganisms, which are mainly composed of proteins, polysaccharides and humic substances. It is widely accepted that EPS have a good adsorption ability for pollutants with different functional groups. However, recent studies showed the EPS had an inhibitory effect on pollutant sorption, which is contradictory to previous viewpoint. Therefore, in this study, three types of activated sludge with different EPS contents and compositions were used to investigate the role of EPS in an antibiotic-trimethoprim (TMP) sorption process at environmentally relevant concentration. The in situ experiments results showed the adsorption capacity of activated sludge for TMP were increased from 2.98, 5.37 and 28.33 μg/g VSS to 7.87, 12.93 and 150.24 μg/g VSS in nitrifying activated sludge, wastewater treatment plant activated sludge and anaerobic ammonia-oxidized activated sludge, respectively after EPS extracted. The adsorption process can be well described by the pseudo-second-order kinetic model. Results of zeta potential, contact angles and infrared spectrum showed TMP replacing proteins embedded into the cell membrane enhancing the TMP adsorption capacity of activated sludge after EPS extraction. Our results demonstrated that less proteins in EPS of activated sludge is more beneficial for TMP adsorption removal.

Quantification of branching within high molecular weight polymers with polyester backbones formed by transfer-dominated branching radical telomerisation (TBRT).

New branched polymerisations offer previously inaccessible macromolecules and architectural understanding is important as it provides insight into the branching mechanism and enables the determination of structure–property relationships. Here we present a detailed inverse gated 13C NMR characterisation of materials derived from the very recently reported Transfer-dominated Branching Radical Telomerisation (TBRT) approach to quantify branching and provide an insight into cyclisation.

Off-line analysis in the manganese catalysed epoxidation of ethylene-propylene-diene rubber (EPDM) with hydrogen peroxide.

The epoxidation of ethylene-propylene-diene rubber (EPDM) with 5-ethylidene-2-norbornene (ENB) as the diene to epoxidized EPDM (eEPDM) creates additional routes to cross-linking and reactive blending, as well as increasing the polarity and thereby the adhesion to polar materials, e.g., mineral fillers such as silica. The low solubility of apolar, high molecular weight polymers in the polar solvents constrains the catalytic method for epoxidation that can be applied. Here we have applied an in situ prepared catalyst comprising a manganese(ii) salt, sodium picolinate and a ketone to the epoxidation of EPDM rubber with hydrogen peroxide (H2O2) as the oxidant in a solvent mixture, that balances the need for polymer and catalyst/oxidant miscibility and solubility. Specifically, a mixture of cyclohexane and cyclohexanone is used, where cyclohexanone functions as a co-solvent as well as the ketone reagent. Reaction progress was monitored off-line through a combination of Raman and ATR-FTIR spectroscopies, which revealed that the reaction profile and the dependence on the composition of the catalyst are similar to those observed with low molar mass alkene substrates, under similar reaction conditions. The combination of spectroscopies offers a reliable method for off-line reaction monitoring of both the extent of the conversion of unsaturation (Raman) and the extent of epoxidation (FTIR) as well as determining side reactions, such as epoxide ring opening and further, aerobic oxidation. The epoxidation of EPDM described, in contrast to currently available methods, uses a non-scarce manganese catalyst and H2O2, and avoids side reactions, such as those that can occur with peracids.

A UHPLC-Q-TOF/MS method for the determination of poloxamer 124 and its application in a tissue distribution study in rats.

Poloxamers are commonly used pharmaceutical excipients. They are high molecular weight polymers formed from polypropylene oxide (PPO) and polyethylene oxide (PEO). However, PL124, a low molecular weight example in the poloxamer family, has rarely been reported, and there is no research into its tissue distribution in the body after administration. In this study, rat tissue samples were quantitatively studied via UHPLC-Q-TOF/MS after the intravenous administration of 10 mg kg-1 PL124. The quantitative method showed good sensitivity and selectivity. The linear range of PL124 was 0.1-5 μg mL-1 and the LLOQ was 0.1 μg mL-1. The relative error in terms of the accuracy was no higher than 13.9%, and the relative standard deviation in terms of the precision was no higher than 9.6%. The extraction recovery, matrix effect, and stability results of the established method were also satisfactory. The research showed that PL124 can be quickly distributed to large amounts of tissue, and tissue with higher levels of blood flow has higher concentrations. PL124 could be rapidly eliminated in 4 h from most organs, except the heart and liver. This study can be helpful for the further analysis of PL124.