Molecular Weight Distribution Profiles Research Articles

Membrane Separation of Chicken Byproduct Hydrolysate for Up-Concentration of Bioactive Peptides.

Membrane processes, such as microfiltration, ultrafiltration, and nanofiltration, are increasingly used for various applications in both upstream and downstream processing. Membrane-based processes play a critical role in the field of separation/purification of biotechnological products, including protein production/purification. The possibility of using membranes to separate peptides from a chicken byproduct hydrolysate and the effect of the performed downstream processing on the DPP-IV dipeptidyl peptidase IV (DPP-IV) inhibitory activity of mechanical deboning chicken residue (MDCR) has been investigated. The chicken byproduct hydrolysate was prepared by enzymatic hydrolysis followed by microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) separation. Comparing all separation treatments, hydrolysates processed only by MF and UF show the best DPP-IV inhibition (59.5-60.0% at 1 mg/mL and 34.2-40.7% at 0.5 mg/mL). These samples show dose-responsive behavior. Bioactivity was correlated with molecular weight distribution profiles and average molecular weights. The nanofiltration process notably decrease the inhibitory activity, and these permeates show low DPP-IV inhibition (9.5-21.8% at 1 mg/mL and 3.6-12.1% at 0.5 mg/mL). The size-exclusion chromatography-organic carbon detection-organic nitrogen detection (LC-OCD-OND) analysis confirms that NF and RO would retain the bioactive peptides in the concentrate in comparison to MF and UF. Bioactivity was correlated with molecular weight distribution profiles and average molecular weights. Permeates after ultrafiltration show an IC50 value of 0.75 mg/mL, comparable to other potent DPP-IV inhibitors derived from various food sources, and significantly more potent compared to the microfiltration sample, which shows an IC50 value of 1.04 mg/mL. The average molecular weight of the permeates calculated from the SEC chromatograms was 883 g/mol for UF and 1437 g/mol for MF. Of the four membranes studied, the UF membrane shows the best separation properties with respect to maximizing the yield and up-concentration of the bioactive peptides. Overall, UF was demonstrated to be a feasible technology for the removal of the undesired high-molecular-weight substances and up-concentration of small-molecular-weight bioactive peptides from chicken byproduct hydrolysate. These peptides might exhibit biological activity and could offer several health benefits. There is a high potential for the use of bioactive peptides, and more research in this field can lead to promising results that have significant effects in the food and medical industries.

Obtaining the Enoxaparin Sodium Substance Equivalent to the Original Clexane® and Lovenox®. The Selection of Technological Parameters and Optimization of the “Greenness” of the Purification Stage

The aim of the study was to adjust and optimize the purification stage of crude enoxaparin sodium to obtain a substance equivalent to the original drugs Clexane® and Lovenox® according to the criteria specified by the FDA. The purification stage involves the reprecipitation of crude enoxaparin in methanol. Determining the ratio of solvents required for the reprecipitation is important for studying the correlation between the experimental conditions of the technological process and the structural characteristics of enoxaparin samples. In the study, the method of purification of enoxaparin sodium described in the patent was assessed, and the following variations of the MeOH:H2O solvent ratio were selected – 4:1; 2:1; 1:1. The obtained samples of enoxaparin sodium were analyzed according to the in-house specification developed on the basis of the pharmacopoeial monograph, as well as by non-pharmacopoeial methods, such as two-dimensional NMR spectroscopy (HSQC) and size exclusion chromatography (SEC) for detailed characterization of the molecule. Strategies of greening of the enoxaparin sodium purification stage by reducing the E-factor were also considered in the study. Considering the principles of “green” chemistry, the method of purification of crude enoxaparin sodium was optimized by the solvent regeneration. It was experimentally possible to demonstrate the effect of the solvent ratio at the stage of purification of crude enoxaparin on the composition, as well as on the number and distribution of oligosaccharide fractions in the molecule. Based on the results of the study, it can be concluded that the ratio of MeOH:H2O=1:1 allows obtaining samples that are closest to Clexane® and Lovenox® in terms of the molecular weight distribution profile and the composition profile. The E-factor was also reduced from 14 to 5.25 by solvent regeneration.

Lactic Acid-Derived Copolymeric Surfactants with Monomer Distribution Profile-Dependent Solution and Thermoresponsive Properties

We report the synthesis and solution properties of novel biobased thermoresponsive amphiphilic copolymers prepared using N,N-dimethyl lactamide acrylate (DMLA) and ethyl lactate acrylate (ELA) as hydrophilic and hydrophobic monomers, respectively. Copolymers with similar overall molecular weight but different monomer distribution profiles, such as random, diblock, triblock, and random–blocks, were prepared using photoinduced electron/energy transfer-reversible addition–fragmentation chain transfer (PET-RAFT) polymerization activated by a Zn-based photoredox catalyst. The synthesized polymers show interesting self-assembly and thermoresponsive behavior in water, depending on the monomers distribution along the chain. Different critical solution temperatures, in the range of 13–70 °C, were observed by tuning the monomers molar ratio and distribution. The formation of aggregates of various types was proven by transmission electron microscopy (TEM). The prepared polymers also display different surface activity with the fully random copolymer being significantly more surface active than block systems. A study of emulsion stabilization was performed with oils of various polarity, showing promising results for applications of these novel polymers as biobased surfactants and water/oil (w/o) emulsion stabilizers.

Post-enzymatic hydrolysis heat treatment as an essential unit operation for collagen solubilization from poultry by-products

Enzymatic protein hydrolysis (EPH) is an invaluable process to increase the value of food processing by-products. In the current work the aim was to study the role of standard thermal inactivation in collagen solubilization during EPH of poultry by-products. Hundred and eighty hydrolysates were produced using two proteases (stem Bromelain and Endocut-02) and two collagen-rich poultry by-products (turkey tendons and carcasses). Thermal inactivation was performed with and without the sediment to study the effect of heat on collagen solubilization. A large difference in molecular weight distribution profiles was observed when comparing hydrolysate time series of the two proteases. In addition, it was shown that 15 min heat treatment, conventionally used for inactivating proteases, is essential in solubilizing collagen fragments, which significantly contributes to increasing the protein yield of the entire process. The study thus demonstrated the possibility of producing tailored products of different quality by exploiting standard heat inactivation in EPH.

Development of polysaccharide-casein gel-like structures resistant to in vitro gastric digestion

Controlling protein digestion is a promising strategy to modulate hormonal responses involved in satiety and appetite regulation. In this context, polysaccharide-casein gel-like structures have been developed and subjected to in-vitro gastrointestinal digestions to evaluate their potential for delaying casein hydrolysis. The effect of the polysaccharide type (agar vs. κ-carrageenan), the polysaccharide:casein ratio and the physical state of the structures (hydrogels vs. aerogels) on the protection ability was investigated. The microstructure evolution of the materials upon the digestions was studied and the molecular weight distribution and peptidomic profile of the digestion products were also determined.During the gastric phase most of the developed structures exerted a protective effect and intact casein clusters were even detected in some of the formulations. In contrast, during the intestinal phase most of the casein was released and hydrolysed to a certain extent. In general, the hydrogels showed a greater protective effect than the aerogels, due to a limited diffusion of the protein towards the liquid medium. Moreover, a higher polysaccharide:protein ratio produced stronger gel networks which provided greater protection. In particular, agar-based and κ-carrageenan hydrogels with 25% polysaccharide and agar-based aerogels with 75% polysaccharide would be the most optimum for delaying casein digestion, since they were able to preserve intact casein after the gastric phase while promoting the release of peptides during the intestinal phase.

Multi-level fingerprinting and cardiomyocyte protection evaluation for comparing polysaccharides from six Panax herbal medicines

The role of polysaccharides in quality control of ginseng is underestimated. Large-scale comparison on the polysaccharides of Panax ginseng (PG), P. quinquefolius (PQ), P. notoginseng (PN), Red ginseng (RG), P. japonicus (ZJS), and P. japonicus var. major (ZZS), was performed by both chemical and biological approaches. Holistic fingerprinting at polysaccharide and the hydrolyzed oligosaccharide and monosaccharide levels utilized various chromatography methods, while OGD and OGD/R models on H9c2 cells were introduced to evaluate the protective effects on cell viability and mitochondrial function. Polysaccharides from six ginseng species exhibited remarkable content difference (RG > PG/ZZS/ZJS/PQ > PN), but weak differentiations in molecular weight distribution and oligosaccharide profiles, while Glc and GalA were richer for monosaccharide compositions of PG and RG polysaccharides, respectively. RG polysaccharides (25/50/100 μg/mL) showed significant cardiomyocyte protection by regulating mitochondrial functions. These new evidences may provide support for the supplementary role of polysaccharides in quality control of ginseng.

Temporal Control over Two- and Three-State Living Coordinative Chain Transfer Polymerization for Modulating the Molecular Weight Distribution Profile of Polyolefins.

A highly versatile new strategy for manipulating the molecular weight profiles, including breadth, asymmetry (skewness) and modal nature (mono-, bi-, and multimodal), of a variety of different polyolefins is reported. It involves temporal control over two- and three-state living coordinative chain transfer polymerization (LCCTP) of olefins in a programmable way. By changing the identity of the R' groups of the chain transfer agent, ER'n , with time, different populations of chains within a bi- or multimodal polyolefin product can be selectively tagged with different end-groups. By changing the nature of the main-group metal of the CTA, programmed manipulation of the relative magnitudes of the dispersities of the different maxima that make up the final MWD profile can be achieved. This strategy can be implemented with existing LCCTP materials and conventional reactor methods to provide access to scalable and practical quantities of an unlimited array of new polyolefin materials.

Temporal Control over Two‐ and Three‐State Living Coordinative Chain Transfer Polymerization for Modulating the Molecular Weight Distribution Profile of Polyolefins

AbstractA highly versatile new strategy for manipulating the molecular weight profiles, including breadth, asymmetry (skewness) and modal nature (mono‐, bi‐, and multimodal), of a variety of different polyolefins is reported. It involves temporal control over two‐ and three‐state living coordinative chain transfer polymerization (LCCTP) of olefins in a programmable way. By changing the identity of the R′ groups of the chain transfer agent, ER′n, with time, different populations of chains within a bi‐ or multimodal polyolefin product can be selectively tagged with different end‐groups. By changing the nature of the main‐group metal of the CTA, programmed manipulation of the relative magnitudes of the dispersities of the different maxima that make up the final MWD profile can be achieved. This strategy can be implemented with existing LCCTP materials and conventional reactor methods to provide access to scalable and practical quantities of an unlimited array of new polyolefin materials.

Enhanced Antimicrobial Activity of Atmospheric Pressure Plasma Treated and Aged Cotton Fibers

ABSTRACT In this work, plasma pretreatment of raw cotton fibers combined with silver sorption was used for the preparation of antimicrobial fabrics. Special attention was given to the aging effect investigated seven days after plasma treatment. Raw cotton fabrics were modified with atmospheric pressure dielectric barrier discharge (DBD) in air, nitrogen, and oxygen. After plasma treatment, surface morphology and chemistry were characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively, molecular weight distribution and functional groups profile in cellulose were determined by GPC-MALLS with fluorescence labeling, while sorption properties were evaluated through wettability and moisture sorption measurements. Silver sorption was performed either immediately after treatment or seven days after plasma treatment, in order to investigate the aging effect on the sorption of Ag+. Antimicrobial activity was tested using agar diffusion test against S. aureus, E.coli, and C. albicans. Results have shown that silver sorption is improved and significantly higher when sorption is performed seven days after plasma treatment and consequently antimicrobial activity is also enhanced. This work confirms the significance of plasma aging in natural cellulose fibers’ functionalization which presents yet another variable that should be taken into account when planning the procedure for fibers functionalization.

Modification of regenerated cellulose ultrafiltration membranes with multi-walled carbon nanotubes for enhanced antifouling ability: Field test and mechanism study.

Although ultrafiltration (UF) has been extensively employed for drinking water purification, it is crucial to further develop novel membrane materials to improve the antifouling capacity and satisfy the practical usage. Multi-walled carbon nanotubes (MWCNTs) have characteristics that could potentially improve the membrane antifouling performance. Therefore, in this study, modified cellulose UF membranes were prepared using MWCNTs of various outer diameters ranging from 10 to 20nm to 40-60nm. The antifouling properties of the modified membrane and natural organic matter (NOM) removal mechanism were investigated while treating water from a local drinking water source river. Overall, the antifouling ability increased by more than one-fold when the nascent cellulose membrane was coated with MWCNTs (outer diameter of 40-60nm) at a loading of 17.4g/m2. The molecular weight distribution profiles of the NOM in the raw water and permeates suggest the superior performance of the modified membranes in removing two major NOM fractions with molecular weights ranging from approximately 5k-30k and 500k-1000k. Based on its hydrophobicity, the NOM of the raw water was fractionated into the strong hydrophobic (SHPO), the weak hydrophobic, the strong hydrophilic and the moderately hydrophilic (MHPI) fractions. The WHPO fraction caused the highest fouling compared with the other fractions under consistent experimental conditions. Meanwhile, the modified membranes showed a preference for removing the MHPI and SHPO fractions. These results imply that MWCNTs can be employed to improve the antifouling property of cellulose UF membranes and have the potential to selectively remove moderately hydrophilic contaminants from water.

Phenyl-bonded monolithic silica capillary column liquid chromatographic separation and detection of fluorogenic derivatized intact proteins.

Prior to the identification of proteins for proteomics analysis in human cells, separation of fluorogenic derivatized proteins with a fluorogenic reagent, 7-chloro-N-[2-(dimethylamino)ethyl]-2,1,3-benzoxadiazole-4-sulfonamide, has typically been performed by using a conventional reversed-phase HPLC column. However, the number of proteins in human cells (HepaRG) that are separated by this conventional approach is limited to approximately 500. In this study, a nanoflow liquid chromatography system with an evaluated phenyl-bonded monolithic silica capillary column (0.1 mm i.d., 700 mm length) was used to increase the number of separated fluorogenic derivatized proteins. This system was used to separate derivatized human cell proteins (K562) and yeast (Saccharomyces cerevisiae) proteins as model cell proteomes. More than 1,300 protein peaks were separated/detected from both cell proteomes. We present a straightforward comparison of multiple separation profiles using a novel chromatogram display approach, termed the "spiderweb" chromatogram. In addition, to validate that the detected peaks are derived from proteins, a mass spectrometer was connected to the capillary column and deconvolution of the obtained mass spectra was performed. Furthermore, different molecular weight distribution profiles of the expressed proteins were observed between the two cell proteomes.

Effect of dough mixing with slightly acidic electrolyzed water on the shelf-life and quality characteristics of fresh wet noodles

This study investigated the effect of dough mixing with slightly acidic electrolyzed water (SAEW) on the shelf-life and qualities of fresh wet noodles. The initial total plate count (TPC) of fresh wet noodles prepared with SAEW was decreased significantly (p < 0.05) and the shelf-life was extended to 5 days. The decrease of polyphenol oxidase activity of noodles was beneficial for browning inhibition purposes and the L* value of noodle sheets did increase after SAEW treatment. Higher SAEW concentration contributed to the increased hardness of fresh wet noodles. The increase of peak viscosity of fresh wet noodles and the closely related enhanced tensile force were mainly due to the chemical cross-linking effect of oxidized starch, which was resulted from the oxidation process during SAEW treatment. Furthermore, the polymerization of monomeric proteins induced by SAEW treatment was also evidenced by molecular weight distribution profiles of proteins and morphology changes in SAEW noodles.

Removal efficiency of dissolved organic matter from secondary effluent by coagulation-flocculation processes

Wastewater reuse has been widely discussed as an essential strategy to minimize the consumption of drinking water for less noble purposes. During biological wastewater treatment, organic matter is converted into a complex matrix containing a variety of soluble organic compounds. The objective of the present study was to evaluate the removal efficiency of the residual organic load in the final effluent from wastewater treatment plant with a conventional activated sludge process by different coagulants and parameters of coagulation-flocculation process, using dissolved organic carbon (DOC) concentration, molecular weight (MW) size distribution by size exclusion chromatography (SEC) coupled to mass spectrometry (MS), and zeta potential (ZP) analyses. The results showed a DOC removal efficiency up to 45% with iron chloride, and of 38% for aluminum sulfate and 31% for PAC coagulants. ZP was also measured during the procedures and authors conclude that the ZP also does not have a determining role in these removals. SEC and MS assessment was able to detect changes on secondary effluent molecular weight distribution profile after effluent coagulation-flocculation, this technique might be a promising tool to understand the composition of effluent organic matter and be helpful to estimate and optimize the performance of wastewater effluents treatment processes.

General route to design polymer molecular weight distributions through flow chemistry

The properties of a polymer are known to be intrinsically related to its molecular weight distribution (MWD); however, previous methodologies of MWD control do not use a design and result in arbitrary shaped MWDs. Here we report a precise design to synthesis protocol for producing a targeted MWD design with a simple to use, and chemistry agnostic computer-controlled tubular flow reactor. To support the development of this protocol, we constructed general reactor design rules by combining fluid mechanical principles, polymerization kinetics, and experiments. The ring opening polymerization of lactide, the anionic polymerization of styrene, and the ring opening metathesis polymerization are used as model polymerizations to develop the reactor design rules and synthesize MWD profiles. The derivation of a mathematical model enables the quantitative prediction of the experimental results, and this model provides a tool to explore the limits of any MWD design protocol.

Physicochemical properties and bioactivities of original and Se-enriched polysaccharides with different molecular weights extracted from Pleurotus ostreatus

Three polysaccharides (WZP1, WZP2, WZP3) and their Se-enriched products (SeWZP1, SeWZP2 and SeWZP3) were obtained from Pleurotus ostreatus using a simple, rapid method and HNO3-Na2SeO3 method, respectively. The molecular weight distribution profiles of all samples except SeWZP2 showed double peaks. The average molecular weights (Mw) of WZP1–3 were 48.6 kDa, 20.2 kDa and 11.8 kDa, respectively, and of SeWZP1–3 were 19.6 kDa, 37.7 kDa, 14.5 kDa, respectively. The complexity of monosaccharide composition of WZP1–3 was inversely proportional to the ethanol concentration used in the ethanol precipitation process. Additionally, the results of biological activity tests indicated that α-glucosidase inhibitory activity of WZP1–3 was related to the molecular weight and the monosaccharide composition complexity. The selenized modification can improve the α-glucosidase-inhibiting, hydroxyl radical-scavenging activity of P. ostreatus polysaccharides. Therefore, by improving their bioactivities by selenization, the polysaccharides of P. ostreatus could be utilized as a natural health food supplement.

Fast and reliable computational strategy for developing a rigorous model-driven soft sensor of dynamic molecular weight distribution

Key polymer properties are substantially directly related to the polymer molecular weight distribution (MWD). On-line monitoring and prediction of dynamic MWD profiles are highly important for on-line quality control of polymerization processes. In this study, a fast and reliable computational strategy for an equation-oriented model-based soft sensor for the high-density polyethylene grade transition process is developed. The simultaneous collocation approach is adopted to discretize the dynamic model. A novel moving finite element method is proposed to improve the on-line performance of the derived large-scale nonlinear equation systems. The sensitivity information of the nonlinear equation systems contributes to a convergence enhancement strategy for the sensor. The prediction accuracy and computational efficiency are demonstrated using industrial data. A potential application to extend the polymerization process with changeable flowsheet is also tested through simulation.

Effect of Low-Frequency Ultrasonic-Assisted Enzymolysis on the Physicochemical and Antioxidant Properties of Corn Protein Hydrolysates

The aim of this study was to investigate the effect of low-frequency ultrasound on the enzymolysis of corn protein. A L9(34) orthogonal design was used to optimize ultrasound pretreatment conditions. Degree hydrolysis (DH), conversion rate of protein (CR), and DPPH IC50were selected as analytical indicators. Under the optimal ultrasound conditions (5 W/L power, 2 s/2 s on/off time, 50°C temperature, and 25 min time), the DH, CR, and radical (DPPH∙,OH∙) scavenging capacities were significantly increased. Molecular weight distribution and amino acid profile analysis showed that ultrasound pretreatment enhanced the formation of short-chain peptides with molecular weight of 200–3000 Da, especially the peptides containing hydrophobic amino acids. Moreover, 40 potential antioxidant peptides were purified by C18 semipreparative column and identified by UPLC-ESI-MS. The results suggest that the optimal ultrasonic-assisted enzymolysis technology could be useful for preparation of antioxidant peptides from corn.

Relationship of molecular weight distribution profile of unreduced gluten protein extracts with quality characteristics of bread

A statistical correlation was established among the molecular weight distribution patterns of unreduced gluten proteins and physicochemical, rheological and bread-making quality characteristics of wheat varieties. Size exclusion chromatography fractionated the gluten proteins apparently into five peaks. Peak I signified glutenins (30–130kDa), peak II as gliadins (20–55kDa), peak III as very low molecular weight monomeric gliadins (10–28kDa), peak IV and V, collectively, as albumins and globulins (<10kDa). Peaks I and II had appreciable effects on dough development time (r=0.830∗∗ and r=−0.930∗∗) and dough stability (r=0.901∗∗ and r=−0.979∗∗). Peak I was associated with R/E ratio (r=0.745∗∗), gluten index (r=0.959∗∗), and gliadin/glutenin ratio (r=−0.952∗∗), while peak II influenced inversely as expected. Peak I exhibited positive statistical significance with bread loaf volume (r=0.848∗∗); however, peak II had negative (r=−0.818∗∗) impact. Bread firmness increased with increment in peak II (r=0.625∗∗), and decreased with accretion in peak I (r=−0.623∗∗).

Influence of molecular-weight polydispersity on the glass transition of polymers.

It is well known that the polymer glass transition temperature T_{g} is dependent on molecular weight, but the role of molecular-weight polydispersity on T_{g} is unclear. Using molecular-dynamics simulations, we clarify that for polymers with the same number-average molecular weight, the molecular-weight distribution profile (either in Schulz-Zimm form or in bimodal form) has very little influence on the glass transition temperature T_{g}, the average segment dynamics (monomer motion, bond orientation relaxation, and torsion transition), and the relaxation-time spectrum, which are related to the local nature of the glass transition. By analyzing monomer motions in different chains, we find that the motion distribution of monomers is altered by molecular-weight polydispersity. Molecular-weight polydispersity dramatically enhances the dynamic heterogeneity of monomer diffusive motions after breaking out of the "cage," but it has a weak influence on the dynamic heterogeneity of the short time scales and the transient spatial correlation between temporarily localized monomers. The stringlike cooperative motion is also not influenced by molecular-weight polydispersity, supporting the idea that stringlike collective motion is not strongly correlated with chain connectivity.

Slow chlorine releasing compounds: A viable sterilisation method for bioabsorbable nanocomposite biomaterials

Selection of the appropriate sterilisation method for biodegradable materials has been a challenging task. Many conventional sterilisation methods are not suitable for the next generation of biomaterials, mainly due to their complex composition, based on nanomaterials, often incorporating bioactive moieties. In this study, we investigate sterilisation efficacy of slow chlorine releasing compound sodium dichloroisocyanurate dihydrate (SDIC) for polyhedral oligomeric silsesquioxane (POSS)-poly(caprolactone urea-urethane) (PCL) scaffolds in comparison with conventional sterilisation methods. POSS-PCL scaffolds were subjected to 70% ethanol, UV, and SDIC sterilisation methods. Samples were immersed in tryptone soya broth (TSB) and thioglycollate medium (THY) and after seven days visually inspected for signs of microbial growth. Bulk and surface properties and molecular weight distribution profiles of the scaffolds after sterilization were investigated using FTIR analysis, surface hydrophilicity, scanning electron microscopy analysis, tensile strength testing, and gel-permeation chromatography (GPC). Adipose-derived stem cells (ADSC) were seeded on the scaffolds and AlamarBlue® viability assay was performed to investigate cell metabolic activity. Confocal imaging of rhodamine phalloidin and Dapi stained ADSC on scaffolds was used to demonstrate cell morphology. GPC results showed that autoclaving led to a significant decrease in the molecular weight of POSS-PCL, whereas ethanol caused visible deformation of the polymer 3D structure and UV radiation did not effectively sterilise the scaffolds. AlamarBlue® analysis showed metabolic activity close to that of tissue culture plastic for ethanol and SDIC. SDIC sterilisation can be safely applied to biodegradable scaffolds unsuitable for the more common sterilisation methods.