Molecular Weight Measurements Research Articles

A Systematic Workflow for Fragmentation Identification of Therapeutic Antibodies by Liquid Chromatography-Mass Spectrometry.

Fragmentation is a phenomenon ubiquitously observed during research and development of therapeutic antibodies. The clear identification of the cleavage site is vital for comprehending fragmentation mechanisms and optimizing processes. Capillary electrophoresis-sodium dodecyl sulfate (CE-SDS) is now widely used to detect and quantify fragments, while its peak identification is hindered by immature capillary electrophoresis-sodium dodecyl sulfate coupled with mass spectrometry techniques. In this study, we developed a systematic workflow for fragment characterization, which integrated direct identification, fragment enrichment, and fragmentation confirmation using multiple techniques, such as microscale peptide mapping (PM), PM of N-termini labeled sample, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in-gel extraction for molecular weight (MW) and PM measurements. By employing this innovative workflow, we successfully identified the cleavage sites of two therapeutic antibodies. In the first case, through direct liquid chromatography-mass spectrometry (LC-MS) characterization, the cleavages leading to the loss of biological function were identified on the linker of a bispecific antibody. In the second case involving a tetravalent antibody, direct LC-MS analysis failed. However, more sophisticated analysis nailed down the critical cleavage at the LC/HC: G105-R106 site in the CDR3 region of the antibody. Our systematic workflow provides a clear and accessible method for identifying cleavage sites with broad applicability across pharmaceutical laboratories.

Optimization of polysaccharide extraction from pumpkin seeds using ultrasonic-assisted enzymatic method

This study aimed to optimize the extraction process of polysaccharides from seed pumpkins. Following initial single-factor experiments, the extraction process using ultrasonic-assisted enzymatic method was optimized through orthogonal experiments. Further optimization of extraction conditions was conducted using response surface methodology with Box-Behnken design, ultimately identifying the optimal extraction parameters. Additionally, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, monosaccharide component analysis, polysaccharide molecular weight measurement, and NMR analysis were performed. Results indicated that ultrasonic-assisted enzymatic extraction significantly enhanced the yield of polysaccharide, reaching up to 43.65%. The findings confirm that the combined use of enzymatic hydrolysis and ultrasonication is an effective strategy for polysaccharide extraction.

Biochar as a UV Stabilizer: Its Impact on the Photostability of Poly(butylene succinate) Biocomposites.

In the present study, biocomposite materials were created by incorporating biochar (BC) at rates of 1, 2.5, and 5 wt.% into a poly(butylene succinate) (PBSu) matrix using a two-stage melt polycondensation procedure in order to provide understanding of the aging process. The biocomposites in film form were exposed to UV irradiation for 7, 14, and 21 days. Photostability was examined by several methods, such as Fourier transform infrared spectroscopy (FTIR), which proved that new carbonyl and hydroxyl groups were formed during UV exposure. Moreover, Differential Scanning Calorimetry (DSC) measurements were employed to record the apparent UV effect in their crystalline morphology and thermal transitions. According to the molecular weight measurements of composites, it was apparent that by increasing the biochar content, the molecular weight decreased at a slower rate. Tensile strength tests were performed to evaluate the deterioration of their mechanical properties during UV exposure, while Scanning Electron Microscopy (SEM) images illustrated the notable surface alternations. Cracks were formed at higher UV exposure times, to a lesser extent in PBSu/BC composites than in neat PBSu. Furthermore, the mechanism of the thermal degradation of neat PBSu and its biocomposites prior to and upon UV exposure was studied by Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS). From all the obtained results it was proved that biochar can be considered as an efficient UV-protective additive to PBSu, capable of mitigating photodegradation.

Recovery of Selenium-Enriched Polysaccharides from Cardamine violifolia Residues: Comparison on Structure and Antioxidant Activity by Different Extraction Methods.

The residues from selenium-enriched Cardamine violifolia after the extraction of protein were still rich in polysaccharides. Thus, the recovery of selenium polysaccharides (SePSs) was compared using hot water extraction and ultrasonic-assisted extraction techniques. The yield, extraction rate, purity, specific energy consumption, and content of total and organic selenium from different SePS extracts were determined. The results indicated that at conditions of 250 W (ultrasonic power), 30 °C, and a liquid-to-material ratio of 30:1 extracted for 60 min, the yield of SePSs was 3.97 ± 0.07%, the extraction rate was 22.76 ± 0.40%, and the purity was 65.56 ± 0.35%, while the total and organic selenium content was 749.16 ± 6.91 mg/kg and 628.37 ± 5.93 mg/kg, respectively. Compared to traditional hot water extraction, ultrasonic-assisted extraction significantly improves efficiency, reduces energy use, and boosts both total and organic selenium content in the extract. Measurements of particle size, molecular weight, and monosaccharide composition, along with infrared and ultraviolet spectroscopy, revealed that ultrasonic-assisted extraction breaks down long-chain structures, decreases particle size, and changes monosaccharide composition in SePSs, leading to lower molecular weight and reduced dispersity. The unique structure of SePSs, which integrates selenium with polysaccharide groups, results in markedly improved antioxidant activity and reducing power, even at low concentrations, due to the synergistic effects of selenium and polysaccharides. This study establishes a basis for using SePSs in functional foods.

Characterization of high Fischer ratio oligopeptides produced from casein

High Fischer ratio oligopeptides mixture is a mixed peptide system which possess many beneficial effects to the human body. Casein, a milk protein, was used as feedstock to prepare high Fischer ratio oligopeptides via enzymatic hydrolysis, adsorption and purification. Gel electrophoresis, densitometric analysis, amino acid assay and molecular weight measurement were used to visualize and quantify the prepared peptides. Casein, with Fischer ratio of 2.17, was subjected to hydrolysis by alcalase® (2.4 AU/g, pH 8.5, temperature 55 °C, enzymolysis time 2 h) and flavorzyme® (3.4 AU/g, temperature 50 °C, enzyme amount 120 μL, enzymolysis time 3 h), followed via AK-220 activated carbon adsorption (carbon-hydrolysate ratio: 1:10, adsorption time 3 h, pH 8.0, temperature 55 °C) and 3 KDa membrane ultrafiltration. In conclusion, the processing parameters for alcalase® / flavorzyme® and AK-220 activated carbon helped to obtain oligopeptides with Fischer ratio 9.87 which is significantly higher than feedstock casein F value (p < 0.05) and could potentially be used as food supplement to enhance product nutritional property.

Comparative degradation behavior of polybutylene succinate (PBS), used PBS, and PBS/Polyhydroxyalkanoates (PHA) blend fibers in compost and marine–sediment interfaces

Amid increasing concerns over microplastic pollution and the persistence of nonbiodegradable polymers in the ocean, this study evaluates the biodegradability of polybutylene succinate (PBS)-based fishing gear under different conditions: pristine PBS fibers, PBS fibers utilized in fishing (PBS_used), and PBS fibers blended with 10% polyhydroxyalkanoate (PHA). By simulating compost and marine–sediment interface environments with reference to ISO 14855 and ISO 19679 standards, respectively, we aimed not only to assess the degradation performance of these fibers but also to examine the physical and chemical property changes pre and postdegradation. PBS, PBS_used, and PBS/PHA (9:1) fibers exhibited degradation rates of 31.9%, 35.5%, and 39.5% in compost environments, and 20.3%, 22.1%, and 25.9% at the seawater–sediment interface, respectively. Through comprehensive physicochemical analyses involving molecular weight measurement, field emission–scanning electron microscope, Fourier transform infrared spectroscopy, tensile property evaluation, and thermogravimetric analysis, the degradation behavior of PBS-based fibers depending on the degradation environment was compared. This study suggests that PBS-based fishing gear can biodegrade under various conditions encountered in the actual fishing sector, thereby preventing ghost fishing and mitigating the issue of abandoned, lost, or otherwise discarded fishing gear.

Influence of Sonication on the Molecular Characteristics of Carbopol® and Its Rheological Behavior in Microgels.

In this work, the effect of sonication on the molecular characteristics of polyacrylic acid (Carbopol® Ultrez 10), as well as on its rheological behavior in aqueous dispersions and microgels, was analyzed for the first time by rheometry, weight-average molecular weight (Mw) measurements via static light scattering (SLS), Fourier transform infrared (FTIR) spectroscopy and confocal microscopy. For this, the precursor dispersion and the microgels containing 0.25 wt.% of Ultrez 10 were sonicated in a commercial ultrasound bath at constant power and at different times. The main rheological properties of the microgel, namely, shear modulus, yield stress and viscosity, all decreased with increasing sonication time, while the microgel's Herschel-Bulkley (H-B) behavior, without thixotropy, was preserved. Also, Mw of Ultrez 10 decreased up to almost one-third (109,212 g/mol) of its original value (300,860 g/mol) after 180 min of sonication. These results evidence a softening of the gel microstructure, which results from the reduction in the Mw of polyacrylic acid with sonication time. Separately, FTIR measurements show that sonication produces scission in the C-C links of the Carbopol® backbone, which results in chains with the same chemistry but lower molecular weight. Finally, confocal microscopy observations revealed a diminution of the size of the microsponge domains and more free solvent with sonication time, which is reflected in a less compact and softer microstructure. The present results indicate that both the microstructure and the rheological behavior of Carbopol® microgels, in particular, and complex fluids, in general, may be manipulated or tailored by systematic high-power ultrasonication.

Controlled Magnetite Grafted Poly(glycidyl methacrylates) for Heavy Metal Absorption and Recovery via SET-LRP

A versatile magnetite based stringent polymer for effective metal capture was prepared by reacting iron oxide based initiator with glycidyl methacrylate monomer via single-electron transfer living radical polymerization (SET-LRP) technique. The versatile grafted polymer was successfully synthesized by metal catalyzed living radical polymerization using the catalyst system Cu/N,N,N',N'',N'''-pentamethyldiethylenetriamine as the ligand. The structural confirmation of the initiator and the grafted polymer was analyzed by using instrumentation methods such as proton nuclear magnetic resonance spectroscopy, UV-visible, TGA, SEM and gel permeation chromatography for molecular weight measurements. As the polymerization time increased, both the conversion and the molecular weight were observed to increase linearly with time. Narrow dispersed lower polydispersity index (PDI) and dispensable magnetite-g-PGMA was utilized for the extract of toxic lead from the wastewater. Sustained binding was observed due to the presence of epoxide ring in the repeating units of the polymer and recovered by magnetic effect. The material shows good stability as evident by TGA curves and better affinity to toxic lead as observed by UV-visible and SEM techniques.

MaDDOSY (Mass Determination Diffusion Ordered Spectroscopy) using an 80MHz Bench Top NMR for the Rapid Determination of Polymer and Macromolecular Molecular Weight.

Measurement of molecular weight is an integral part of macromolecular and polymer characterization which usually has limitations. Herein, this article presents the use of a bench-top 80MHz Nuclear Magnetic Resonance (NMR) spectrometer for diffusion-ordered spectroscopy as a practical and rapid approach for the determination of molecular weight/size using a novel solvent and polymer-independent universal calibration.

Characterization by Gel Permeation Chromatography of the Molecular Weight of Supramolecular Polymers Generated by Forming Polyrotaxanes through the Introduction of External Stoppers.

Supramolecular polymers find wide applications across diverse domains, and the molecular weight exerts a critical influence on their applicability. Consequently, the measurement of molecular weight for supramolecular polymers assumes paramount significance. Gel Permeation Chromatography (GPC) requiring low-concentration condition is a common characterization employed for molecular weight determination, which is not suitable for supramolecular polymers possessing concentration-independence property. Here, to break this threshold, we synthesized M1 embodying dibenzo-24-crown-8 (DB24C8) moiety as well as dibenzylammonium salt (DBA) group, which was capable of self-assembling into supramolecular polymers terminated with aldehyde groups at its end. Upon the addition of (4- (1,2,2-Triphenylvinyl) phenyl) methylamine (TPE-NH2), supramolecular polymers underwent a transition into polyrotaxanes, for which it was led by the generation of imine bonds. By virtue of GPC, the molecular weight of polyrotaxanes was obtained, then it was available to gain the molecular weight of supramolecular polymers with the help of transformation efficiency.

Frothers in flotation: A review of performance and function in the context of chemical classification

The significance of frothers in the context of mineral flotation is widely recognized, particularly in relation to their impact on bubble size and dispersion, coalescence inhibition, as well as the structure and stability of the froth. All these parameters hold substantial importance in determining the feasibility of the process including the overall recovery of valuable minerals and concentrate grade in flotation process. This review aims to offer a comprehensive overview of the importance of frothers in the flotation process focusing on their performance and function in the context of their chemical classification. The characterisation of flotation frothers is discussed, focusing on the most often used parameters including molecular weight, hydrophilic-lipophilic balance (HLB), dynamic frothability, and interfacial tension measurement. Additionally, the importance of advanced characterisation techniques such as single rising bubble experiments, high-speed video microscopy and infrared reflection absorption spectroscopy (IRRAS) is highlighted. Finally, the application of biodegradable and environmentally friendly biosurfactants such as rhamnolipids as “green frothers” in enhancing flotation rates is outlined.

Cell wall polysaccharides from Annona squamosa: Chemical and functional characterization

Several extraction methods were used to find out what the custard apple cell wall polysaccharides were made of and how they were structured. These included water (WSP), chelator (CSP), sodium carbonate (NSP), potassium hydroxide at 1 mol/L (KSH-1), and potassium hydroxide at 4 mol/L (KSH-4). The five fractions had different structures and make-ups, as shown by FT-IR, molecular weight measurements, sugar composition analysis, and methylation experiments. The results indicated that NSP made up the majority of the fruit's cell wall polysaccharide fraction. As for apparent viscosity, the viscosity and thermal stability of WSP were highest. In terms of apparent viscosity and thermal stability, WSP ranked highest. The stability of NSP and KSH-1 was better. Methylation analysis showed that CSP had galactose and galacturonic acid as the main chains. KSH-4 had a xyloglucan backbone. Compared to the other three fractions, NSP and CSP had the highest antioxidant capacity. Through this study, there is potential for custard apple polysaccharides to be used in the food and biological industries.

Fully Bio-Based and Solvent-Free Polyester Polyol for Two-Component Polyurethane Coatings

In recent years, many efforts are being devoted to the development of new materials that originate from renewable resources. Polyesters are one of the most important classes of such materials and several bio-based monomers are available for their synthesis. In this work, the development of fully bio-based and solvent-free polyester polyol used for two-component polyurethane coatings on industrial scale is presented. Fossil-based raw materials were substituted with bio-based alternatives that are commercially available on a large scale. Properties of polyols and coatings were determined and measured. Polyols were characterized by the determination of acid number, hydroxyl number, glass transition temperature and refractive index, and measurement of viscosity, color and molecular weight. Coatings were characterized by the determination of mechanical properties, such as hardness, elasticity and impact resistance, and the measurement of optical properties such as gloss, haze, distinctness of image (DOI) and reflected image quality (RIQ) and weathering resistance. Three variations of bio-based polyol were synthesized, then the most suitable version was validated in a clear coat. The results showed that the properties of the bio-based polyol and coating met the requirements and were comparable to the properties of the synthetic counterpart. Results indicate that this newly developed 100% bio-based and solvent-free polyol can be used as a drop-in replacement for synthetic polyol. Furthermore, this work implies that the supply chain is established which allows the green transition in the paint industry.

Biosynthesis of highly flexible lignosulfonate–starch based materials

The need to replace polymers from fossil sources with bio-based renewable sources is increasingly imminent. This work reports on the synthesis of biofilms obtained from the polymerization of lignosulfonates using laccase as a biocatalyst and blending with starch. The effect of the reaction conditions on the formation of stable starch-lignosulfonate polymers was evaluated by monitoring changes in viscosity, molecular weight (Mw), and fluorescence measurements. Enzymatic polymerization led to molecular weights of ∼ 400 kDa and viscosities of ∼ 1.00 Pas and decreases in lignosulfonates-OH groups by about 46% after 1 h of reaction carried out at pH 7 and adding starch at the end of the polymerization reaction. Additionally, the effect of the starch concentration on the mechanical, thermal, and water absorption properties was studied. As a result, the addition of up to 7% starch was found to improve the mechanical properties of the lignosulfonate films as indicated by the increase in elongation at break, tensile strength, and Young's modulus, reaching values of 157%, 1.19 MPa, and 0.22 MPa, respectively. This study demonstrated a green alternative for creating 100% biobased films composed of starch and lignosulfonates.

Computational-Simulation-Based Behavioral Analysis of Chemical Compounds

This research focuses on obtaining the behavior of chemical compounds with respect to their molecular weight and optimization energy based on the variation in properties in organic carbon links. Here, behavioral analysis of compounds is used in the application of a metal organic framework to denote the high-grade compounds. The grade was selected based on the essential measure of optimization energy and molecular weight, and in turn, depicts the stability of material. Computation of the optimization energy and molecular weight of chemical compounds was performed with Avogadro software. Several force fields can be considered to compute optimized energy. Exclusively, three force fields, namely, the Universal Force Field (UFF), the General Amber Force Field (GAFF), and the Ghemical force field (Ghemical) were selected from Avogadro as these were more relevant to compounds considered in this research. The various chemical compounds examined in this work are Aluminum (Al), Boron (Br), Calcium (Ca), Chlorine (Cl), Indium (In), Potassium (K), Scandium (Sc), Silicon (Si), and Tungsten (W). Hence, molecular modeling of different compounds incorporated with three different force fields was evaluated in this work. In this study, we found that the In structure has more energy reduction, of 22.673 kJ mol−1 in UFF, when compared with the other two force fields. Thus, In has higher potential with more stability.

Improved low water solubility of fisetin by enzymatic encapsulation reaction using cycloamylose produced by cyclodextrin glucanotransferase

Fisetin was encapsulated with cycloamylose (CA), an intermediate product of cyclodextrin glucanotransferase (CGTase; EC 2.4.1.19), which is known to produce cyclodextrin (CD). The molecular weight measurement of the cycloamylose-fisetin inclusion complex (CA-FST) confirmed that it contained fisetin and CA with a degree of polymerization (DP) of 9–18. The aqueous solubility of CA-FST was approximately 3700 times higher than that of fisetin, with a solubility of 37.1 mg/mL. CA-FST showed a stability of 97.9 % at 4 °C over 1 week. CA-FST dissolved in water exhibited about 80 % antioxidant activity compared to the same amount of fisetin dissolved in methanol. In the analysis of anti-inflammatory effects, CA-FST decreased cytokine expression more effectively than fisetin, indicating that CA encapsulation using CGTase could be an effective method for overcoming the limited solubility of fisetin.

Synthesis of a Room-Temperature Curable Acrylic-Urethane Polymer Binder for Road Markings with High Transmittance.

Triol acrylic-urethane (t-AU) was synthesized from an addition reaction using trimethylolpropane, hexamethylene diisocyanate, and 2-hydroxyethyl methacrylate. The novel acrylic-urethane polymer was applied to a high-performance binder to prepare a reliable road marking paint. Acrylic-urethane polymer binder formulations were designed to optimize the effect of t-AU on the physical properties. The t-AU content in the formulation affected the adhesion and optical properties. The improvement in the adhesive performance and transparency ability for road markings was attributed to the optimal chemical structure or design of the acrylic-urethane polymer. The synthesis of t-AU was confirmed by Fourier transform infrared spectroscopy, and molecular weight and polydispersity index (PDI; PDI = Mw/Mn) measurements. The tensile and shear strength, hardness, gel fraction, crosslink density, contact angle, and transmittance of the acrylic-urethane polymer binder (AUP) were evaluated by curing at room temperature using a redox initiator system. An optimized AUP by adding 5 wt.% t-AU provides a viable alternative to high-performance binders in road marking paints.

Lotus Root Polysaccharide-Phenol Complexes: Interaction, Structure, Antioxidant, and Anti-Inflammatory Activities.

This research aimed to explore the interaction between lotus root polysaccharides (LRPs) and phenolic compounds, and to study the effects of phenolic binding on the structural and functional properties of LRPs. The influences of pH, temperature, and NaCl and phenol concentration on the binding ratio of gallic acid (GA)/epigallocatechin (EGC) to LRPs were evaluated. LRP-GA/EGC complexes with different phenolic binding amounts were then prepared and characterized via ultraviolet-visible (UV-Vis) and Fourier-transform infrared (FTIR) spectroscopy, and average molecular weight (MW) measurements. The results suggest that hydrogen bonds contributed to the binding of GA/EGC and LRPs. The phenolic binding led to significant changes in the structure and MW of LRPs. Moreover, antioxidant activity and the macrophage-stimulating effect of LRPs were improved after binding with GA/EGC, depending on the binding amount and type of polyphenol. Interestingly, LRP-GA/EGC complexes with polyphenol binding amounts of 105.4 mg/g and 50.71 mg/g, respectively, showed better stimulation effects on the anti-inflammatory cytokine IL10 secretion of macrophages when compared to LRPs. These results show the great potential of phenolic binding to be applied to improve the structure and functional activity of LRPs.

Predictive Modeling of Phase Behavior of Reservoir Fluids under Miscible Gas Injection Using the Peng-Robinson Equation of State and the Aromatic Ring Index.

Improved correlations among critical temperature, critical pressure, and acentric factor are developed for an extensive database of hydrocarbons. The correlations rely on measurements of molecular weight and refractive index at ambient conditions and utilize the concept of the aromatic ring index (ARI) recently developed by Abutaqiya et al. as a distinctive characterization factor for nonpolar hydrocarbons [Abutaqiya M. I. L.Aromatic Ring Index (ARI): A Characterization Factor for Nonpolar Hydrocarbons from Molecular Weight and Refractive Index. Energy Fuels2021, 35( (2), ), 1113-1119.]. The new correlations are then implemented for modeling the phase behavior of a variety of oils under miscible gas injection in a fully predictive manner using the Peng-Robinson equation of state (PR EOS). The results indicate that the proposed modeling framework yield accurate predictions for bubble pressure of oil/gas blends with an average absolute deviation of 6.4% for a wide variety of oils and injection gases including lean, rich, H2S, CO2, and N2. Additionally, an interesting crossover behavior in the phase envelope of live oils under CO2 injection is observed using PR EOS. This behavior has been previously reported in the literature for modeling results using PC-SAFT EOS and seems to be characteristic of CO2.

Antiradical properties of peptides from hydrobionts

Antiradical activity of water-soluble components of tissues is investigated for 26 species of marine organisms belonged to 7 classes: Bivalvia, Cephalopoda, Malacostraca, Holothuroidea, Asteroidea, Echinoidea, and Actinopterygii. Molecular weight of the proteins and peptides was measured in the water extracts using the modular liquid chromatograph (Agilent Technologies 1260 Infinity, USA) with UV detection at 280 nm in TSK gel column G 3000PWXL 7.8 mm I.D. × 30 cm (TOSOH Corporation, Japan) under flow rate of 0.3 mL/min and temperature of 25о C. All samples were twice prepared and double measured. The mobile phase consisted of 0.1 N NaCI 20 mM Tris-HCI buffer with pH 7.8. The following standard protein samples were used as a reference for the molecular weight measurement: bovine serum albumin (MW 66.3 kDa), egg albumin (44.3 kDa), myoglobin (18.0 kDa), cytochrome C (12.4 kDa), aprotinin (6.5 kDa), and bacitracin (1.4 kDa) (Sigma-Aldrich Co., USA). All samples were filtered before injection through 0.2 µm syringe filter (Whatman, PVDF). Molecular weight of peptides was calculated by the elution time. Scavenging effect on DPPH free radical was measured by Molyneux method and on ABTS radical – by the method proposed by Re et al. The maximum antiradical activity (measured by mg of ascorbic acid per 1 g) was found for the tissue of Patiria pectinifera (5.21), its various values were determined for the tissue of bivalve mollusks (Corbicula japonica, Mercenaria stimpsoni, Spisula sachalinensis, and Glycymeris yessoensis — 5.10; 1.15; 1.36 and 1.08, respectively) and medium values — for gonads of Strongylocentrotus intermedius and S. nudus (2.18 and 2.21, respectively). The amount of proteins and peptides with low molecular weight (1–5 kDa) correlated well with the radical scavenging activity (Pearson correlation coefficient 0.801, r2 = 0.642).