Foreword

Characterization of branched ultrahigh molar mass polymers by asymmetrical flow field-flow fractionation and size exclusion chromatography

Molar mass characterization of cellulose acetates over a wide range of high DS by size exclusion chromatography with multi-angle laser light scattering detection

Background:Many exopolysaccharides from the endophytes in medicinal plants possess various potential bioactivities.Materials and Methods:The endophytic fungus JY25 was isolated from the leave of the Chinese medicinal plant Gynostemma pentaphylla and identified as Chaetomium sp. by its phylogenetic and physiological analysis. One exopolysaccharide (EPS) fraction was isolated from the fermentation broth by ethanol precipitation and purified by gel filtration chromatography on Sepharose CL-6B. The molecular characteristics were examined by GC-MS, FT-IR, and multiangle laser light scattering (MALLS).Results:The monosaccharide composition analysis indicated that the purified EPS was mainly composed of glucose, mannose, arabinose, and galactose with the molecular ratio of 78.29: 8.99: 8.64: 4.08. FT-IR spectral analysis of the purified EPS revealed prominent characteristic groups, such as carbonyl bond, pyranose ring, and so on. The weight-average molar mass and the polydispersity ratio of the EPS were revealed to be 1.961×104 g/mol and 1.838, respectively. Furthermore, thermo gravimetric analysis (TGA) indicated that the degradation temperature of the purified EPS was 305° C. The purified EPS from the endophytic fungus Chaetomium sp. displayed antioxidant and antiproliferative activities.Conclusion:The results demonstrated that the EPS could be used as a healthful food and material source in pharmaceutical industries.SUMMARY An exopolysaccharides (EPS) with antioxidant and antiproliferative activities from an endophytic fungus Chaetomium sp. was reported. Abbreviations used: ANOVA: Analysis of variance; DPPH: 2,2-diphenyl-1-picrylhydrazyl; EPS: Exopolysaccharide; FT-IR: Fourier transform infrared spectroscopy; GC-MS: Gas chromatography–mass spectrometry; Mw: Mass weight; MALLS: Multiangle laser light scattering; SEC: Size Exclusion Chomatography; SPSS: Statistical Package of the Social Science; TGA: Thermo gravimetric analysis; TFA: Trifluoroacetic acid.

Size-exclusion chromatography (SEC) equipped with refractive index (RI) and multi-angle light scattering (MALS) detectors was carried out on a polystyrene (PS) sample with the weight-average molecular weight 2.07 ×€104 along with the matrix-assisted laser desorption flight time mass spectrometry (MALDI-TOF-MS). The MALDI-TO-MS result was corrected by the relative sensitivity, which was found to decay exponentially with the molecular weight. Exchanging the elution volume for molecular weight by the calibration relation, the molecular-weight distribution (MWD) curves were obtained from the chromatograms. The MWD curve determined by the SEC chromatogram was much broader than that obtained by MALS and MALDI-TOF-MS because of the peak-broadening effect. Based on the MWD determined by MALDI-TOF-MS, the RI chromatogram was closely described by the calculated values using the Gaussian function. Based on the results of the PS sample, RI and MALS data of polyethylene oxide samples in water were analyzed using the exponentially modified Gaussian equation.

Characterization of enzymatically synthesized amylopectin analogs via asymmetrical flow field flow fractionation

Determination of Modification Degree of Succinylated Gelatin by Size Exclusion Chromatography Coupled with Multi Angle Laser Light Scattering

The number of monoclonal antibodies and derivatives such as Fc-fusion proteins available on the market is rapidly increasing. With the expiration of their patents, biosimilars are emerging. Biosimilars represent medicines that are highly similar but not identical to the reference products. To assess the comparability between those products, dedicated analytical methods are required. In this work, a monoclonal antibody, adalimumab, and a Fc-fusion protein, etanercept, were studied and compared to one of their biosimilars. Samples submitted to stress conditions (agitation and high temperature) were used for method development. The developed methods were also applied to samples reduced by beta-mercaptoethanol (BME) to evaluate their capability to distinguish the expected species. Capillary gel electrophoresis (CGE), reversed-phase liquid chromatography (RPLC) and size-exclusion chromatography (SEC) methods coupled with UV detection were used to analyze the biopharmaceuticals. Their complementarity was investigated. For further molecular weight determination, SEC- multi-angle light scattering (MALS) and RPLC-quadrupole time-of-flight (QTOF) were occasionally used. For adalimumab, a larger amount of fragments and aggregates was observed in the biosimilar compared to the reference product. For etanercept, more related species were found in the reference product. Those three separation techniques showed good complementarity. Indeed, RPLC enabled the separation of hydrophilic and hydrophobic degradation products. CGE provided good selectivity for several adalimumab fragments and SEC was useful for the analysis of aggregates and certain fragments that cannot be separated by the other approaches. Moreover, those formulations were submitted to mild stress conditions (30°C, 300 rpm for 4 hours) that mimic shipping conditions. No additional peak was found under these conditions for the two studied biopharmaceuticals.

The objective of this work was to assess the methods for determining the degree of long-chain branching in polysaccharides by light scattering and viscosity techniques in combination with size exclusion chromatography (SEC). The samples used were branched dextrans and the reference linear polymers were pullulans. The first method involved determining the ratio of the radii of gyration for branched and linear polymers having the same molecular weight by SEC with multi-angle laser light scattering (MALLS). In the second and third methods, branching was determined by the ratio of the intrinsic viscosities (IV) of branched and linear polymer having the same molecular weight for the SEC slices as well as for the whole polymer, using different values for the structure and solvent factor, e. The average frequencies obtained for long-chain branching for the whole polymers by light scattering, as well as by viscometry and for the slices by viscometry, agreed well with each other and with those reported fr...

Characterization of High-Molecular-Weight Nonnative Aggregates and Aggregation Kinetics by Size Exclusion Chromatography With Inline Multi-Angle Laser Light Scattering

The present work demonstrates that the use of a nonionic surfactant in the mobile phase together with light scattering coupled to size exclusion chromatography (SEC) provides an accurate determination of macromolecular dimensions of hydrophobically modified water-soluble polymer and polyelectrolyte, i.e., weight-average molar mass M(w) and polydispersity I(p). This method, called micellar SEC, is based on the dissociation of the aggregates in aqueous solution and the formation of mixed micelles between the surfactant and the polymer hydrophobic groups. The methodology and its application are presented for synthetic sulfonated polyacrylamides (5 and 20 mol %) modified with three hydrophobic alkyl side groups (C8, C12, and C18) and with Triton X-100 as a nonionic surfactant and are discussed according to the associativity of polymers. The results are compared to those obtained by classical SEC in 0.1 M NaNO(3) and by static light scattering in formamide solution.

Single wall carbon nanotubes (SWNTs) dispersed in aqueous medium by the use of DNA are separated by size using a size exclusion chromatographic (SEC) column. On-line measurements are made of SWNT concentration, molar mass, and size using UV−vis absorption detection and multi-angle light scattering (MALS). Molar mass and length distributions are calculated for SWNT dispersions from this data. The SWNTs are shown to separate primarily by a SEC mechanism, but the elution times are affected by a high performance liquid chromatography (HPLC) mechanism in which adsorption on the column delays the elution of the components. This mechanism is most evident by the elution of small quantities of large, polydisperse SWNTs after the SEC column limit. MALS data are fit with a polydisperse anisotropic rod scattering function giving low polydispersity for most of the fractions with higher polydispersities near the large size exclusion limit and beyond the small size exclusion limit of the SEC column. These fits indicate that molar mass is proportional to the rod length over a wide range indicating rigid-rod behavior.

Solution properties of poly(diallyldimethylammonium chloride) (PDDA)

Simultaneous determination of protein aggregation, degradation, and absolute molecular weight by size exclusion chromatography–multiangle laser light scattering

Distribution analysis of ultra-high molecular mass poly(ethylene oxide) containing silica particles by size-exclusion chromatography with dual light-scattering and refractometric detection

Modelling molecular weight changes induced in polydimethylsiloxane by gamma and electron beam irradiation