Gel Filtration Research Articles

One-Pot Synthesis of Amphiphilic Linear and Hyperbranched Polyelectrolytes and Their Stimuli-Responsive Self-Assembly in Aqueous Solutions.

Stimuli-responsive polymeric nanostructures are compelling vectors for a wide range of application opportunities. The objective we sought was to broaden the array of self-assembling amphiphilic copolymers with stimuli-responsive characteristics by introducing a hydrophilic tunable monomer, (2-dimethylamino)ethyl methacrylate (DMAEMA), together with a hydrophilic one, lauryl methacrylate (LMA), within linear and branched copolymer topologies. Size exclusion chromatography was used to evaluate the resultant linear and hyperbranched copolymers' molecular weight and dispersity, and FT-IR and 1H-NMR spectroscopy techniques were used to delineate their chemical structure. The structural changes in the obtained self-organized supramolecular structures were thoroughly investigated using aqueous media with varying pH and salinity by dynamic light scattering (DLS), fluorescence spectroscopy (FS), and transmission electron microscopy (TEM). The nanoscale assemblies formed by the amphiphiles indicate significant potential for applications within the field of nanotechnology.

Physicochemical stability of bevacizumab biosimilar CT-P16 (Vegzelma) concentrate for solution stored in original vials after first opening

ObjectiveAfter patent expiry of the bevacizumab originator product, several biosimilars were approved by the European Medicines Agency. In centralised preparation units, product-specific in-use stability data must be considered. Based on...

Isolation of Cellulase Enzyme from Water Used in White Pepper Processing

Cellulase, an enzyme that helps soften fruit peel, is produced by plants during the fruit ripening phase. Utilizing the immersing water from the white pepper processing to extract cellulase will help minimizing environmental waste and retrieving valuable compounds. Some factors affecting the cellulase yield from the immersing water of pepper were studied, including the degree of ripeness of peppercorn, immersing temperature and time. We then assess the precipitating yield of (NH4)2SO4 and etanol, purify cellulase by gel Sephadex G-75 filtration, and determine the preliminary compound mass by electrophoresis method. In comparison with the unripe peppercorn, the ripe peppercorn releases more cellulase. The highest cellulase activity in the water of immersed pepper was recorded at 40oC for 48 hours, with an activity of 1.98 U/ g peppercorn. The yield of cellulase extraction was highest when precipitating with 70% ethanol, with a cellulase recovery of 48% and protein recovery of 37%. The results of gel filtration and electrophoresis showed that the cellulase mass was less than 75 kB.

Proteomics of Extracellular Vesicles: Recent Updates, Challenges and Limitations

Extracellular vesicles (EVs) are lipid-bound vesicles secreted by cells, including exosomes, microvesicles, and apoptotic bodies. Proteomic analyses of EVs, particularly in relation to cancer, reveal specific biomarkers crucial for diagnosis and therapy. However, isolation techniques such as ultracentrifugation, size-exclusion chromatography, and ultrafiltration face challenges regarding purity, contamination, and yield. Contamination from other proteins complicates downstream processing, leading to difficulties in identifying biomarkers and interpreting results. Future research will focus on refining EV characterization for diagnostic and therapeutic applications, improving proteomics tools for greater accuracy, and exploring the use of EVs in drug delivery and regenerative medicine. In this review, we provide a bird’s eye view of various challenges, starting with EV isolation methods, yield, purity, and limitations in the proteome analysis of EVs for identifying protein targets.

Ultrasensitive Homogeneous Electrochemiluminescence Biosensor for N-Nitrosodimethylamine Detection Based on Vertically-Ordered Mesoporous Silica Film-Modified Electrode and CRISPR/Cas12a-Driven HRCA with Triple Signal Amplification.

Herein, we present an innovative electrochemiluminescence (ECL) biosensor for the ultrasensitive detection of N-nitrosodimethylamine (NDMA). The biosensor utilizes a triple signal amplification strategy, combining rolling circle amplification (RCA), CRISPR/Cas12a-driven hyperbranched rolling circle amplification (HRCA), and electrostatic repulsion with size exclusion effects from vertically ordered mesoporous silica film (VMSF)/indium tin oxide (ITO) on double-stranded DNA (dsDNA)-Ru(phen)32+ complexes. In this system, aptamers and circular DNA undergo RCA reactions, followed by the CRISPR/Cas12a-mediated HRCA process, producing abundant dsDNA. The electropositive ECL indicator, namely Ru(phen)32+, was subsequently adsorbed onto the electronegative dsDNA, forming dsDNA-Ru(phen)32+ complexes. These complexes are subjected to electrostatic repulsion and size exclusion by the VMSF-modified ITO electrode, resulting in a lower ECL intensity. Upon introducing NDMA, the aptamer preferentially binds to NDMA, thereby preventing the formation of long dsDNA. This process releases free Ru(phen)32+, which diffuses to the electrode surface through narrow mesoporous channels via electrostatic adsorption. Consequently, an enhanced and strong ECL signal is observed. The integration of VMSF enhances selectivity and sensitivity by excluding larger impurities and promoting the electrostatic repulsion of dsDNA-Ru(phen)32+ complexes near the electrode surface. Additionally, the CRISPR/Cas12a system eliminates the formation of primer dimers and reduces false positives through its unique cis- and trans-cleavage activities. The biosensor demonstrated excellent performance with a linear correlation between the ECL signal and NDMA concentration in the range spanning from 10 pg/mL to 10 μg/mL, achieving a low limit of detection of 5.33 pg/mL. This platform offers a reliable and robust solution for detecting NDMA in complex matrices, making it a promising tool for environmental monitoring, public health, and safety applications.

Pillared Laminar Vermiculite Membranes with Tunable Monovalent and Multivalent Ion Selectivity.

Effective membrane separation of Li+ from Na+ and Mg2+ is crucial for lithium extraction from water yet challenging for conventional polymeric membranes. Two dimensional (2D)membranes with ordered laminar structures and tunable physicochemical properties offer distinctive ion-sieving capabilities promising for lithium extraction. Recently, phyllosilicates are introduced as abundant and cost-effective source materials for such membranes. However, their water instability and low inherent ion transport selectivity hinder practical applications. Herein, a new class of laminar membranes with excellent stability and tunable ion sieving is reported by incorporating inorganic alumina pillars into vermiculite interlayers. Crosslinking vermiculite flakes with alumina pillars significantly strengthens interlamellar interactions, resulting in robust water stability. Doping of Na+ before the pillaring process reverses the membrane's surface charge, substantially boosting Li+ separation from multivalent cations via electrostatic interactions. Lithium extraction is often complicated by the presence of co-existing monovalent cations (e.g., Na+) at higher concentrations. Here, by introducing excess Na+ into the membrane after the pillaring process, the separation of Li+ from monovalent cations is enhanced through steric effects. This work realizes both monovalent/multivalent and monovalent/monovalent selective ion sieving with the same membrane platform. A separation mechanism is proposed based on Donnan exclusion and size exclusion, providing new insights for membrane design for resource recovery applications.

Improved Dewatering of Mature Fine Tailings Using High Molecular Weight Polyacrylamide Grafted From an Activated Carbon Surface by Surface‐Initiated ATRP

ABSTRACTThe remediation of mature fine tailings remains a critical challenge in oil sand processing due to the inability to dewater the tailings effectively. In this study, high molecular weight polyacrylamide (PAM) (106 g/mol) was grafted from the surface of hydrophobic activated carbon using surface‐initiated atom transfer radical polymerization (SI‐ATRP) to enhance tailings dewatering. Grafting was done using two SI‐ATRP methods, standard and activators regenerated by electron transfer, to evaluate each method's ability to form high molecular weight brushes from a prefunctionalized activated carbon surface that was oxidized and attached with ATRP initiators. Size exclusion chromatography showed that the grafted PAM brushes achieved molecular weights greater than 106 g/mol, while thermogravimetric analysis showed that they had activated carbon contents of 0.5–5.8 wt%. The dewatering performance of the resulting high molecular weight PAM from activated carbon was evaluated against neat PAM by performing settling tests on dilute mature fine tailings. In summary, this work demonstrates the successful grafting of high molecular weight PAM from activated carbon, improving the dewatering of mature fine tailings shown by the increase of solids content up to 50 wt% compared to neat PAM, which only reached 20 wt%. This work advances the application of hybrid flocculants and paves the way for improved water recovery and sustainable tailings management.

Toward Identification of Markers for Brain-Derived Extracellular Vesicles in Cerebrospinal Fluid: A Large-Scale, Unbiased Analysis Using Proximity Extension Assays.

Extracellular vesicles (EVs) captured in biofluids have opened a new frontier for liquid biopsies. To enrich for vesicles coming from a particular cell type or tumour, scientists utilize antibodies to transmembrane proteins that are relatively unique to the cell type of interest. However, recent evidence has called into question the basic assumption that all transmembrane proteins measured in biofluids are, in fact, EV-associated. To identify both candidate markers for brain-derived EV immunocapture and cargo proteins to validate the EVs' cell of origin, we conducted an unbiased Olink screen, measuring 5416 unique proteins in cerebrospinal fluid after size exclusion chromatography. We identified proteins that demonstrated a clear EV fractionation pattern and created a searchable dataset of candidate EV-associated markers-both proteins that are cell type-specific within the brain, and proteins found across multiple cell types for use as general EV markers. We further implemented the DeepTMHMM deep learning model to differentiate predicted cytosolic, transmembrane, and external proteins and found that intriguingly, only 10% of the predicted transmembrane proteins have a clear EV fractionation pattern based on our stringent criteria. This dataset further bolsters the critical importance of verifying EV association of candidate proteins using methods such as size exclusion chromatography before downstream use of the targets for EV analysis.

Self-packed size-exclusion columns enable versatile high-throughput native, top-down, and ion mobility-mass spectrometry studies on proteins and complexes.

Self-packed size-exclusion columns enable versatile high-throughput native, top-down, and ion mobility-mass spectrometry studies on proteins and complexes.

Different oligomerization dynamics of reduced and oxidized human peroxiredoxin 1 and 2.

Different oligomerization dynamics of reduced and oxidized human peroxiredoxin 1 and 2.

A novel directed enzymolysis strategy for the preparation of umami peptides in Stropharia rugosoannulata and its mechanism of taste perception.

A novel directed enzymolysis strategy for the preparation of umami peptides in Stropharia rugosoannulata and its mechanism of taste perception.

Structural characterization and in vitro anti-inflammatory activity of exopolysaccharide produced by Pediococcus pentosaceus 4412.

Structural characterization and in vitro anti-inflammatory activity of exopolysaccharide produced by Pediococcus pentosaceus 4412.

The molecular structure of leaf starch from three cereal crops

The molecular structure of leaf starch from three cereal crops

High-Purity Preparation and Biophysical Characterization of OX40-TC in Lipid Nanodiscs.

High-Purity Preparation and Biophysical Characterization of OX40-TC in Lipid Nanodiscs.

Characterization of SARS-CoV-2 nucleocapsid protein oligomers.

Characterization of SARS-CoV-2 nucleocapsid protein oligomers.

Potential of size-exclusion chromatography and asymmetric flow field-flow fractionation in separation and characterization of plant polysaccharides.

Potential of size-exclusion chromatography and asymmetric flow field-flow fractionation in separation and characterization of plant polysaccharides.

Fractionation and Characterization of Humic Substances in Nutritional Supplements Using Immobilized Metal Affinity Chromatography.

This work presents the study of the immobilized metal affinity chromatography method for the analysis of humic substances in a few food supplements. Separation mechanisms of the immobilized metal affinity chromatography method are based on the affinity of functional groups of humic substances to metal ions. The immobilized metal affinity chromatography system employed an Iontosorb Salicyl sorbent with immobilized aluminum ions. A step-wise gradient was used for elution, consisting of two mobile phases of acetate buffer solution at varying pH values and a mixture of sulfuric acid and sodium sulfate. The change in concentration and volume of Al(III) ions and pH of the eluent have been studied for sorption characteristics and immobilized metal affinity chromatography separation. The chosen value was 0.20mmol of aluminum per 1g of the chelating sorbent at pH 7.0. The immobilized metal affinity chromatography system has been studied by using a pair of substances with different chelating properties (phenol and salicylic acid) and a mixture of eleven substances, which represented a simplified model structure of humic substances. The results of these studies have been applied to the fractionation of humic substance standards and to the characterization of humic substances in food supplements containing humic substances by the immobilized metal affinity chromatography system. To better characterize particular humic substances, the immobilized metal affinity chromatography fractions were further analyzed by size-exclusion chromatography. Based on the results obtained, the immobilized metal affinity chromatography method appears to be a promising tool for the analysis of humic substances, and it may help in the characterization of their structure and understanding their interactions with metal ions.

Highly flexible free-standing bacterial cellulose-based filter membrane with tunable wettability for high-performance water purification.

Highly flexible free-standing bacterial cellulose-based filter membrane with tunable wettability for high-performance water purification.

Enhancing rejection of short-chain per- and polyfluoroalkyl substances by tailoring the surface charge of nanofiltration membranes.

Enhancing rejection of short-chain per- and polyfluoroalkyl substances by tailoring the surface charge of nanofiltration membranes.

MIL-100-Fe self-assembled cellulose nanofibers sponge for Diclofenac cascade encapsulation.

MIL-100-Fe self-assembled cellulose nanofibers sponge for Diclofenac cascade encapsulation.