High Molecular Weight Research Articles

Degradation strategies for structural characterization of insoluble synthetic polymers by mass spectrometry.

With the advent of soft ionization techniques such as electrospray (ESI) and matrix-assisted laser desorption/ionization (MALDI) to produce intact gas-phase ions from nonvolatile macromolecules, mass spectrometry has become an essential technique in the field of polymeric materials. However, (co)polymers of very high molecular weight or with reticulated architectures still escape ESI or MALDI, mainly due to solubility issues. Strategies developed to tackle such an analytical challenge all rely on sample degradation to produce low-mass species amenable to existing ionization methods. Yet, chain degradation needs to be partial and controlled to generate sufficiently large species that still contain topological or architectural information. The present article reviews the different analytical degradation strategies implemented to perform mass spectrometry of these challenging synthetic polymers, covering thermal degradation approaches in sources developed in the 2000s, off-line sample pre-treatments for controlled chemical degradation of polymeric substrates, and most recent achievements employing reactive ionization modes to perform chemolysis on-line with MS.

Electrolyte-Electrocatalyst Interfacial Effects of Polymeric Materials for Tandem CO2 Capture and Conversion Elucidated Using In Situ Electrochemical AFM.

Integrating CO2 capture and electrochemical conversion has been proposed as a strategy to reduce the net energy required for CO2 regeneration in traditional CO2 capture and conversion schemes and can be coupled with carbon-free renewable electricity. Polyethylenimine (PEI)-based materials have been previously studied as CO2 capture materials and can be integrated in these reactive capture processes. PEI-based electrolytes have been found to significantly increase the CO2 loading, and impact selectivity and rate of product formation when compared to the conventional aqueous electrolytes. However, the influence of these materials at the catalyst-electrode interface is currently not well understood. In this study, PEI-based electrolytes were prepared and their impact on the morphology of a silver electrode performing electrochemical CO2 reduction (CO2R) was studied using in situ electrochemical atomic force microscopy (EC-AFM). The presence of PEI on the electrode surface could be distinguished based on nanomechanical properties (DMT modulus), and changes were observed as negative polarization was applied, revealing a reorganization of the PEI chains due to electrostatic interactions. These changes were impacted by the electrolyte composition, including the addition of supporting electrolyte KHCO3 salt, as well as CO2 captured by the PEI-based electrolyte, which minimized the change in surface mechanical properties and degree of PEI alignment on the electrode surface. The changes in surface mechanical properties were also dependent on the PEI polymer length, with higher molecular weight PEI showing different reconfiguration than the shorter polymer brushes. The study highlights that the choice of polymer material, the electrolyte composition, and CO2 captured impact the near-electrode environment, which has implications for CO2R, and presents EC-AFM as a new tool that can be used to probe the dynamic behavior of these interfaces during electrocatalysis.

Multistrategy Engineering of an Inulosucrase to Enhance the Activity and Thermostability for Efficient Production of Microbial Inulin.

Inulin has found commercial applications in the pharmaceutical, nutraceutical, and food industries due to its beneficial health effects. The enzymatic biosynthesis of microbial inulin has garnered increasing attention. In this study, molecular modification was applied to Lactobacillus mulieris UMB7800 inulosucrase, an enzyme that specifically produces high-molecular weight inulin, to enhance its catalytic activity and thermostability. Among the 18 variable regions, R5 was identified as a crucial region significantly impacting enzymatic activity by replacing it with more conserved sequences. Site-directed mutagenesis combined with saturated mutagenesis revealed that the mutant A250 V increased activity by 68%. Additionally, after screening candidate mutants by rational design, four single-point mutants, S344D, H434P, E526D, and G531P, were shown to enhance thermostability. The final combinational mutant, M5, exhibited a 66% increase in activity and a 5-fold enhancement in half-life at 55 °C. These findings are significant for understanding the catalytic activity and thermostability of inulosucrase and are promising for the development of microbial inulin biosynthesis platforms.

Enhancing Suppression of Chain Transfer via Installing Bulky N‐ortho‐Aryl Substituents into α‐Diimine Nickel System

AbstractRecently, the important role of sterically bulky aromatic substituents at the axial position of the metal center for synthesizing high‐performance catalysts were recognized. In this study, a series of α‐diimine nickel complexes with bulky N‐ortho‐aryl substituents were designed and synthesized. The as‐synthesized nickel complexes showed high activities (up to 2.3×107 g ⋅ mol−1 ⋅ h−1) and superior thermostability, giving access to moderately branched polyethylenes (35–86/1000 C) with high molecular weights (up to 197.5×104 g ⋅ mol−1). The polyethylene materials generated by these nickel complexes at 80 °C exhibited outstanding tensile mechanical. In addition, these nickel complexes could also catalyze the copolymerization of ethylene and polar monomer with modest activity (such as undecenoic acid, 10‐undecen‐1‐ol and 6‐chlorohex‐1‐ene), yielding functionalized polyolefin with adjustable molecular weights (6.8–222.9×104 g ⋅ mol−1) and incorporation ratios (0.2–4.3 mol %).

Dynamic Covalent Boronic-Acid-Functionalized Alginate/PVA Hydrogels for pH and Shear-Responsive Drug Delivery

Herein, we investigated hydrogels composed of boronic-acid-functionalized alginate and blended with polyvinyl alcohol (PVA) of different molecular weights to control the release of metoclopramide hydrochloride as a function of pH and shear stress. The functionalization of alginate introduced dynamic covalent bonding and pH-responsive properties that can modulate network connectivity. The study investigated the viscoelastic properties of the hydrogels, their drug release profiles, and their responsiveness to changes in pH and shear forces. The results showed that a higher PVA molecular weight and alkaline pH conditions increased hydrogel viscosity and stiffness due to a more stable and interconnected network structure than acidic pH. Metoclopramide release revealed that the hydrogels exhibited pH-responsive drug release behavior. The drug was more readily released under acidic conditions due to the instability of sp2-hybridized boronate ester bonds. The influence of shear forces on the release of metoclopramide was also investigated at shear rates of 1, 10, and 100 s−1, revealing their effect on matrix stiffening. Research shows that AlgBA/PVA hydrogels have unique properties, such as dynamic covalent bonding, that make them sensitive to external mechanical forces. This sensitivity makes them ideal for applications where physiological conditions trigger drug release.

Optimization of concentrations of natural antioxidants (curcumin) to enhance the thermal stability of ultra high molecular weight polyethylene (UHMWPE)

Optimization of concentrations of natural antioxidants (curcumin) to enhance the thermal stability of ultra high molecular weight polyethylene (UHMWPE)

Astrochemistry and Astrobiology over the last 20 years

A review of the achievements of astrochemistry and astrobiology over the past 20 years is given. Advances in astrochemistry in understanding the processes of emergence and survival high molecular weight chemical compounds are directly related to the conditions of prebiomolecules origin, like -amino acids and complex hydrocarbons. And if on the case of amino acids and hydrocarbons synthesis , the astrophysical picture seems quite clear, then on the case of the emergence of chiral amino acids, of which the proteins of living organisms are composed, there is no generally accepted point of view. Probably they occurred in certain photochemical transformations under the influence of circularly polarized radiation in the conditions of star formation regions of molecular clouds.

Enabling low molecular weight electrospinning through binary solutions of polymer blends

The formation of nanofibrous membranes via electrospinning is typically restricted to high molecular weight polymers in an appropriate solvent, correlated with the necessary formation of polymer chain entanglements that are needed to achieve successful production of electrospun fibers. The present work extends the electrospinning of low molecular weight polymers by investigating the electrospinning of a binary solution system consisting of two different low molecular weight polymers, using as a model system polycaprolactone (PCL) and gelatin in different ratios. The viscosities of the polymer solutions were characterized as a proxy for polymer chain entanglement and the resulting fibers were morphologically characterized by SEM imaging and further assessed water contact angle and molecular composition to determine the impact and homogeneity of the binary mixtures. We found that unitary solutions of either PCL or gelatin failed to generate proper fibers despite indications of chain entanglement. In contrast, binary solutions of low molecular weight PCL and gelatin generated different fiber quality and size distributions, depending on the ratio used, with direct correlations between fiber properties and the PCL:Gelatin ratio. It was discovered that the ratio of PCL to gelation was most predictive for successful fiber generation, with effective electrospinning occurring only for a define intermediate range of high blend ratios while both low and high blended binary solutions resulted in poor fiber production. Our study confirmed that this behavior was independent from absolute polymer concentration, indicating a unique interaction between these binary species which exists only under specific ratio concentrations and indicates promising new avenues to process low molecular weight polymers solutions.

Solid-Phase Synthesis of Well-Defined Multiblock Copolymers by Atom Transfer Radical Polymerization.

Solid-phase polymer synthesis, historically rooted in peptide synthesis, has evolved into a powerful method for achieving sequence-controlled macromolecules. This study explores solid-phase polymer synthesis by covalently immobilizing growing polymer chains onto a poly(ethylene glycol) (PEG)-based resin, known as ChemMatrix (CM) resin. In contrast to traditional hydrophobic supports, CM resin's amphiphilic properties enable swelling in both polar and nonpolar solvents, simplifying filtration, washing, and drying processes. Combining atom transfer radical polymerization (ATRP) with solid-phase techniques allowed for the grafting of well-defined block copolymers in high yields. This approach is attractive for sequence-controlled polymer synthesis, successfully synthesizing di-, tri-, tetra-, and penta-block copolymers with excellent control over the molecular weight and dispersity. The study also delves into the limitations of achieving high molecular weights due to confinement within resin pores. Moreover, the versatility of the method is demonstrated through its applicability to various monomers in organic and aqueous media. This straightforward approach offers a rapid route to developing tailored block copolymers with unique structures and functionalities.

Radioactive ADME Demonstrates ARV-110's High Druggability Despite Low Oral Bioavailability.

Proteolysis-targeting chimeras (PROTACs) have emerged as potentially effective therapeutic medicines, but their high molecular weight and poor solubility directly impact their oral bioavailability. This work synthesized 14C-labeled bavdegalutamide (ARV-110) as a model compound of PROTACs to evaluate its ADME features. Compared with targeted antitumor drugs, the use of food increased oral bioavailability of ARV-110 in rats from 10.75% to 20.97%, which is still undesirable. However, the therapeutic effect of ARV-110 at a low dose was much better than that of enzalutamide, demonstrating the specific catalytic medicinal properties of PROTACs. Moreover, the specific distribution of ARV-110 in subcutaneous prostate tumors was determined by quantitative whole-body autoradiography (QWBA). Notably, the specificity and activity of PROTACs take precedence over their oral absorption, and high oral bioavailability is not necessary to produce excellent therapeutic effects. This work presents a roadmap for developing future PROTAC medications from a radioactive drug metabolism and pharmacokinetics (DMPK) perspective.

Spatial patterns and environmental functions of dissolved organic matter in grassland soils of China

Soil dissolved organic matter (DOM) is crucial to atmospheric, terrestrial and aquatic environments as well as human life. Here, by characterizing DOM from 89 grassland soils throughout China, we reveal the spatial association between DOM geochemistry in the dry season vs annual ecosystem exchange and cancer cases. The humic-like and high molecular weight (3.4–25 kDa) fractions with lower biodegradability, decline from the northern to the southern regions of China, and are correlated with lower soil respiration and net ecosystem productivity at the continental scale. The <1.2 kDa and proteinaceous fractions could serve as a geographical indicator of nasopharyngeal cancer incidence and mortality, while the 3.4–25 kDa and humified fractions are potentially associated with pancreatic cancer cases (P < 0.05). Our findings highlight that exploiting the environmental functions of soil DOM and mitigating the negative impacts are necessary, and require actions tailored to local soil DOM conditions.

Assessing the Impact of Pre-Soaking to Enhance Laundering Efficacy of Firefighter Turnout Gear

Firefighters are exposed to hazardous chemicals at fire scenes, including polycyclic aromatic hydrocarbons (PAHs) among many others, which pose significant health risks. Current laundering practices are ineffective at removing persistent contaminants from turnout gear, necessitating further research to optimize cleaning methods. This study explores the impact of presoaking prior to the laundering process and the factors that can affect its effectiveness, including the presoaking duration and detergent concentration, in PAH removal when laundering. For this, contaminated fabric swatches were subjected to various presoaking durations (1, 3, and 12 h) and detergent concentrations (99:1 and 90:10 water-to-detergent ratios) before undergoing bench-scale washing. The cleaning efficacy was assessed for 16 PAH compounds, including both low-molecular-weight (LMW) PAHs and high-molecular-weight (HMW) PAHs. Moreover, the removal mechanisms of PAHs from turnout gear were fundamentally explained using partition coefficients and standard affinities with different parameters during washing. The results demonstrate that 3 h and 12 h of presoaking lead to 2.8 and 4.3 times greater HMW PAH removal, respectively. After 12 h of presoaking in a 90:10 water-to-detergent ratio, 97% of the LMW PAHs and 78% of the HMW PAHs were removed, compared to only an 11% removal of the HMW PAHs with a 99:1 ratio. Additionally, direct washing with a 90:10 ratio achieved comparable efficacy to that of presoaking with the same water-to-detergent ratio, indicating the crucial role of detergent concentration during laundering. These findings offer valuable insights for optimizing firefighter safety practices, emphasizing the role of presoaking and the appropriate methods to perform presoaking to mitigate firefighters’ occupational exposure risks to toxic substances and ensure gear reliability.

Adjustment of electronic (OMe and NO2) and steric (CHPh2) effects in bis(imino)pyridinyliron precatalysts for producing high molecular weight linear PE

Adjustment of electronic (OMe and NO2) and steric (CHPh2) effects in bis(imino)pyridinyliron precatalysts for producing high molecular weight linear PE

Preparation and properties of phosphorus-containing thermotropic liquid crystal copolyester fibers with excellent flame retardance and mechanical property

In order to acquire polymeric fibers have both excellent flame retardance and mechanical properties, high molecular weight phosphorus-containing liquid crystal copolyesters derived from 6-hydroxy-2-naphthenic acid (HNA), terephthalic acid (TA) and 10-(2,5-dihydroxypheny)-10-hydro-9-oxa-10-phospha phenanthrene-10-oxide (DOPO-HQ) were synthesized via “one-pot” melt polymerization, and then the fibers were obtained by melt spinning method. The structure and property of the copolyesters were studied elaborately by experimental characterization technique and molecular simulation method. Shear shinning behavior was observed from rheology measurement, indicating that the copolyesters had excellent melt fluidity and spinnability. The rigidity of molecular chain was efficiently improved by the phosphorus-containing monomer DOPO-HQ and naphthalene HNA units which could be reflected by the molecular simulation results as well as high Tg values. The flame retardant mechanism of the phosphorus-containing flame retardant copolyester was systematically studied via limiting oxygen index (LOI), vertical burning (UL-94) test, cone calorimetry, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results showed that the copolyesters exhibit synergistic flame retardant mechanism of gas phase and condensed phase. Meanwhile, mechanical property of the as-spun fibers could be significantly improved by increasing the spinneret draw ratio (SDR) attributed to high molecular chain orientation. The maximum tensile strength of the as-spun fiber was 0.77 GPa observed for P-HNA60P20 at a relatively low SDR of 29. It was shown the unique combination of good thermal stability, spinnability as well as mechanical and flame retardant properties of the copolyesters would make them could be used as high-performance flame retardant materials.

Sediment porewaters serve as a transient organic carbon pool at the land-ocean interface

The organic carbon (OC) cycle at the land-ocean interface is an important component of the global carbon budget, yet the processes that control the transfer, transformation, and burial of OC in these regions remain poorly understood. In this work, we examined sedimentary OC (SOC) in short core sediments, dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), and chromophoric dissolved organic matter (CDOM), as well as other solutes in sediment porewaters of the Changjiang Estuary and adjacent East China Sea (ECS) shelf. The main goal of this work is to investigate the variation of the sources and composition of different forms of carbon in estuarine sediments associated with different sedimentary regimes, to further understand the role of sediment porewater in carbon sequestration at the land-ocean interface. Concentrations of Fe2+ and Mn2+ in porewaters of the muddy sediments are much higher than those in the sandy sediments, and SO42− decreases with depth in the deep sediment layer, indicating the degradation of SOC in mobile muds is mainly driven by suboxic and/or anoxic diagenetic processes (e.g., iron-manganese reduction). The accumulation of DIC in the muddy sediment is higher compared to the sandy sediment, indicating relatively complete SOC remineralization. The DOC in porewaters of the muddy areas is mainly composed of highly degraded and low molecular weight humic-like substances (C1), whereas in the sandy area, porewater DOC is mainly composed of less degraded and high molecular weight protein-like substances (C2 and C3). The average DOC stock (28.5 t/km2) in the upper 30 cm sediment porewaters is significantly higher than that of DIC (12.5 t/km2) in sandy area, but less in muddy areas (17.0 t/km2 of DOC vs. 25.4 t/km2 of DIC). The total DOC stock in sediment porewaters of the sandy area accounted for ∼61 % of DOC stock in water column of the ECS, indicating that the porewater is an important DOC pool in the ECS. However, this DOC pool is rather transient due to its high reactivity and mobility, especially in sandy area. Nevertheless, compared with other marine environments, the carbon stock of DOC (average of 43.8 t/km2) in porewaters of stable sedimentary environments is much higher than that of DIC (average of 21.7 t/km2). This work further supports the notion that sedimentary regime plays an important role in OC cycling at the land-ocean interface and highlights the significance of sediment porewaters as a vast carbon pool in marine ecosystems.

Transethosomal gel for enhancing transdermal delivery of natural therapeutics.

Transethosomes, a fusion of transferosomes and ethosomes, combine the advantageous attributes of both vesicular systems to enhance deformability and skin permeation. While skin delivery is effective for drug transport, overcoming the skin barrier remains a significant challenge, particularly for plant-based products with poor permeability. Transethosomes offer a promising solution, but their low viscosity and retention on skin surfaces led to the development of transethosomal gels. These gels can entrap unstable and high molecular weight herbal extracts, fractions and bioactive compounds, facilitating enhanced drug delivery to the inner layers of the skin. This review focuses on the superior performance of transethosomes compared with conventional lipid-based nanovesicular systems, offering an advanced approach for transdermal delivery of plant-based drugs with improved permeability and stability.

Integrated system for temperature-controlled fast protein liquid chromatography. IV. Continuous ‘one-column’ ‘low-salt’ hydrophobic interaction chromatography

Systematic development of a temperature-controlled isocratic process for one-column low-salt hydrophobic interaction chromatography (HIC) of proteins employing a travelling cooling zone reactor (TCZR) system, is described. Batch binding and confocal scanning microscopy were employed to define process conditions for temperature-reversible binding of bovine serum albumin (BSA) which were validated in pulse-response temperature switching HIC experiments, before transferring to TCZR-HIC. A thin-walled stainless-steel column mounted with a movable assembly of copper blocks and Peltier elements (travelling cooling zone, TCZ) was used for TCZR-HIC. In pulse-response TCZR-HIC, 12 TCZ movements along the column desorbed 86.3% of the applied BSA monomers in 95.3% purity depleted >6-fold in 2–4 mers and nearly 260-fold in higher molecular weight (HMW) species. For continuous TCZR-HIC, the TCZ was moved 49–58 times during uninterrupted loading of BSA feeds at 0.25, 0.5 or 1 mg·mL-1. Each TCZ movement generated a sharp symmetrical elution peak. In the best case, (condition 1: 0.25 mg·mL-1 BSA; >17 mg BSA applied per mL of bed) the height of TCZ elution peaks approached pseudo-steady midway through the loading phase with no rise in baseline UV280 signal between peaks. Peak composition remained constant averaging 94.4% monomer, 5.6% 2–4 mers and <0.05% HMW. Monomers were recovered in quantitative yield depleted >3.1 fold in 2–4 mers and 92-fold in HMW species cf. the feed (63.6% monomers, 21.8% 2–4 mers, 14.6% HMW). However, increasing the BSA concentration to 1 mg·mL-1 (condition 2) or employing a fouled HIC column with 0.5 mg·mL-1 BSA (condition 3) compromised monomer purification performance.

Unlocking the potential of higher-molecular-weight 5-HT7R ligands: Synthesis, affinity, and ADMET examination

An increasing number of drugs introduced to the market and numerous repositories of compounds with confirmed activity have posed the need to revalidate the state-of-the-art rules that determine the ranges of properties the compounds should possess to become future drugs. In this study, we designed a series of two chemotypes of aryl-piperazine hydantoin ligands of 5-HT7R, an attractive target in search for innovative CNS drugs, with higher molecular weight (close to or over 500). Consequently, 14 new compounds were synthesised and screened for their receptor activity accompanied by extensive docking studies to evaluate the observed structure–activity/properties relationships. The ADMET characterisation in terms of the biological membrane permeability, metabolic stability, hepatotoxicity, cardiotoxicity, and protein plasma binding of the obtained compounds was carried out in vitro. The outcome of these studies constituted the basis for the comprehensive challenge of computational tools for ADMET properties prediction. All the compounds possessed high affinity to the 5-HT7R (Ki below 250 nM for all analysed structures) with good selectivity over 5-HT6R and varying affinity towards 5-HT2AR, 5-HT1AR and D2R. For the best compounds of this study, the expression profile of genes associated with neurodegeneration, anti-oxidant response and anti-inflammatory function was determined, and the survival of the cells (SH-SY5Y as an in vitro model of Alzheimer’s disease) was evaluated. One 5-HT7R agent (32) was characterised by a very promising ADMET profile, i.e. good membrane permeability, low hepatotoxicity and cardiotoxicity, and high metabolic stability with the simultaneous high rate of plasma protein binding and high selectivity over other GPCRs considered, together with satisfying gene expression profile modulations and neural cell survival. Such encouraging properties make it a good candidate for further testing and optimisation as a potential agent in the treatment of CNS-related disorders.

Generation of chlorinated toxic by-products during phenol oxidation by persulfate: Species, toxicity assessments, and kinetic studies

Persulfate (PS) advanced oxidation technologies are commonly used to remediate phenol-contaminated groundwater. However, the presence of chloride ions (Cl−) can lead to the generation of chlorine toxic by-products (Cl-TBPs), and the specific mechanisms of their generation are poorly understood. We investigated the quantity, type, and toxicity of Cl-TBPs associated with phenol and elucidated the generation trends and mechanisms of Cl-TBPs. Six types of Cl-TBPs with strong ecological toxicity were detected during phenol degradation. 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), and 2,4-dichlorophenol (2,4-DCP) were present at high concentrations in the system. The elevation of temperature, PS, phenol, and Cl− concentration enhanced the generation of 2-CP, 4-CP, and 2,4-DCP, while HCO3− inhibited their generation. The concentrations of 2-CP and 4-CP initially increased and then decreased, with maximum concentrations of 57.6 μmol/L and 20.7 μmol/L, respectively. A total of 289 Cl-TBPs with high molecular weights were observed, with a molecular formula containing only CHO as the main component (85.8 %). The two chlorine-containing Cl-TBPs accounted for 75.9 % of the total Cl-TBPs, which consisted of highly unsaturated and aromatic compounds formed through addition reactions. This study provides a theoretical basis for revealing the generation mechanism of Cl-TBPs in the process of persulfate oxidation of groundwater.

Method for isolation of high molecular weight genomic DNA from Botryococcus biomass.

The development of high molecular weight (HMW) genomic DNA (gDNA) extraction protocols for non-model species is essential to fully exploit long-read sequencing technologies in order to generate genome assemblies that can help answer complex questions about these organisms. Obtaining enough high-quality HMW gDNA can be challenging for these species, especially for tissues rich in polysaccharides such as biomass from species within the Botryococcus genus. The existing protocols based on column-based DNA extraction and biochemical lysis kits can be inefficient and may not be useful due to variations in biomass polysaccharide content. We developed an optimized protocol for the efficient extraction of HMW gDNA from Botryococcus biomass for use in long-read sequencing technologies. The protocol utilized an initial wash step with sorbitol to remove polysaccharides and yielded HMW gDNA concentrations up to 220 ng/μL with high purity. We then demonstrated the suitability of the HMW gDNA isolated from this protocol for long-read sequencing on the Oxford Nanopore PromethION platform for three Botryococcus species. Our protocol can be used as a standard for efficient HMW gDNA extraction in microalgae rich in polysaccharides and may be adapted for other challenging species.