Macromolecular Properties Research Articles

Molekular Docking Senyawa Anti Covid-19 terhadap Enzim 3c-Like Protease

The Organization (WHO) declared COVID-19 a pandemic on March 11, 2020 (Ministry of Health of the Republic of Indonesia, 2020). COVID-19 spreads rapidly through contact transmission, aerosols, and droplets). SARS-CoV-2 is a beta-corona virus that infects the upper respiratory tract (i.e. sinuses, nose, and throat) and lower respiratory tract (i.e. throat and lungs). Patients typically experience symptoms ranging from mild to severe that are life-threatening, including cough, sore throat, fever, dyspnea, fatigue, diarrhea, acute respiratory distress syndrome, sepsis and septic shock The purpose of this study is to determine the interaction of anti-viral compounds with the enzyme papain-like protease in covid-19 through molecular tethering to predict the macromolecular properties of proteins The research method is a literature review system. The results obtained from several studies of compounds in some plants have anti-covid properties.

Aqueously diffusible RNA-bound amyloid-β aggregates in Alzheimer disease brain (P1-6.004)

<h3>Objective:</h3> To define the macromolecular properties of naturally occurring, aqueously diffusible aggregates of amyloid-β protein (Aβ) to inform the next generation of treatments for Alzheimer disease. <h3>Background:</h3> Aqueously extractable and diffusible aggregates of Aβ (often called “oligomers” or “protofibrils”) are principal drug targets in AD, including for lecanemab. The structure, size, and molecular binding partners of these aggregates obtained from human brain are unknown. <h3>Design/Methods:</h3> Diffusible “soaking extracts” of AD brain were made by soaking minced cerebral cortex in aqueous buffer followed by ultracentrifugation. The soaking extracts were analyzed by isopycnic cesium chloride centrifugation, rate-zonal centrifugation, and size exclusion chromatography (SEC), followed by high-sensitivity Aβ₄₂ ELISA, as well as immunoprecipitation and RNA urea-PAGE. <h3>Results:</h3> Aβ aggregates in aqueous soaking extracts of AD brain exhibited higher density by isopycnic centrifugation than did synthetic Aβ fibrils, suggesting the presence of nucleic acids. RNAse treatment reduced the density of Aβ aggregates but increased their mass as measured by rate-zonal centrifugation. SEC using a high molecular weight cutoff resin showed three size peaks of Aβ, one of which disappeared with RNAse treatment. RNAse did not affect the total amount of monomeric or aggregated Aβ measurable in the AD brain soaking extracts. Aβ aggregate-directed antibodies immunoprecipitated a small RNA population from AD but not control brain soaking extracts. <h3>Conclusions:</h3> A sub-population of diffusible Aβ aggregates in human AD brain is bound to small RNAs. Its importance for disease progression and treatment is under investigation. <b>Disclosure:</b> Dr. Stern has nothing to disclose. Miss Meunier has nothing to disclose. Mrs. Liu has nothing to disclose. Dr. Selkoe has received personal compensation in the range of $50,000-$99,999 for serving as a Consultant for Prothena Biosciences. Dr. Selkoe has received personal compensation in the range of $500-$4,999 for serving as a Consultant for EISAI.

Enhanced Organic Electrochemical Transistor Performance of Donor-Acceptor Conjugated Polymers Modified with Hybrid Glycol/Ionic Side Chains by Postpolymerization Modification.

Emergent bioelectronic technologies are underpinned by the organic electrochemical transistor (OECT), which employs an electrolyte medium to modulate the conductivity of its organic semiconductor channel. Here we utilize postpolymerization modification (PPM) on a conjugated polymer backbone to directly introduce glycolated or anionic side chains via fluoride displacement. The resulting polymers demonstrated increased volumetric capacitances, with subdued swelling, compared to their parent polymer in p-type enhancement mode OECTs. This increase in capacitance was attributed to their modified side chain configurations enabling cationic charge compensation for thin film electrochemical oxidation, as deduced from electrochemical quartz crystal microbalance measurements. An overall improvement in OECT performance was recorded for the hybrid glycol/ionic polymer compared to the parent, owing to its low swelling and bimodal crystalline orientation as imaged by grazing-incidence wide-angle X-ray scattering, enabling its high charge mobility at 1.02 cm2·V-1·s-1. Compromised device performance was recorded for the fully glycolated derivative compared to the parent, which was linked to its limited face-on stacking, which hindered OECT charge mobility at 0.26 cm2·V-1·s-1, despite its high capacitance. These results highlight the effectiveness of anionic side chain attachment by PPM as a means of increasing the volumetric capacitance of p-type conjugated polymers for OECTs, while retaining solid-state macromolecular properties that facilitate hole transport.

Correction to 2,3-Butanediol as a Biobased Chain Extender for Thermoplastic Polyurethanes: Influence of Stereochemistry on Macromolecular Architectures and Properties

ADVERTISEMENT RETURN TO ARTICLES ASAPPREVAddition/CorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to 2,3-Butanediol as a Biobased Chain Extender for Thermoplastic Polyurethanes: Influence of Stereochemistry on Macromolecular Architectures and PropertiesAntoine Duval*Antoine DuvalMore by Antoine Duvalhttps://orcid.org/0000-0002-6161-8379, Alexandru SarbuAlexandru SarbuMore by Alexandru Sarbu, Florent DalmasFlorent DalmasMore by Florent Dalmashttps://orcid.org/0000-0002-6179-0881, David AlbertiniDavid AlbertiniMore by David Albertini, and Luc Avérous*Luc AvérousMore by Luc Avéroushttps://orcid.org/0000-0002-2797-226XCite this: Macromolecules 2023, XXXX, XXX, XXX-XXXPublication Date (Web):April 7, 2023Publication History Received23 March 2023Published online7 April 2023https://doi.org/10.1021/acs.macromol.3c00536© 2023 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views-Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (561 KB) Get e-Alerts Get e-Alerts

HIV-1 Gag specificity for PIP2 is regulated by macromolecular electric properties of both protein and membrane local environments

HIV-1 assembly occurs at the plasma membrane, with the Gag polyprotein playing a crucial role. Gag association with the membrane is directed by the matrix domain (MA), which is myristoylated and has a highly basic region that interacts with anionic lipids. Several pieces of evidence suggest that the presence of phosphatidylinositol-(4,5)-bisphosphate (PIP2) highly influences this binding. Furthermore, MA also interacts with nucleic acids, which is proposed to be important for the specificity of GAG for PIP2-containing membranes. It is hypothesized that RNA has a chaperone function by interacting with the MA domain, preventing Gag from associating with unspecific lipid interfaces. Here, we study the interaction of MA with monolayer and bilayer membrane systems, focusing on the specificity for PIP2 and on the possible effects of a Gag N-terminal peptide on impairing the binding for either RNA or membrane. We found that RNA decreases the kinetics of the protein association with lipid monolayers but has no effect on the selectivity for PIP2. Interestingly, for bilayer systems, this selectivity increases in presence of both the peptide and RNA, even for highly negatively charged compositions, where MA alone does not discriminate between membranes with or without PIP2. Therefore, we propose that the specificity of MA for PIP2-containing membranes might be related to the electrostatic properties of both membrane and protein local environments, rather than a simple difference in molecular affinities. This scenario provides a new understanding of the regulation mechanism, with a macromolecular view, rather than considering molecular interactions within a ligand-receptor model.

GAFF-AIC: reoptimisation of the GAFF force field for realistic densities and viscosities in aromatic isocyanates

ABSTRACT Molecular mechanical force field methods, which help to investigate material properties beyond molecular scales, describe the intra- and intermolecular interactions of molecules assuming a classical force field comprised of several terms. Force fields should accurately describe the energy interactions of all moleculer elements to, eventually, accurately reproduce macromolecular properties of that materials. In the case of aromatic isocyanates, general purpose force fields failed to properly account for molecular interactions and, consequently, at the prediction of macromolecular properties of isocyanate-based materials. The present study presents a new force field based on the General AMBER Force Field (GAFF), namely GAFF-AIC, which shows improved results for the prediction of macromolecular properties, in particular density and viscosities, of materials based on aromatic isocyanates. For that, a new set of parameters for intramolecular and intermolecular interactions has been optimised by means of a least square fitting. It is shown that GAFF-AIC is able to accurately reproduce the experimental density and viscosity of liquid 1-naphtyl isocyanate. Moreover, these newly proposed force field parameters were evaluated to see how efficient they were at predicting the liquid densities and viscosities for several considered aromatic isocyanates, resulting in an accurate estimation that is in excellent agreement with experimental results.

Ocean warming and acidification affect the transitional C:N:P ratio and macromolecular accumulation in the harmful raphidophyte Heterosigma akashiwo

Despite an increase in ocean warming and acidification that is expected to increase the number of harmful algal species worldwide, the population of the raphidophyte Heterosigma akashiwo has been reported to be reduced. However, how this species physically and metabolically modifies transitional C:N:P ratio and macromolecule accumulation is unknown. Considering 1st, 10th, and 20th culture generations under present (low-temperature; low-carbon-dioxide [LTLC] 21 °C; pCO2 400 ppm) and future (high-temperature; high-carbon-dioxide [HTHC] 25 °C; pCO2 1000 ppm) ocean conditions, we examined transitional C:N:P ratio and macromolecule level changes and performed transcriptome sequencing. The results showed that compared to 1st generation cells, 20th generation cells under HTHC conditions showed a large decrease in carbon quota (QC: 34%), nitrogen quota (QN: 36%), and phosphorus quota (QP: 32%), which were reflected in an overall reduction in DNA and RNA quantity. Decreased activation of photosynthetic, carbon fixation and lipid metabolic pathways coincided with changes in photosynthetic efficiency, carbon concentration, and lipid accumulation after long-term (20th generation) exposure to HTHC conditions. We observed that these variations in internal metabolic pathways were caused by external changes in temperature, which activated the (Ca+) signaling pathway, and external changes in pCO2, which altered proton exchange pathways. Our results suggest that H. akashiwo in a temperate environment will undergo profound changes in C:N:P ratio and macromolecular properties, leading to programmed cell death, in the future.

Capsular Exopolysaccharides from Two Streptococcus thermophilus Strains Differ in Their Moisture Sorption Behavior.

Streptococcus thermophilus is a species frequently used in the manufacture of fermented milk. Apart from acid production, some strains additionally synthesize exopolysaccharides (EPS) which contribute to texture improvement and syneresis reduction, both being attributable to the EPS's high water binding capacity. There are two different types of EPS that may be produced, namely free exopolysaccharides (fEPS) which are secreted into the medium, and capsular EPS (cEPS) which remain attached to the bacterial cell wall. This study aims to analyze their individual contribution to techno-functional properties of fermented milk by determining the moisture sorption behavior of isolated fEPS and cell-attached cEPS from two S. thermophilus strains separately: ST-1G, a producer of non-ropy fEPS and cEPS, and ST-2E, a producer of ropy fEPS and cEPS. Differences in moisture load and sorption kinetics, determined for the first time for microbial EPS, were related to structural and macromolecular properties. The observed data are discussed by using previously published data on the physical properties of stirred fermented milk produced with these two strains. ST-1G EPS showed a higher cEPS fraction, a higher moisture load and slower moisture desorption than EPS produced by ST-2E, thus contributing to lower syneresis in fermented milk. For ST-2E, higher gel viscosity was related to a higher intrinsic viscosity and molecular mass of the ropy fEPS. Both strains produced complex EPS or EPS mixtures with clearly different molecular structures.

Evaluation of Selected Cellulose Macromolecular Properties after Its Chemical Treatment Using Size Exclusion Chromatography.

This work evaluates the effect of using selected inorganic chemicals as the main components of waterborne wood preservative systems on the degradation of the cellulose constituent in wood from model samples. The polymeric properties of cellulose and the homogeneity of the degradation process primarily reflect very well the degree of cellulose deterioration. Whatman papers, as pure cellulose model samples, were impregnated with 10 different 5 wt% solutions of inorganic salts and distilled water and consequently subjected to wet-thermal accelerated aging (T = 85 °C, RH = 65%, for 30 days). The samples were then derivatized to cellulose tricarbanilates (CTCs) through two different procedures (by precipitation in a methanol-water mixture/by evaporation of pyridine from the reaction mixture) and finally analyzed using size exclusion chromatography (SEC). Chemically treated and aged cellulose samples showed different changes in the degree of polymerization (DP) and polydispersity (PD) in terms of untreated non-aged standard caused by different ongoing degradation reactions, such as dehydration, hydrolysis, oxidation, and crosslinking. In general, the lowest degradation rate after treatment by chemicals and after accelerated aging was observed in samples treated by borates, NaCl, and ZnSO4·7H2O. The greatest depolymerization after treatment and after accelerated aging was caused by sulphates containing NH4+, Cu2+, and Fe3+ cations, with aging by NH4Cl and (NH4)2HPO4-treated samples also leading to significant depolymerization. The higher DP values are linked to the precipitated method of CTC preparation, though not for chlorides and phosphates. PD is also generally higher in precipitated and aged samples and is heavily influenced by the presence of low molecular weight products. This paper brings new insights regarding the complex evaluation of the polymeric properties of degraded cellulose by considering all important factors affecting the sample and the analysis itself through the use of statistics. From the statistical point of view, the influences of all factors (solution, aging, method) and their interactions (except aging*method) on DP are statistically significant. The influence of the sample processing method used for analysis of the desired results becomes important mainly in practice. This work recommends the evaporation method for more accurate description of more degraded cellulose.

Revisiting macromolecular hydration with HullRadSAS.

Hydration of biological macromolecules is important for their stability and function. Historically, attempts have been made to describe the degree of macromolecular hydration using a single parameter over a narrow range of values. Here, we describe a method to calculate two types of hydration: surface shell water and entrained water. A consideration of these two types of hydration helps to explain the "hydration problem" in hydrodynamics. The combination of these two types of hydration allows accurate calculation of hydrodynamic volume and related macromolecular properties such as sedimentation and diffusion coefficients, intrinsic viscosities, and the concentration-dependent non-ideality identified with sedimentation velocity experiments.

A novel approach to mineral carbonation using deep eutectic solvents for the synthesis of nano-sized amorphous CaCO3

This paper proposes a novel synthesis method for nanosized amorphous CaCO3 based on advanced mineral carbonation using the macromolecular properties of deep eutectic solvents (DESs). DESs are generally synthesized by mixing hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs), and their properties vary depending on the HBDs and HBAs used for the synthesis. To synthesize DESs with CO2-philic properties, monoethanolamine (MEA) was selected as the HBD because it possesses a CO2-active site. However, alkanolamine-based DESs are difficult to use in practical applications because of their high viscosity following CO2 absorption. To mitigate the onset of high viscosity, H2O was added to the synthesized DESs, with the molar ratio HBA:HBD:H2O as 1:5:10 and 1:5:15. In the proposed process, CO2 was captured by the DESs-H2O system and converted into particle-size- and morphology-controlled CaCO3. Nanosized amorphous CaCO3 (ACC) with average particle sizes of 38.1 and 48.0 nm was formed by DESs based on the molar ratio of 1:5:10. The results demonstrated the need for an adequate ratio of H2O to DES to form nanosized ACC, implying that the strength of hydrogen bonding in DES-H2O systems is the primary factor affecting the performance of the solvent. The DES-H2O systems with inter- and intramolecular hydrogen bonding inhibited the crystallization of CaCO3. The findings of this study are applicable to CO2 utilization processes designed for the production of nanosized ACC.

Fractionation of Technical Lignin from Enzymatically Treated Steam-Exploded Poplar Using Ethanol and Formic Acid.

Lignocellulosic biorefineries produce lignin-rich side streams with high valorization potential concealed behind their recalcitrant structure. Valorization of these residues to chemicals, materials, and fuels increases the profitability of biorefineries. Fractionation is required to reduce the lignins' structural heterogeneity for further processing. We fractionated the technical biorefinery lignin received after steam explosion and saccharification processes. More homogeneous lignin fractions were produced with high β-O-4' and aromatic content without residual carbohydrates. Non-toxic biodegradable organic solvents like ethanol and formic acid were used for fractionation and can be adapted to the existing biorefinery processes. Macromolecular properties of the isolated fractions were carefully characterized by structural, chemical, and thermal methods. The ethanol organosolv treatment produced highly soluble lignin with a reasonable yield, providing a uniform material for lignin applications. The organosolv fractionation with formic acid and combined ethanol-formic acid produced modified lignins that, based on thermal analysis, are promising as thermoresponsive materials.

Correlations on the Structure and Properties of Collagen Hydrogels Produced by E-Beam Crosslinking.

In this study, a collagen hydrogel using collagen exclusively produced in Romania, was obtained by electron beam (e-beam) crosslinking. The purpose of our study is to obtain new experimental data on the crosslinking of collagen and to predict as faithfully as possible, its behavior at high irradiation doses and energies. To pursue this, the correlations between macromolecular structure and properties of collagen hydrogels were determined by rheological analysis, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Differential Scanning Calorimetry (DSC), respectively. The gel fraction, swelling degree, and network parameters of the collagen hydrogels were also investigated at different irradiation doses. Through experimental exploration, we concluded that irradiation with e-beam up to 25 kGy induces crosslinking processes in collagen structure without producing advanced degradation processes. E-beam technology is a great method to develop new materials for medical applications without adding other chemical reagents harmful to human health. The future aim is to develop new wound dressings for rapid healing based on collagen, through irradiation technologies.

Highly Aligned Centrifugal Spun Polyacrylonitrile Nanofibers Collected and Processed with Automated Tracks

AbstractA parallel automated track collector is integrated with a rationally designed centrifugal spinning head to collect aligned polyacrylonitrile (PAN) nanofibers. Centrifugal spinning is an extremely promising nanofiber fabrication technology due to high production rates. However, continuous oriented fiber collection and processing presents challenges. Engineering solutions to these two challenges are explored in this study. A 3D‐printed head design, optimized through a computational fluid dynamics simulation approach, is utilized to limit unwanted air currents that disturb deposited nanofibers. An automated track collecting device has pulled deposited nanofibers away from the collecting area. This results in a continuous supply of individual aligned nanofibers as opposed to the densely packed nanofiber mesh ring that is deposited on conventional static post collectors. The automated track collector allows for simple integration of the postdraw processing step that is critical to polymer fiber manufacturing for enhancing macromolecular orientation and mechanical properties. Postdrawing has enhanced the mechanical properties of centrifugal spun PAN nanofibers, which have different crystalline properties compared with conventional PAN microfiber. These technological developments address key limitations of centrifugal spinning that can facilitate high production rate commercial fabrication of highly aligned, high‐performance polymer nanofibers.

Glucose Scavenging with Pectin Hydrazide: A Step toward Designing Innovative, Functional, All‐Sugar‐Based Polymers

AbstractPolygalacturonic acid hydrazide (PGH) is one of only a few polysaccharide derivatives with pronounced nucleophilic characteristics known today. This water‐soluble and benign material could be reacted with the hydrophilic aldehydes D‐glucose in water, without any catalyst and at room temperature, resulting in a product that is the first example of new family of all‐sugar‐based polysaccharide derivatives. The reaction is reversible, allowing for D‐glucose loading and unloading of the PGH. The D‐glucose binds as the α−, and β anomer of the glucopyranosyl form. The reaction is orthogonal to the reactivity of the hydroxyl groups in the polysaccharide and enables the mild generation of new bio‐inspired polysaccharide derivatives. The glucose attachment could be rendered irreversibly by reducing the hydrazone with sodium cyanoborohydride, leading to the acyclic sugar derivative. A brief hydrodynamic and light scattering study of the polymers showed varying macromolecular properties at consistent molar mass values of the modified polysaccharide derivatives.

Quantitative MRI Evidence for Cognitive Reserve in Healthy Elders and Prodromal Alzheimer's Disease.

Cognitive reserve (CR) has been postulated to contribute to the variation observed between neuropathology and clinical outcomes in Alzheimer's disease (AD). We investigated the effect of an education-occupation derived CR proxy on biological properties of white matter tracts in patients with amnestic mild cognitive impairment (aMCI) and healthy elders (HC). Educational attainment and occupational complexity ratings (complexity with data, people, and things) from thirty-five patients with aMCI and twenty-eight HC were used to generate composite CR scores. Quantitative magnetic resonance imaging (qMRI) and multi-shell diffusion MRI were used to extract macromolecular tissue volume (MTV) across major white matter tracts. We observed significant differences in the association between CR and white matter tract MTV in aMCI versus HC when age, gender, intracranial volume, and memory ability were held constant. Particularly, in aMCI, higher CR was associated with worse tract pathology (lower MTV) in the left and right dorsal cingulum, callosum forceps major, right inferior fronto-occipital fasciculus, and right superior longitudinal fasciculus (SLF) tracts. Conversely higher CR was associated with higher MTV in the right parahippocampal cingulum and left SLF in HC. Our results support compensatory CR mechanisms in aMCI and neuroprotective mechanisms in HC and suggest differential roles for CR on white matter macromolecular properties in healthy elders versus prodromal AD patients.

2,3-Butanediol as a Biobased Chain Extender for Thermoplastic Polyurethanes: Influence of Stereochemistry on Macromolecular Architectures and Properties

2,3-Butanediol as a Biobased Chain Extender for Thermoplastic Polyurethanes: Influence of Stereochemistry on Macromolecular Architectures and Properties

3D Porous MXene Films for Advanced Electromagnetic Interference Shielding and Capacitive Storage

The construction of abundant pore channels between the layers of Ti3C2Tx MXene film is an important approach to fully exploit the 2D macromolecular properties of MXene (Ti3C2Tx), which is of great significance for further realizing the practical application of MXene macroscopic assemblies in the field of electromagnetic interference shielding and capacitive storage. However, there is still a lack of systematic introductions and prospects of this field, thus far. In this review, starting from the preparation of MXene macroscopic assemblies, the 3D porous MXene films, constructed by sacrificial templating, vapor foaming, and light foaming, as well as their corresponding properties of electromagnetic interference shielding and capacitive storage, are introduced. In addition, the current bottlenecks and great challenges of 3D porous MXene films are deeply analyzed, and effective solutions for future application development trends are proposed.

Cystic Fibrosis Airway Mucus Hyperconcentration Produces a Vicious Cycle of Mucin, Pathogen, and Inflammatory Interactions that Promotes Disease Persistence.

The dynamics describing the vicious cycle characteristic of cystic fibrosis (CF) lung disease, initiated by stagnant mucus and perpetuated by infection and inflammation, remain unclear. Here we determine the effect of the CF airway milieu, with persistent mucoobstruction, resident pathogens, and inflammation, on the mucin quantity and quality that govern lung disease pathogenesis and progression. The concentrations of MUC5AC and MUC5B were measured and characterized in sputum samples from subjects with CF (N = 44) and healthy subjects (N = 29) with respect to their macromolecular properties, degree of proteolysis, and glycomics diversity. These parameters were related to quantitative microbiome and clinical data. MUC5AC and MUC5B concentrations were elevated, 30- and 8-fold, respectively, in CF as compared with control sputum. Mucin parameters did not correlate with hypertonic saline, inhaled corticosteroids, or antibiotics use. No differences in mucin parameters were detected at baseline versus during exacerbations. Mucin concentrations significantly correlated with the age and sputum human neutrophil elastase activity. Although significantly more proteolytic cleavages were detected in CF mucins, their macromolecular properties (e.g., size and molecular weight) were not significantly different than control mucins, likely reflecting the role of S-S bonds in maintaining multimeric structures. No evidence of giant mucin macromolecule reflecting oxidative stress-induced cross-linking was found. Mucin glycomic analysis revealed significantly more sialylated glycans in CF, and the total abundance of nonsulfated O-glycans correlated with the relative abundance of pathogens. Collectively, the interaction of mucins, pathogens, epithelium, and inflammatory cells promotes proteomic and glycomic changes that reflect a persistent mucoobstructive, infectious, and inflammatory state.

Internal and External Catalysis in Boronic Ester Networks.

In dynamic materials, the reversible condensation between boronic acids and diols provides adaptability, self-healing ability, and responsiveness to small molecules and pH. The thermodynamics and kinetics of bond exchange determine the mechanical properties of dynamic polymer networks. Here, we investigate the effects of diol structure and salt additives on the rate of boronic acid-diol bond exchange, binding affinity, and the mechanical properties of the corresponding polymer networks. We find that proximal amides used to conjugate diols to polymers and buffering anions induce significant rate acceleration, consistent with an internal and external catalysis, respectively. This rate acceleration is reflected in the stress relaxation of the gels. These findings contribute to the fundamental understanding of the boronic ester dynamic bond and offer molecular strategies to tune the macromolecular properties of dynamic materials.