Gel Permeation Chromatography Research Articles

The Antimicrobial Effects of Myrosinase Hydrolysis Products Derived from Glucosinolates Isolated from Lepidium draba.

Lepidium draba (hoary cress) is a perennial plant belonging to the Brassicaceae family that produces two dominant glucosinolates (GLSs): glucoraphanin (GRN) and sinalbin (SBN). They represent the stored form, which is converted upon the myrosinase (Myr) hydrolysis activity to active compounds, mainly isothiocyanates (ITCs) such as sulforaphane (SFN) or p-hydroxybenzyl isothiocyanate (pHBITC). Research on ITCs that have proven anticancer, antimicrobial, and chemoprotective properties is usually conducted with pure commercially available compounds. However, these are chemically reactive, making it difficult to use them directly for preventive purposes in dietary supplements. Efforts are currently being made to prepare dietary supplements enriched with GLS and/or Myr. In this study, we report a simple but efficient chromatographic procedure for the isolation and purification of GLSs from MeOH extract from hoary cress based on a combination of ion exchange and gel permeation chromatography on DEAE-Sephadex A-25 and Sephadex LH-20. To obtain the Myr required for efficient hydrolysis of GLSs into antibacterial ITCs, we developed a rapid method for its extraction from the seeds of Lepidium sativum (garden cress). The yields of GLSs were 22.9 ± 1.2 mg GRN (purity 96%) and 10.4 ± 1.1 mg SBN (purity 92%) from 1 g of dry plant material. Both purified GLSs were used as substrates for the Myr. Analysis of the composition of hydrolysis products (HPs) revealed differences in their hydrolysis rates and in the degree of conversion from GLSs to individual ITCs catalyzed by Myr. When GRNs were cleaved, SFNs were formed in an equimolar ratio, but the formation of pHBITCs was only half that of cleaved SBNs. The decrease in pHBITC content is due to its instability compared to SFN. While SFN is stable in aqueous media during the measurement, pHBITC undergoes non-enzymatic hydrolysis to p-hydroxybenzyl alcohol and thiocyanate ions. Testing of the antimicrobial effects of the HPs formed from GRN by Myr under premix or in situ conditions showed inhibition of the growth of model prokaryotic and eukaryotic microorganisms. This observation could serve as the jumping-off point for the design of a two-component mixture, based on purified GLSs and Myr that is, usable in food or the pharmaceutical industry in the future.

Thermal Oxidative Aging Effect on Chemo-Rheological and Morphological Evolution of Crumb Rubber Modified Asphalt Binders with Wax-Based Warm Mix Additives

Wax-based warm mix additives can decrease the viscosity and improve the workability of crumb rubber (CR)-modified asphalt, but the mechanism of influence on the aging performance of CR-modified asphalt is not clear. To investigate the thermal aging behavior and mechanism of wax-based warm mix CR-modified asphalt, polyethylene wax (PEW) and polyamide wax (PAW) were mixed to prepare warm mix CR-modified asphalt. The effect of thermal aging on the rheological and mechanical properties was characterized by a basic property test, frequency sweep test, and multiple stress creep recovery test. The chemical composition changes during aging were then analyzed by Fourier transform infrared spectroscopy and gel permeation chromatography. Finally, the phase morphology during thermal aging was observed by fluorescence microscopy. The results showed that compared with the degradation of CR, the oxidative aging of the asphalt binder played a dominant role in the process. Not only did PEW and PAW attach to the asphalt surface in the form of crystallization to prevent its reaction with oxygen but they also promoted the dissolution of CR, and released polymerization chains, thereby enhancing the antiaging properties of CR-modified asphalt. Furthermore, the antiaging of PAW/CR-modified asphalt was better than that of PEW/CR-modified asphalt, because the amide group of PAW reacted with CR-modified asphalt to form a polymer structure.

Zwitterionic ring expansion polymerization of tert‐butyl glycidyl ether with B(C6F5)3 towards the generation of cyclic chains

AbstractThe synthesis of cyclic polymers via zwitterionic ring expansion polymerization is limited to a few number of monomer and catalyst pairs. Herein we report the synthesis of cyclic poly(tert‐butyl glycidyl ether) through the polymerization of tert‐butyl glycidyl ether (tBGE) with B(C6F5)3 in different reaction conditions that include different solvents, monomer to initiator ratio, monomer concentration and temperature. We found that bimodal molecular weight distribution is formed in almost all reaction conditions caused by cyclization of short chains. Subsequent chain elongation leads to the formation of cycles of higher molecular weight, particularly in cyclohexane and under bulk conditions. The formation of non‐cyclic byproducts is common in all the systems investigated. Low molecular weight cyclic chains (Mn = 0.7 kDa, Ð = 1.1) of high topological purity were successfully isolated by preparative gel permeation chromatography. By using a click scavenging protocol, the non‐cyclic byproducts were eliminated from the high molecular weight fraction (Mn = 3 kDa, Ð = 1.3) generating pure cyclic chains. Mechanistic investigation using density functional theory calculations was performed on the formation of zwitterionic intermediates and the transfer reaction to the monomer, which notably affects chain growth by the attack of the glycidyl oxygen of the monomer on the growing chain.

Lignin phenolation by graft copolymerization to boost its reactivity

Lignin is the most abundant phenolic biopolymer and a renewable resource of aromatics. It can be used as a phenol substitute in the synthesis of phenolic resins. However, lignin is not as reactive as phenol, so phenolation is generally carried out to improve lignin reactivity. In this work, we suggest a solution to circumvent the limitations of traditional phenolation (e.g., high temperature, strong acids/bases, limited reactivity, and phenol toxicity). We first attempt new lignin phenolation by graft copolymerization in which polymeric phenol, instead of toxic phenol, is introduced to lignin. Organosolv lignin from hardwood was modified with 2-bromoisobutyryl bromide to act as a lignin macroinitiator (L-Br). A protected phenolic monomer, 4-acetoxystyrene, was graft copolymerized onto L-Br using CuBr2/tris[2-(dimethylamino)ethyl]amine as a catalyst/ligand, after which the resultant lignin copolymer was deacetylated to produce lignin grafted with poly(4-hydroxystyrene). This poly-phenolation process was conducted at room temperature without the strong acids/bases and toxic phenol required in conventional phenolation. The poly-phenolated lignin was analyzed using 1H-, 13C-, and 31P NMR spectroscopy and gel permeation chromatography. This novel phenolation process enhanced the reactive sites of lignin more than tenfold. It also reduced the dark color of technical lignins significantly, thereby overcoming a serious obstacle to their applicability.

Impact of Molecular Weight Variations in Dendrobium officinale Polysaccharides on Antioxidant Activity and Anti-Obesity in Caenorhabditis elegans.

This research investigates the impact of Dendrobium officinale polysaccharides (DOP) with different molecular weights on antioxidant effects, lifespan enhancement, and obesity reduction, utilizing both in vitro analyses and the Caenorhabditis elegans (C. elegans) model. Through a series of experiments-ranging from the extraction and modification of polysaccharides, Gel Permeation Chromatography (GPC), and analysis of composition to the evaluation of antioxidant capabilities, this study thoroughly examines DOP and its derivatives (DOP5, DOP15, DOP25) produced via H2O2-Fe2+ degradation. The results reveal a direct relationship between the molecular weight of polysaccharides and their bioactivity. Notably, DOP5, with its intermediate molecular weight, demonstrated superior antioxidant properties, significantly extended the lifespan, and improved the health of C. elegans. Furthermore, DOP15 appeared to regulate lipid metabolism by affecting crucial lipid metabolism genes, including fat-4, fat-5, fat-6, sbp-1, and acs-2. These findings highlight the potential application of DOP derivatives as natural antioxidants and agents against obesity, contributing to the development of functional foods and dietary supplements.

Characterization and anti-aging activities of polysaccharide from Rana dybowskii Guenther.

Introduction: Rana dybowskii Guenther (RDG), as a traditional Chinese medicine, has been shown to have antioxidant effects. However, studies on the anti-aging effect of RDG are still limited. Methods: In this study, we prepared polysaccharides from the skin of RDG (RDGP) by hot water extraction, alcohol precipitation, ion-exchange chromatography and gel chromatography. The proteins were removed using the Sevage method in combination with an enzymatic method. The structural features were analyzed using high-performance gel permeation chromatography, β-elimination reaction and Fourier transform infrared spectra. The anti-aging effect of RDGP was investigated by using D-Gal to establish an aging model in mice, and pathological changes in the hippocampus were observed under a microscope. Results: We obtained the crude polysaccharide DGP from the skin of RDG, with a yield of 61.8%. The free protein was then removed by the Sevage method to obtain DGPI and deproteinated by enzymatic hydrolysis combined with the Sevage method to further remove the bound protein to obtain the high-purity polysaccharide DGPII. Then, DGPIa (1.03 × 105Da) and DGPIIa (8.42 × 104Da) were obtained by gel chromatography, monosaccharide composition analysis showed that they were composed of Man, GlcA, GalNAc, Glc, Gal, Fuc with molar ratios of 1: 4.22 : 1.55: 0.18 : 8.05: 0.83 and 0.74 : 1.78: 1: 0.28: 5.37 : 0.36, respectively. The results of the β-elimination reaction indicated the presence of O-glycopeptide bonds in DGPIa. The Morris water maze test indicated that mice treated with DGPIIa exhibited a significantly shorter escape latency and increased time spent in the target quadrant as well as an increase in the number of times they traversed the platform. Pathologic damage to the hippocampus was alleviated in brain tissue stained with hematoxylin-eosin. In addition, DGPIIa enhanced the activities of SOD, CAT, and GSH-Px and inhibited the level of MDA in the serum and brain tissues of aging mice. Discussion: These results suggest that RDGP has potential as a natural antioxidant and provide useful scientific information for anti-aging research.

One-pot in situ bulk polymerization of triblock copolymer PCL-b-PA6-b-PCL based on PA6 by using tetraphenyl tin

The preparation of polyesteramides (PEAs) with regular block structure has long been a challenge, owing to the occurrence of the ester-amide exchange during the polymerization at high tempereture. In this work, we report a simple and green method to prepare polyamide 6 (PA6) based triblock PEA whose structure is poly(ε-caprolactone)-block-PA6-block-poly(ε-caprolactone) (PCL-b-PA6-b-PCL) using tetraphenyl tin as catalyst without solvent. The first segment PA6 was synthesized via cationic ring-opening polymerization (ROP) of ε-caprolactam (CPL), later, ROP of ε-caprolactone (CL) was involved to extend polycaprolactone (PCL) segments by using tetraphenyl tin as catalyst. By varying the proportion of CPL and CL, series PA6-based PEAs was prepared and characterized by gel permeation chromatography, 1H, DOSY, and 13C NMR. The results showed that PEA containing more proportion of CL presented a higher molecular weight with narrow polydisperse index. In particular, the lower water absorption and lower oligomers content infers that the PEA could have a prospective application in processing precision electronic devices.

An Undergraduate Laboratory Module Integrating Organic Chemistry and Polymer Science.

Polymer science is receiving wider acceptance in the organic chemistry community; thus, it is imperative to include it in the undergraduate organic chemistry curriculum. Despite the ever-increasing popularity of the topic of polymer chemistry in undergraduate curricula, a comprehensive laboratory experiment module describing a polypeptide synthesis by ring-opening polymerization of N-carboxyanhydride (NCA ROP) and a homopolymer synthesis by activators-regenerated by electron-transfer for atom transfer radical polymerization (ARGET ATRP) has yet to be proposed. Herein, we report a semester-long, ten week undergraduate laboratory module focusing on the synthesis and analytical characterization of polyalanine and polystyrene for an advanced organic chemistry class. Students received hands-on-experiences in synthesizing polymers followed by their characterization via proton nuclear magnetic resonance (1H NMR) spectroscopy, electrospray ionization-mass spectrometry (ESI-MS), gel permeation chromatography (GPC), thermogravimetry (TGA), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM), which are not well-presented in the typical organic chemistry curricula. These engaging hands-on lessons in the newly designed laboratory module not only increase students' interests in an interdisciplinary environment of organic chemistry and polymer science but also cultivate their research interests and communication skills and promote critical thinking.

Structure – property relationships of different natural rubber grades

The effects of various natural rubber (NR) grades, namely RSS 3, STR 5L, STR 10, STR 20 and STR 20CV, towards their final properties were investigated. The molecular characteristics of these NR grades were assessed by gel permeation chromatography and by determining protein contents. The highest molecular weight was found for RSS 3, while STR 20CV had the lowest molecular weight. No relationship between molecular weight and protein content was seen in this study. A higher molecular weight rubber provided greater maximum torque and torque difference, and a better resistance to degradation during processing. However, no significant difference was found among molecular weights higher than 1.25 × 106 g/mol. The final torque during processing and the Mooney viscosity of rubber increased with molecular weight due to tie chain entanglements, as later confirmed by a dynamic mechanical analyzer. Thermo-stability and stress relaxation of the various NR grades were also largely governed by their molecular weights. Stability of rubber at an elevated temperature improved with molecular weight. Also, the tensile properties and the strain-induced crystallization varied with the molecular weight. The tensile strength of various NR grades varied from 15 to 18 MPa while the elongation at break was 600%–800%. The molecular weight of NR was found to have a great effect on the processing, thermomechanical, dynamic, and mechanical properties of the vulcanizates. In addition, a narrow molecular weight distribution also affected the mechanical properties. The crystallinities of the NRs during stretching were closely related to their tensile behavior, and the alignment of crystal structures during stretching was almost parallel to the stretching direction in all NR samples. The molecular weight of NR appears to be a key factor associated with the mechanical properties and reinforcement behavior of vulcanizates.

The Physicochemical Properties and Antioxidant Activities of the Hawthorn Pectin Extracted Using Ultra-High Pressure Assisted Acid Extraction (UPAAE).

This study aims to investigate the positive effects of ultra-high pressure assisted acid extraction (UPAAE) on both physicochemical properties and antioxidant activities of hawthorn pectin. The basic indicators, structure characterization, and antioxidant activities were measured, which could indicate the disadvantages and advantages among traditional water extraction (WE), acid extraction (AE), and UPAAE. The results show that the hawthorn pectin of UPAAE has a decrease in esterification degree, protein content, and total polyphenols, but has an increase in total galacturonic acid aldehyde compared to the hawthorn pectin of AE. In the Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) analyses, the hawthorn of UPAAE has typical pectin absorption peaks in the FT-IR spectrum and a distinct layered structure in the SEM surface image. The ion chromatography profiles show that the molar ratio of galacturonic acid to arabinose in the hawthorn pectin of UPAAE increases and 5.50 μg/mg ribose appears compared to the pectin of AE and WE. The high performance gel permeation chromatography (HPGPC) profile indicates that the molecular weight distribution of hawthorn pectin of UPAAE is more concentrated and has the highest molecular weight compared to the pectin of the other two extraction methods. In the vitro antioxidant activity analysis, the pectin of UPAAE exhibits the highest scavenging rate against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals (93.70%), which is close to the scavenging rate of vitamin C (96.30%). These findings demonstrated that UPAAE is a more efficient and environmentally friendly method for pectin extraction from hawthorn. It is also an effective way to enhance its antioxidant activity, which has great application prospects in the food industries.

Rubber Oxygenase Degradation Assay by UV-Labeling and Gel Permeation Chromatography.

A versatile and robust end-group derivatization approach using oximes has been developed for the detection of oxidative degradation of synthetic polyisoprenes and polybutadiene. This method demonstrates broad applicability, effectively monitoring degradation across a wide molecular weight range through ultraviolet (UV)-detection coupled to gel permeation chromatography. Importantly, it enables the effective monitoring of degradation via derivatization-induced UV-maximum shifts, even in the presence of an excess of undegraded polyene, overcoming limitations previously reported with refractive index detectors. Notably, this oxime-based derivatization methodology is used in enzymatic degradation experiments of synthetic polyisoprenes characterized by a cis: trans ratio with the rubber oxygenase LcpK30. It reveals substantial UV absorption in derivatized enzymatic degradation products of polyisoprene with molecular weights exceeding 1000g mol-1 - an unprecedented revelation for this enzyme's activity on such synthetic polyisoprenes. This innovative approach holds promise as a valuable tool for advancing research into the degradation of synthetic polyisoprenes and polybutadiene, particularly under conditions of low organocatalytic or enzymatic degradation activity. With its broad applicability and capacity to reveal previously hidden degradation processes, it represents a noteworthy contribution to sustainable polymer chemistry.

Influence of Thiol-Functionalized Polysilsesquioxane/Phosphorus Flame-Retardant Blends on the Flammability and Thermal, Mechanical, and Volatile Organic Compound (VOC) Emission Properties of Epoxy Resins.

In this study, thiol-functionalized ladder-like polysesquioxanes end-capped with methyl and phenyl groups were synthesized via a simple sol-gel method and characterized through gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and thermogravimetric analysis (TGA). Additionally, epoxy blends of different formulations were prepared. Their structural, flame-retardant, thermal, and mechanical properties, as well as volatile organic compound (VOC) emissions, were determined using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), TGA, scanning electron microscopy (SEM), limiting oxygen index (LOI), cone calorimetry, and a VOC analyzer. Compared to epoxy blends with flame retardants containing elemental phosphorus alone, those with flame retardants containing elemental phosphorus combined with silicon and sulfur exhibited superior thermal, flame-retardant, and mechanical properties with low VOC emissions. SEM of the residual char revealed a dense and continuous morphology without holes or cracks. In particular, LOI values for the combustion of methyl and phenyl end-capped polysilsesquioxane mixtures were 32.3 and 33.7, respectively, compared to 28.4% of the LOI value for the blends containing only phosphorus compounds. The silicon-sulfur-phosphorus-containing blends displayed reduced flammability concerning the blends using a flame retardant containing only phosphorus. This reflects the cooperative effects of various flame-retardant moieties.

Structural Characterization and Immunoenhancing Properties of Polysaccharide CPTM-P1 from Taxus media.

Polysaccharides extracted from Taxus media hrough an aqueous method were further refined by removing proteins via the Sevag technique and purified by dialysis. The separation of these polysaccharides was accomplished using a DEAE-cellulose chromatog-raphy column, yielding two distinct fractions, named CPTM-P1 and CPTM-P2. Notably, CPTM-P1 emerged as the primary polysaccharide component within Taxus media. Consequently, a comprehensive analysis focusing exclusively on CPTM-P1 was undertaken. The molecular weight of CPTM-P1 was established through gel permeation chromatography (GPC), and its monosaccharide composition was deciphered using HPLC-MS. The structure was further elucidated through nuclear magnetic resonance (NMR) spectroscopy. The molecular weight of CPTM-P1 was determined to be 968.7 kDa. The monosaccharide composition consisted of galactose (Gal), arabinose (Ara), galacturonic acid (Gal-UA), glucose (Glc), rhamnose (Rha), xylose (Xyl), mannose (Man), fucose (Fuc), glucuronic acid (Glc-UA), and ribose (Rib). The proportional distribution of these components was 30.53%, 22.00%, 5.63%, 11.67%, 11.93%, 1.69%, 8.50%, 1.23%, 5.63%, and 1.17%, respectively. This confirmed CPTM-P1 as an acidic heteropolysaccharide with a glycuronic acid backbone. Moreover, CPTM-P1 showed immunoenhancing properties, effectively augmenting the secretion of nitric oxide and cytokines (TNF-α, IL-1β, and IL-6). Additionally, it significantly enhances the phagocytic capacity of RAW264.7 cells. These findings underscore the potential application of these polysaccharides in functional foods and pharmaceuticals, providing a solid scientific basis for further exploration and utilization of Taxus media polysaccharides.

Boosting the Biodegradation and Bioactivity of PBS‐DLS Copolymers via Incorporation of PEG

AbstractBiodegradable polymers play a crucial role in the development of materials for biomedical applications. This study investigates the enzymatic biodegradation, bioactivity, and cytotoxicity of poly(butylene succinate‐dilinoleic succinate) (PBS‐DLS) copolymers modified with poly(ethylene glycol) (PEG). Two copolymer variations with different segmental compositions (70 wt.% and 60 wt.% of hard segments) are synthesized. After modifying the copolymers with PEG, the presence of a lipase catalyst accelerated degradation after 20 days, evidenced by reduced residual content. Gel permeation chromatography analysis showed up to 40% decrease in molecular weight, while gravimetric analysis indicated a mass loss of up to 10%. Morphological examination revealed that the enzymatic breakdown, facilitated by hydrolase activity (boosted by the presence of PEG), resulted in surface erosion, holes, and changes in spherulitic morphology. Bioactivity studies demonstrated the formation of biomimetic calcium/phosphate (Ca/P) crystals. Copolymers with higher crystallinity (70 wt.% hard segments) favored tricalcium phosphate‐like crystal formation, while those with lower crystallinity (60 wt.% hard segments) are more susceptible to hydroxyapatite precipitation. In vitro cytotoxicity tests exhibited excellent cell viability and attachment for all copolymers. The ability to control degradation through PEG modification, along with their bioactivity and cell compatibility, positions them as promising candidates for diverse biomedical applications.

Preparation and Characterization of Guaiacol-Furfuramine Benzoxazine and Its Modification of Bisphenol A-Aniline Oxazine Resin.

A new type of benzoxazine resin has been synthesized using a natural phenol source, guaiacol, and a biomass amines, furfuramine. The synthesis conditions were optimized; when the reaction molar ratio of guaiacol, furfuramine, and polyformaldehyde was 1:1:4, the highest synthetic yield was reached. The product was characterized via testing using transform infrared spectroscopy (FT-IR), gel permeation chromatography (GPC), mass spectrogram (MS), and nuclear magnetic resonance (1H-NMR) to confirm its molecular structure. A differential scanning calorimetry (DSC) test was conducted to analyze the thermodynamic properties of the product, and the results showed that the product decomposed and evaporated at around 180 °C, making it impossible to achieve self-curing. However, the prepared guaiacol-furfuramine benzoxazine resin (GFZ) can be blended and cured in certain proportions with bisphenol A-aniline oxazine resin (BAZ) as a GFZ/BAZ binary system (5:95, 10:90, 20:80, and 40:60). Dynamic mechanical analysis (DMA) test results showed that when the content of GFZ was 10%, the storage modulus of the copolymer resin was greatly improved. After conducting impact strength tests on the copolymer resin, it was found that the toughness of the copolymer resin had improved, and the maximum impact strength had increased by nearly three times. This indicates that the flexible long-chain structure in GFZ can effectively improve the toughness of the cured copolymer system. The reaction of active groups on benzoxazine molecules with other resins can not only improve the mechanical properties of their cured products, but also has important significance in the preparation of low-cost and environmentally friendly sustainable composite materials with excellent comprehensive performance.

Insoluble Network Skeleton and Soluble Components of Nylon 6,6-Sputtered Nanoparticles: Insights from Liquid-State and Solid-State NMR Analysis.

In this study, we performed a detailed analysis of -sputtered-nylon 6,6 plasma polymer nanoparticles (NPs). Following a previous study using standard techniques such as X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy, we employed unconventional approaches, specifically solid- and liquid-state high-resolution nuclear magnetic resonance (NMR) spectroscopy, supplemented by gel permeation chromatography (GPC). Scanning electron microscopy (SEM) was also used to examine changes in the size of the NPs after contact with solvents and after heating. Our investigations revealed suspected strong binding and networking of the NPs, and a soluble monomer/oligomer phase was identified and characterised. This fraction is removable using solvent or heat treatment without significantly affecting the size of the NPs. Additionally, we suggested the chemical structure of this soluble phase. Our findings support the proposed rubber-like character of plasma polymer NPs and explain their strong tendency to reflect from substrates upon high-speed impact.

Laccase-Mediated Oxidation of Phenolic Compounds from Wine Lees Extract towards the Synthesis of Polymers with Potential Applications in Food Packaging.

Laccase from Trametes versicolor was applied to produce phenolic polymeric compounds with enhanced properties, using a wine lees extract as the phenolic source. The influence of the incubation time on the progress of the enzymatic oxidation and the yield of the formed polymers was examined. The polymerization process and the properties of the polymeric products were evaluated with a variety of techniques, such as high-pressure liquid chromatography (HPLC) and gel permeation chromatography (GPC), Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The enzymatic polymerization reaction resulted in an 82% reduction in the free phenolic compounds of the extract. The polymeric product recovery (up to 25.7%) and the molecular weight of the polymer depended on the incubation time of the reaction. The produced phenolic polymers exhibited high antioxidant activity, depending on the enzymatic oxidation reaction time, with the phenolic polymer formed after one hour of enzymatic reaction exhibiting the highest antioxidant activity (133.75 and 164.77 μg TE mg-1 polymer) towards the ABTS and DPPH free radicals, respectively. The higher thermal stability of the polymeric products compared to the wine lees phenolic extract was confirmed with TGA and DSC analyses. Finally, the formed phenolic polymeric products were incorporated into chitosan films, providing them with increased antioxidant activity without affecting the films' cohesion.

Revealing the structural changes of lignin in Chinese quince (Chaenomeles sinensis) fruit as it matures

Chinese quince fruits (Chaenomeles sinensis) contain substantial amounts of lignin; however, the exact structure of lignin remains to be investigated. In this study, milled wood lignins (Milled wood lignin (MWL)-1, MWL-2, MWL-3, MWL-4, MWL-5, and MWL-6) were extracted from fruits harvested once a month from May to October 2019 to investigate their structural evolution during fruit growth. The samples were characterized via High-performance anion exchange chromatography (HPAEC), Fourier transform–infrared spectroscopy (FT-IR), gel permeation chromatography (GPC), thermogravimetric (TGA), pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) and NMR (2D-heteronuclear single quantum coherence (HSQC) and 31P). The MWL samples in all fruit growth stages were GS-type lignin and lignin core undergoing minimal alterations during fruit development. The predominant linkage in the lignin structure was β-O-4′, followed by β-β' and β-5′. Galactose and glucose were the main monosaccharides associated with MWL. In MWL-6, the lignin exhibited the highest homogeneity and thermal stability. As the fruit matured, a gradual increase in the β-O-4′ proportion and the ratio of S/G was observed. The results provide comprehensive characterization of the cell wall lignin of quince fruit as it matures. This study could inspire innovative applications of quince fruit lignin and provide the optimal harvest time for lignin utilization.

Synthesis and Evaluation of Boronated 4‐Arm Polyethylene Glycol for Application in Transmucosal Drug Delivery

AbstractPolyethylene glycol (PEG) exhibits poor residence on mucosal membranes in the presence of biological fluid, and the influence of PEG boronation on its properties has never been investigated. This project aimed to synthesise boronated 4‐arm PEG and evaluate their pH stability, thermal properties and mucoadhesiveness for potential transmucosal applications. Two types of boronated 4‐armed PEG (B4PEG1 & B4PEG2) and a boronated linear PEG (BLPEG) were synthesized. The degree of boronation, mucoadhesiveness, thermal and pH stability of the polymers were assessed using 1H NMR spectroscopy, viscometry, thermogravimetric analysis and UV–visible spectroscopy, respectively. Gel Permeation Chromatography was employed to confirm PEG boronation. The respective degrees of boronation for B4PEG1 and B4PEG2 were 32.8 % and 46.2 %. The molecular architecture and degree of PEG boronation had a remarkable influence on mucoadhesiveness, pH, and thermal stability. B4PEG2, with a branched architecture and the greatest degree of boronation, exhibited superior mucoadhesiveness and colloidal stability at pH 4 to 8, relative to B4PEG1 and BLPEG. Boronation improved the thermal stability of 4‐arm PEG. This study is the first to demonstrate that PEG boronation could enhance the pH‐sensitivity, thermal stability and mucoadhesiveness of 4‐arm PEG. Boronated 4‐arm PEGs could serve as mucoadhesive polymeric excipients for transmucosal drug delivery.

The Structural, Thermal and Morphological Characterization of Polylactic Acid/Β-Tricalcium Phosphate (PLA/Β-TCP) Composites upon Immersion in SBF: A Comprehensive Analysis.

Biocomposite films based on PLA reinforced with different β-TCP contents (10%, 20%, and 25%wt.) were fabricated via solvent casting and immersed in SBF for 7, 14, and 21 days. The bioactivity, morphological, and thermal behavior of composites with immersion were studied using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) microanalysis, weight loss (WL), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and gel permeation chromatography (GPC). This broad analysis leads to a deeper understanding of the evolution of the polymer-filler interaction with the degradation of the biocomposites. The results showed that β-TCP gradually evolved into carbonated hydroxyapatite as the immersion time increased. This evolution affected the interaction of β-TCP with PLA. PLA and β-TCP interactions differed from PLA and carbonated hydroxyapatite interactions. It was observed that β-TCP inhibited PLA hydrolysis but accelerated the thermal degradation of the polymer. β-TCP retarded the cold crystallization of PLA and hindered its crystallinity. However, after immersion in SBF, particles accelerated the cold crystallization of PLA. Therefore, considering the evolution of β-TCP with immersion in SBF is crucial for an accurate analysis of the biocomposites' degradation. These findings enhance the comprehension of the degradation mechanism in PLA/β-TCP, which is valuable for predicting the degradation performance of PLA/β-TCP in medical applications.