Gel Permeation Chromatography Research Articles

Chromatographic approaches to food quality control by chemical compo-sition

The article provides an overview of chromatographic methods, which, when used comprehensively, ensure food quality control and safety. It considers gas chromatography methods that allow analysing volatile components in products using a flame ionization detector, an electron capture detector, and mass-selective detectors (GC-FID, GC-ECD, GC-MS, and GC-MS/MS). The article provides a list of analytes that can be detected by high performance liquid chromatography in combination with refractometric, spectrometric, and mass selective detectors (HPLC-RMD, HPLC-UV, HPLC-SPD, HPLC-MS, and HPLC-MS/MS). The study showed how ion chromatography and capillary electrophoresis with electrochemical detectors (IC-ECD, CE-ECD) can be used to detect ionogenic compounds. It highlighted the importance of thin layer chromatography (TLC) in combination with optical digital colour recording devices in the qualitative and quantitative analysis of contaminants in food products. Since it has been established that micro- and nanoplastics have a negative impact on human health, it is very important to detect these particles in food products. This task can be solved by using gel permeation chromatography (GPC) and hydrodynamic chromatography (HDC), as well as the method of field-flaw fractionation (FFF). It was shown that the GC-MS method is now becoming a priority instrumental method used in accredited analytical laboratories to identify impurities of contaminants in agricultural products. The pyrolytic GC-MS method is promising in this regard. The pyrolytic cell does not require the transfer of a solid sample into a solution for its analysis. The paper considers extraction and sorption methods for the preparation of samples for chromatographic analysis. A variety of liquid-liquid extraction (LLE) and solid-phase extraction (SPE.) methods are most commonly used. Recently, the QuEChERS method has been developed and widely implemented. The overview is primarily based on the papers dedicated to chromatography and related separation methods published by researchers belonging to Voronezh scientific schools.

Basic characterization of three kinds of bio-asphalt and research on the low-temperature performance of bio-asphalt mixtures

Bio-oil is a by-product of waste biomass treatment using high-pressure liquefaction, bio-enzymatic, or high-temperature thermal cracking techniques, and can alleviate the shortage of petroleum asphalt resources. This study investigated the production of bio-oil from selected raw materials, including corn stover, castor oil from castor beans, and epoxy vegetable oil from soybeans for the preparation of bio-asphalt. The properties and mechanisms of modification of the three modified bio-asphalts were explored by assessment of basic physical properties, gel permeation chromatography (GPC), temperature scanning (DSR), and thermogravimetric analysis, as well as Semi-Circular Bending (SCB), low-temperature bending, and fatigue tests. Bio-oil was found to improve the low-temperature cracking resistance of the asphalt mixtures, with the improvement further enhanced by changing the blending amount. The bio-oil was observed to negatively affect the low-temperature fatigue performance of the mixes, and the decrease in the n-value indicated that the bio-oil could make the asphalt mixtures less stress-sensitive under repeated loading, with improved anti-fatigue performance of bio-asphalt mixtures observed when the stress ratio was 0.5. Finally, the low-temperature cracking performance index of the corn stover bio-asphalt mixtures was correlated with the gray entropy. The use of the SCB fracture index was found to be more appropriate when using the semicircular bending test to characterize the low-temperature cracking performance of bio-asphalt mixtures.

Facile synthesis of iminated lignin for enhanced free radical and lead ion scavenging capabilities

Kraft lignin (KL) holds significant potential as a renewable resource for the development of innovative materials that are currently not fully utilized. In this study, a novel iminated lignin (IL) was synthesized by grafting primary amine lignin (N−KL) onto salicylaldehyde. The effects of the dosage and reaction temperature on the nitrogen content of N-KL were evaluated. The maximum nitrogen content in N-KL reached to 3.32 %. Characterization by spectroscopy techniques (FT-IR, XPS, and NMR), elemental analysis, and gel permeation chromatography confirmed the imination of lignin. Additionally, the antioxidant activity of the lignin samples was investigated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability. Moreover, the DPPH radical scavenging capacity of IL-6 (IC50 = 38.6 ± 3.9 μg/mL) was close to that of commercial antioxidant butylated hydroxytoluene (BHT) (IC50 = 37.7 ± 4.5 μg/mL). Furthermore, the adsorption equilibrium results indicated that IL-6 had a maximum uptake of 115.6 mg/g Pb2+, which was 3.2-fold higher than that of KL. Kinetic adsorption experiments suggested that IL-6 adsorption follows a pseudo-second-order model. Therefore, the synthesized iminated lignin is a promising candidate for the development of environmentally friendly materials with applications as an antioxidant and lead-ion adsorbent.

Inherited Structure Properties of Larch Arabinogalactan Affected via the TEMPO/NaBr/NaOCl Oxidative System.

Arabinogalactan (AG), extracted from larch wood, is a β-1,3-galactan backbone and β-1,6-galactan side chains with attached α-1-arabinofuranosyl and β-1-arabinopyranosyl residues. Although the structural characteristics of arabinogalactan II type have already been studied, its functionalization using 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) oxidation remains a promising avenue. In this study, the oxidation of AG, a neutral polysaccharide, was carried out using the TEMPO/NaBr/NaOCl system, resulting in polyuronides with improved functional properties. The oxidation of AG was controlled by analyzing portions of the reaction mixture using spectrophotometric and titration methods. To determine the effect of the TEMPO/NaBr/NaOCl system, air-dried samples of native and oxidized AG were studied by Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy, as well as by gel permeation chromatography. Compounds that model free (1,1-diphenyl-2-picrylhydrazyl (DPPH)) and hydroxyl radicals (iron(II) sulfate, hydrogen peroxide, and salicylic acid) were used to study the antioxidant properties. It was found that, in oxidized forms of AG, the content of carboxyl groups increases by 0.61 mmol compared to native AG. The transformation of oxidized AG into the H+ form using a strong acid cation exchanger leads to an increase in the number of active carboxyl groups to 0.76 mmol. Using FTIR spectroscopy, characteristic absorption bands (1742, 1639, and 1403 cm-1) were established, indicating the occurrence of oxidative processes with a subsequent reduction in the carboxyl group. The functionality of AG was also confirmed by gel permeation chromatography (GPC), which is reflected in an increase in molecular weights (up to 15,700 g/mol). A study of the antioxidant properties of the oxidized and protonated forms of AG show that the obtained antioxidant activity (AOA) values are generally characteristic of polyuronic acids. Therefore, the TEMPO oxidation of AG and other neutral polysaccharides can be considered a promising approach for obtaining compounds with the necessary controlled characteristics.

Interaction of composite fume suppression and odor elimination agents with crumb rubber modified asphalt: Inhibition behavior of volatile organic compounds (VOCs) and inorganic fume

The production and construction of crumb rubber modified asphalt (RMA) at high temperatures can produce a large amount of toxic fume, which is detrimental to human health and environment. In this study, a series of composite fume suppression and odor elimination agents (CSEAs) with both physical adsorption and chemical capture functions were adopted to reduce the emissions of volatile organic compounds (VOCs) and hydrogen sulfide (H2S). The material composition, microstructure, and specific surface area of CSEA were analyzed by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and N2 adsorption-desorption isotherm (BET). The inhibitory effects of adding CSEA on toxic fume emissions from RMA at high temperatures were investigated through a combination of fume emission tests, H2S gas detection, gel permeation chromatography (GPC), and gas chromatography–mass spectrometry technology (GC–MS). The adsorption behavior of CSEA on H2S was analyzed through adsorption dynamics. Results showed that the physical and chemical properties of CSEA are stable while chemical adsorption dominates the CSEA's effect on H2S. ZnO and Ca(OH)2 exhibit good crystallization effects on the surface of the carrier by forming mesoporous structures mostly above 3.4 nm in size. The incorporation of CSEA significantly reduced the total emissions of RMA fume and the main components of VOCs in which the average inhibition rate of H2S can reach 44 % at an initial 30 mins.

Linking Chemical Structure to the Linear and Nonlinear Properties of Asphalt Binders

The study described in this paper aims to establish the relationship between the chemical composition and rheological properties of asphalt binders in both the linear viscoelastic (LVE) and nonlinear viscoelastic (NLVE) domains. Two asphalt binders with different penetration grades were subjected to four distinct aging treatments of varying severity, resulting in changes in their chemical fingerprints. Chemical characteristics of the asphalt binders were analyzed using thin-layer chromatography (TLC), Fourier Transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). Frequency sweep tests were conducted to evaluate the LVE behavior of the asphalt binders, while multiple stress creep recovery (MSCR) tests were employed to assess their NLVE properties. With regard to the LVE properties, rheological index ( R) and zero shear viscosity (ZSV) derived from the Christensen-Anderson-Marasteanu (CAM) model exhibited high correlations with FTIR and molecular weight distribution (MWD) parameters. Additionally, the polydispersity index (PDI) displayed a stronger correlation with LVE-based parameters. Findings from the MSCR tests revealed that the sensitivity of the percentage recovery ( %R) to chemical composition, as opposed to nonrecoverable creep compliance ( Jnr), can be largely attributed to the degree of nonlinearity. Furthermore, it was observed that lower molecular weight molecules exert a greater influence on %R in the nonlinear domain. Finally, it was found that Jnrslope is a more reliable parameter than Jnrdiff for assessing the effects of chemical makeup on stress and temperature sensitivity.

Non‐isocyanate polyurethane‐acrylate as UV‐ and thermo‐responsive plasticizer for thermoplastic elastomer

AbstractA UV‐ and thermo‐responsive polyurethane‐acrylate prepolymer was synthesized from palm olein (POo) via a non‐isocyanate route. The process included epoxidation of POo, carbonation of epoxidized palm olein (EPOo) into polycyclic carbonate in a solvent‐free and mild condition (100°C, 1 atm), followed by reacting with ethylene diamine and acrylic acid. The chemical structure of the non‐isocyanate polyurethane‐acrylate (NIPUA) prepolymer was elucidated by 1H and 13C nuclear magnetic resonance (NMR) and Fourier transform‐infrared spectroscopy (FTIR), while weight average molecular weight of NIPUA was determined by gel permeation chromatography (GPC). The NIPUA (0–20 wt%) was incorporated with thermoplastic elastomer (TPE) as a plasticizer and cured under UV light and thermal stimulations. The cured NIPUA/TPE films were characterized by FTIR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile strength test. Under UV and thermal stimulations, the NIPUA/TPE demonstrated enhanced tensile properties (elongation at break >1280%, Young's modulus ~25 MPa), thermal properties (lower Tg), lower water contact angle, and shortened curing time as compared with the blank TPE. The 20 wt% NIPUA/TPE films exhibited susceptibility to enzymatic biodegradation and noncytotoxic to HEK 293 cells in vitro, demonstrated it's potential as a UV‐ and thermo‐responsive plasticizer for TPE in manufacturing of medical devices.

(Mechano)chemical modification of polyvinyl chloride with azole-based drugs

Polyvinyl chloride (PVC) plays an important role in industry; however, due to its uncontrolled accumulation in the environment, the methods for its utilization are of high demand. Herein we wish to report an approach for the utilization of PVC via its use as a carrier for some azole-based drugs, such as 2-mercaptobenzothiazole (multi-activity drug), 4-oxo-1,4-dihydropyrazolo[5,1-c]-1,2,4-triazine-3,8-dicarboxylic acid diethyl ester (antidiabetic drug) and 5-methyl-6-nitro-7-oxo-1,2,4-triazolo[1,5-a]pyrimidinide (antiviral drug). The abovementioned approach involves the reaction between PVC and potassium or sodium salts of these azole-based drugs either in solution or under ball-milling conditions. The as-obtained PVCs modified with azole-based drugs were isolated for the first time and characterized by means of 1H NMR-spectroscopy as well as gel-permeation chromatography (GPC).

Characterization of a polysaccharide from Amauroderma rugosum and its proangiogenic activities in vitro and in vivo

Amauroderma rugosum (AR), also known as “Blood Lingzhi” in Chinese, is a basidiomycete belonging to the Ganodermataceae family. Four polysaccharide fractions were systematically isolated and purified from AR. Subsequently, their compositions were examined and analyzed via high-performance gel permeation chromatography (HPGPC), analysis of the monosaccharide composition, Fourier-transform infrared spectroscopy (FT-IR), and 1H nuclear magnetic resonance (NMR). The zebrafish model was then used to screen for proangiogenic activities of polysaccharides by inducing vascular insufficiency with VEGF receptor tyrosine kinase inhibitor II (VRI). The third fraction of AR polysaccharides (PAR-3) demonstrated the most pronounced proangiogenic effects, effectively ameliorating VRI-induced intersegmental vessel deficiency in zebrafish. Concurrently, the mRNA expression levels of vascular endothelial growth factor (VEGF)-A and VEGF receptors were upregulated by PAR-3. Moreover, the proliferation, migration, invasion, and tube formation of human umbilical vein endothelial cells (HUVECs) were also stimulated by PAR-3, consistently demonstrating that PAR-3 possesses favorable proangiogenic properties. The activation of the Akt, ERK1/2, p38 MAPK, and FAK was most likely the underlying mechanism. In conclusion, this study establishes that PAR-3 isolated from Amauroderma rugosum exhibits potential as a bioresource for promoting angiogenesis.

Preparation and photocuring performance of itaconic acid-derived hyperbranched macromers with internal and terminal C[dbnd]C bonds catalyzed by tetramethylguanidine

A series of hyperbranched polymers derived from biomass itaconic acid was prepared via aliphatic nucleophilic substitution polycondensation reaction under mild conditions by using bis(2-bromoethyl) itaconate and trimeric acid as A2 and B3 monomers, respectively, and tetramethylguanidine as catalyst. On this basis, the hyperbranched macromers that contained C = C double bonds in the internal skeleton and the periphery were obtained by further adding A1 monomer (2-bromoethyl acrylate) directly into the reaction system. The successful synthesis of these macromers were confirmed via proton nuclear magnetic resonance, Fourier transform infrared and gel permeation chromatography. The results of photo-differential scanning calorimetry and rheological experiments showed that these macromers exerted a positive effect on the ultraviolet (UV) curing of commercial resin. The properties of cured splines and coatings, such as mechanical properties, pencil hardness, and thermal stability, were considerably improved with the addition of hyperbranched macromers. They were significantly better than those of linear macromers and macromers that contained polymerizable groups only in the inner framework or their terminal units. The results show that both the inner and terminal C = C double bonds of hyperbranched macromers can participate in UV cross-linking. Thus, such macromers may be used as potential additives for high-performance UV curable coatings.

Preparation and luminescence properties of polypyrrole-thiophene derivatives

Four kinds of polypyrrole-thiophene derivatives (PPy-Th) are prepared via solution polycondensation using pyrrole, 3-acylpyrrole, and 2-thenaldehyde as monomers. The structure, molecular weight, micromorphology, thermal degradation, ultraviolet-visible absorption, and luminescence performance of the derivatives are investigated by fourier transform infrared (FTIR), hydrogen nuclear magnetic resonance (1HNMR) spectroscopy, gel permeation chromatography (GPC), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), ultraviolet-visible (UV-Vis), and fluorescence spectra. FTIR and 1HNMR confirm that the derivatives have been successfully fabricated, and GPC indicates that the derivatives belong to oligomers with narrow molecular weight distribution. For acyl-substituted derivatives, the microstructures are mainly lamellar accumulation. Furthermore, under ultraviolet excitation, the derivatives can produce blue or green light emission, corresponding to the transitions of large π electrons in the conjugated structure of the molecular chains. Especially, the maximum emission wavelengths and Stokes shifts of the acyl-substituted derivatives are markedly larger than that of the non-acyl-substituted derivatives. The fluorescence quantum yield and band gap of the PVT are 4.46% and 2.01 eV, respectively. The fabricated PPy-Th can be used as luminescent materials in the development and application of polymer light-emitting diodes.

Extraction of Pithecellobium clypearia Benth polysaccharides by dual-frequency ultrasound-assisted extraction: Structural characterization, antioxidant, hypoglycemic and anti-hyperlipidemic activities

In this research, the extraction process of polysaccharides from Pithecellobium clypearia Benth (PCBPs) was optimized using dual-frequency ultrasound-assisted extraction (DUAE). The biological activities of PCBPs were investigated by in vitro antioxidant, hypoglycemic, and anti-hyperlipidemic assay. High-performance anion-exchange chromatography, high-performance gel permeation chromatography, SEM, UV–Vis spectroscopy, and FT-IR spectra were used to analyze the monosaccharide composition, molecular weight, microscopic morphology, and characteristic structure of PCBPs. The results showed that the maximum extraction rate of PCBPs was 9.90 ± 0.16% when the ultrasonic time was 8 min, the liquid-to-material ratio was 32 mL/g, and the ultrasonic power was 510 W. The PCBPs also possessed excellent in vitro antioxidant, hypoglycemic, and anti-hyperlipidemic activities. In addition, the average molecular weight of PCBPs was 15.07 kDa. PCBPs consisted of rhamnose, arabinose, galactose, glucose, xylose, mannose, and glucuronic acid, with the molar ratios of 11.07%, 18.54%, 48.17%, 10.44%, 4.62%, 4.96%, and 2.20%, respectively. Moreover, the results of SEM showed that PCBPs mainly showed a fine spherical mesh structure. The above studies provided a valuable theoretical basis for the subsequent in-depth study of PCBPs.

Synthesis and Characterization of Graft Copolymers with Poly(ε-caprolactone) Side Chain Using Hydroxylated Poly(β-myrcene-co-α-methyl styrene).

Graft copolymers have unique application scenarios in the field of high-performance thermoplastic elastomers, resins and rubbers. β-myrcene (My) is a biomass monomer derived from renewable plant resources, and its homopolymer has a low glass transition temperature and high elasticity. In this work, a series of tapered copolymers P(My-co-AMS)k (k = 1, 2, 3) were first synthesized in cyclohexane by one-pot anionic polymerization of My and α-methyl styrene (AMS) using sec-BuLi as the initiator. PAMS chain would fracture when heated at high temperature and could endow the copolymer with thermal degradation property. The effect of the incorporation of AMS unit on the thermal stability and glass transition temperature of polymyrcene main chain was studied. Subsequently, the double bonds in the linear copolymers were partially epoxidized and hydroxylated into hydroxyl groups to obtain hydroxylated copolymer, which was finally used to initiate the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) to synthesize the graft copolymer with PCL as the side chain. All these copolymers before and after modifications were characterized by proton nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), thermogravimetry analysis (TGA), and differential scanning calorimeter (DSC).

Unveiling the ability of protic and aprotic ionic liquids to dissolve and modify Kraft lignin

Lignin, a renewable macromolecule abundant in lignocellulosic biomass, holds significant promise as a renewable source for producing biofuels, biomaterials, and fine chemicals, offering a potential avenue to reduce dependence on petroleum-derived products. However, the lignin complex structure poses challenges for its effective utilization, often requiring some special treatments. In recent decades, ionic liquids (ILs) have been pointed out as promising candidates for lignin processing due to their appealing properties, which include low vapor pressure/flammability, high chemical and thermal stability, and efficacy as lignin solvents. ILs may be categorized as protic (PILs) or aprotic ionic liquids (AILs), and these two classes offer distinct advantages. PILs are readily synthesized by mixing an acid and a base in stoichiometric proportions, forming a mixture containing neutral species that remain in equilibrium with cations and anions. In contrast, AILs present cations with enduring positive charges and are not in equilibrium with their precursors as the PILs, though AILs are frequently more expensive and challenging to produce. Within the biorefinery context, the ability to dissolve Kraft lignin is pivotal for developing new strategies and technologies. Moreover, chemical transformations may occur during lignin dissolution in IL solutions. In this study, the solubility of Kraft lignin was evaluated in four neat imidazolium-based AILs, five neat pyrrolidinium-based PILs, and in aqueous solutions of these ILs, at 313.2 K. The highest solubility value ((77.71 ± 1.03) wt%) was observed for pyrrolidinium octanoate (PIL), while 1-butyl-3-methylimidazolium methyl sulfate exhibited the highest solubility ((73.93 ± 1.27) wt%) among the studied AILs. Whenever possible, the solubilities measured in the present work were critically compared with data available in the literature. Finally, lignin recovered from the IL solutions was analyzed by Gel Permeation Chromatography (GPC), Fourier Transform Infrared (FTIR), and Nuclear Magnetic Resonance (NMR) spectroscopy to assess the solvent ability to induce structural modifications in this macromolecule. The analysis revealed that ILs effectively cleaved β-O-4 linkages in lignin molecules, and concurrent condensation reactions might increase the precipitated lignin molecular weight.

Synthesis of Room Temperature Curable Polymer Binder Mixed with Polymethyl Methacrylate and Urethane Acrylate for High-Strength and Improved Transparency.

Urethane acrylate (UA) was synthesized from various di-polyols, such as poly(tetrahydrofuran) (PTMG, Mn = 1000), poly(ethylene glycol) (PEG, Mn = 1000), and poly(propylene glycol) (PPG, Mn = 1000), for use as a polymer binder for paint. Polymethyl methacrylate (PMMA) and UA were blended to form an acrylic resin with high transmittance and stress-strain curve. When PMMA was blended with UA, a network structure was formed due to physical entanglement between the two polymers, increasing the mechanical properties. UA was synthesized by forming a prepolymer using di-polyol and hexamethylene diisocyanate, which were chain structure monomers, and capping them with 2-hydroxyethyl methacrylate to provide an acryl group. Fourier transform infrared spectroscopy was used to observe the changes in functional groups, and gel permeation chromatography was used to confirm that the three series showed similar molecular weight and PDI values. The yellowing phenomenon that appears mainly in the curing reaction of the polymer binder was solved, and the mechanical properties according to the effects of the polyol used in the main chain were compared. The content of the blended UA was quantified using ultravioletvisible spectroscopy at a wavelength of 370 nm based on 5, 10, 15, and 20 wt%, and the shear strength and tensile strength were evaluated using specimens in a suitable mode. The ratio for producing the polymer binder was optimized. The mechanical properties of the polymer binder with 5-10 wt% UA were improved in all series.

Antioxidant activities of sea buckthorn polysaccharides and their potential application in cosmetic industry

BackgroundMany natural polysaccharides have been reported to protect against skin aging through antioxidant pathways, but sea buckthorn polysaccharides have been less well studied in terms of antioxidant activity, and the related studies are not well developed. ObjectiveBy examining the chemical structure of sea buckthorn polysaccharides, this research aimed to offer a scientific foundation for their use in cosmetics and explore the in vitro antioxidant potential of these polysaccharides. Materialsand Methods: We made SP (sea buckthorn crude polysaccharide) using both hot water extraction and ultrasonic extraction. Then, we used the anion exchange method to separate and purify it to get three different polysaccharides: SPA (polysaccharide eluted from deionized water), which is a neutral polysaccharide, and SPB (polysaccharides eluted from 0.1 M NaCl) and SPC (polysaccharide eluted from 0.2 M NaCl), which are acidic polysaccharides. The characteristics of the four polysaccharides (SP, SPA, SPB and SPC) were determined using high-performance gel permeation chromatography (HPGPC), high-performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and x-ray diffractometry (XRD). In vitro antioxidant assays were used to test their antioxidant activities. ResultsThe in vitro antioxidant assay showed that the four sea buckthorn polysaccharides (SP, SPA, SPB, and SPC) were good at getting rid of superoxide anion and DPPH radicals, especially ABTS radicals. They were also better at getting rid of free radicals than VC at low concentrations, and they were also good at reducing other molecules. ConclusionThese results showed that sea buckthorn polysaccharide has certain antioxidant activity; therefore, sea buckthorn polysaccharide has a strong potential to be applied in antioxidant and anti-aging functional cosmetics.

Effect of Oligoricinoleic Acid on Degradation of Polylactic Acid

ABSTRACT The objective of this research is to explore the impact of oligoricinoleic acid (ORA) on the degradation of polylactic acid (PLA). ORA was synthesized from ricinoleic acid using tin (II) 2-ethylhexanoate as a catalyst. The chemical structures of the obtained ORA were confirmed by Fourier-transform infrared spectrometer (FT-IR) and proton nuclear magnetic resonance spectroscopy (1H-NMR). PLA/ORA films were prepared through the casting method by varying ORA concentrations as 0.1%wt, 0.3%wt, 0.5%wt, 1.0 wt%, and 3.0%wt. Degradation of the films via hydrolysis was studied by soaking the films in deionized water and stirring at 120 rpm in an incubator at 37°C. Alterations in the structure and properties of the films were investigated after soaking for 7, 14, 21, and 28 days using ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectrometer (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), and universal testing machine (UTM). Gel permeation chromatography (GPC) was performed to confirm the decrease in molecular weight (MW). The presence of 3%wt ORA could promote both ductility and degradation of PLA films. ORA further enhances thermal stability, indicating potential for prevention of thermal degradation during melt processing.

Structural characteristics and antioxidant activities of a novel polysaccharide from Euphorbia himalayensis root

Euphorbia himalayensis Boiss. is an alpine member of the Euphorbiaceae family. Its dried roots have been used to treat digestive problems and chest congestion in traditional Tibetan and Mongolian medicine. Despite thousands of years of use in medicine, the bioactive compounds of the root remain unknown. Herein, we isolated a novel aqueous-soluble polysaccharide (EHP2) from the E. himalayensis root and determined its structural characteristics via high-performance gel permeation chromatography, Fourier-transform infrared spectroscopy, gas chromatography–mass spectrometry, and nuclear magnetic resonance spectrometry. The homogeneous molecular weight of EHP2 was 23.6 kDa with narrow polydisperity (Mw/Mn = 1.4), and EHP2 mainly comprised of glucose (86.4%), galactose (11.9%) and mannose (1.7%). The major backbone of EHP2 was →4)-α-D-GalAp-(1 → 4)-α-D-Glcp-(1 → and the branch chain was α-D-Glcp-(1→. The antioxidant activity of the EHP2 was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide anion radical scavenging assays, and antioxidant enzyme activity (SOD, GSH and MDA) was determined in human umbilical vein endothelial cells (HUVECs). The EHP2 demonstrated lower potential scavenging effects on DPPH and superoxide free radical scavenger than ascorbic acid, and in HUVECs, it led to increased SOD and GSH activities and decreased MDA levels. This study is the first to describe an E. himalayensis polysaccharide compound with potential antioxidant activity.

PH‐responsive polyurethane‐acrylate from palm olein and sunflower oil: Sustainable synthesis, enhanced lovastatin solubility, and potential drug carrier for targeted delivery

AbstractA pH responsive non‐isocyanate polyurethane‐acrylate (NIPUA) is synthesized through utilizing palm olein and sunflower oil as feedstock. The unsaturated acyl chains of both vegetable oils are converted into epoxy rings through epoxidation and subjected to carbonation with binary catalytic system under a solventless and mild condition to produce the cyclic carbonates. The cyclic carbonates were reacted with 1,4‐butanediamine and itaconic acid to produce the NIPUA. The intermediates and product were characterized by FTIR spectroscopy, NMR spectroscopy and gel permeation chromatography. The NIPUA was incorporated with poly(vinyl pyrrolidone) (PVP) to form a polymer carrier system loaded with a hydrophobic model drug, lovastatin (LOV). All NIPUA/PVP preformulations demonstrated pH responsiveness, with 1 to 2‐folds enhanced solubility at pH 7.4 compared to pH 2.0. NIPUA/PVP exhibited solubility enhancer effect by significantly enhanced solubility (2–4 times) compared to pure LOV, LOV‐loaded PVP, and Medostatin tablets at both pH levels. LOV‐loaded NIPUA/PVP exhibited lower enthalpy energy in DSC thermogram than LOV‐loaded PVP, indicating disruption of LOV's crystalline structure. In MTT assay, IC50 values were 30.76 μg mL−1 for pure LOV and 273.53 μg mL−1 for NIPUA/PVP, demonstrating the potential of NIPUA as an environmentally friendly, pH responsive drug carrier for controlled release of poorly water‐soluble drugs.

The Effect of Chain Tacticity on the Thermal Energy Parameters of Isotactic and Syndiotactic Polypropylene

The thermal energy properties in any material affect the substance’s capacity to store or transfer heat. This study investigated the effect of the polymeric chains’ tacticity on the thermal properties of polypropylene related directly to the thermal power, i.e., the heat capacity and thermal conductivity. The study selected different commercial polypropylene groups with two steric modes: isotactic and syndiotactic. The aim is to determine the parameters: isotacticity index, degree of crystallinity, glass-transition temperature, melting point, heat capacity, and thermal conductivity. The data were collected using gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC). The results showed that methyl groups randomly distributed within the homo-polypropylene changed the overall content of meso diads, i.e., less isotacticity index. The differences between isotactic and syndiotactic polypropylene groups were 20-40% the degree of the crystallinity, 5-10°C the glass-transition temperature, and 10-20°C the melting point. Using suitable mathematical models, these parameters can be related directly to specific heat capacity and thermal conductivity.