Gel Permeation Chromatography Research Articles

Experimental teaching reform of polymer molar mass determination using gel permeation chromatography coupled with light scattering

Gel permeation chromatography coupled with light scattering (GPC-LS) is among the most common methods for determining the molar masses of polymers. GPC-LS is widely used in polymer science research and has been adopted for many industrial applications owing to its high sensitivity, accuracy, and precision. The determination of polymer molar masses using GPC-LS is an important experimental component of the "Polymer Physics Experiments" course. However, the present GPC-LS experimental teaching content tends to be overly simplistic and lacking in depth. Herein, the original experimental content is expanded and multiple sets of experiments are redesigned: (1) Using commercial polystyrene as an experimental sample, the molar mass, molar mass distribution, radius of gyration, and other molecular structure parameters are determined using GPC-LS; (2) Using two polyacrylonitriles with similar molecular structure parameters, subtle differences in the molar mass distributions of the samples are explored using differential mass distribution curves; (3) By comparing the chromatograms of a series of polyethylene glycols with different molar masses, the effect of molar mass on chromatographic peaks is investigated; and (4) For three different polymers (polyacrylonitrile, poly(methyl methacrylate), and poly(β-cyclodextrin)), the polymer chain conformations are analyzed using conformation plots (i.e., radius of gyration vs. molar mass). In addition, the experimental teaching method is modified to convert passive learning into active learning, thereby improving the students' self-directed learning ability. This experimental teaching reform will help students obtain a more comprehensive understanding of GPC-LS principles and applications, stimulate their enthusiasm for learning, and improve the teaching quality of the experimental course.

Nanoplastic Contamination in Freshwater Biofilms Using Gel Permeation Chromatography and Plasmonic Nanogold Sensor Approaches

Nanoplastic Contamination in Freshwater Biofilms Using Gel Permeation Chromatography and Plasmonic Nanogold Sensor Approaches

The Motility of β-Cyclodextrins Threaded on the Polyrotaxane Based Triblock Polymer and Its Influences on Mechanical Properties

Polyrotaxane (PR) has garnered increasing attention due to its unique structure and exceptional performance. In this study, a polypseudorotaxane (PPR) initiator was prepared through the self-assembly of bromine-capped Pluronic F68 and β-cyclodextrins (β-CD) in water. Polyrotaxane-containing triblock copolymers (PR copolymers) were successfully synthesized by atom transfer radical polymerization (ATRP) of butyl methacrylate (BMA) using the PPR initiator in the presence of Cu(I)Br/PMDETA. The structure of the PR copolymers was thoroughly characterized using infrared spectroscopy (IR), proton nuclear magnetic resonance (1H NMR), and gel permeation chromatography (GPC). The mobility of β-CD in the PR copolymers was demonstrated through dielectric measurements. Mechanical tests, including tensile strength assessments, thermal mechanical analysis, and dynamic mechanical analysis, confirmed the excellent mechanical properties and good processability of the PR copolymer, attributed to the PBMA blocks. Furthermore, the mechanical properties were found to be modulated by the motility of the threaded β-CDs. Consequently, the superior mechanical properties and the high mobility of the threaded β-CDs suggest promising potential for the as-prepared PR polymer in various advanced applications.

Rebuttal to “Reply to road markings and microplastics…” by Järlskog et al

A rebuttal to “Reply to road markings and microplastics- a critical literature review” by Järlskog et al. is necessary because authors of the “Reply…” simultaneously agree with the major issues raised in the review and try to discredit it through presenting a different perspective; thus, clarifications of some key issues are due. In response to “binders derived from, e.g., modified rosin oils are still polymers” (“Reply…”, p. 3), to confirm our claim that such materials are not necessarily polymeric, we are providing a Gel Permeation Chromatography spectrum of an esterified rosin designed for the use as a binder in thermoplastic road markings. Hence, while the value of the “Reply…” is in highlighting differences in definitions, it is unfortunate that no new knowledge about microplastics originating from road markings was provided and none of the multiple research needs and uncertainties were clarified.

What are the mechanisms of functional monomers' effect on air entrainment of polycarboxylate superplasticizers in cement paste and mortar?

This study focuses on developing three kinds of polycarboxylate superplasticizers (PCEs), i.e., ether-type polycarboxylate superplasticizer (T-PCE), fluorine-type polycarboxylate superplasticizer (F-PCE), and phosphate-type polycarboxylate superplasticizer (P-PCE) synthesized respectively with three functional monomers, i.e., isopentenyl polyoxyethylene ether (TPEG3000), hexafluorobutyl methacrylate (HFBMA), and 2-hydroxyethyl methacrylate phosphate (HEMAP) for improved dispersion and low air entrainment in cementitious systems. The molecular structures of PCEs were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Gel Permeation Chromatography (GPC), and Proton Nuclear Magnetic Resonance (1H NMR). Further, the influence and mechanism of the functional monomers on the dispersion and air entrainment of PCEs in cement paste and mortar were investigated. Finally, the mechanisms of the functional monomers' effect on the air entrainment of PCEs in the cement paste and mortar were discussed. The results showed that T-PCE, F-PCE, and P-PCE were successfully synthesized, and P-PCE had the optimal effect on the fluidity (at W/C=0.35, 305.5 mm), the lowest foaming height (11.000 mm), and the fastest rate of defoaming of the cementitious systems, followed by F-PCE and T-PCE. Complexation, adsorption, surface activity, and polar hydrophobic mechanisms were identified. For unmodified T-PCE, there are more hydrophilic groups (-COOH), stronger surface activity. Therefore, T-PCE shows strong air entrainment; T-PCE has a high density of carboxylate and often forms a complex with 1 Ca2+ in the form of 4 carboxyl groups before reaching the adsorption equilibrium, so the concentration of free Ca2+ with foam stabilizing effect is high, which leads to strong air entrainment of T-PCE. The adsorption and complexation ability of F-PCE with Ca2+ is weaker than that of T-PCE. However, the hydrophobicity of F-PCE molecules is enhanced and the surface tension of F-PCE is reduced due to the ester group and C-F bonds in the structure of HFBMA, so the air entrainment of F-PCE is lower than that of T-PCE through Marangoni effect. P-PCE exhibited the lowest surface activity and the largest surface tension. Defoaming effect is promoted due to increased additional pressure on the bubble surface. Moreover, its adsorption and complexation with Ca2+ surpassed those of T-PCE and F-PCE due to the phosphate group has two negative charges, and the free Ca2+ is reduced, which also reduces the bubble stability. Therefore, P-PCE has minimal air entrainment in the cementitious systems.

RG-I-containing sugar domains from Centella Asiatica bind strongly to galectin-3 to inhibit cell–cell interactions

BackgroundCentella Asiatica has been shown to have beneficial value for the treatment of tumors. However, its active ingredients and molecular mechanisms of action have not been fully elucidated. Pectic polysaccharides are the primary active components from medicinal plants. Moreover, these polysaccharides are regarded as potential inhibitors of galectins, such as galectin-1, -3, -7, that generally promote tumor growth. Nevertheless, detailed structural analysis of pectic polysaccharides from Centella Asiatica is sorely lacking, as is knowledge of their interactions with galectins.MethodsWater-soluble pectic polysaccharides (WCAP) isolated from Centella Asiatica were purified into two homogeneous fractions (WCAP-A2b and WCAP-A5b) by a combination of anion-exchange and gel-permeation chromatography. Monosaccharide composition, FT-IR, NMR and enzymatic analyses were used to characterize their structural features. Furthermore, the interactions between galectin-1, -3, -7 and a series of these polysaccharides, including two pectin fractions and their structural domains produced by enzymatic hydrolysis, were evaluated by using hemagglutination and biolayer interferometry.ResultsWCAP-A2b and WCAP-A5b have weight averaged molecular weights of 30.0 kDa and 34.0 kDa, respectively, and both polysaccharides consist of rhamnogalacturonan I (RG-I), rhamnogalacturonan II (RG-II) and homogalacturonan (HG) domains, with mass ratios of 1.3: 1.0: 1.4 and 1.1: 1.0: 2.4, respectively. Their RG-I domains contain arabinan, galactan, and/or arabinogalactan, along with neutral sugar side chains that are more prevalent in WCAP-A2b than in WCAP-A5b. Hemagglutination and biolayer interferometry binding assays indicate that galectin-3 vis-à-vis galectin-1 and -7, binds strongly to the RG-I domain (likely via its neutral side chains) in WCAP-A5b, thereby inhibiting galectin-3-mediated cell–cell interactions.ConclusionsOur study provides structural information on pectin polysaccharides from Centella Asiatica. Results suggest that RG-I domains from WCAP-A5b and WCAP-A2b may be developed as potential inhibitors of galectin-3-mediated cell–cell adhesion and tumor growth.Graphical

Effects of cutting temperature on the genes and fatigue properties of asphalt during its refining process

Asphalt binders performance is affected by refining process and crude oil. In this work, we investigated the effect of cutting temperature on the genes and fatigue properties of asphalt during asphalt refining. Five cutting temperatures (420 °C to 440 °C, interval of 5 °C) were set during the asphalt preparation, expanded the asphalt samples through ageing method. Fourier Transform Infrared (FTIR), Gel Permeation Chromatography (GPC), Nuclear Magnetic resonance Spectrum (1HNMR), Elemental analyzer, and improved Brown-Ladner method were used to characterize the asphalt genes. The fatigue performance of asphalt through Linear Amplitude Sweep (LAS) combined with the Simplified Viscoelastic Continuum Damage (S-VECD). Finally, the Pearson correlation method was used to analyze the correlation between genes and fatigue parameters of binders. The results showed that the cutting temperature and aging process changed the genes distribution of binders and these influence the fatigue properties of binders. In addition, the fatigue life of asphalt decreased at high strain levels and increased at low strain levels as the cutting temperature and the degree of ageing increased. The Pearson correlation results indicated a significant correlation between the genes and fatigue parameters of asphalt, however, the key genes affecting low-strain (2.5% and 5 %) and high-strain (10% and 20%) level fatigue in asphalt are significantly different. The outcomes of the paper provide insights about the influence of cutting temperature on the variation of asphalt genes and fatigue parameters, to allow more informed to promote of asphalt preparation.

Synthesis of azelaic acid copolyester plasticizers and their application in PVC.

A series of 2-methyl-1,3-propanediol (MPO) modified azelaic acid and hexylene glycol copolyester (PHMAZ) plasticizers with varying contents were synthesized using a direct esterification melt polycondensation method, and their structures were characterized systematically. Analysis using infrared spectroscopy and nuclear magnetic resonance spectroscopy confirmed the synthesis of the designed copolyester structure. Gel permeation chromatography (GPC) tests indicated that the number average molecular weight of each copolyester sample ranged between 2000 and 3000. These copolyesters were used to plasticize polyvinyl chloride (PVC) resin, and the glass transition temperature of the plasticized PVC samples was tested using a differential scanning calorimeter (DSC). Further characterization of the plasticizing effects was conducted using an electronic universal testing machine. The research results showed that as the content of MPO increased, the plasticizing effect of the copolyester initially increased and then decreased. Specifically, the copolyester containing 45% MPO, PHMAZ-45, demonstrated the best plasticizing effect on PVC, with the glass transition temperature of the plasticized PVC system around -35 °C, elongation at break at 908.4%, and a plasticizing efficiency of 254.5%. Additionally, this new type of copolyester plasticizer uses bio-based raw materials, exhibits excellent plasticizing effects, and the preparation process is stable and controllable. It holds promising potential to replace traditional volatile and toxic phthalate esters, presenting significant industrial application value.

Solvent-free synthesis of polysilane-carbazole – A green route to develop fluorescent polysilanes with amplified emission characteristics via bridge intramolecular charge transfer effect

This work presents the synthesis of a new polysilane-carbazole structure (PSCB) by hydrosilylation in solvent-free conditions. For this purpose a polyhydrosilane (PSH) with a high content in methylhydrosilyl groups was mixed with 2-(((2-(9H-carbazol-9-yl)ethoxy)carbonyl)amino)ethyl methacrylate (CB) and triturated in the presence of Karstedt catalyst. The reaction proceeds smoothly in normal conditions of pressure and temperature in a dry atmosphere. The chemical structure of the resulted polymer was determined using Fourier-transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopies. Gel permeation chromatography (GPC) analysis proved the completion of the addition reaction in high yields. The computational analysis reveals the electronic structures of both CB and the PSCB molecule and highlights the significance of conformational effects on electronic structure and emission properties. The carbazole moiety acts as an electron donor, while the polysilane chain serves as an acceptor, enabling an intra-molecular through bridge charge transfer. Fluorescence measurements validate the unique structure, demonstrating an amplified emission due to the cumulative effect of the polysilane chain. The polysilane-carbazole polymer holds promise for various applications, emphasizing its potential in optoelectronic devices and sensing technologies.

Empowering PLA Bioplastics: Elevating applications horizon through groundbreaking Eco-Innovative Fibrillation, chain Extension, and crosslinking techniques

This comprehensive study introduces pioneering techniques in the toughening of polylactic acid (PLA) by incorporating thermoplastic polyurethane (TPU) nanofibrils, leveraging two distinct crosslinking methods to significantly enhance the material’s mechanical performance. Method 1 employs a silane/moisture crosslinking process, whereas Method 2 utilizes a tailored diisocyanate crosslinking approach, offering a more environmentally sustainable alternative. Molecular structural analysis was performed extensively by using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), rheological assessments, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). Method 2 not only preserves TPU nanofibrils but also elevates the mechanical properties of PLA-TPU composites beyond the capabilities of Method 1. Notably, by leveraging the simultaneous crosslinking of TPU and chain extension of PLA with the tailored diisocyanate approach, we enhance PLA’s mechanical properties and energy absorption capabilities. These advancements are achieved without a high rubber content, which typically compromises strength/stiffness, thermomechanical stability, crystallization, and transparency of PLA. The resulting composites prepared via Method 2 display remarkable increases in tensile toughness, ranging from 30-60 MPa, and impact strength, achieving a span of 60–140 J/m. This is primarily due to the occurrence of a brittle-to-ductile transition (BDT) at only 3 wt% nanofibril TPU content while maintaining a high PLA modulus of 3 GPa. This critical balance between chain-extending and crosslinking reactions ensures the maintenance of PLA’s inherent strength/stiffness, crystallization, and optical clarity. The research presented here marks a significant shift in the development of tougher, more thermally stable, transparent, and sustainable polymer blends and composites. Method 2, with its tailored fiber size reduction (90–280 nm), and environmental consciousness, broadens the horizon of PLA’s applications.

Anti-Oxidative and Anti-Apoptotic Oligosaccharides from Pichia pastoris-Fermented Cress Polysaccharides Ameliorate Chromium-Induced Liver Toxicity.

Oxidative stress impairs the structure and function of the cell, leading to serious chronic diseases. Antioxidant-based therapeutic and nutritional interventions are usually employed for combating oxidative stress-related disorders, including apoptosis. Here, we investigated the hepatoprotective effect of oligosaccharides, produced through Pichia pastoris-mediated fermentation of water-soluble polysaccharides isolated from Lepidium sativum (cress) seed mucilage, on chromium(VI)-induced oxidative stress and apoptosis in mice. Gel permeation chromatography (GPC), using Bio-Gel P-10 column, of the oligosaccharides product of fermentation revealed that P. pastoris effectively fermented polysaccharides as no long chain polysaccharides were observed. At 200 µg/mL, fractions DF73, DF53, DF72, and DF62 exhibited DPPH radical scavenging activity of 92.22 ± 2.69%, 90.35 ± 0.43%, 88.83 ± 3.36%, and 88.83 ± 3.36%, respectively. The antioxidant potential of the fermentation product was further confirmed through in vitro H2O2 radical scavenging assay. Among the screened samples, the highest H2O2 radical scavenging activity was displayed by DF73, which stabilized the free radicals by 88.83 ± 0.38%, followed by DF53 (86.48 ± 0.83%), DF62 (85.21 ± 6.66%), DF72 (79.9 4± 1.21%), and EPP (77.76 ± 0.53%). The oligosaccharide treatment significantly alleviated chromium-induced liver damage, as evident from the increase in weight gain, improved liver functions, and reduced histopathological alterations in the albino mice. A distinctly increased level of lipid peroxide (LPO) free radicals along with the endogenous hepatic enzymes were evident in chromium induced hepatotoxicity in mice. However, oligosaccharides treatment mitigated these effects by reducing the LPO production and increasing ALT, ALP, and AST levels, probably due to relieving the oxidative stress. DNA fragmentation assays illustrated that Cr(VI) exposure induced massive apoptosis in liver by damaging the DNA which was then remediated by oligosaccharides supplementation. Histopathological observations confirmed that the oligosaccharide treatment reverses the architectural changes in liver induced by chromium. These results suggest that oligosaccharides obtained from cress seed mucilage polysaccharides through P. pastoris fermentation ameliorate the oxidative stress and apoptosis and act as hepatoprotective agent against chromium-induced liver injury.

Characterization of PLGA versus PEG-PLGA intracochlear drug delivery implants: Degradation kinetics, morphological changes, and pH alterations

Drug delivery to the inner ear presents a unique challenge due to the complex inner ear anatomy and its tight physiological barriers. This study investigates the degradation behavior of intracochlear drug delivery implants (IDDI) composed of dexamethasone and poly(lactic-co-glycolic acid) (PLGA) or polyethylene glycol–poly(lactic-co-glycolic acid) (PEG-PLGA), respectively. IDDI were incubated in artificial perilymph and implants' degradation kinetics, morphological changes, water uptake behavior, and pH alterations were assessed. Microscopy revealed significant changes in appearance, with PLGA IDDI exhibiting rapid expansion, reaching up to 183 % in diameter and 185 % in length. PEG-PLGA implants showed gradual expansion, reaching a maximum of 178 % in diameter and 144 % in length. Despite these morphological changes, the IDDIs could still be applicable in terms of cochlear dimensions in combination with cochlear implants (CI) in humans or in a domestic pig animal model. Scanning electron microscopy analysis demonstrated surface alterations of PLGA implants, while PEG-PLGA implants remained shape-stable. Gravimetric analysis and gel permeation chromatography revealed distinct degradation profiles, with PLGA implants displaying rapid water uptake and mass loss, while PEG-PLGA implants showed delayed water uptake and minimal mass reduction. pH measurements using the pH-sensitive fluorescent dye SNARF™-1 showed initial pH reduction in artificial perilymph for PLGA implants while PEG-PLGA implants maintained pH stability.

Performance of Aromatic Amine-Modified Metallocene Polyalphaolefin Lubricant Base Oil

With the continuous advancement of industrial technology, higher demands have been placed on the properties of gear oils, such as oxidation stability and shear resistance. Herein, the oxidation stability of high-viscosity metallocene poly-α-olefins (mPAOs) was improved by chemical modification via aromatic amine alkylation. The modified mPAO base oils were synthesized separately with diphenylamine (mPAO-DPA) and N-phenyl-α-naphthylamine (mPAO-NPA), and their applicability in industrial gear oil formulations was evaluated. The composition and physicochemical properties of the obtained samples were assessed using 1H NMR spectroscopy, Fourier transform infrared spectroscopy, gel permeation chromatography, and the American Society for Testing and Materials standards (ASTM D445, ASTM D2270, ASTM D92, etc.) confirming the successful completion of the alkylation reaction. The oxidation stability of the samples was also evaluated using pressurized differential scanning calorimetry. The initial oxidation temperature of mPAO-NPA (230 °C) was 53 °C higher than that of mPAO, and the oxidation induction period of mPAO-DPA was nearly twice that of mPAO-NPA. Thermogravimetric analysis in air revealed the increased thermal decomposition temperature and improved thermal stability of modified mPAO. ISO VG 320 industrial gear oils were formulated using mPAO alkylated with N-phenyl-α-naphthylamine(Lub-2) and commercially purchased PAO100 (Lub-1) as base oil components. The antioxidant performance of two industrial gear oils was evaluated through oven oxidation and rotating oxygen bomb tests. The oxidation induction period of Lub-2 was 30% higher than that of Lub-1, with the latter having a lower acid number and a smaller increase in viscosity at 40 °C. Finally, the friction performance of the samples was assessed on a four-ball friction tester, revealing the synergistic effect of the mPAO-NPA base oil with the HiTEC 3339 additive, forming a more stable oil film with a smaller wear scar diameter.

Novel DNA-Binding Activity Exhibited by Poly(aspartic acid) Hydrolase-1 Inhibits Poly(aspartic acid) Hydrolase Activity.

Significant attention has been shifted toward the use and development of biodegradable polymeric materials to mitigate environmental accumulation and potential health impacts. One such material, poly(aspartic acid) (PAA), is a biodegradable alternative to superabsorbent poly(carboxylates), like poly(acrylate). Three enzymes are known to hydrolyze PAA: PahZ1KT-1 and PahZ2KT-1 from Sphingomonas sp. KT-1 and PahZ1KP-2 from Pedobacter sp. KP-2. We previously reported the X-ray crystal structure for PahZ1KT-1, which revealed a homodimer complex with a strongly cationic surface spanning one side of each monomer. Here, we report the first characterization of any polymer hydrolase binding to DNA, where modeling data predict binding of the polyanionic DNA near the cationic substrate binding surface. Our data reveal that PahZ1 homologues from Sphingomonas sp. KT-1 and Pedobacter sp. KP-2 bind ssDNA and dsDNA with nanomolar binding affinities. PahZ1KT-1 binds ssDNA and dsDNA with an apparent dissociation constant, KD,app = 81 ± 14 and 19 ± 1 nM, respectively, and these estimates are similar to the same behaviors exhibited by PahZ1KP-2. Gel permeation chromatography data reveal that dsDNA binding promotes inhibition of PahZ1-catalyzed PAA biodegradation for each homologue. We propose a working model wherein binding of PahZ1 to extracellular biofilm DNA aids in the localization of the hydrolase to the environment in which PAA would first be encountered, thereby providing a mechanism to degrade extracellular PAA and potentially harvest aspartic acid for nutritional uptake.

Structural characterization and hypoglycemic effect of polysaccharides of Polygonatum sibiricum.

Polygonatum sibiricum polysaccharide (PSP) was extracted and purified from raw material obtained from P. sibiricum. The structural features of PSP were investigated by Congo red, circular dichroism spectrum, high-performance gel permeation chromatography, scanning electron microscope, atomic force microscope, ultraviolet spectroscopy, and Fourier transform infrared spectroscopy analysis. In vitro simulations were conducted to investigate the kinetics of PSP enzyme inhibition. Moreover, a type II diabetes mouse model (T2DM) with streptozotocin-induced insulin resistance was established, and the indexes of lipid quadruple, insulin resistance index, oral glucose tolerance (OGTT), organ index, and pancreatic morphology of model mice were measured. The results showed that PSP mainly consists of monosaccharides, such as mannose, glucose, galactose, xylose, and arabinose. It also has a β-glycosidic bond of a pyranose ring and an irregular reticulated aggregated structure with a triple helix. In vitro enzyme inhibition assays revealed that PSP acts as a reversible competitive inhibitor of α-glucosidase and α-amylase. Furthermore, PSP was found to reduce insulin resistance index, increase OGTT and serum insulin levels, decrease free fatty acid content to improve lipid metabolism, and lower glycated serum protein content to enhance glucose metabolism in T2DM mice, thereby leading to a reduction in blood glucose concentration. Additionally, PSP exhibited reparative effects on the damaged liver tissue cells and pancreatic tissue in T2DM mice. The experiment results provide a preliminary basis for the therapeutic mechanism of PSP about type II diabetes and a theoretical reference for application in food and pharmaceutical development.

Synthesis of new polyazomethine-based pyrazole moieties as promising biologically active macromolecules

ABSTRACT Using the polycondensation technique, it was possible to synthesize a new class of biologically active polyazomethine based on pyrazole moiety. The polymerization occurred through the interaction between terephthalaldehyde and various derivatives of diaminopyrazole. The polymers that were made were given the letters PAZm/Py1–4 to reflect the different diaminopyrazole derivatives that were used. The monomer and polymer structures were investigated by common spectral characterization methods. The new PAZm/Py1–4 were examined by gel permeation chromatography (GPC), solubility tests, thermogravimetric analysis (TGA), X-ray diffraction analysis (XRD), and scanning electron microscopy (SEM). The newly synthesized polymers have high thermal stability and normal crystalline behavior. The antibacterial properties of all synthesized polymers were evaluated against the Gram-positive bacteria and the Gram-negative bacteria. Additionally, two types of fungi were used to test how well the prepared polymers worked against fungi. PAZm/Py1 and PAZm/Py4 showed slight antibacterial activity against the representative Gram-positive bacteria, while PAZm/Py2 and PAZm/Py3 had no significant influence. All the tested polymers showed slight to moderate antibacterial activity against the representative Gram-negative bacteria. PAZm/Py1 and PAZm/Py4 had a greater antifungal influence than other polymers.

Convenient determination of polystyrene microplastics in soils by gel permeation chromatography-ultraviolet detection analysis

Microplastics (MPs), especially polystyrene microplastics (PS-MPs), have emerged a new worldwide pollutant, prompting significant public concern regarding their detection in environmental media. Analysis of PS-MPs in soil remains as a challenging task for analysts due to the highly intricate matrices. This work presents a practical approach for detecting PS-MPs in soil, which involves dilute HCl-assisted extraction and gel permeation chromatography- ultraviolet detection (GPC-UV) analysis. The presence of MPs in soil was confirmed through the use of a scanning electron microscope in conjunction with energy dispersive spectroscopy investigation. PS-MPs was isolated from soil, by agitating it with a diluted HCl solution, filtering the resulting liquid, and dissolving the residue on the filter with THF. The extractant was subsequently determined by GPC-UV. The introduction of a small amount of HCl into the extraction system was found to greatly expedite the settling of soil in water and enhance the efficacy of extracting PS-MPs in about 30 min. The linear range of PS-MPs was from 1.0 to 100 μg/mL with R2 > 0.999. Good reproducibility was obtained with the intra-day relative standard deviation (RSD, n = 3) of 1.36 % and the inter-day RSD (n = 3) of 4.78 %. The concentration of PS-MPs in soil samples were N.D. - 2.33 μg/g, and the good recoveries were 76.7–100.3 %. The corresponding AFGEEprer score was calculated to be 0.59, indicating the concept of green analytical chemistry for the pretreatment method. These results indicated that this method has a powerful potential for the accurate and rapid determination of PS-MPs in soil.

Core-Tunable Dendritic Polymer: A Folate-Guided Theranostic Nanoplatform for Drug Delivery Applications.

Clinical application of anticancer drugs is mostly limited due to their hydrophobic nature, which often results in lower bioavailability and lesser retention in systemic circulation. Despite extensive research on the development of targeted drug delivery systems for cancer treatment, delivery of hydrophobic therapeutic drugs to tumor cells remains a major challenge in the field. To address these concerns, we have precisely engineered a new hyperbranched polymer for the targeted delivery of hydrophobic drugs by using a malonic acid-based A2B monomer and 1,6-hexanediol. The choice of monomer systems in our design allows for the formation of higher molecular weight polymers with hydrophobic cavities for the efficient encapsulation of therapeutic drugs that exhibit poor water solubility. Using several experimental techniques such as NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform-infrared (FT-IR), and gel permeation chromatography (GPC), the synthesized polymer was characterized, which indicated its dendritic structure, thermal stability, and amorphous nature, making it suitable as a drug delivery system. Following characterizations, theranostic nanoplatforms were formulated using a one-pot solvent diffusion method to coencapsulate hydrophobic drugs, BQU57 and doxorubicin. To achieve targeted delivery of loaded therapeutic drugs in A549 cancer cells, the surface of the polymeric nanoparticle was conjugated with folic acid. The therapeutic efficacy of the delivery system was determined by various cell-based in vitro experiments, including cytotoxicity, cell internalizations, reactive oxygen species (ROS), apoptosis, migration, and comet assays. Overall, findings from this study indicate that the synthesized dendritic polymer is a promising carrier for hydrophobic anticancer drugs with higher biocompatibility, stability, and therapeutic efficacy for applications in cancer therapy.

Modeling and tracing of polycarbonate (PC) degradation in soil microcosm with a PC microplastics quantification method based on pyrolysis GC–MS

Understanding the migration and transformation of polycarbonate (PC) plastic wastes in the natural environment is crucial for assessing their environmental impact and bioremediation. In this study, PC plastic degradation was modeled and traced in soil microcosm by investigating physiochemical properties changes of PC, the formation of microplastics, and changes in soil microbial communities. Notably, PC microplastics quantification method was also successfully devised by pyrolysis gas chromatography mass spectrometry and also applied herein. Through gel permeation chromatography analysis, the molecular weight of the naturally aged PC film obviously reduced, whereas no change for unaged ones. After 12 months of soil burial, the surface corrosion and holes formation were emerged on the surfaces of both PC films in the non-sterilized soil harboring indigenous microorganisms by scanning electron microscope. The worsened thermal stability of both PC films in non-sterilized soil was demonstrated by thermogravimetric analysis. Meanwhile, the presence of increased hydroxyl group absorption and decreased carbonyl peak highlighted molecular chain breakage in both PC films by Fourier transform infrared spectroscopy. In particular, all the changes were more significant in aged PC than unaged ones. Furthermore, the increase of quantified PC microplastics on the surface of PC film in the non-sterilized soil accompanied the decreasing of microbial diversity and the enrichment of potential functional microorganisms. These findings revealed that the combination of natural aging and indigenous microbes exhibited a noticeable performance in PC plastics degradation in soil microcosm, providing new insights into the degradation mechanism of PC plastic wastes in the natural environment.

Comparative studies on composition of feed additives for juvenile fish produced with bioconversion of fish raw materials

Technology of feed additive for fry feeding in fish farms is developed to provide both important nutrients (proteins, lipids, etc.) and optimal peptide composition of protein that is achieved using proteolysis of raw materials under certain conditions. For this purpose, enzymatic hydrolysis of substandard small-sized frozen pollock was used. The rational duration of the hydrolysis process was 60 min. that provided the degree of protein hydrolysis of 26–28 %. The experimental fermentolysate was concentrated to a water content of 3–4 % and presented as a feed additive TINRO-60. This product is compared with other feed additives (dried fermentolysates) produced in Russia from fish raw materials using bioconversion, such as Biomarin, Bioprom and Vakhob. General chemical composition of tested products was determined by standard methods of analytical chemistry; composition and content of fatty acids — by gas-liquid chromatography; microand macroelements, as well as toxic metals — by atomic absorption spectrophotometry; fractional composition of proteins and peptides — by high pressure gel permeation chromatography; amino acid composition — by ion exchange chromatography on a high-speed analyzer. All tested samples contain similar amount of the main feed component — protein substances. The quantitative ratio of peptide fractions is also comparable, the sum of the most active fractions (MW 0.1−10.0 kDa) in TINRO-60 and Biomarin is close to their level in tissues of Artemia, natural food for fish fry. The content of essential amino acids, EPA and DHA is significant in Biomarin, TINRO-60 and Bioprom, but almost twice lower in Vakhob. Analysis of mineral composition showed that bioconversion into dry fermentolysates does not cause concentration of toxic elements. High quality of the protein feed additive TINRO-60 produced by bioconversion of nonstandard fish raw materials under certain conditions is proved.