Search Results (148)

Low-concentration N₂O (≤5%) emissions from agricultural fields and waste treatment facilities in China reach 7.333 × 10⁵ t annually, making them a significant but inadequately controlled contributor to global warming. Agricultural wastes were selected as precursors to prepare biochar, including pecan shell (SH), poplar sawdust (JM), wheat straw (XM), and corn straw (YM), which were subsequently acid-modified with 0.1 mol L⁻¹ HCl. The objectives were (i) to quantify the enhancement in N₂O capture achievable by acid treatment, (ii) to elucidate the underlying chemisorption mechanism, and (iii) to identify the most efficient feedstock for practical deployment. Acid modification increased the oxygen content, specific surface area, and the number of hydroxyl and carboxyl groups on the biochar surface. Both modified and unmodified biochar followed the pseudo-second-order kinetic model (R² ≥ 0.960), indicating chemisorption-dominated processes. The adsorption performance ranked as XM > JM > SH > YM, with XM exhibiting the highest adsorption capacity (26.000 mol/kg unmodified, 43.088 mol/kg modified, 65.72% increase). The Langmuir model provided a better fit for N₂O adsorption, suggesting dynamic multilayer heterogeneous adsorption. The findings demonstrate that acid-modified biochar derived from agricultural waste is a scalable, economical, and environmentally friendly adsorbent for mitigating low-concentration N₂O emissions. Full article

The inherent hydrophobic nature of PVDF material renders it challenging to establish a stable aqueous hydration layer, thereby limiting its suitability as a substrate for the preparation of nanofiltration (NF) membranes. In this study, we developed a novel modification approach that effectively enhances the hydrophilicity of PVDF substrates through the incorporation of sulfonic acid-doped polyaniline (SPANI) and hyperbranched polyester (HPE) into the PVDF casting solution, followed by cross-linking with trimesoyl chloride (TMC). The introduction of SPANI and HPE, which contain reactive polar amino and hydroxyl groups, improved the hydrophilicity of the substrate, while the subsequent cross-linking with TMC effectively anchored these components within the substrate through the covalent linking between TMC and the reactive sites. Additionally, the hydrolysis of TMC yielded non-reactive carboxyl groups, which further enhanced the hydrophilicity of the substrate. As a result, the modified PVDF substrate exhibited improved hydrophilicity, facilitating the construction of an intact polyamide layer. In addition, the fabricated TFC NF membrane demonstrated excellent performance in the advanced treatment of tap water, achieving a total dissolved solid removal rate of 57.9% and a total organic carbon removal rate of 85.3%. This work provides a facile and effective route to modify PVDF substrates for NF membrane fabrication. Full article

An important class of analytes are volatile organic carbons (VOCs), particularly aliphatic primary alcohols. Here, we report the straightforward modification of a commercially available carbon monoxide sensor to detect a range of aliphatic primary alcohols at room temperature. The mass transport mechanisms governing the performance of the sensor were investigated using diffusion in multiple layers of the sensor to model the response to an abrupt change in analyte concentration. The sensor was shown to have a large capacitance because of the nanoparticulate nature of the platinum working electrode. It was also shown that the modified sensor had performance characteristics that were mainly determined by the condensation of the analyte during diffusion through the membrane pores. The sensor was capable of a quantitative amperometric response (sensitivity of approximately 2.2 µA/ppm), with a limit of detection (LoD) of 17 ppm methanol, 2 ppm ethanol, 3 ppm heptan-1-ol, and displayed selectivity towards different VOC functional groups (the sensor gives an amperometric response to primary alcohols within 10 s, but not to esters or carboxylic acids). Full article

Humic acid (HA), a major component of soil organic matter, is a naturally occurring macromolecule formed through the decomposition of plant and microbial residues. Its molecular structure comprises functional groups such as carboxyl, phenolic, hydroxyl, and carbonyl functional groups, which enable HA to interact with soil particles, nutrients, and biological systems. These interactions significantly contribute to soil fertility and overall plant productivity. Functionally, HA enhances soil health by increasing cation exchange capacity, improving water retention, and promoting the formation and stabilization of soil aggregates. In addition to its role in soil conditioning, HA is essential in mitigating plant stress. It achieves this by modulating antioxidant enzyme activity, stabilizing cellular membranes, and alleviating the adverse effects of abiotic stressors such as salinity, drought, and heavy metal toxicity. This review highlights the structural characteristics of HA, its structure-based functions, and the mechanisms involved in plant stress alleviation. Additionally, we explore how HA can be modified through physical, chemical, and biological approaches to enhance its agronomic performance. These modifications are designed to improve HA agronomic efficiency by increasing nutrient bioavailability, reducing environmental losses through minimized leaching and volatilization, and supporting sustainable agricultural practices. Overall, this review underscores the multifaceted roles of HA in promoting plant resilience to environmental stress, highlighting its potential as a key agent in the development of sustainable and eco-friendly crop production systems. Full article

The by-products that may contain tetrodotoxin (TTX) produced during the processing of farmed pufferfish have caused food safety risks and environmental pollution. Peptidoglycan (PG) of lactic acid bacteria could adsorb TTX; however, its complex structure and poor solubility limited adsorption efficiency. In this study, hydroxyl modifications of three PGs (A3α, A1γ and A4α) were realized via TEMPO-mediated selective oxidation of the primary hydroxyl group. Compared with PGs, it was found that the carboxyl density of hydroxyl-modified PGs (HM-PGs) increased from 1.66 mmol/g to 3.33 mmol/g and the surface electronegativity increased from −36 mV to −59 mV. The adsorption capacity of HM-PGs to TTX reached 1.48 μg/mg, which was comparable to the adsorption of the conventional adsorbent chitosan for aflatoxin B1 (1.39 μg/mg). Moreover, HM-PGs decreased the toxicity of TTX from strong toxic to nearly non-toxic, with the toxicity reduction rate reached 99.85%. After treatment with HM-PGs, the mouse hippocampus and neuronal cell model confirmed that lower neural injury and sodium channel blocking effects were observed in the residual TTX, whose neurotoxicity was lower. Molecular docking simulation and physicochemical analysis revealed that the adsorption of TTX by HM-PGs was a complex adsorption mode driven by the synergy of physicochemical interaction. There were both physical adsorptions based on electrostatic and hydrophobic interactions and chemical binding with strong hydrogen bonding (1.46 Å) and Mayer bond order (0.1229). This study not only developed a new, efficient and safe tool for TTX removal, but also provided a theoretical basis for the development of biological toxin removal material. Full article

We developed a novel biodegradable poly(lactic-co-glycolic acid) (PLGA) polymer chemically modified with paclitaxel (PTX) to form a PLGA-PTX hybrid. Pre-modification of PTX enhanced its loading in PLGA-PTX nanoparticles (NPs). Background/Objectives: PTX is one of the most effective chemotherapy agents used in cancer therapy. The primary mode of PTX’s action is the hyperstabilization of microtubules leading to cell growth arrest. Although highly potent, the drug is water insoluble and requires the Cremophor EL excipient. The toxic effects of the free drug (e.g., neurotoxicity) as well as its solubilizing agent are well established. Thus, there is strong clinical rationale and need for exploring alternative PTX delivery approaches, retaining biological activity and minimizing systemic effects. Methods: The PTX modification method features reacting the C-2′ and C-7 residues with a linker (succinic anhydride) to produce easily accessible carboxyl groups on the PTX for enhanced coupling to the hydroxyl group of PLGA. The PLGA-PTX hybrid, formed via esterification reaction, was used to formulate lipid-coated PLGA-PTX NPs. As proof of concept, the PLGA-PTX NPs were tested in ovarian cancer (OvCA) models, including several patient-derived cell lines (PDCLs), one of which was generated from a platinum-resistant patient. Results: The PLGA-PTX NPs critically remained stable in water and serum while enabling slow drug release. Importantly, PLGA-PTX NPs demonstrated biological activity. Conclusions: We suggest that this approach offers both a new and effective PTX formulation and a possible path towards the development of a new generation of OvCA treatment. Full article

Spent coffee grounds (SCG) are produced in large quantities during coffee brewing, contributing to environmental concerns. Additionally, cationic dyes from textile, paper, and leather wastewater pose a major pollution issue. This study explores SCG as an adsorbent for methylene blue (MB) dye. A novel comparison of SCG cleaning methods with warm water, accelerated solvent extraction (ASE), supercritical fluid extraction (SFE), and ultrasound-induced cavitation (US) is presented. In addition, the chemical modifications of SCG using acetylation, acid (HNO₃), and base (KOH) treatment that have not been reported before are presented. ATR-FTIR confirmed the inclusion of functional groups, for example, the nitro group in SCG treated with HNO₃, and an increase in carboxylic groups in the samples treated with KOH and HNO₃. SEM analysis revealed a consistent porous texture across samples, with SCG-SFE, SCG-US, and SCG-HNO₃ showing smaller pores, and SCG-ASE displaying elongated cavities. Adsorption isotherm tests followed the Freundlich and Langmuir models, indicating favorable adsorption. The Langmuir maximum adsorption capacity (q_max) varied among cleaning methods from 65.69 mg/g (warm water) to 93.32 mg/g (SFE). In contrast, in base- and acid-treated SCG, a three- to four-fold increase in adsorption capacity was observed, with q_max values of 171.60 mg/g and 270.64 mg/g, respectively. These findings demonstrate that SCG washed with warm water and chemically treated achieves adsorption capacities comparable to other biosorbents reported in the literature. Therefore, SCG represents a promising, low-cost, and sustainable material for removing cationic dyes from wastewater, contributing to waste valorization and environmental protection. Full article

To comparatively study the effects of cold plasma activation and chemical treatment on the adsorption capacities of biomass carbon nanofiber membranes (BCNMs), microcrystalline cellulose (MCC) and chitosan (CS) were used to fabricate porous BCNMs by electrospinning and carbonization. Two modification methods, including oxygen (O₂) plasma activation and chemical treatment using nitric acid (HNO₃), sulfuric acid (H₂SO₄), hydrogen peroxide (H₂O₂), and urea, were further employed to enhance their adsorption performance. Various carbonyl group (C=O), ether bond (C-O), carboxyl group (O-C=O) and pyridinic nitrogen (N), pyrrolic N, and quaternary N functional groups were successfully introduced onto the surface of the BCNMs by the two methods. The BCNM-O₂ showed optimal formaldehyde absorption capacity (120.67 mg g⁻¹), corresponding to its highest contents of N, O-containing functional groups, and intact network structure. However, chemical treatment in strong acid or oxidative solutions destructed the microporous structures and changed the size uniformity of fibers in the BCNMs, resulting in a decline in formaldehyde adsorption capacity. A synergistically physical–chemical adsorption took place during formaldehyde adsorption by the modified biomass nanofiber membranes, due to the coexistence of suitable functional groups and porous structures in the membranes. Full article

As a cost-effective sorbent, modified biochar has received increasing attention for the removal of heavy metal contaminants. Among several chemical modification methods, introducing thiol functional groups onto the surface of biochar has been identified as an effective enhancement approach for the heavy metal sorption and removal capacity of this porous adsorbent material. In general, chemical impregnation is a widely used method to graft thiol groups onto the surface of carbon-based materials. However, limited comparative data are available on the efficacy of the present biochar thiolation methods. In this study, the biochar of nine different organic sources was modified by two frequently used agents with distinct thiolation mechanisms: 3-Mercaptopropyltrimethoxysilane (3-MPTS) and β-mercaptoethanol. In addition to chemical impregnation, the ball milling method, a simple and environmentally friendly alternative thiolation method, was also evaluated. A comprehensive structural characterization of the biochar samples was completed before and after thiolation. A higher concentration of sulfur on the surface of the biochar was achieved through thiolation with β-mercaptoethanol, in which the thiolation mechanism is performed through an esterification reaction with the carboxylic acid functional groups of the activated biochar. Chemical impregnation was found to be a more effective thiolating method than ball milling using the same thiolating agent. Full article

Getting through the cell membrane is challenging, and transporting a therapeutic agent while entering the cell is even more complicated. Cell-penetrating peptides (CPPs) are valuable tools for solving this problem, although they have drawbacks. In this work, the synthesis and investigation of efficient CPPs are described. We used an aromatic group, 1-pyrene carboxylic acid (PCA), to enhance internalization. We designed oligoarginines to investigate the effect of PCA in different positions at the N-terminus or in the side chain. Our novel peptide derivatives showed remarkable internalization on tumor cell lines, and more than one endocytic pathway plays a role in their internalization mechanism. With this modification, there is an opportunity to design short oligoarginines that can rival well-known CPPs like octaarginine in internalization. Full article

This review gives an overview of Si-, Ge- and Sn-compounds with (O,N)-bi- and -oligodentate ligands, which have the α-amino carboxylic acid motif N–C(R,R′)–C(=O)O in common (R,R′ = H or hydrocarbyl). While the amino acids themselves are encountered as mono- and di-anionic ligands, modifications at the N-terminus (e.g., extension of the ligand backbone by, e.g., additional alkane carboxylic acid groups) give rise to a wealth of ligands, which bear the α-amino carboxylic acid motif. With particular interest in the coordination features of these ligands, crystallographically characterized complexes are the focus of this review. Full article

Background: In the era of resistance, the design and search for new “small” molecules with a narrow spectrum of activity that target a protein or enzyme specific to a certain bacterium with high selectivity and minimal side effects remains an urgent problem of medicinal chemistry. In this regard, we developed and successfully implemented a strategy for the search for new hybrid molecules, namely, the not broadly known [2-(3-R-1H-[1,2,4]-triazol-5-yl)phenyl]amines. They can act as “building blocks” and allow for the introduction of certain structural motifs into the desired final products in order to enhance the antistaphylococcal effect. Methods: The “one-pot” synthesis of the latter is based on the conversion of substituted 4-hydrazinoquinazolines or substituted 2-aminobenzonitriles and carboxylic acid derivatives to the target products. The possible molecular mechanism of the synthesized compounds (DNA gyrase inhibitors) was investigated and discussed using molecular docking, and their further study for antistaphylococcal activity was substantiated. Results: A significant part of the obtained compounds showed high antibacterial activity against Staphylococcus aureus (MIC: 10.1–62.4 µM) and 5-bromo-2-(3-(furan-3-yl)-1H-1,2,4-triazol-5-yl)aniline and 5-fluoro-2-(3-(thiophen-3-yl)-1H-1,2,4-triazol-5-yl)aniline, with MICs of 5.2 and 6.1 µM, respectively, approaching the strength of the effect of the reference drug, “Ciprofloxacin” (MIC: 4.7 µM). The conducted SAR and ADME analyses confirm the prospects of the further structural modification of these compounds. The obtained [2-(3-R-1H-[1,2,4]-triazol-5-yl)phenyl]amines reveal significant antimicrobial activity and deserve further structural modification and detailed study as effective antistaphylococcal agents. The SAR analysis revealed that the presence of a cycloalkyl or electron-rich heterocyclic fragment in the third position of the triazole ring was essential for the antibacterial activity of the obtained compounds. At the same time, the introduction of a methyl group into the aniline moiety led to an enhancement of activity. The introduction of halogen into the aniline fragment has an ambiguous effect on the level of antistaphylococcal activity and depends on the nature of the substituent in the third position. Conclusions: Obtained [2-(3-R-1H-[1,2,4]-triazol-5-yl)phenyl]amines reveal significant antistaphylococcal activity and deserve for further detailed study as effective antibacterial agents. Full article

Nowadays, nucleic acid derivatives capable of modulating gene expression at the RNA level have gained widespread recognition as promising therapeutic agents. A suitable degree of biological stability of oligonucleotide therapeutics is required for in vivo application; this can be most expeditiously achieved by the chemical modification of the internucleotidic phosphate group, which may also affect their cellular uptake, tissue distribution and pharmacokinetics. Our group has previously developed a strategy for the chemical modification of the phosphate group via the Staudinger reaction on a solid phase of the intermediate dinucleoside phosphite triester and a range of, preferably, electron deficient organic azides such as sulfonyl azides during automated solid-phase DNA synthesis according to the conventional β-cyanoethyl phosphoramidite scheme. Polyfluoro compounds are characterized by unique properties that have prompted their extensive application both in industry and in scientific research. We report herein the synthesis and isolation of novel oligodeoxyribonucleotides incorporating internucleotidic perfluoro-1-octanesulfonyl phosphoramidate or 2,2,2-trifluoroethanesulfonyl phosphoramidate groups. In addition, novel oligonucleotide derivatives with fluorinated zwitterionic phosphate mimics were synthesized by a tandem methodology, which involved (a) the introduction of a carboxylic ester group at the internucleotidic position via the Staudinger reaction with methyl 2,2-difluoro-3-azidosulfonylacetate; and (b) treatment with an aliphatic diamine, e.g., 1,1-dimethylethylenediamine or 1,3-diaminopropane. It was further shown that the polyfluoro oligonucleotides obtained were able to form complementary duplexes with either DNA or RNA, which were not significantly differing in stability from the natural counterparts. Long-chain perfluoroalkyl oligonucleotides were taken up into cultured human cells in the absence of a transfection agent. It may be concluded that the polyfluoro oligonucleotides described here can represent a useful platform for designing oligonucleotide therapeutics. Full article

As a promising polymer for the production of biomaterials and drug delivery systems, poly(lactic acid) (PLA) is characterized by its relative hydrophobicity, as well as its chemical and biological inertness. Here, we aimed to improve the biological properties of PLA-based materials via the covalent attachment of a hydrophilic biocompatible glycopolymer, namely poly(2-deoxy-N-methacrylamido-D-glucose) (PMAG) on their surface. PMAG is a water-soluble polymer that contains glucose units in its side chains, which are responsible for good biocompatibility and the ability to attach bioactive molecules. In the developed protocol, PMAG was synthesized by controlled radical polymerization in the presence of a reversible addition–fragmentation chain transfer (RAFT) agent, followed by the conversion of glycopolymer terminal dithiobenzoate functionality into a primary amino group (PMAG-NH₂). PLA-based films served as model aliphatic polyester materials for developing the surface biofunctionalization protocol. According to that, PMAG-NH₂ covalent immobilization was carried out after alkali treatment, allowing the generation of the surface-located carboxyl groups and their activation. The developed modification method provided a one-point attachment of hydrophilic PMAG to the hydrophobic PLA surface. PMAG samples, which differed by the degree of polymerization, and the variation of polymer concentration in the reaction medium were applied to investigate the modification efficacy and grafting density. The developed single-point polymer grafting approach provided the efficient functionalization with a grafting density in the range of 5–23 nmol/cm². The neat and modified polymer films were characterized by a number of methods, namely atomic force microscopy, thermogravimetric analysis, ellipsometry, and contact angle measurements. In addition, an ArgGlyAsp-containing peptide (RGD peptide) was conjugated to the PMAG macromolecules grafted on the surface of PLA films. It was shown that both surface modification with PMAG and with PMAG-RGD peptide enhanced the adhesion and growth of mesenchymal stem cells as compared to a neat PLA surface. Full article

The paper presents the process of cellulose extraction from rice straw using water–alkaline solution treatment and the subsequent process of carboxymethylation of the obtained product when activated by microwave radiation. After mercerization of rice straw, the obtained product contained 89.2% cellulose and 6.7% lignin. The X-ray diffraction pattern of the obtained lignocellulose shows three diffraction peaks in the region typical for the polymorphic modification of cellulose Iβ (2θ = 15.50(78), 21.70(145), 34.70(52)). The degree of crystallinity was 65%. The product was heat-stable up to 247 °C. The synthesis of carboxymethylcellulose (CMC) based on the obtained product included successive processes of thermostating in alcohol–alkali solution and cellulose esterification reaction using monochloroacetic acid. To activate the carboxymethylation process, microwave radiation was used (350 W for 90 s), which made it possible to reduce the reaction time by more than 100 times. Functional group analysis of the carboxylated lignocellulose from rice straw was carried out using an FTIR spectrometer. In the IR spectra, a band with a maximum of 1742 cm⁻¹ was recorded, corresponding to stretching vibrations of >C(O)OH groups. The degree of polymerization was recorded by mass spectrometry. Full article