Search Results (159)

Titanium dioxide (TiO₂), a widely used semiconductor in photocatalysis owing to its adequate potential for water hydrolysis, chemical stability, low toxicity, and low cost. However, its efficiency is limited by fast charge-carrier recombination and poor visible light absorption. Coupling TiO₂ with a p-type semiconductor, such as nickel oxide (NiO), forming a p-n heterojunction, decreases the recombination of charge carriers and increases photocatalytic activity. In this work, the surface of TiO₂ modified with NiO nanoparticles (NPs) induced by radiolysis for photocatalytic hydrogen production was studied. The photocatalytic activity of NiO/TiO₂ was evaluated using methanol as a hole scavenger under UV–visible light. All modified samples presented superior photocatalytic activity compared to bare TiO₂. The dynamics of the charge carriers, a key electronic phenomenon in photocatalysis, was investigated by time-resolved microwave conductivity (TRMC). The results highlight the crucial role of Ni-based NPs modification in enhancing the separation of the charge carrier and activity under UV–visible irradiation. Furthermore, the results revealed that under visible irradiation, NiO-NPs inject electrons into the conduction band of titanium dioxide. Full article

The development of ceria (CeO_2−x)-based nanoantioxidants requires fine-tuning of structural and surface properties for enhancing antioxidant behavior in biological environments. In this contest, here ultrasmall water-dispersible CeO_2−x nanoparticles (NPs), characterized by a high Ce³⁺/Ce⁴⁺ ratio, were synthesized in a non-polar solvent and phase-transfer to an aqueous environment through ligand-exchange reactions using citric acid (CeO_2−x@Cit) and post-treatment with dopamine hydrochloride (CeO_2−x@Dopa). The concept behind this work is to enhance via surface engineering the intrinsic antioxidant properties of CeO_2−x NPs. For this purpose, thanks to electron transfer reactions between dopamine and CeO_2−x, the CeO_2−x@Dopa was obtained, characterized by increased surface Ce³⁺ sites and surface functionalized with polydopamine bearing o-quinone structures as demonstrated by complementary spectroscopic (UV–vis, FT-IR, and XPS) characterizations. To test the antioxidant properties of CeO_2−x NPs, the scavenging activity before and after dopamine treatment against artificial radical 1,1-diphenyl-2-picrylhydrazyl (DPPH^·) and the ability to reduce the reactive oxygen species in Diencephalic Immortalized Type Neural Cell line 1 were evaluated. CeO_2−x@Dopa demonstrated less efficiency in DPPH^· scavenging (%radical scavenging activity 13% versus 42% for CeO_2−x@Cit before dopamine treatment at 33 μM DPPH^· and 0.13 mg/mL loading of NPs), while it markedly reduced intracellular ROS levels (ROS production 35% compared to 66% of CeO_2−x@Cit before dopamine treatment with respect to control—p < 0.001 and p < 0.01, respectively). While steric hindrance from the dopamine-derived polymer layer limited direct electron transfer from CeO_2−x NP surface to DPPH^·, within cells the presence of o-quinone groups contributed with CeO_2−x NPs to break the autoxidation chain of organic substrates, enhancing the antioxidant activity. The functionalization of NPs with o-quinone structures represents a valuable approach to increase the inherent antioxidant properties of CeO_2−x NPs, enhancing their effectiveness in biological systems by promoting additional redox pathways. Full article

Skin is the first line of defence between the human body and the outside world, and it is constantly exposed to external injuries and wounds for a variety of reasons. Collagen is a structural protein of the extracellular matrix and an important component of the dermis. As a wound dressing, collagen not only provides nutrients to wounds but also enhances the immune response in the pre-healing phase, making it an excellent biomaterial for healing. In this study, we used electrospinning and freeze-drying technology to prepare a Bovine Achilles Tendon Collagen (BATC) electrospun composite membrane and a BATC freeze-dried composite membrane using BATC as a substrate supplemented with 16.7% Polyethylene oxide (PEO) and 0.2% Kukoamine B (KuB). The physicochemical properties and biocompatibility of the BATC composite membrane were verified via scanning electron microscopy, Fourier-transform infrared spectroscopy, and DSC analysis and by measuring the DPPH radical-scavenging capacity, water absorption, water retention, in vitro drug release, and extract cytotoxicity. The BATC composite membrane was found to have a significant effect on skin wound healing, especially in the middle stage of healing, in a mouse full-thickness skin injury model. The BATC/PEO/KuB electrospun composite membrane (EBPK) had the best capacity for promoting wound healing and can be used as a wound dressing for in-depth research and development, and KuB, a monomer component with a clear structure and mechanism of action, can be used as a candidate component of composite dressings. Full article

Antioxidant gel foams are promising materials for coal mine fire prevention due to their unique physicochemical properties. To address the limitations of conventional suppression methods under high-temperature conditions, this study investigates a newly developed antioxidant gel foam and its mechanism in inhibiting coal spontaneous combustion. A novel antioxidant gel foam was formulated by incorporating TBHQ and modified montmorillonite into a sodium alginate-based gel system. This formulation enhances the thermal stability, water retention, and free radical scavenging capacity of the gel. This study uniquely combines multi-scale experimental methods to evaluate the performance of this material in coal fire suppression. Multi-scale experiments, including FTIR, leakage air testing, programmed temperature rise, and small-scale fire extinction, were conducted to evaluate its performance. Experimental results indicate that the antioxidant gel foam exhibits excellent thermal stability in the temperature range of 200–500 °C. Its relatively high decomposition temperature enables it to effectively resist structural damage in high-temperature environments. During thermal decomposition, the gel releases only a small amount of gas, while maintaining the integrity of its internal micro-porous structure. This characteristic significantly delays the kinetics of coal oxidation reactions. Further research revealed that the spontaneous combustion ignition temperature of coal samples treated with the gel was significantly higher, and the oxygen consumption rate during spontaneous combustion was significantly reduced, indicating that the gel not only effectively suppressed the acceleration of the combustion reaction but also significantly reduced the release of harmful gases such as HCl. Scanning electron microscope analysis confirmed that the gel maintained a good physical structure under high temperatures, forming an effective oxygen barrier, which further enhanced the suppression of coal spontaneous combustion. These findings provide important theoretical and practical guidance for the application of antioxidant gel foams in coal mine fire prevention and control, confirming that this material has great potential in coal mine fire safety, offering a new technological approach to improve coal mine safety. Full article

Biflavonoids are a unique subclass of dietary polyphenolic compounds known for their diverse bioactivities. Despite these benefits, these biflavonoids remain largely underexplored due to their limited natural availability and harsh conditions required for their synthesis, which restricts broader research and application in functional foods and nutraceuticals. To address this gap, we synthesized a library of rare biflavonoids using a radical–nucleophile coupling reaction previously reported by our group. The food grade coupling reaction under weakly alkaline water at room temperature led to isolation of 28 heterocoupled biflavones from 11 monomers, namely 3′,4′-dihydroxyflavone, 5,3′,4′-trihydroxyflavone, 6,3′,4′-trihydroxyflavone, 7,3′,4′-trihydroxyflavone, diosmetin, chrysin, acacetin, genistein, biochanin A, and wogonin. The structures of the dimers are characterized by nuclear magnetic resonance spectroscopy (NMR) and high-resolution mass spectroscopy (HRMS). In addition, we evaluated the antioxidant potential of these biflavones using a DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay and the DPPH value ranges between 0.75 to 1.82 mM of Trolox/mM of sample across the 28 synthesized dimers. Additionally, a three-dimensional quantitative structure–activity relationship (3D-QSAR) analysis was conducted to identify structural features associated with enhanced antioxidant activity. The partial least squares (PLS) regression QSAR model showed acceptable r² = 0.936 and q² = 0.869. Additionally, the average local ionization energy (ALIE), electrostatic potential (ESP), Fukui index (F-), and electron density (ED) were determined to identify the key structural moiety that was capable of donating electrons to neutralize reactive oxygen species. Full article

Walnuts, which are rich in unsaturated fatty acids (UFAs), are highly susceptible to oxidation during storage, leading to quality degradation. Consequently, antioxidant technologies for the oxidative stability of walnuts have garnered significant attention. The addition of antioxidants remains the most cost-effective and efficient method currently available, with synergistic effects enhancing the efficacy of mixed antioxidant combinations compared to single antioxidants. In this study, four lipophilic antioxidants—tert-butylhydroquinone (TBHQ), butylated hydroxytoluene (BHT), dilauryl thiodipropionate (DLTP), and propyl gallate (PG)—were paired with four hydrophilic antioxidants—rosemary extract (RE), phytic acid (PA), tea polyphenols (TPs), and sodium ascorbate (SA)—resulting in 16 experimental groups to investigate synergistic effects. The effects of water-soluble and fat-soluble antioxidant combinations on walnut oxidation were systematically evaluated through peroxide value, acid value, thiobarbituric acid reactive substances, and DPPH radical scavenging capacities. Additionally, fatty acid composition analysis was employed to assess the preservation of beneficial UFAs. Mechanistic insights were obtained via thermogravimetric analysis and electron paramagnetic resonance spectroscopy. Notably, two combinations, 0.03% TBHQ + 0.03% TPs (w/w) and 0.03% DLTP + 0.03% SA (w/w), exhibited good oxidative stability of walnut kernels. These formulations demonstrated superior antioxidant performance and effectively inhibited oxidative pathways while maintaining UFA integrity, demonstrating their potential as advanced preservation strategies for lipid-rich foods. Full article

Sulfamethoxazole (SMX), a widely used antibiotic, persists in aquatic environments due to its resistance to conventional wastewater treatments. This work examined the breakdown of SMX in both purified water and urban wastewater through the application of electron beam irradiation (EBI). Experiments were conducted across doses of 0.5–3.0 kGy and varying pHs (2.70, 6.13, 9.00 and 11.10) and initial concentrations (5, 10, 15, 20 and 30 mg/L), and the role of reactive species was investigated with the help of scavengers. The results showed that SMX degradation followed pseudo-first-order kinetics and was most efficient at lower pH and concentrations. The scavenger experiments confirmed hydroxyl radicals as the dominant oxidizing agents responsible for SMX degradation, while wastewater constituents slightly inhibited the process. Nevertheless, over 99% SMX degradation was achieved at higher doses (1.5–3.0 kGy). TOC analysis revealed the partial mineralization of SMX, indicating the persistence of intermediate by-products despite high degradation efficiency. LC-MS analysis revealed multiple transformation products including hydroxylated sulfonamides and nitro-substituted derivatives, reflecting diverse degradation pathways. These results demonstrate that EBI is a highly effective laboratory-scale method for degrading SMX from water and wastewater, with promising potential for practical application. Full article

Croton cajucara Benth and Copaifera reticulata Ducke are prominent species in the traditional medicine of the Amazon region of Brazil. Copaifera species produce oil resin rich in bioactive diterpenes, and C. cajucara is a prolific producer of the diterpene 19-nor-clerodane trans-dehydrocrotonin (t-DCTN). This research aimed to develop a self-nanoemulsion drug delivery system (SNEDDS) by using copaiba oil resin (C. reticulata) as a carrier for t-DCTN. A stable SNEDDS single-phase nanoemulsion comprising Tween 80 (7%, w/w) and copaiba oil (0.5%, w/w) afforded a fine oil-in-water carrier system (SNEDDS-CO). The dropwise solubilization of t-DCTN (1 mg) into SNEDDS-CO resulted in the nanoformulation called SNEDDS-CO-DCTN. Transmission electron microscopy (TEM) analysis revealed spherical nanodevices, while particle size, polydispersity index (PDI), and zeta potential measurements indicated small nanodroplets (about 10 nm), uniformly distributed (between 0.1 and 0.2) and negatively charged for both systems. The in vitro kinetic of t-DCTN-loaded (SNEDDS-CO-DCTN) analyzed by using simulated conditions of the gastrointestinal microenvironment, as perspective for oral drug delivery, showed a controlled release profile, and corresponded to the Fickian diffusion model. The in vitro antioxidant activity of the samples (t-DCTN, SNEDDS-CO, and SNEDDS-CO-DCTN) was confirmed through total antioxidant capacity (TAC), reducing power, copper ion chelation, and hydroxyl radical scavenging assays. The antioxidant activity of SNEDDS-CO-DCTN which contained 1 mg of t-DCTN per mL⁻¹ of the carrier SNEDDS-CO was similar or even better when compared to the unload t-DCTN solubilized in DMSO (10 mg mL⁻¹). The SNEDDS formulations herein described were successfully obtained under moderated and controlled conditions, exhibiting effective physicochemical data and release characteristics with huge bioaccessibility for co-loading copaiba oil and t-DCTN. The novel colloidal system SNEDDS-CO-DCTN is a potential antioxidant nanoproduct and, from now on, is available for further pharmacological investigations. Full article

Electrochemical reduction is a promising strategy for the dechlorination of halogenated organic compounds, offering advantages such as enhanced electron transfer efficiency and increased hydrogen atom concentration. It has garnered significant attention for application in mitigating halogenated disinfection by-products (DBPs) in drinking water, owing to its high efficiency and simple operation. In this study, trichloroacetic acid (TCAA), a representative DBP, was selected as the target contaminant. A novel composite cathode comprising a metal–organic framework MIL-53(Fe)@C supported on an Nd magnet (MIL-53(Fe)@C-MAG) and its dechlorination performance for TCAA were systematically investigated. The innovative aspect of this study is the magnetic attachment of the MOF catalyst to the carbonized cathode surface treated through carbonization, which fundamentally differs from conventional solvent-based adhesion methods. Compared to the bare electrode, the MIL-53(Fe)@C-MAG achieved a TCAA removal efficiency exceeding 96.03% within 8 h of contact time. The structural characterization revealed that the α-Fe⁰ crystalline phase serves as the primary active center within the MIL-53(Fe)@C catalyst, facilitating efficient electron transfer and TCAA degradation. The scavenger experiments revealed that TCAA reduction involves a dual pathway: direct electron transfer and atomic hydrogen generation. The modified MIL-53(Fe)@C-MAG electrode exhibited robust electrolytic performance over a broad pH range of 3–7, with TCAA removal efficiency showing a positive correlation with current density within the range of 10–50 mA/cm². Furthermore, the electrode maintained exceptional stability, retaining more than 90% removal efficiency after five consecutive operational cycles. The versatility of the system was further validated by the rapid and efficient dechlorination of various chlorinated DBPs, demonstrating the broad applicability of the electrode. The innovative magnetic composite electrode demonstrates a significant advancement in electrochemical dechlorination technology, offering a reliable and efficient solution for the purification of drinking water contaminated with diverse halogenated DBPs. These results provide valuable insights into the development of electrolysis for dechlorination in water treatment applications. Full article

Background: Luteolin, a flavonoid with well-documented antioxidant properties, has garnered significant attention for its potential therapeutic effects. Objectives: This study aims to investigate the antioxidant properties of luteolin under the influence of solvents, utilizing computational techniques to elucidate its interactions and its potential role as a modulator of enzymatic activities, particularly with Cytochrome 17A1. Methods: Density Functional Theory (DFT) calculations were employed to determine luteolin’s electronic and structural characteristics. Key aspects analyzed included electron density distribution and the energies of the frontier molecular orbitals (HOMO and LUMO). Free radical scavenging mechanisms were explored by comparing the dissociation enthalpy of the O–H bond in the absence and presence of water molecules. Additionally, molecular docking simulations were performed to assess the interactions of luteolin with Cytochrome 17A1, identifying preferred binding sites and interaction energies. Results: The findings indicate that luteolin possesses distinct structural and electronic features that contribute to its effectiveness in protecting against oxidative stress. However, hydrogen bonding interactions with water molecules were found to influence the dissociation enthalpy of the O–H bond. Docking simulations revealed significant interaction profiles between luteolin and Cytochrome 17A1, suggesting its potential role as a modulator of this protein. Conclusions: This study underscores the therapeutic potential of luteolin and highlights the importance of computational techniques in predicting and understanding the molecular interactions of bioactive compounds with biological targets. The results provide valuable insights that may aid in developing new therapeutic strategies for diseases associated with oxidative stress. Full article

The green synthesis of silver nanoparticles (AgNPs) using Elephantorrhiza elephantina (Burch) bulb extracts and evaluation of their antimicrobial, cytotoxic, and antioxidant properties were investigated. The crude plant extracts were prepared using distilled water, ethanol, and methanol for a comparison. Silver nanoparticles were synthesized and characterized via UV–Visible spectroscopy (UV–VIS), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The formation of silver nanoparticles was confirmed using the UV–VIS spectra at 550 nm. The TEM confirmed the nanoparticle morphology as a mixed dispersed sphere, oval, and triangular shapes with a size range of 7.8 nm to 31.3 nm. The secondary metabolites were detected using TLC, DPPH, and LC-MS. Antimicrobial activity was assessed based on agar-well diffusion; cytotoxicity was examined through MTS assays. Various phytochemical constituents were detected through TLC and LC-MS. The crude extracts and methanol-extract-capped AgNP were able to scavenge free radicals, as shown by the developments of inhibitory bands on the TLC plate. The agar well diffusion test revealed that the AgNP capped methanol extract had potent antimicrobial activity against Gram-positive and Gram-negative multidrug resistant bacteria in comparison with penicillin and neomycin, with inhibition zones ranging between 10 mm and 14 mm for the methanol-extract-capped AgNP. The in vitro MTS assay revealed that methanol crude extracts and methanol-extract-capped AgNP had a less cytotoxic effect on the HEK293 cells in comparison with untreated cells (control). We therefore conclude that methanol was the best reducing solvent with the best overall nanoparticle morphology and performance in antimicrobial and cytotoxicity, in comparison to ethanol and distilled water. Full article

The use of metal nanoparticles is gaining popularity owing to their low cost and high efficacy. We focused on green synthesis of silver nanoparticles (AgNPs) using Tinospora cordifolia (Tc) leaf extracts. The structural characteristics of Tc nanoparticles (TcAgNPs) were determined using several advanced techniques. Pharmacological activities, including antioxidant, anti-inflammatory, and antibacterial properties, were evaluated through in vitro studies. In the results, the change in sample color from yellow to brown after adding silver nitrate revealed the synthesis of TcAgNPs, and the UV–visible spectrum confirmed their formation. X-ray diffraction studies showed the presence of reducing agents and the crystalline nature of the nanoparticles. Fourier-transform infrared spectra revealed the existence of essential secondary metabolites, which act as reducing/capping agents and stabilize the nanoparticles. The size of the TcAgNPs was small (range 36–168 nm) based on the measurement method. Their negative zeta potential (−32.3 mV) ensured their stability in water suspensions. The TcAgNPs were predominantly spherical, as evidenced from scanning electron microscopy and transmission electron microscopy. Atomic absorption spectroscopy data further revealed the conversion of silver nitrate into silver nanoparticles, and thermogravimetric analysis data showed their thermal stability. The TcAgNPs showed significant DPPH/ABTS radical scavenging ability in a concentration-dependent manner (25–100 µg/mL). Membrane lysis assays showed an effective anti-inflammatory activity of the TcAgNPs. Furthermore, the TcAgNPs showed potent antibacterial effects against multidrug-resistant bacteria (Pseudomonas aeruginosa, Klebsiella pneumonia, Escherichia coli, and Staphylococcus aureus). The TcAgNPs treatment also exhibited antibiofilm activity against bacterial strains, in a concentration-dependent manner. Our findings demonstrate the structural characteristics of green-synthesized TcAgNPs using advanced techniques. TcAgNPs can be developed as potential antioxidant, anti-inflammatory, and antibacterial drugs. Full article

St. John’s wort (Hypericum perforatum) has been used for centuries in traditional medicine owing to its high content of various bioactive metabolites and wide geographic occurrence. Nowadays, it plays an important role in the pharmaceutical industry and is increasingly significant in modern cosmetology. The objective of this study was to assess the antioxidant activity and compare the content of polyphenolic compounds in two commercial extracts of H. perforatum, glycerol–water and propylene glycol–water, which are used as cosmetic raw materials. The HPLC method was used to determine phenolic compounds. The total polyphenol content and total flavonoid content of H. perforatum extracts were determined using spectrophotometric methods. Free radical-scavenging properties were analyzed using a 2,2-diphenyl-1-picrylhydrazyl radical assay with electron paramagnetic resonance spectroscopy (DPPH-EPR assay), as well as the ferric reducing antioxidant power (FRAP) method. St. John’s wort extracts were able to scavenge free radicals, indicating beneficial cellular protection against oxidative stress. The use of non-toxic extractants makes it possible to obtain extracts with high antioxidant potential, which can be safely used in the pharmaceutical and cosmetics industries. The results of this study, i.e., the values for TPC, TFC, and antioxidant activity (DPPH and FRAP), suggest that Hypericum perforatum, especially the glycerol–water extract, has antioxidant potential. Full article

Fe-based heterogeneous catalytic advanced oxidation processes show great potential for treating wastewater. However, catalyst instability often hinders their practical use, mainly due to the slow regeneration of Fe²⁺ sites. Herein, we developed a Fe₃S₄/WO₃ catalyst, where the electron-rich Wx and Sx sites promoted efficient electron transfer, enabling continuous regeneration of Fe²⁺ active sites on the catalyst surface. The Fe₃S₄/WO₃ catalyst exhibited outstanding degradation efficiency for tetracycline (TC) in the peroxymonosulfate (PMS) system, achieving a 92.5% removal efficiency, significantly higher than its individual components of Fe₃S₄ (52.8%), WO₃ (43.1%), and WS₂ (53.2%). Moreover, the Fe₃S₄/WO₃/PMS system demonstrated a broad operational pH range (3.0–9.0), excellent degradation efficiency for various emerging pollutants, minimal interference from background electrolytes and organic matter, and strong stability in real water treatment. Chemical scavenger tests and electron paramagnetic resonance (EPR) analysis confirmed that the oxidative degradation of TC was driven by multiple reactive species, including SO₄^•−, ^•OH, ^•O₂⁻, and ¹O₂. This study provides a novel strategy for regulating active sites in Fe-based catalysts to ensure sustained performance, offering a pathway for the rational design of next-generation Fenton-like catalysts for efficient and sustainable micropollutant removal from wastewater. Full article

Carbon dots (CDs) derived from biomass are promising fluorescent probes for specific analyte detection due to their specificity, biocompatibility, selectivity, and sensitivity. In this work, carbon dots were prepared hydrothermally from natural material, Myrica esculenta fruits (hereafter referred to as MPCDs), without adding any chemicals. The prepared MPCDs were characterized using optical, microscopic, and spectroscopic methods that revealed the presence of numerous functional groups and fluorescent properties. MPCDs exhibited exceptional characteristics such as water solubility, photostability, excitation-dependent fluorescence emission, and ionic stability. Transmission electron microscopy found that the average size of the MPCDs was 8 nm. MPCDs exhibited remarkable sensing ability for hemin, with a good linearity (R² = 0.999) and a lower limit of detection of 14.1 nM. MPCDs demonstrated fluorescence quenching-based detection of hemin, primarily owing to ground state complex formation and the inner filter effect. Furthermore, the prepared material exhibited excellent antioxidant potential against 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radicals with EC₅₀ values of 25.4 and 205.4 µg/mL, respectively. The study suggests that CDs from Myrica esculenta fruits could be used as optical sensors for hemin detection as well as to scavenge selected radicals. Full article