Hydroxyl Radical Research Articles

A triple-mode strategy combining low-temperature photothermal, photodynamic, and chemodynamic therapies for treating infectious skin wounds.

The skin is the first natural barrier of the human body. Bacterial infections severely hinder the healing process of skin wounds and pose a great threat to human health. Therefore, it is particularly urgent to develop new antimicrobial strategies for bacterial pathogen clearance and wound healing. In this study, a metal-organic framework (MOF), Fe-MIL88B-NH2, was incorporated with the photosensitizer indocyanine green (ICG) to construct composite nanoparticles (MOF@ICG NPs) with multiple antibacterial activities. Under mild near-infrared (NIR) irradiation, the photosensitizer ICG in the MOF@ICG NPs undergoes photothermal conversion (∼45 °C) and photodynamic reactions to generate heat and singlet oxygen (1O2). In addition, the Fenton reaction of the NPs with hydrogen peroxide (H2O2) in the bacterial infection microenvironment resulted in the generation of hydroxyl radicals (˙OH), thus achieving the three-mode combination of low-temperature photothermal therapy (PTT)/photodynamic therapy (PDT)/chemodynamic therapy (CDT). The in vitro experimental results showed that MOF@ICG MPs had excellent antibacterial properties and good cytocompatibility, with some ability to promote the migration of L-929 fibroblasts. Furthermore, under NIR irradiation, MOF@ICG NPs could significantly kill bacteria and promote skin wound healing according to the results of animal experiments. The wound healing rate reached 87.1% after 7 days of treatment. The research results break through the limitations of single-mode antibacterial technology and provide certain theoretical guidance and technical support for the research and development of new antibacterial materials.

Optimization of the Process of Extracting Polysaccharides from Agrocybe aegerita and In Vitro Antioxidant and Anti-Aging Tests.

The extraction process of crude polysaccharides from Agrocybe aegerita was optimized, and the antioxidant and anti-aging effects of the crude polysaccharides were evaluated. The optimal extraction parameters for the polysaccharide were identified using the response surface methodology. The DPPH, hydroxy radical, and superoxide anion radical scavenging capacities were evaluated to determine the antioxidant properties of the AAPs. The effects of the AAPs on the lifespan, head-swing frequency, swallowing frequency, body-bending frequency, and stress resistance of Caenorhabditis elegans were determined. The optimal extraction conditions included a solid-to-liquid ratio that resulted in an extraction solution concentration of 0.034 g/mL, an extraction temperature of 92.64 °C, and an extraction time of 2.82 h. Under these conditions, the yield of the AAPs was 11.325% ± 0.996%. The IC50 of the AAPs for superoxide anion radical scavenging was 4.693 mg/mL. The AAPs reached their maximum activity at concentrations of about 2 mg/mL for DPPH and 5 mg/mL for the hydroxyl radical. The AAPs could prolong the lifespan and improve locomotion and the stress resistance of C. elegans. Our findings illustrate the potential of AAPs as an anti-aging and antioxidant agent, highlighting the use of this natural compound in the fields of food and pharmacology.

Insights into Catechin-Copper Complex Structure and Biologic Activity Modulation.

Compounds of natural origin found in varying quantities in plant-based products constitute a highly significant category, possessing structural significance as well as the capacity to regulate oxidative processes. The activity of these compounds may be modulated by the composition of the biological environment in which they operate, the pH of the environment, or the presence of metal cations in plants or plant extracts. A successful complexation reaction was mainly confirmed by FT-IR, observing the shift from the original transmittance of catechin bonds, especially O-H ones. This work shows the synthetic methodology and the optimization process that took place to synthesize a catechin-copper complex, which demonstrated antioxidant activity. It was tested for iron chelation ability, hydroxyl radicals, and the inhibition of lipoxygenase (15-LOX). An antidiabetic assay was performed by determining the inhibition of alpha-amylase and alpha-glucosidase, finding that the synthesized complex had similar inhibitory potential as pure catechin. The antibacterial tests showed results against Staphylococcus aureus and the antifungal properties of the complex against Candida albicans.

Black Carbon Radiative Impacts on Surface Atmospheric Oxidants in China with WRF-Chem Simulation

Black carbon (BC) changes the radiative flux in the atmosphere by absorbing solar radiation, influencing photochemistry in the troposphere. To evaluate the seasonal direct radiative effects (DREs) of BC and its influence on surface atmospheric oxidants in China, the WRF-Chem model was utilized in this study. The simulation results suggested that the average annual mean values of the clear-sky DREs of BC at the top of the atmosphere, in the atmosphere and at the surface over China are +2.61, +6.27 and −3.66 W m−2, respectively. Corresponding to the seasonal variations of BC concentrations, the relative changes of the mean surface photolysis rates (J[O1D], J[NO2] and J[HCHO]) in the four seasons range between −3.47% and −6.18% after turning off the BC absorption, which further leads to relative changes from −4.27% to −6.82%, −2.14% to −4.40% and −0.47% to −2.73% in hydroxyl (OH) radicals, hydroperoxyl (HO2) radicals and ozone (O3), respectively. However, different from the relative changes, the absolute changes in OH and HO2 radicals and O3 after turning off BC absorption show discrepancies among the different seasons. In the North China Plain (NCP) region, O3 concentration decreases by 1.79 ppb in the summer, which is higher than the magnitudes of 0.24–0.88 ppb in the other seasons. In southern China, the concentrations of OH and HO2 radicals reach the maximum decreases in the spring and autumn, followed by those in the summer and winter, which is due to the enhancement of solar radiation and the summer monsoon. Thus, BC inhibits the formation of atmospheric oxidants, which further weakens the atmospheric oxidative capacity.

Decolorization of Acid Red 337 dye with hydroxyl and sulfate radical based advanced oxidation processes using different iron Catalyst: An experimental and statistical Investigation

The removal efficiencies of Acid Red 337 dye were investigated by combining advanced oxidation processes based on OH and SO4− radicals. The photocatalytic oxidation processes were carried out at the natural pH (5.4) and acidic pH (3.0) values of the dye solution. In the experiments, iron (II) sulfate (Fe2+) and potassium ferrioxalate (FeOx) were used as catalysts, hydrogen peroxide (H2O2) and peroxymonosulfate (PMS) were used as oxidants to compare dye removal efficiency and to determine the optimum doses. This comparison provided the opportunity to identify suitable catalysts and oxidants for dye removal. Furthermore, time-based comparisons were conducted from 2 to 10 min using the optimum catalyst doses. It was obtained that PMS was more effective as an oxidant in the presence of both iron catalysts for colour removal. The colour removal efficiency of 98.2 % was achieved in the PMS/Fe2+/UV process with doses of 1 mM PMS and 0.1 mM Fe2+ at pH 5.4 and an irradiation time of 10 min. In experiments using light-sensitive ferrioxalate (FeOx), colour removal was achieved in the PMS/FeOx/UV process with an efficiency of 97.8 %. Additionally, an artificial neural networks (ANNs) model effectively optimized the oxidation parameters, with predicted values closely matching the experimental data. The ANNs model yielded excellent statistical performance, with a root mean square error (RMSE) of 0.0317, 0.0223 and coefficient of determination (R2) of 0.9690 and 0.9854 for UV/Fe2+/H2O2-UV/FeOx/H2O2 and UV/Fe2+/PMS-UV/FeOx/PMS oxidation systems respectively.

OH Radical Oxidation of Organosulfates in the Atmospheric Aqueous Phase.

Organosulfates (OS, ROSO3-), ubiquitous constituents of atmospheric particulate matter (PM), influence both the physicochemical and climatic properties of PM. Although the formation pathways of OS have been extensively researched, only a few studies have investigated the atmospheric fate of this class of compounds. Here, to better understand the reactivity and transformation of OS under cloudwater- and aerosol-relevant conditions, we investigate the hydroxyl radical (OH) oxidation bimolecular rate constants (kOS+OHII) and products of five atmospherically relevant OS as a function of pH and ionic strength: methyl sulfate (MeS), ethyl sulfate (EtS), propyl sulfate (PrS), hydroxyacetone sulfate (HaS) and phenyl sulfate (PhS). Our results show that OS are oxidized by OH with kOS+OHII between 108 - 109 M-1 s-1, which corresponds to atmospheric lifetimes of minutes in aqueous aerosol to days in cloudwater. We find that kOS+OHII increases with carbon chain length (MeS < EtS < PrS) and aromaticity (PrS < PhS), but does not depend on solution pH (2, 9). In addition, we find that whereas the OH reactivity of the aliphatic OS studied here decreases by ∼2× with increasing ionic strength (0-15 M), the reactivity of PhS decreases by ∼10×. The oxidation of EtS and PrS produced organic peroxides (ROOH) as first-generation oxidation products, which subsequently photolyzed; the oxidation of PhS resulted in hydroxylated aromatic products. These results highlight the need for inclusion of OS loss pathways in atmospheric models, and suggest caution in using ambient OS concentration measurements alone to estimate their production rates.

A Dual Approach by Nanostructured α-Mangostin-Copper Oxide Complexes Against Dental Pathogen Biofilms and Oral Cancer via Apoptosis Gene Modulation.

The development of effective treatments for dental pathogens and oral cancer remains a significant challenge. Copper oxide nanoparticles (CuO NPs) are recognized for their strong antimicrobial properties, attributed to the synthesis of oxygen-dependent radicals. α-Mangostin (MG), a natural xanthone from mangosteen fruit, is well-known for its antioxidant, antimicrobial, and anticancer potential. Antioxidant activity was assessed using superoxide anion and hydroxyl radical anion. The anticancer potential was evaluated by examining apoptosis induction in oral cancer cell lines, focusing on the expression of key apoptotic markers such as Caspase-3, Caspase-8, and FasL. Molecular docking simulations were performed to understand the interaction between MG and biofilm receptors. The CuO-MG NPs evidenced significant antimicrobial efficacy against all tested oral pathogens, with enhanced efficacy attributed to the combined effects of CuO-induced oxidative stress and the antimicrobial properties of MG. Molecular docking studies revealed strong binding affinities of MG to key biofilm receptors, disrupting pathogen adhesion and biofilm formation. CuO-MG NPs demonstrate synergistic antimicrobial, antioxidant, and anticancer properties, offering a potential approach for the management of oral infections and oral cancer. Further preclinical and clinical studies are recommended to ensure their safety and stability in medical applications.

Photocatalytic degradation of ampicillin antibiotics in aqueous solution utilizing ZnFe2O4/MWCNTs/TiO2 ternary nanocomposite under solar light irradiation

In this study, a novel photocatalyst composed of zinc ferrite (ZnFe₂O₄), titanium dioxide (TiO₂), and multi-walled carbon nanotubes (MWCNTs) was successfully synthesized via the hydrothermal method, and evaluated for the degradation of ampicillin (AMP) in aqueous solutions. The synthesized nanocomposites were thoroughly characterized using various analytical techniques, including XRD, HR-SEM, HR-TEM, EDX, UV-Vis, FT-IR, BET, and XPS analysis. Crystallite sizes of 24.18 nm for ZnFe₂O₄ and 17.8 nm for TiO₂ were determined. The composite exhibited a band gap of 1.4 eV, indicating its enhanced photocatalytic activity. The photocatalytic performance was assessed under varying conditions, including different nanocomposite dosages (0.3–1 g/L), AMP concentrations (10–50 mg/L), and pH values (2–12). The optimal AMP degradation efficiency of 99.2 % was achieved using 0.7 g/L of the photocatalyst, 10 mg/L of AMP, and a pH of 12 under 90 min of solar irradiation. These optimal parameters were then applied to evaluate AMP degradation using ZnFe2O4, TiO2, and ZnFe2O4/MWCNTs individually, with the degradation rate analyzed using a pseudo-first-order model. The superior photocatalytic efficiency can be primarily attributed to improved charge transfer dynamics and effective electron-hole separation, enabled by the doping of MWCNTs. Hydroxyl radicals (OH•) were identified as the primary reactive species responsible for AMP degradation. Furthermore, the catalyst retained 91 % of its photocatalytic efficiency after eight consecutive cycles, demonstrating excellent stability and reusability. These results underscore the potential of the ZnFe₂O₄/MWCNTs/TiO₂ composite as a highly effective and sustainable photocatalyst for removing pharmaceutical pollutants from aquatic environments.

Tetracycline removal via photo-Fenton processes using Fe-based metal-organic frameworks loaded with Bi2S3: Performance evaluation and insights into the charge-transfer mechanism

Combining photocatalytic technology with the Fenton system may help overcome these technologies’ limitations. Photo-Fenton catalysis is economical and eco-friendly. The Fe based heterogeneous photo-Fenton process appears to be a promising wastewater treatment technology. Herein, an Fe based metal–organic framework (MIL-101 (Fe)) was produced via hydrothermal processing. Subsequently, Bi2S3 was loaded onto the surface of MIL-101 (Fe) to form a composite catalyst. A type-II heterojunction was established between MIL-101 (Fe) and Bi2S3. The 10 % Bi2S3-loaded MIL-101 (Fe) (MBS-10) was effective in the photocatalytic degradation of tetracycline, particularly after H2O2 addition. This outcome was due to the enhanced generation of radical species through the photo-Fenton process. The MBS-10 photocatalyst promoted Fe (II)/Fe (III) cycling in the presence of H2O2 and under visible light irradiation. MBS-10 also showed a higher kinetic rate constant during the photocatalytic reaction compared to MIL-101 (Fe) and Bi2S3, suggesting enhanced activity through greater electron-hole separation. Furthermore, MBS-10 proved to be stable and reusable photocatalyst after four testing cycles. The charge-transfer mechanism was elucidated through radical scavenging experiments which demonstrated that superoxide and hydroxyl radicals are the major charge carriers. Therefore, the Bi2S3-MIL-101 (Fe) composite exhibits great potential for degrading tetracycline antibiotics.

In-depth analysis of the roles and mechanisms of sulfate radical and hydroxyl radical in the degradation of metal-cyanide complexes

Persulfate-based advanced oxidation processes (PS-based AOPs), characterized by the coexistence of SO₄•⁻ and HO•, have been proven effective in treating a series of cyanide-bearing pollutants. However, the mechanisms of these reactive species in the degradation of cyanides, especially metal-cyanide complexes, remain unclear or contradictory. The degradation behavior of representative cyanides (including potassium cyanide and potassium ferricyanide) at different pH conditions (2, 7 and 12) in thermally activated persulfate system (T = 60 °C) was explored, and the roles of SO₄•⁻ and HO• in cyanide degradation were explored by leveraging the distinct characteristics of reactive species under different pH conditions. The study found that both HO• and SO₄•⁻ can react with free cyanide (CN⁻ and HCN). However, the reaction barrier between CN⁻ and HO• is lower than that between HCN and SO₄•⁻, resulting in a higher removal rate of free cyanide under alkaline conditions compared to acidic and neutral conditions. For complexed cyanide, the complex bonds in ferricyanide were completely broken within 24 h by thermally activated persulfate at pH 2, releasing free cyanide, indicating the effectiveness of SO₄•⁻ in breaking the Fe-C bonds in ferricyanide. In contrast, ferricyanide was barely decomposed at pH 12, implying the inefficacy of HO• in breaking the Fe-C bonds. This study also innovatively found that SO₄•⁻ breaks the Fe-C bonds by oxidizing Fe(Ⅲ) in ferricyanide to Fe(Ⅳ) or Fe(Ⅴ), releasing CN⁻, which is then converted to CNO⁻ by SO₄•⁻ and HO•. CNO⁻ is further mineralized to NO₃⁻, NH₄⁺, and N₂ through hydrolysis or oxidation reactions. This research clarifies, for the first time, the activity of SO₄•⁻ and HO• toward cyanide degradation in PS-based AOPs.

Ag induced plasmonic TiO2 for photocatalytic degradation of pharmaceutical under visible light: Insights into mechanism, antimicrobial and cytotoxicity studies

Global concerns include water scarcity and shortage, which are escalated by organic pollutants such as naproxen (NPX) that deteriorate drinking water and taint access to safe drinking water by humans. Moreover, NPX may cause gastrointestinal difficulties, cardiovascular risks, kidney damage, allergic reactions, liver toxicity, bleeding issues and pregnancy risks, hence it is essential to remove it in water. Ag-TiO2 was synthesized by hydrothermal method for NPX degradation. Ag on TiO2 reduced the band gap and surface area of TiO2 and resulted in a plasmonic Ag-TiO2 composite of 0.2 % Ag. The photocatalytic degradation of 0.2 % Ag-TiO2 was 80 % in 180 minutes using a solar simulator during NPX degradation with a first order reaction rate that was 3.6 times faster than that of pure TiO2 and the catalyst showed good stability for four cycles. The dual activity of Ag0 surface plasmon resonance improved light absorption capability and enhanced charge transfer for increased photodegradation rate and stability. The antibacterial studies demonstrated that 0.2 % Ag-TiO2 posted strong antibacterial properties under light irradiation and less in the dark, with a greater effect on gram-negative than gram-positive bacteria. The minimum inhibitory concentration (MIC) values of 620, 1250, 2500, 2500 µg/mL were attained against B. subtilis, S. aureus, E. coli and S. typhimurium bacteria, respectively. The low cell toxicity of 0.2 % Ag-TiO2 was determined using human embryonic kidney (HEK293) cells with an inhibitory concentration (IC50) of 61.09 ± 0.24 µg/mL under light irradiation. Radical trapping experiments demonstrated that hydroxyl radicals (OH•) played a vital role during the degradation and bactericidal activity of NPX under light irradiation. This work advances new insights on the synthesis of less toxic nanoparticles with high photocatalytic and bactericidal activity for possible applications at industrial scale.

Excited-State Decay and Photolysis of O-Nitrophenol before Proton Transfer. I: A Theoretical Investigation in the Microsolvated Atmospheric Environment.

As a potential source of the hydroxyl (OH) radical and nitrous acid (HONO), photolysis of o-nitrophenol (ONP) is of significant interest in both experimental and theoretical studies. In the atmospheric environment, the number of water molecules surrounding ONP changes with the humidity of the air, leading to an anisotropic chemical environment. This may have an impact on the photodynamics of ONP and provide a mechanism that differs from previously reported ones in the gas phase or in solution. Herein, the high-level MS-CASPT2//CASSCF method was performed to elucidate the excited-state decay and the generation of the OH radical for ONP before proton transfer in the microsolvated surrounding. We found that the varying number of water molecules affects the ground-state structures and alters the energy levels of nπ* and ππ* at the Franck-Condon (FC) region. Nevertheless, this is not the case for the excited-state minima, which exhibit very similar adiabatic excitation properties. In addition, the presence of water molecules also significantly influences the intersection structures since hydrogen bonds will hinder or alleviate the rotation or pyramidalization of the nitro (NO2) group. This will, in turn, change the excited-state relaxation mechanism of ONP. Finally, we speculated that the OH radical might be formed in the hot ground state of ONP in the microsolvated surrounding after exploring all possible electronic states.

Sonochemical preparation of powerful S-scheme Zr(HPO4)2/g-C3N4 heterojunction for photocatalytic degradation of rhodamine B under natural solar radiations

An effective Zr(HPO4)2/g-C3N4 S-scheme heterojunction was synthesized by sonochemical coupling of Zr(HPO4)2 nanoparticles as an oxidative photocatalyst [EVB = +3.0 eV] with g-C3N4 nanosheets as an effective reductive photocatalyst [ECB = −1.25 eV] for photocatalytic degradation of rhodamine B dye under natural solar radiation of 1000 W power. The physicochemical properties of the as-synthesized heterojunctions were investigated by X-ray diffraction [XRD], N2-adsorption-desorption isotherm, diffuse reflectance spectrum [DRS], photoluminescence [PL], scanning electron microscope [SEM], X-ray photoelectron spectroscope [XPS], and high resolution transmission electron microscope [HRTEM]. The experimental results implied the agglomeration of Zr(HPO4)2 nanoparticles on g-C3N4 sheets which reduced the specific surface area of the solid specimen from 88 to 21 m2/g. The significant increase in the photocatalytic degradation rate of RhB dye with introducing Zr(HPO4)2 nanoparticles implied that Zr(HPO4)2 plays a crucial role in reducing the band gap energy and remarkable increasing in the rate of electron-hole separation. The photocatalytic experiments implied that incorporation of 5 wt% Zr(HPO4)2 on g-C3N4 sheets destroyed 98 % of RhB dye during 3 h of light illumination with pseudo-first-order rate of 0.048 min−1. The remarkable enhancement in the photocatalytic performance of Zr(HPO4)2/g-C3N4 heterojunctions was ascribed to successful generation of an effective S-scheme heterojunction with strong redox power, utilizing of both hydroxyl and superoxide radicals in the degradation process and limiting the electron-hole recombination rate. Based on scavenger experiments and terephthalic acid PL analysis, the S-scheme pathway was chosen as the proposed mechanism for photocatalytic charge transfer. The as-synthesized Zr(HPO4)2/g-C3N4 heterojunction with exceptional redox power is considered a novel candidate for destructing organic pollutants that exist in industrial wastewater.

Iron Single-Atom Nanozyme with Inflammation-Suppressing for Inhibiting Multidrug-Resistant Bacterial Infection and Facilitating Wound Healing.

Infection with drug-resistant bacteria and the formation of biofilms are the main factors contributing to wound healing insufficiency. Antibacterial agents with enzyme-like properties have exhibited considerable potential for efficient eradication of drug-resistant microorganisms due to their superior sensitivities and minimal side effects. In this work, we prepared a kind of Fe-centered single-atom nanozyme (Fe-SAzyme) with high biocompatibility and stability via a facile one-pot hydrothermal method, which was suitable for the treatment of wounds infected with drug-resistant bacteria. The Fe-SAzyme exhibited remarkable peroxidase-like catalytic activities, catalyzing the conversion of hydrogen peroxide (H2O2) to highly toxic hydroxyl radicals (•OH), which could not only damage bacterial cells but also inhibit, disrupt, and eradicate the formation of bacterial biofilms. Thus, Fe-SAzyme demonstrated a broad-spectrum antibacterial performance capable of effectively eliminating multidrug-resistant bacteria. The coexistence of ferrous (Fe2+) and ferric (Fe3+) ions in Fe-SAzyme conferred the nanozyme with anti-inflammatory activity, effectively suppressing excessive inflammation. Meanwhile, Fe-SAzyme could significantly downregulate inflammatory cytokines tumor necrosis factor-α and interleukin-1β and upregulate growth factors VEGF and epidermal growth factor, which can prevent bacterial infection, mitigate inflammation, promote fibroblast proliferation, and improve wound closure. Thus, Fe-SAzyme had shown favorable therapeutic efficiency in promoting bacteria-infected wound healing. This study provides Fe-SAzyme as a promising candidate for the development of new strategies to treat multidrug-resistant bacterial infections.

Dual Cocatalysts on Covalent Organic Framework as Charge Transfer Mediator Facilitating Photocatalytic Water Oxidation

AbstractCovalent organic frameworks (COFs) have been regarded as promising photocatalytic materials. However, the sluggish diffusion of photoinduced charges in a single‐component COF remains the obstacles that have to be overcome. Here, we demonstrate a synthesis of a COF bearing dual cocatalysts Co3O4 and Re complex as photocatalyst for water oxidation. The dual cocatalysts are coordinated on the COF, and enable the spatial separation of photoinduced charges. The generated electrons were attracted to Re moiety, while the holes were localized on Co3O4 cocatalyst for water oxidation to produce O2 product. The synergy of dual cocatalysts of COF promote the charge separation and redox reaction. Moreover, hydroxyl radicals generated from the hydration of COF contribute to O−O bond formation, which is the key step of O2 formation. Accordingly, an excellent O2 production rate of 400 μmol g−1 h−1 under visible light irradiation was obtained. This work may pave the way to the development of highly efficient COF photocatalysts for solar energy conversion.

Inhibitory effect of L-arginine on the oxidative aggregation behavior of myofibrillar proteins in the Antarctic krill (Euphausia superba): pH and antioxidation

In this study, the effect of L-arginine (L-Arg) on the oxidative aggregation of myofibrillar proteins (MPs) in Antarctic krill was evaluated. The results showed that the oxidized aggregation of MPs was significantly inhibited after the addition of 20 mM L-Arg compared to the oxidized group, the solubility of MPs significantly increased by 25.74 %, the turbidity reduced from 0.56 to 0.18. These effects were primarily attributed to the addition of L-Arg, which prevented the unfolding of the spatial structure of MPs after oxidation, inhibited the formation of disulfide bonds and dityrosine, and improved the stability of MPs structure. Analysis of carbonyl content and hydroxyl radical (•OH) inhibitory capacity showed that carbonyl formation and hydroxyl radicals were effectively reduced by the pH and guanidinium group of L-Arg. The pH of L-Arg exhibited a significantly higher effect than the guanidinium group in inhibiting the oxidative aggregation of MPs.

Enhancing Microplastic Degradation through Synergistic Photocatalytic and Pretreatment Approaches.

Microplastics (MPs) pollution has emerged as a pressing environmental concern in recent years. Owing to their minute dimensions, conventional plastic remediation approaches are inadequate for addressing the challenges posed by MPs. Herein, spherical (BOC-S) and nanosheet (BOC-N) BiOCl photocatalysts were prepared and applied to the degradation of poly(ethylene terephthalate) (PET) MPs after hydrothermal pretreatment. The results indicated that the degradation efficiency of pretreated PET MPs using BOC-S and BOC-N photocatalysts was 8.8 and 6.9 times that of the unpretreated MPs under the same conditions. Comparative experiments confirmed the excellent performance of the photocatalysis-pretreatment system. The creation of pores on the surface of pretreated PET MPs facilitates the entry of active substances into the interior to cause damage, while the enhancement of hydrophilicity and specific surface area facilitates the contact between the catalyst and PET MPs, thus increasing the degradation efficiency. Free radical trapping experiments revealed that hydroxyl radicals (·OH) produced by photocatalysis had the greatest influence on the degradation performance of pretreated PET MPs. Finally, a possible photocatalytic degradation mechanism for PET MPs was proposed. This research offers a novel perspective on MPs degradation, providing valuable insights for advancing the efficacy of the process.

Optimization of Ultrasonic Extraction, Functional Properties, and Antioxidant Activity of Naematelia aurantialba Polysaccharides

AbstractNaematelia aurantialba (N. aurantialba) is a fungus rich in polysaccharides with medicinal and edible properties. Polysaccharides are the main active components of N. aurantialba; however, their biological activities and functional properties have not been widely explored. In this study, the ultrasonic extraction process for N. aurantialba polysaccharides (NAP) is optimized, and the physicochemical, functional, and antioxidant activities of the homogeneous fraction (NAP) are investigated. The optimal extraction conditions are a liquid–solid ratio of 50 mL g−1, ultrasonic power of 430 W, ultrasonic time of 32 min, resulting in an extraction rate of N. aurantialba polysaccharides of 48.68% ± 0.83%. NAP has a molecular weight of 915 kDa. The monosaccharide composition of NAP is as follows: mannose (59.04% ± 0.12%), xylose (23.89% ± 0.03%), glucuronic acid (14.07% ± 0.24%), galacturonic acid (2.12% ± 0.02%), and glucose (0.76% ± 0.02%). NAP exhibites water and oil retention capacities of 14.62 ± 0.25 g g−1 and 23.73 ± 0.85 g g−1, respectively. Furthermore, NAP demonstrates favorable moisture absorption and retention properties. The results show that NAP has a significantly stronger antioxidant effect, as demonstrated by its concentration‐dependent scavenging of ABTS, DPPH, and hydroxyl radicals.

Oxidative Processes and Xenobiotic Metabolism in Plants: Mechanisms of Defense and Potential Therapeutic Implications.

Plants are continuously exposed to environmental challenges, including pollutants, pesticides, and heavy metals, collectively termed xenobiotics. These substances induce oxidative stress by generating reactive oxygen species (ROS), which can damage cellular components such as lipids, proteins, and nucleic acids. To counteract this, plants have evolved complex metabolic pathways to detoxify and process these harmful compounds. Oxidative stress in plants primarily arises from the overproduction of hydrogen peroxide (H2O2), superoxide anions (O2•-), singlet oxygen (1O2), and hydroxyl radicals (•OH), by-products of metabolic activities such as photosynthesis and respiration. The presence of xenobiotics leads to a notable increase in ROS, which can result in cellular damage and metabolic disruption. To combat this, plants have developed a strong antioxidant defense mechanism that includes enzymatic antioxidants that work together to eliminate ROS, thereby reducing their harmful effects. In addition to enzymatic defenses, plants also synthesize various non-enzymatic antioxidants, including flavonoids, phenolic acids, and vitamins. These compounds effectively neutralize ROS and help regenerate other antioxidants, offering extensive protection against oxidative stress. The metabolism of xenobiotic substances in plants occurs in three stages: the first involves modification, which refers to the chemical alteration of xenobiotics to make them less harmful. The second involves conjugation, where the modified xenobiotics are combined with other substances to increase their solubility, facilitating their elimination from the plant. The third stage involves compartmentalization, which is the storage or isolation of conjugated xenobiotics in specific parts of the plant, helping to prevent damage to vital cellular functions. Secondary metabolites found in plants, such as alkaloids, terpenoids, and flavonoids, play a vital role in detoxification and the defense against oxidative stress. Gaining a deeper understanding of the oxidative mechanisms and the pathways of xenobiotic metabolism in plants is essential, as this knowledge can lead to the formulation of plant-derived strategies aimed at alleviating the effects of environmental pollution and enhancing human health by improving detoxification and antioxidant capabilities, as discussed in this review.

Z-scheme driven charge transfer in g-C3N4/α-Fe2O3 nanocomposites enabling photocatalytic degradation of crystal violet and chromium reduction

In this study, we demonstrated the design and fabrication of iron oxide-embedded protonated graphitic carbon nitride (α-Fe2O3/p-g-C3N4) nanocomposites for photocatalytic dye degradation and heavy metal reduction applications under sunlight irradiation. The developed nanocomposites, with varying weight percentages of α-Fe2O3, were characterized for their structural (XRD, FTIR, XPS), optical (absorption and photoluminescence), morphological (FE-SEM, TEM), and electrochemical (EIS) properties to elucidate their structure-property relationships. The synthesis method ensures the uniform dispersion of α-Fe2O3 nanoparticles, with a particle size range of 50–60 nm, onto p-g-C3N4. XPS analysis suggests the formation of an electrical layer at the interface of α-Fe2O3/p-g-C3N4, facilitating the formation of a Z-scheme heterojunction. The photoluminescence and EIS spectra of the nanocomposite indicated effective separation and transfer of photo-induced charge carriers, aided by a reduced bandgap energy of ∼2.63 eV. Notably, the optimized 10 wt% α-Fe2O3/p-g-C3N4 nanocomposite exhibited superior photocatalytic activity, degrading nearly 100 % of crystal violate dye and reducing 98 % of Cr(VI) ions, compared to bare p-g-C3N4, which degraded around 43 % of the dye and reduced 39 % of Cr(VI) ions under sunlight irradiation. Scavenger studies indicated that α-Fe2O3/p-g-C3N4 nanocomposites produce adequate superoxide anions and hydroxyl radicals for dye degradation and heavy metal ion reduction. The composite also demonstrated consistent recyclability up to 5 cycles with around 100 % cyclical efficiency. The pH-dependent photoreduction and cyclic dye degradation by the 10 wt% α-Fe2O3/p-g-C3N4 photocatalyst indicated excellent stability, making it suitable for the treatment of multi-pollutant wastewater.