Hydroxyl Radical Research Articles

Comediating Adsorption and Electron Transfer via Dual-Active Site Catalyst Construction for Improving the Treatment of Extraction Wastewater.

Solvent extraction is widely applied, while extraction wastewater treatment remains a hugechallengebecause of the stability of extractants.Heterogeneous Fenton-like catalysis is a promising method, but the short half-life of hydroxyl radicals (•OH)generated by hydrogen peroxide (H2O2)activation results in unsatisfactory •OH utilization and organics removal.Herein, an efficient strategy for treating extraction wastewater based on comediating adsorption and electron transfer by fluorine and nitrogen co-doped carbon (FNC) catalyst with dual-active site was developed. Specially, N sites adsorb organics andFsites activateH2O2, shortening the migration distanceof •OH. Theoretical calculation and di(2-ethylhexyl) phosphoric acid (D2EHPA)extraction wastewater degradation experimentshowed that F sitewith electron acquisition can transfer electrons provided by electron-rich D2EHPA enriched at N sites toH2O2,facilitating the continuous generation of •OH through lowering the energy barrier for H2O2activation.As a result, 96.49% D2EHPA in simulated wastewaterand 90.26% total organic carbonin realextraction wastewaterwere removed. Moreover, FNC catalystexhibited excellent reusability and ionic adaptability, and can be extended to the removal of various extractants. The proposed dual-active site catalyst providesan effective strategyforFenton-likereactiontotreatrefractory extraction wastewater, promotingsustainable development of solvent extraction industry.

Catalytically Active Ti-Based Nanomaterials for Hydroxyl Radical Mediated Clinical X-Ray Enhancement.

Nanoparticle radioenhancement offers a promising strategy for augmenting radiotherapy by locally increasing radiation damage to tumor tissue. While past research has predominantly focused on nanomaterials with high atomic numbers, such as Au and HfO2, recent work has revealed that their radioenhancement efficacy decreases considerably when using clinically relevant megavoltage X-rays as opposed to the orthovoltage X-rays typically employed in research settings. Here, radiocatalytically active Ti-based nanomaterials for clinical X-ray therapy settings are designed. A range of candidate materials, including TiO2 (optionally decorated with Ag or Pt nanoseeds), Ti-containing metal-organic frameworks (MOFs), and 2D Ti-based carbides known as Ti3C2Tx MXenes, is investigated. It is demonstrated that these titanium-based candidates remain consistently performant across a wide energy spectrum, from orthovoltage to megavoltage. This sustained performance is attributed to the catalytic generation of reactive oxygen species, moving beyond the simple physical dose enhancements associated with photoelectric effects. Beyond titania, emergent materials like titanium-based MOFs and MXenes exhibit encouraging results, achieving dose-enhancement factors of up to three in human soft tissue sarcoma cells. Notably, these enhancements are absent in healthy human fibroblast cells under similar conditions of particle uptake, underscoring the selective impact of titanium-based materials in augmenting radiotherapy across the clinically relevant spectral range.

L-Theanine Effectively Protects Against Copper-Facilitated Dopamine Oxidation: Implication for Relieving Dopamine Overflow-Associated Neurotoxicities.

Non-physiological disorders release dopamine into extracellular brain fluid to induce neurodegenerative brain diseases. The harmful mechanism of dopamine overflow is attributed to the dopamine-mediated production of hydroxyl radicals, suggesting that transition metal copper which is high in the brain is involved in promoting dopamine oxidation. MPP+ , an intermediate formed from the conversion of MPTP, is one of the most potent dopamine-releasing agents. It has been reported that L-theanine could improve motor dysfunction in MPTP-treated mice, suggesting that L-theanine may restrain copper-mediated oxidation of released dopamine. The present study examined the influences of L-theanine on extracellular dopamine-mediated cytotoxicity in the absence and presence of copper in SH-SY5Y cells. L-theanine significantly but only moderately suppressed cytotoxicity caused by dopamine alone. Surprisingly, dopamine together with copper rapidly and dramatically caused apoptotic responses by massively disrupting redox homeostasis. Nonetheless, L-theanine exhibited an extraordinary protective effect against these devastating events by chelating copper. The above great contrast in terms of copper could be recapitulated in a cell-free system. Though L-theanine reduced dopamine autoxidation as detected by HPLC, the capacity was not impressive, since a molar ratio of 10,000 (L-theanine to dopamine) was required for fully suppressing dopamine decrease. However, HPLC measurement showed that L-theanine was highly efficient in suppressing copper-mediated dopamine oxidation because only a molar ratio of 10 was required for fully suppressing dopamine decrease. Since copper plays a crucial role in promoting extracellular dopamine oxidation, our results suggest that L-theanine by chelating copper is an attractive food-based protective agent against dopamine overflow.

Degradation of sulfamethoxazole in a falling film dielectric barrier discharge system: Performance, mechanism and toxicity evaluation

The ubiquitous presence of sulfonamides (SAs) in wastewater poses serious risks to human health and ecosystem safety. This study evaluated the performance of a falling film dielectric barrier discharge (DBD) system on the removal of five SAs, namely sulfamethoxazole (SMX), sulfisoxazole (SIZ), sulfathiazole (STZ), sulfadiazine (SDZ) and sulfamerazine (SMR). Removal efficiencies >99 % were observed for all target SAs within 30 min of treatment, with pseudo-first order rate constants varying between 0.17 and 0.27 min−1. Superior removal efficiencies were achieved under acidic conditions compared to neutral and alkaline conditions. Using SMX as a model compound, mechanistic investigations revealed that the synergy of reactive oxygen species (ROS) and reactive nitrogen species (RNS) led to its efficient degradation, with peroxynitrites (ONOO−/ONOOH) and hydroxyl radical (OH) playing pivotal roles. SMX degradation pathways encompassing nitration/nitrosation, hydroxylation, deamination, CS and SN bond cleavage were proposed. The toxicity evaluation results demonstrated that the solution toxicity diminished following the plasma treatment under specific conditions. In particular, the solution treated with air or oxygen discharge enhanced the growth of wheat seedlings, suggesting the potential for reusing plasma-treated wastewater in agriculture. This study enhances our understanding of the underlying mechanisms involved in the plasma degradation of SAs and reveals the significant potential of plasma technology as a sustainable approach for treating wastewater.

Bacteria-Mediated Tumor-Targeting Delivery of Multienzyme-Mimicking Covalent Organic Frameworks Promoting Pyroptosis for Combinatorial Sono-Catalytic Immunotherapy.

Pyroptosis, an inflammatory cell death, has attracted great attention for potentiating a strong immune response against tumor cells. However, developing powerful pyroptosis inducers and then activating specific pyroptosis still remains challenging. Herein, a PEG-CuP-COF@∆St nanosystem is rationally designed, consisting of PEG-CuP-COF nanozyme pyroptosis inducers and tumor-targeting bacteria of the Salmonella Typhimurium strain VNP20009 (ΔSt), with an affinity for the tumor hypoxic microenvironment. The PEG-CuP-COF nanozymes possessed excellent sonodynamic performance and multienzyme-mimicking activities to generate reactive oxygen species (ROS) and then induce potent pyroptosis. The superoxide dismutase- and peroxidase-mimicking activities of PEG-CuP-COF catalytically produced hydrogen peroxide (H2O2) and hydroxyl radicals (•OH) which have important value in triggering acute inflammatory responses and pyroptosis. Moreover, PEG-CuP-COF showed outstanding glutathione peroxidase-mimicking activities, impairing the antioxidant defense in tumor cells and enhancing sonodynamic efficiency by making them more vulnerable to ROS-induced damage. During in vivo studies, PEG-CuP-COF@∆St nanosystem with its self-driven property exhibited impressive tumor-targeting capability and activated Caspase-3/gasdermin E-dependent pyroptosis to inhibit tumor growth. More importantly, it induced a powerful immune memory effect to prevent bone metastasis. In summary, this study introduces an innovative approach for combinatorial sono-catalytic immunotherapy using bacteria-mediated tumor-targeting delivery of nanozymes as specific pyroptosis inducers.

Iron complexes synthesized from FeOCl with carboxylic acid based ligands as Fenton-like catalysts for the highly efficient degradation of organic dyes over a wide pH range

Iron-based materials have garnered significant attention as Fenton-like catalysts for the degradation of organic dyes. However, challenges remain in optimizing hydroxyl radical (•OH) utilization and broadening the effective pH range for practical applications. In this study, three iron-based catalysts (complex 1, 2, 3) were synthesized via a hydrothermal method, utilizing iron oxychloride (FeOCl) as the metal ion source and 4,5-imidazole dicarboxylic acid, furan-2,5-dicarboxylic acid, and 5-hydroxyisophthalic acid as ligands, respectively. The results indicate that these synthesized Fe-based catalysts exhibit enhanced visible light absorption and superior photo-Fenton activity, outperforming FeOCl in the degradation of rhodamine B (Rh-B), crystal violet (CV), and methylene blue (MB). Moreover, the Fe-based catalyst system operates effectively over a wide pH range (1–8) and efficiently degrades organic dyes. In free radical scavenging experiments, hydroxyl radicals (•OH) and superoxide radicals (•O2-) were identified as the primary agents responsible for photocatalytic degradation. Among the catalysts, complex 1 displayed notable stability, retaining its catalytic activity after three reuse cycles. This work presents a promising approach for designing highly efficient and stable Fenton-like catalysts, offering excellent environmental remediation capabilities across a broad pH range.

α-Nucleophilic Addition to α,β-Unsaturated Carbonyl Compounds via Photocatalytically Generated α-Carbonyl Carbocations.

We report the photocatalytic oxidation of α-carbonyl radicals of amides or esters to the corresponding α-carbonyl carbocations through super photoreductant CBZ6 induced redox-neutral photocatalysis. The α-carbonyl radicals are formed by the β-addition of alkyl radicals generated in situ by the photocatalytic fragmentation of N-hydroxyphthalimide esters to the α,β-unsaturated amides and esters. This method enables the α-nucleophilic addition of hydroxyl or alkoxyl radicals to amides and esters without any prefunctionalization.

Kinetic Modeling of Brilliant Blue Discoloration by Ozonation

This paper presents the results of investigations on the kinetic modeling of Brilliant Blue FCF (BB) discoloration reactions in aqueous solutions with different ozone concentrations and pH conditions. Kinetic studies involve knowledge of the structure and properties of dye and ozone, as well as of the experimental conditions. In general, scientists admit that the predominant oxidation pathway is direct (by free oxygen atoms) or indirect (by free hydroxyl radicals); this will depend on influencing factors such as the physicochemical properties of the dye, the pH of the aqueous solution, ozone concentration, reaction time, and the contact mode with/without stirring. In this experimental research, two pathways were chosen following CBB = f(t)—1. a constant dye concentration and different ozone concentrations, in the concentration range of 100–250 mg/L, in three pH media (acidic, neutral, and basic), with and without stirring; 2. a constant concentration of ozone and different dyes in the concentration range of 2.5–10 mg/L, under the conditions of point 1. With the obtained experimental data, the curves CBB = f(t) were drawn and processed according to the integral method of classical kinetics, based on first- and second-order equations. Unfortunately, this simple procedure did not give any results for the pH values studied. The rate constants were negative, and/or the reaction order depended on the initial conditions. Due to its structure, the BB dye has several chromophore groups, and thus multiple attack centers, resulting in several oxidation by-products, which is why the 1H-NMR spectrum was recorded for the discoloration of BB with ozone. Since the stoichiometry of the overall oxidation reaction, as well as the relationship between the rate constant and the reaction conditions mentioned above, is not known, a kinetic model based on mass transfer coupled with a chain reaction in the bulk liquid phase was proposed and successfully tested at pH = 7. This research approach also involves the consolidation of the theoretical bases of the ozonation process through the kinetic study carried out, as well as the proposal of a kinetic model. These systematics lead to results that are applicable to other aqueous systems that are impure with dyes, allowing for generalizations and the development of the field, ensuring the sustainability of the research.

Antioxidant peptides from silver carp steak by alkaline protease and flavor enzyme hydrolysis: Characterization of their structure and cytoprotective effects against H2O2-induced oxidative stress.

Silver carp steak is a rarely utilized silver carp processing byproduct. This study aimed to optimize a dual enzymatic method to extract antioxidant peptide components from silver carp steak and characterize their structure and in vitro antioxidant activity through ultrafiltration purification, response surface methodology, molecular docking, and radical scavenging activity analysis. The optimal extraction conditions for silver carp steak antioxidant peptides (SCSAP) were determined as 1:6 solid-liquid ratio, 1500 U/g alkaline protease addition, 4 h alkaline protease hydrolysis time, 1946 U/g flavor enzyme addition, and 2.5 h flavor enzyme hydrolysis time. The <3 kDa SCSAP component (SCSAP-3kDa) showed the strongest antioxidant activity, with its 1,1-diphenyl-2-trinitrophenyl hydrazine (DPPH) radical scavenging rate, ABTS radical scavenging rate, hydroxyl radical scavenging rate, metal ion chelating rate, and reducing capacity reaching 88.75%, 91.21%, 67.02%, 69.07%, and 0.985, respectively. Moreover, the three peptides (PF-7, GP-8, and YF-10) of 100 µg/mL could protect HepG2 cells from oxidative stress damage by reducing the oxidative damage level and activating Keap1-Nrf2-ARE pathways, enabling an increase of superoxide dismutases (SOD) activity, and a decrease of malondialdehyde (MDA) content and reactive oxygen species (ROS) level. The integrated results indicate the enormous potential of SCSAP-3kDa as a functional food ingredient in the food industry. PRACTICAL APPLICATION: This study selected the antioxidant capacity of silver carp steak peptides as the index and developed a facile dual enzymatic hydrolysis method to obtain three antioxidant peptides (PF-7, GP-8, and YF-10) with biological activity, providing a theoretical basis for bioavailability of antioxidant peptides from silver carp steak and contributing to their application in new functional foods.

Indirect photodegradation of pharmaceutical and personal care products in dissolved black carbon solution: The role of microheterogeneous distribution of hydroxyl radical and sorption

Dissolved black carbon (DBC) with a hyperconjugated structure is ubiquitous in nature, and plays a crucial role in the migration and transformation of environmental contaminants due to its prominent properties of accepting electrons and sorption. However, little is known about the DBC-induced phototransformation of pharmaceutical and personal care products (PPCPs) in natural waters. Herein, the photodegradation kinetics of PPCPs were investigated in DBC solution under simulated solar irradiation and compared with those in Suwannee River natural organic matter (SRNOM) solution. The decay rates for the positively charged PPCPs (mean 1.484 ± 0.041 h-1) were significantly higher than those for the negatively charged PPCPs (mean 0.014 ± 0.002 h-1) in DBC solution due to the charge interaction. Moreover, the decay rates for the positively charged PPCPs in DBC solution were approximately 3–16 times of those in SRNOM solution due to the discrepant sorption and ability to produce bonded HO•. Finally, a microheterogeneous photodegradation mechanism of HO•-labile PPCPs in DBC solution involving the sorption and subsequent reaction with bonded HO• in the DBC microphase was proposed, which was verified using isopropanol and isopropamide as selective HO• scavengers. This work will provide useful insights into the photochemistry of DBC and also the DBC-involved phototransformation of PPCPs in aquatic environments.

Breakdown cost and recycling processes of Bentonite/TiO2 quantum dots of photo and solar degradation of Congo Red dye and industrial dyes wastes

This research presents the preparation, characterization, and application of a novel bentonite- TiO2 quantum dot (Bent/TQ) nanocomposite for the efficient photodegradation of Congo Red dye, a common pollutant in industrial wastewater. The composite was prepared via a co-precipitation method followed by calcination, which facilitated the uniform dispersion of TiO2 quantum dots within the bentonite matrix. The resulting material exhibited a high specific surface area of 205.45 m2/g and an optimized band gap of 3.15 eV, making it suitable for visible light photocatalysis. The photocatalytic efficiency of Bent/TQ was evaluated under both xenon lamp irradiation and natural sunlight. The composite demonstrated a significant degradation rate constant of 23.35 × 10⁻³ s⁻1, which is comparable to that of pure TiO2 quantum dots (28.86 × 10⁻³ s⁻1). Mechanistic studies revealed that the primary active species responsible for the degradation were hydroxyl radicals (•OH), generated through the interaction of photogenerated electron-hole pairs with H2O molecules and molecular oxygen. Total Organic Carbon (TOC) and Chemical Oxygen Demand (COD) analyses were employed to assess the mineralization efficiency of the composite. The Bent/TQ catalyst achieved a COD removal efficiency of 84.5% and a TOC reduction of 76.2% after 240 minutes of irradiation under natural sunlight. Reusability tests indicated that the photocatalyst retained approximately 80% of its original efficiency after seven consecutive cycles, though a slight decline was observed due to particle agglomeration under prolonged light exposure. The economic analysis suggested that the use of Bent/TQ nanocomposites could reduce operational costs by 29.12% compared to conventional TiO2-based systems, making it a cost-effective solution for large-scale wastewater treatment. This work highlights the potential of Bent/TQ nanocomposites as sustainable and efficient photocatalysts for environmental remediation, with future efforts aimed at enhancing their long-term stability and expanding their applicability to a broader range of pollutants.

Construction and degradation mechanism of the magnetic CoFe1.95Y0.05O4/Ag/g-C3N4 Z-scheme heterojunction for enhanced photocatalytic activity

In this study, a Z-scheme heterojunction CoFe1.95Y0.05O4/Ag/g-C3N4 (CFYO/ACN) magnetic nanocomposite was prepared by hydrothermal synthesis. The composite was characterised and analysed using different characterisation tools and its photocatalytic degradation activity towards methylene blue (MB) was investigated. The results showed that the CFYO/ACN photocatalyst compared to CoFe1.95Y0.05O4 (CFYO) and Ag/g-C3N4 (ACN), the composite CFYO/ACN had the highest degradation efficiency of MB, which was up to 97% within 120 min, which was 1.26 and 1.09 times higher than that of ACN and CFYO, respectively. The enhancement of the catalytic performance of CFYO/ACN was attributed to the fact that the heterogeneous junction formation effectively inhibited the complexation of photogenerated carriers. In addition, five consecutive cyclic degradation experiments showed that CFYO/ACN exhibited efficient photocatalytic degradation, stable crystal structure, and easy recycling in the photodegradation process. Finally, the capture experiments confirmed that superoxide radicals () and hydroxyl radicals (·OH) play a major role in the degradation process. This study provides an effective strategy for the construction of efficient photocatalysts.

Significant Biogenic Source of Oxygenated Volatile Organic Compounds and the Impacts on Photochemistry at a Regional Background Site in South China.

Oxygenated volatile organic compounds (OVOCs) significantly modulate atmospheric chemistry, but the sources and air quality impacts of OVOCs in aged urban outflows remain to be elucidated. At a background site in South China, the ozone formation potential of six nonformaldehyde OVOCs studied was equivalent to that of 3.56 ppbv of formaldehyde, more than half of which was contributed by acetaldehyde. Source apportionment incorporating photochemical age revealed that considerable fractions (52.7%-62.6%) of the OVOCs were of biogenic origin, except for ethanol, which was primarily derived from anthropogenic emissions. The oxidation of cis-/trans-2-butene explained 71.1% of the in situ acetaldehyde formation. In contrast, α/β-pinenes and isoprene contributed 73.8% and 28.4% to acetone and methylglyoxal formation, respectively. An average of 12.4% of net in situ ozone (O3) production rate was attributed to the OVOCs studied, where the biogenic fractions accounted for 59%. The changes in the O3 production rate and hydroxyl radical (OH) concentration caused by OVOCs were mainly affected by ozone formation sensitivity. The effects of primary acetaldehyde and acetaldehyde-led O3 on secondary acetaldehyde formation were weak at this background site; however, they cannot be ignored in polluted areas. This study provides a scientific basis for mitigating O3 pollution driven by biogenic emissions and OVOCs.

Low-frequency contact-electro-catalysis driven by friction between the PTFE-coated fabric and dye solution

The process of contact electrification occurs when two materials with dissimilar work functions are in contact and charged. Contact-electro-catalysis may occur when electron exchange at the liquid-solid interface initiates a redox reaction. This type of catalysis falls under the mechanically-driven tribocatalysis and has been demonstrated to be able to degrade dye under high-frequency ultrasonic excitation. In this work, a high RhB dye decomposition ratio of 91.5% is achieved by harnessing the ordinary low-frequency solid-liquid friction energy through the design and use of the recyclable fabric with PTFE coating as a solid friction source to agitate the dye solution. In the absence of PTFE coating, the RhB dye decomposition ratio is about 14.8% under the same friction conditions. The enhanced contact-electro-catalysis may be attributed to the high electronegativity of PTFE coating. According to the quenching experiments with active species, it is found that hydroxyl radical (·OH) and superoxide radical (·O2-) are the main active species induced by low-frequency solid-liquid friction. The fabric with PTFE coating after being dried and reused for 5 cycles still possesses 87.9% RhB dye decomposition ratio. With these advantages of high decomposition ratio of organic pollution, low cost, good recyclability, and environmental friendliness, the developed low-frequency contact-electro-catalysis in this work, is potential for organic wastewater treatment application through utilizing waste solid materials to harvest the mechanical friction energy between solid waste fabrics and ordinary waterflow in future.

Mercury Reduction by Agricultural Organic Waste-Derived Dissolved Organic Matter: Kinetic Analysis and the Role of Light-Induced Free Radicals.

Agricultural organic wastes can leach dissolved organic matter (DOM) into surrounding water bodies, establishing them as significant sources of aquatic DOM. Given the importance of DOM in the biogeochemical cycling of mercury (Hg), this DOM may further mediate divalent Hg (Hg(II)) reduction, a process that remains poorly understood. This study investigated the Hg(II) reduction using DOM derived from six representative agricultural wastes, categorized into livestock manure (chicken, pig, cow) and crop straw (rice, corn, rapeseed), with systematic considerations of the kinetics of reduction processes and the involvement of key free radicals. Results revealed that photoreduction was the primary pathway for Hg(II) reduction, with pig manure DOM exhibiting the highest efficiency at 36%. Key DOM quality parameters, such as protein-like components, have been identified as critical determinants of Hg(II) photoreduction capacity. Furthermore, free radicals induced by DOM could either enhance or inhibit Hg(II) reduction capacities. Specifically, in livestock manure, the superoxide anion (O2•-)·was identified as the primary radical promoting Hg(II) photoreduction of pig manure DOM. In crop straw, hydroxyl radicals (·OH) were found to inhibit Hg(II) photoreduction, whereas O2•- promoted the Hg(II) photoreduction of rice straw DOM. These findings provide valuable insights into the role of agricultural organic wastes in the biogeochemical cycling of Hg within aquatic ecosystems.

Structural characteristics of Lacticaseibacillus rhamnosus ACS5 exopolysaccharide in association with its antioxidant and antidiabetic activity in vitro

A novel structure of exopolysaccharide from the Lactic Acid Bacteria (LAB) Lacticaseibacillus rhamnosus ACS5, isolated from home-made Turkish cheese, is described. After lyophilization, the L-EPS-ACS5 was characterized in production and functional activities in vitro, including antioxidant and antidiabetic activities. The physicochemical characterizations of the L-EPS-ACS5 were determined through molecular weight, UV, FTIR, SEM, TGA, HPLC, NMR, methylation, and GC–MS analysis. Strong antioxidant activities of L-EPS-ACS5 were confirmed from the results obtained in the hydroxyl radical, DPPH, ABTS, FRAP, superoxide anion radical, total antioxidant activity, and DNA damage protective effect, and also the L-EPS-ACS5 exhibited high antidiabetic activity (60 %). This study isolated L-EPS-ACS5 from a home-made cheese L. rhamnosus strain, demonstrating its novel and enhanced functionalities compared to existing strains. This opens exciting avenues for its development in the fields of biomedicine and pharmaceuticals.

Enhancing carbamazepine degradation in electrochemical systems: The interplay of sulfur vacancies and absorbed peroxydisulfate in molybdenite electrodes

Achieving high reaction efficiency with low energy input is crucial for electrochemical water remediation processes, yet remains a significant challenge. This study reported a practicable method, utilizing natural molybdenite as particle electrodes in an electro-activated peroxydisulfate (PDS) process (3D system) to develop a cost-efficient electrocatalytic oxidation system. Molybdenite’s unique ability to generate sulfur vacancies during electrocatalysis significantly enhances system efficiency. The 3D system enhanced the rate constant of carbamazepine (CBZ) abatement sixfold compared to the system without molybdenite. Additionally, a substantial decrease in electrical energy per order (EE/O) from 7.13 kWh/m3 to 0.326 kWh/m3 indicates a near 22-fold increase in energy efficiency. Characterizations involving electron microscopies, electrochemical experiments and density functional theory calculations confirm that hydroxyl radicals (•OH) and adsorbed PDS(PDS*) are the main active species. Molybdenite’s surface with plenty of edge-S, released S vacancy during electrocatalytic oxidation, providing adsorption and activation sites for PDS and H2O. This led to more active sites and facilitating the generation of PDS*, lowering the energy barrier for •OH formation and boosting the oxidation performance of the 3D system. The results underscore the constructed 3D system is a robust and energy-efficient method for practical water treatment.

Potential of homogeneous persulfate activation as a strategy for the oxidative treatment of tetramethylammonium hydroxide: Superiority of sulfate radical over hydroxyl radical in the oxidation of methylammoniums

Tetramethylammonium hydroxide (TMAH) as the etching and chelating agent exhibits the extreme recalcitrance to advanced oxidation processes utilizing hydroxyl radical (OH). This study showed that based on the relative position of PDS/heat and PDS/UV against H2O2/UV in terms of TMAH degradation efficiency, sulfate radical (SO4−) was superior to OH in oxidizing TMAH. PDS/heat (at 60 °C) and PDS/UV at the initial pH = 7 achieved TMAH degradation efficiency of ∼ 80–90 % within 1 h whereas H2O2/UV barely eliminated TMAH, which contrasted with H2O2/UV decomposing phenol faster than the activated PDS. The high susceptibility of TMAH (in which four methyl groups bonded to nitrogen removed the lone pair of electrons) to oxidation by SO4− aligned with the pH–dependent efficiency of PDS/heat for the treatment of methylamines. PDS/heat effectively degraded methylammoniums (lacking nitrogen lone pair available for electron transfer due to amine protonation) under non–alkaline conditions, whereas acidification caused the efficiency loss of ∼ 90 % for H2O2/UV. Methylammoniums as radical scavengers retarded benzoic acid degradation by PDS/heat to a more pronounced extent than counterparts with deuterated N–methyl groups, which implied that hydrogen–atom abstraction primarily contributed to the SO4−–induced oxidation of methylammoniums. Estimation of the bimolecular reaction rate constants using laser flash photolysis and electron paramagnetic resonance spectroscopic detection of TMAH–derived carbon–centered radical supported the superiority of SO4− over OH in TMAH oxidation. These findings suggested the potential of homogeneous persulfate activation in the pH-insensitive oxidative treatment of alkylamines and quaternary ammonium cations structurally analogous to TMAH.

Piezo-modulated interface field facilitating hydroxyl radical formation of SrTiO3/ZnO heterojunction for water purification

Piezo-modulated interface engineering is an effective method for tuning the charge transfer process to enhance piezocatalytic dynamics. In this study, SrTiO3/ZnO heterojunctions were successfully synthesized via hydrothermal methods to degrade carbamazepine in water. The optimal SrTiO3/ZnO-5 % sample exhibited a remarkable 99.9 % degradation efficiency of carbamazepine within 60 min under ultrasonic vibration. The piezocatalytic reaction rate (k value = 0.0746 min−1) was 4.63 times and 10.97 times higher than that of pure SrTiO3 and pure ZnO, respectively. Reactive species scavenger tests, electron paramagnetic resonance techniques, and bands gap analysis revealed that the enhanced activity can be attributed to the construction of an interfacial electric field in SrTiO3/ZnO heterojunctions and the modification of an internal piezoelectric polarized field. This allowed charge redistribution and transport across the SrTiO3/ZnO heterojunction interface, and facilitated the generation of hydroxyl radicals (HO•) through simultaneous hole oxidation and electron reduction. This study provides a comprehensive mechanistic understanding about piezoelectric heterojunctions in the catalytic redox reactions, and offers valuable insights for designing more effective piezoelectric heterojunctions for the degradation of pharmaceutical organic pollutants.

TME-Activated MnO2/Pt Nanoplatform of Hydroxyl Radical and Oxygen Generation to Synergistically Promote Radiotherapy and MR Imaging of Glioblastoma.

Radiotherapy (RT) is currently recognized as an important treatment for glioblastoma (GBM), however, it is associated with several challenges. One of these challenges is the radioresistance caused by hypoxia, whereas the other is the low conversion efficiency of the strongly oxidized hydroxyl radical (•OH), which is produced by the decomposition of water due to high-energy X-ray radiation. These factors significantly limit the clinical effectiveness of radiotherapy. To address these limitations, we developed a highly stable and efficient nanoplatform (MnO2/Pt@BSA). Compared to MnO2@BSA, this platform demonstrates high stability, a high yield of oxygen (O2), enhanced production of •OH, and reduced clearance of •OH. The system exhibited increased O2 production in vitro and significantly improved oxygen production efficiency within 100 s at the Pt loading of 38.7%. Furthermore, compared with MnO2, the expression rate of hypoxia-inducible factor (HIF-1α) in glioma cells treated with MnO2/Pt decreased by half. Additionally, the system promotes •OH generation and consumes glutathione (GSH), thereby inhibiting the clearance of •OH and enhancing its therapeutic effect. Moreover, the degradation of the nanoplatform produces Mn2+, which serves as a magnetic resonance imaging (MRI) contrast agent with a T1-weighted enhancement effect at the tumor site. The nanoplatform exhibited excellent biocompatibility and performed multiple functions related to radiotherapy, with simpler components. In U87 tumor bearing mice model, we utilized MnO2/Pt nanocatalysis to enhance the therapeutic effect of radiotherapy on GBM. This approach represents a novel and effective strategy for enhancing radiotherapy in gliomas, thereby advancing the field of catalytic radiotherapy and glioma treatment.