Oxygen Radicals Research Articles

Advancements in iron-based photocatalytic degradation for antibiotics and dyes.

The accelerated growth of the economy and advancements in medical technology have led to the discharge of a diverse range of organic pollutants into water sources. Recent investigations into water treatment have demonstrated the potential for integrating photocatalysis with techniques such as photocatalytic persulfate activation and the Photo-Fenton process for more efficient wastewater management. Iron-based photocatalysts responsive to visible light offer several advantages, including non-toxicity, safety, affordability, and excellent chemical and optical properties. Currently, there is a notable increase in research activity focused on the iron-based photocatalytic degradation of antibiotics and dyes. Given their abundance, cost-effectiveness, and eco-friendliness, iron-based photocatalysis shows considerable promise for various applications, including water treatment, air purification, and energy conversion. The use of iron-based photocatalysts has been demonstrated to facilitate the production of more reactive oxygen radicals, achievable through the Photo-Fenton process, direct photocatalysis, and the photocatalytic activation of persulfates. This approach has been demonstrated to enhance the degradation efficiency of antibiotics and dyes. Ongoing research encompasses the preparation and refinement of iron-based materials, exploration of photocatalytic mechanisms, and expansion of practical applications. Future directions include material innovation, elucidation of mechanisms, scaling up applications, and multifunctionalization, with the objective of enhancing photocatalytic efficiency, transitioning the technology from laboratory settings to practical scales, and providing effective solutions to environmental challenges and energy constraints.

Development of optical microneedle–lens array for photodynamic therapy

Recently, photodynamic therapy (PDT) which involves a photosensitizer (PS), a special drug activated by light, and light irradiation has been widely used in treating various skin diseases such as port-wine stain as well as cancers such as melanoma and non-melanoma skin cancers. PDT comprises two general steps: the introduction of PS into the body or a specific spot to be treated, and the irradiation process using a light source with a specific wavelength to excite the PS. Although PDT is gaining great attention owing to its potential as a targeted approach in the treatment of skin cancers, several limitations still exist for practical use. One of the biggest challenges is the limited penetration of light owing to scattering, reflection, and absorption of light inside the skin layers. In addition, accidental light exposure of the target area causes additional cellular damage, which causes unexpected complications. To solve these issues, we introduced an optical microneedle–lens array (OMLA) to improve the efficiency and safety of PDT treatment. We designed and fabricated a novel optical microneedle–lens array with controlled dimensions to optimize light transmission. In addition, PS was coated uniformly over the tips of the OMLA using the dip coating method. Finally, we confirmed that the PS coated on the OMLA was released into the target area and subsequently generated radical oxygen by light irradiation. We expect that our proposed OMLA for PDT treatment can realize a new light-transmission platform optimized for PDT with targeting various types of skin cancers.Graphical abstract

Tyre rubber exposure causes oxidative stress and intracellular damage in the Baltic clam (Macoma balthica).

Car tyres are considered to release a substantial amount of particles to the environment. Due to the high emission volumes and the chemical risks associated with tyre rubber, there is an urgent need to quantify their ecotoxicological effects. The effects of exposure to particles derived from end-of-life tyres were investigated on the Baltic clam (Macoma balthica), which is one of the key invertebrate species living in the soft-bottom sediments of the northern Baltic Sea. Tyre rubber particles (10-188µm) were added to the aquaria in an environmentally relevant concentration (1.08g per kg dry sediment), and the clams had either direct or indirect contact to the particles for 5 and 29days. The effects of exposure were studied by applying a battery of biomarkers and cell ultrastructure examination of clam tissues, and the concentrations of selected polycyclic aromatic hydrocarbons and trace metals originating from tyre rubber were quantified from the exposure water and clam tissues. The exposure did not affect the mortality of the clams but induced multiple sublethal responses, including an elevated glutathione S-transferase activity, a reduction in the activity of superoxide dismutase, and increased oxygen radical absorbance capacity during the prolonged exposure. Macromolecular damage was indicated by elevated cytogenetic damage and ultrastructural changes in mitochondria and lysosomes. The results demonstrate the potential of environmentally relevant concentrations of tyre rubber particles to disturb the health of marine biota and underline their importance as a yet understudied environmental contaminant.

Comparative study of ergosterol and 7-dehydrocholesterol and their endoperoxides: Generation, identification, and impact in phospholipid membranes and melanoma cells.

Melanoma is an aggressive cancer that has attracted attention in recent years due to its high mortality rate of 80%. Damage caused by oxidative stress generated by radical (type I reaction) and singlet oxygen, 1O2 (type II reaction) oxidative reactions may induce cancer. Thus, studies that aim to unveil the mechanism that drives these oxidative damage processes become relevant. Ergosterol, an analogue of 7-dehydrocholesterol, important in the structure of cell membranes, is widely explored in cancer treatment. However, to date little is known about the impact of different oxidative reactions on these sterols in melanoma treatment, and conflicting results about their effectiveness complicates the understanding of their role in oxidative damage. Our results highlight differences among ergosterol, 7-dehydrocholesterol (7-DHC), and cholesterol in membrane properties when subjected to distinct oxidative reactions. Furthermore, we conducted a comparative study exploring the mechanisms of cell damage by photodynamic treatment in A375 melanoma. Notably, endoperoxides from ergosterol and 7-DHC generated by 1O2 showed superior efficacy in reducing the viability of A375 cells compared to their precursor molecules. We also describe a step-by-step process to produce and identify endoperoxides derived from ergosterol and 7-DHC. While further studies are needed, this work provides new insights for understanding cancer cell death induced by different oxidative reactions in the presence of biologically relevant sterols.

In vitro immunotoxic evaluation of herbicides in RAW 264.7 cells

ABSTRACT Weeds are a concern in agriculture and the use of herbicides constitutes an effective, efficient, and economical way to control their growth. Recent discoveries of herbicides are promising for the management of resistant weeds. However, there is a gap in the knowledge of the toxic effects of some herbicides previously reported on immune cells. The present study aimed to examine cellular immunotoxicity of three herbicides (clomazone, glyphosate, and sulfentrazone) after 96 hr incubation utilizing RAW 264.7 BALB/c mouse monocyte/macrophage-like cell line to elucidate the role of some toxicological pathways. Data demonstrated the herbicides clomazone, glyphosate, and sulfentrazone initiated a cytotoxic effect as evidenced by EC50 values of 429.2; 53.7; 866.6 mg/L, respectively. Clomazone and sulfentrazone, at all concentrations, induced excess production of reactive oxygen (ROS) and reactive nitrogen (RNS) free radicals. An immunosuppression was observed in RAW 264.7 cells after incubation with 50 or 100 mg/L glyphosate and 500 or 1000 mg/L sulfentrazone. In addition, all herbicides produced mitochondrial depolarization and decreased tumor necrosis factor-α (TNF-α) levels. This constitutes the first report of the effects of clomazone and sulfentrazone on RAW 264.7 cells, including reduced TNF-α levels, indicating the adverse influence of herbicides on the immune system.

A Density Functional Theory (DFT) Modeling Study of NO Reduction by CO over Graphene-Supported Single-Atom Ni Catalysts in the Presence of CO2, SO2, O2, and H2O.

The mechanisms of NO reduction by CO over nitrogen-doped graphene (N-graphene)-supported single-atom Ni catalysts in the presence of O2, H2O, CO2, and SO2 have been studied via density functional theory (DFT) modeling. The catalyst is represented by a single Ni atom bonded to four N atoms on N-graphene. Several alternative reaction pathways, including adsorption of NO on the Ni site, direct reduction of NO by CO, decomposition of NO to N2O followed by reduction of N2O to N2, formation of active oxygen radical O*, and reduction of O* by CO, were hypothesized and the energy barrier corresponding to each of the reaction steps was calculated using DFT. The most probable pathway was found to be that NO adsorbed on the Ni site decomposes via the Langmuir-Hinshelwood mechanism to form N2O and subsequently N2, leaving an active oxygen radical (O*) on the surface, which is then reduced by CO. The large adsorption energy of NO on the Ni site results in strong resistance to CO2, SO2, O2, and water vapor. The activation energy of N2O reduction to N2 was found to be larger than those of NO decomposition to N2O and active oxygen radical reduction by CO, illustrating that the step of N2O reduced to N2 is the rate-controlling step.

Predicting Color Development and Texture Changes in Tomatoes Treated With Hot Water and Exposed to High-Temperature Ethylene Using Support Vector Regression.

This study investigated the impacts of hot water treatment (HWT) at 50°C or 25°C for 5 min and high-temperature ethylene (HTE) exposure at varying temperatures (20°C, 30°C, or 35°C) and durations (24, 48, or 72 h) on the postharvest quality and antioxidant properties of mature green tomatoes (MG). Color changes, physicochemical characteristics, antioxidant compounds, and overall antioxidant ability were assessed. HWT increased β-carotene levels and oxygen radical absorbance capacity (ORAC) while preserving color metrics, despite later HTE exposure. Exposure to HTE delayed ripening, increased titratable acidity, and reduced dry matter content. The effects on antioxidant compounds varied depending on temperature and duration of exposure. A support vector regression (SVR) model predicted color parameters with high performance (R2 > 0.85) for lightness (L*), greenness-redness (a*), blueness-yellowness (b*), chroma, and hue values. The findings highlight the potential of HWT in postharvest quality management and underscore the complex interplay between HWT and HTE on tomato quality parameters.

Catalyst-Free Nitrogen Fixation by Microdroplets through a Radical-Mediated Disproportionation Mechanism under Ambient Conditions.

Nitrogen fixation is essential for the sustainable development of both human society and the environment. Due to the chemical inertness of the N≡N bond, the traditional Haber-Bosch process operates under extreme conditions, making nitrogen fixation under ambient conditions highly desirable but challenging. In this study, we present an ultrasonic atomizing microdroplet method that achieves nitrogen fixation using water and air under ambient conditions in a rationally designed sealed device, without the need for any catalyst. The total nitrogen fixation rate achieved is 6.99 μmol/h, yielding ammonium as the reduction product and nitrite and nitrate as the oxidation products, with hydrogen peroxide produced as a byproduct at a rate of 4.29 μmol/h. Using electron paramagnetic resonance (EPR) spectroscopy, we captured reactive species, including hydrogen, hydroxyl, singlet oxygen, superoxide anion, and NO radicals. In conjunction with in situ mass spectrometry (MS) and isotope labeling, we confirmed the presence of nitrogen-containing intermediates, such as HN═NOH+•, H2N-N(OH)2+•, HNO+, and NH2OH+•. Supported by these findings and theoretical calculations, we propose a radical-mediated nitrogen disproportionation mechanism. Simulations of naturally occurring condensed microdroplets also demonstrated nitrogen redox fixation. This microdroplet-based method not only offers a potential pathway for nitrogen fixation in practical applications and sustainable development but also deepens our understanding of the natural nitrogen cycle.

Photochemical Formation of Trifluoroacetic Acid: Mechanistic Insights into a Fluoxetine-Related Aryl-CF3 Compound.

Trifluoroacetic acid (TFA) is a ubiquitous environmental contaminant; however, its sources are poorly constrained. One understudied source is from the photochemical reactions of aromatic compounds containing -CF3 moieties (aryl-CF3) including many pharmaceuticals and agrochemicals. Here, we studied the aqueous photochemistry of 4-(trifluoromethyl)phenol (4-TFMP), a known transformation product of the pharmaceutical fluoxetine. When exposed to lamps centered at UV-B, 4-TFMP formed up to 9.2% TFA at a steady state under acidic conditions and 1.3% under alkaline conditions. TFA yields of fluoxetine were similar to 4-TFMP for acidic and neutral pH, but higher at alkaline pH, suggesting that fluoxetine may have a mechanism of TFA formation in addition to via the 4-TFMP intermediate. Use of an 13CF3 isotopologue of 4-TFMP allowed for the tracking of TFA formation, which formed via multiple oxidative additions prior to oxidative ring cleavage. The oxidation is mediated by reactive oxygen species (ROS) generated through self-sensitized photolysis, with singlet oxygen and hydroxyl radicals as the key ROS. In addition to the TFA formation mechanism, other photochemical reactions of 4-TFMP resulted in defluorination and dimerization. Overall, this work expands our understanding of how TFA forms from aryl-CF3 compounds to better understand the total global burden of TFA.

Effect of eicosapentaenoic acid on innate immune responses in Atlantic salmon cells infected with infectious salmon anemia virus

Aquaculture is one of the world's fastest-growing sectors in food production but with multiple challenges related to animal handling and infections. The disease caused by infectious salmon anemia virus (ISAV) leads to outbreaks of local epidemics, reducing animal welfare, and causing significant economic losses. The composition of feed has shifted from marine ingredients such as fish oil and fish meal towards a more plant-based diet causing reduced levels of eicosapentaenoic acid (EPA). The aim of this study was to investigate whether low or high levels of EPA affect the expression of genes related to the innate immune response 48 h after infection with ISAV. The study includes seven experimental groups: ± ISAV and various levels of EPA up to 200 µM. Analysis of RNA sequencing data showed that more than 3000 genes were affected by ISAV alone (without additional EPA). In cells with increasing levels of EPA, more than 2500 additional genes were differentially expressed. This indicates that high levels of EPA concentration have an independent effect on gene expression in virus-infected cells, not observed at lower levels of EPA. Analyses of enriched biological processes and molecular functions (GO and KEGG analysis) revealed that EPA had a limited impact on the innate immune system alone, but that many processes were affected by EPA when cells were virus infected. Several biological pathways were affected, including protein synthesis (ribosomal transcripts), peroxisome proliferator activated receptor (PPAR) signaling, and ferroptosis. Cells exposed to both increasing concentrations of EPA and virus displayed gene expression patterns indicating increased formation of oxygen radicals and that cell death via ferroptosis was activated. This gene expression pattern was not observed during infection at low EPA levels or when Atlantic salmon kidney (ASK) cells were exposed to the highest EPA level (200 μM) without virus infection. Cell death via ferroptosis may therefore be a mechanism for controlled cell death and thus reduction of virus replication when there are enough polyunsaturated fatty acids (PUFAs) in the membrane.

Comparative Study of Bulgarian Linden Honey (Tilia sp.).

The present study aims to evaluate and compare some of the main indicators characterizing Bulgarian linden honey depending on the geographical origin. A total of 18 samples were collected from the six regions of Bulgaria, with 3 samples from each region taken from different producers during the 2023 harvest. The physicochemical indicators: hydroxymethylfurfural content, diastase activity, pH, color, water content and electrical conductivity, as well as organoleptic and pollen characteristics, were analyzed. Antioxidant activity was also investigated by several methods: total phenolic content (TPC), phenolic compounds by the Glories method, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical activity, CUPRAC (Cupric Reducing Antioxidant Capacity), iron-reducing antioxidant capacity (FRAP) assay, and radical scavenging capacity in terms of ABTS•+, ORAC (oxygen radical antioxidant capacity). Differences were found depending on the region. All the studied honeys from the Northern Central Region contained higher Tilia sp. pollen. In the Southwestern Region, Tilia sp. pollen was not detected in any of the honey samples. The highest sensory score was awarded to linden honey from the Northern Central Region. An overall assessment ranks linden honey from the Northern Central region, the richest in linden forests, as the highest quality among the six studied regions. Another key finding was that 39% of linden honey labeled or declared as monofloral linden honey on the Bulgarian market does not meet the established criteria for monofloral honey.

Retinal Protection of New Nutraceutical Formulation.

Background/Objectives: Retinal ganglion cell (RGC) protection represents an unmet need in glaucoma. This study assessed the neuroprotective, antioxidant, and anti-inflammatory effect of a new nutraceutical formulation named Epicolin, based on citicoline, homotaurine, epigallocatechin-3-gallate, forskolin, and vitamins, through in vitro and in vivo studies. Methods: The neuroprotective effect of Epicolin or its single components, and Epicolin compared to an untreated control and two marketed formulations [Formulation G (FG) and N (FN)], was evaluated in neuroblastoma cells (SH-SY5Y) challenged with staurosporine. The antioxidant potential and the scavenging activity of Epicolin compared to the untreated control, and FG and FN, was evaluated in SH-SY5Y cells and through oxygen radical absorbance capacity acellular assay, respectively. Moreover, the protective effect against hypoxic damage was evaluated in Muller cells (MIO-M1) subjected to hypoxia. The efficacy of Epicolin was also evaluated in DBA/2J glaucomatous mice through the use of a pattern electroretinogram (PERG), immunostaining, and real-time PCR. Results: Among the nutraceutical formulations tested, only Epicolin showed a significant neuroprotective effect on SH-SY5Y attributable to the synergistic action of its single ingredients. As for antioxidant and scavenging activity, Epicolin showed a higher efficacy compared to FG and FN. Furthermore, Epicolin showed the same protective effect on MIO-M1 cells reducing HIF-1α expression. Finally, Epicolin treatment on DBA/2J mice protected the RGCs from loss of function, as demonstrated by PERG analysis, and attenuated their death by enhancing brain-derived neurotrophic factor (BDNF) and reducing interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) expression. Conclusions: Epicolin, due to its neuroprotective, antioxidant, and anti-inflammatory properties, represents a promising potential treatment for glaucoma.

Tracking the Geometric and Positional Isomerization of Lipid C═C Bonds in the Bacterial Stress Responses by Mass Spectrometry.

The position and configuration of the C═C bond have a significant impact on the spatial conformation of unsaturated lipids, which subsequently affects their biological functions. Double bond isomerization of lipids is an important mechanism of bacterial stress response, but its in-depth mechanistic study still lacks effective analytical tools. Here, we developed a visible-light-activated dual-pathway reaction system that enables simultaneous [2 + 2] cycloaddition and catalytic cis-trans isomerization of the C═C bond of unsaturated lipids via directly excited anthraquinone radicals. Density functional theory calculations revealed the oxygen radical addition transition state and the addition-elimination isomerization mechanism of the reaction. A full-dimensional resolution method for C═C bond position and configuration was developed based on the bifunctional reaction and liquid chromatography-mass spectrometry. This method was then applied to the study of bacterial environmental stress response mechanisms. The C═C bond cis-trans and positional isomerization patterns of Pseudomonas membrane lipids under temperature stress were discovered, and the effect of temperature stress on fatty acid biosynthesis was also revealed. This study not only provides an effective tool and key information for the study of bacterial stress response mechanisms, but also enriches the toolbox of visible light chemical reactions.

Catalytic degradation of diclofenac by ZnO-Co3O4: identification of major intermediates and degradation pathway.

ZnO-Co3O4 material was successfully synthesized by the co-precipitation method and used as a catalyst for the removal of diclofenac sodium (DCF). ZnO-Co3O4 exhibited higher catalytic activity in the catalytic process compared to the photocatalytic processes. Under optimum conditions, the activation of peroxymonosulfate (PMS) by ZnO-Co3O4 achieved approximately 99% removal of DCF, confirming the effective adsorption and activation of PMS. Quenching experiments indicated that the reactive oxygen species (ROS) responsible for the degradation of DCF by the ZnO-Co3O4/PMS system are singlet oxygen (1O2) and superoxide radicals (O2•-). The activation of PMS by ZnO-Co3O4 was associated with the coexistence and interaction between Co(II) and Co(III), as well as the formation of oxygen vacancies (V0) in ZnO. Cobalt leaching was negligible, and the degradation rate remained constant after four cycles, indicating the excellent stability and reusability of the ZnO-Co₃O₄ catalyst. Additionally, eight degradation products of DCF were identified by LC-ESI-MS, and their toxicity was evaluated using ECOSAR software (version 2.2). In conclusion, the ZnO-Co3O4/PMS system is a promising catalytic process for the degradation of organic molecules.

Effect of bromelain on ischemia-reperfusion injury in the torsion model created in polycystic and normal ovarian tissues.

Due to its increased volume, polycystic ovarian tissue is more prone to torsion than normal ovarian tissue. In treating ovarian torsion, detorsion is applied to ensure oxygenation of hypoxic tissues. However, the resulting oxygen radicals cause tissue damage. Bromelain is a substance obtained from pineapple, and studies in the literature show it is used as an antioxidant. This study aimed to evaluate the damage caused by ischemia-reperfusion (I/R) in the torsion-detorsion model created in normal and polycystic ovarian tissue and investigate the role of bromelain in this damage. Polycystic ovarian tissue was created by applying dihydroepiandrosterone sulfate to rats. Afterward, a torsion-detorsion model was used for all rats. The rats were divided into six groups: the polycystic ovary sham-operated group (P-S), the normal ovary sham-operated group (N-S), the polycystic ovary ischemia/reperfusion group (P-IR), the normal ovary ischemia/reperfusion group (N-IR), the polycystic ovary ischemia/reperfusion group treated with bromelain (P-IRB), and the normal ovary ischemia/reperfusion group treated with bromelain (N-IRB). After the procedure, tissues were collected for histopathological examination, and MDA, TUNEL, and NF-κB levels were measured. This study detected significant decreases in MDA and NF-κB levels and apoptotic cell numbers assessed by TUNEL staining in groups with IR damage and given bromelain compared to the control groups. The number of TUNEL-positive cells was found to be highest in the P-IR group (8.80 ± 2.98) and significantly lower in the bromelain-administered P-IRB (1.04 ± 1.09) and N-IRB (0.52 ± 0.58) groups (p< 0.05). NF-κB expression was also high in P-IR and N-IR groups, while it was significantly decreased in bromelain-treated groups (P-IRB and N-IRB) (p< 0.05). In addition, IR damage was more pronounced in polycystic ovary tissue than in normal ovary tissue. Ischemia perfusion damage may be more pronounced in polycystic ovarian tissue than in normal ovarian tissue. Bromelain may be preferred to prevent I/R injury caused by ovarian torsion. It is also thought that bromelain may function in treating polycystic ovaries, and further studies can be conducted on this subject.

Aggregated gold nanoparticles as photoactivators for the photopolymerization of proteins.

Photopolymerization of bovine serum albumin was carried out using reactive oxygen species (ROS) generated by the irradiation of citrate-stabilized gold nanoparticles by a pulsed Nd3+:YAG laser. The ROS in this case, singlet oxygen (1O2), targets aromatic amino acids within the protein to induce photopolymerization or crosslinking. Other ROS, like the hydroxyl radical, can also form in solution and under high-energy irradiation. The gold nanoparticles were aggregated using different cations in order to maximize singlet oxygen production. Experimental parameters like exposure time and laser power were optimized to minimize damage and maximize crosslinking efficiency, and damage-free crosslinking was observed at laser exposures up to 60s with samples containing calcium demonstrating most efficient crosslinking. To confirm the role of ROS in crosslinking, the reactive oxygen scavengers sodium azide and mannitol were added at different concentrations to scavenge the singlet oxygen and hydroxyl radical, respectively, and both were observed to stop or slow the formation of crosslinking. The use of gold nanoparticles offers an inert and biocompatible alternative to organic crosslinking agents like rose Bengal and methylene blue.

Radical formation in skin and preclinical characterization of a novel medical plasma device for dermatology after single application.

Cold atmospheric plasma (CAP) enables painless tissue treatment by producing reactive species including excited molecules and charged particles and is of great interest for medical applications. Medical CAP sources work in contact with air at ambient pressure, resulting in the generation of substantial amounts of reactive oxygen and nitrogen radicals. These radicals have a significant influence on cellular biochemistry, are crucial components of the immune system, and play a central role in wound therapy. CAP has a variety of applications, with a particular emphasis on tissue treatment in dermatology. It eradicates microorganisms by preventing biofilm formation so that wounds can be effectively disinfected and treated antiseptically. Using both in vitro and ex vivo methods, a comprehensive preclinical assessment of a novel battery-operated cold plasma handheld device with a reusable, and autoclavable glass cylinder was performed. The objectives were to evaluate the potential impact of single CAP application on radical formation with and without wound dressing, by directly measuring radicals in skin, to investigate the influence of CAP application on antimicrobial activity and cytotoxicity in vitro, and to assess skin tolerance ex vivo. The direct effect of CAP on the formation of radicals in the skin after plasma application at different levels with and without wound dressing was demonstrated quantitatively for the first time using electron paramagnetic resonance spectroscopy. Free radicals were measured in the skin as a function of the duration of CAP treatment. Furthermore, it was found that an alginate or wound plaster dressing does not significantly inhibit radical formation in skin compared to application without a dressing. In vitro and ex vivo data showed no cytotoxic potential with simultaneous efficacy against bacteria strains and no risk of temperature rise, pH change, skin barrier or DNA damage. These results show a high potential for wound healing applications in vivo.

The smartphone-assisted sensing platform based on manganese dioxide nanozymes for the specific detection and degradation of hydroquinone.

Hydroquinone (HQ) is a prevalent pollutant in aquatic environments, posing significant risks to ecosystems and human health. Practical methods for the simultaneous detection and degradation of HQ are essential. To address this requirement, a dual-mode detection and degradation strategy has been developed utilizing designed nanozymes (DM) consisting of a porous SiO2 core and MnO2 shell. Due to the catalytic activity of DM nanozymes, the three types of reactive oxygen species (ROS), singlet oxygen (1O2), superoxide anion (O2•-), and hydroxyl radical (•OH), were generated to induce the color transferring of 3,3',5,5'-tetramethylbenzidine (TMB) from colorless to blue form (oxTMB). During the reductive HQ-mediated oxTMB fading, the DM has significant selectivity towards HQ from isomers (catechol and resorcinol) due to the differing reductive reaction rates, with an excellent linear range of 0.2-45 μM with a detection limit as low as 0.11 μM. In addition, according to the color parameter changes in the sensing process, colorimeters and smartphones are utilized to achieve on-site and convenient HQ detection. Besides, the DM nanozyme can oxidatively decompose HQ without auxiliary equipment. We believe this research provides a powerful tool for detecting and removing HQ precisely.

Photocatalytic detoxification of a sulfur mustard simulant using donor-enhanced porphyrin-based covalent-organic frameworks.

Photocatalytic detoxification of sulfur mustards (e.g., bis (2-chloroethyl) sulfide, SM) is an effective approach for protecting the ecological environment and human health. In order to fabricate COFs with high performance for the selective transformation of the SM simulant 2-chloroethyl ethyl sulfide (CEES) to nontoxic 2-chloroethyl ethyl sulfoxide (CEESO), three porphyrin-based COFs with different donor groups (R = H, OH, and OMe) were synthesized. Among these COFs, COF-OMe, which possesses the strongest electron-donating ability, demonstrated a faster and higher detoxification rate of CEES at various concentrations, achieving selective oxidation of CEES to non-toxic CEESO with 99.2% conversion and 100% selectivity using white LED light irradiation within three hours. The facilitated charge transfer and separation as well as efficaciously produced reactive oxygen species (ROS), including singlet oxygen (1O2) and superoxide radical anions (O2˙-) are supposed to contribute to the excellent performance. The results demonstrated that the donor-enhanced porphyrin-based COFs could act as heterogeneous photocatalysts for visible light driven organic transformation and detoxification of sulfur mustards.

Oxidative degradation of sulfamethazine by manganese oxide supported biochar activated periodate: Effect and mechanism.

In this study, manganese oxide supported biochar (MBC) was used as a catalyst of periodate (PI) for the oxidative degradation of sulfonamide antibiotic sulfamethazine (SMZ). The degradation rate of 10 mg/L SMZ reached 99 % in 60 min in the MBC/PI system, and the optimal condition was pH 3.5, 0.12 g/L of MBC, and 0.17 mM of PI. Combined with quenching experiment and electron paramagnetic resonance (EPR) characterization, it was determined that the reactive oxygen species (ROS) participating in the reaction include iodate radical (IO3∙), singlet oxygen (1O2), and hydroxyl radical (∙OH). ROS, Mn(III) and electron transfer are three crucial SMZ removal mechanisms in MBC activated PI system, and the conversion process of reactive species was deduced. The manganese redox cycles, oxygen-containing functional groups on MBC surface, and BC-O-Mn(II) complex participated in reactive species production. The loading of manganese oxide increases the number of oxygen-containing functional group on the surface of BC, and BC-O-Mn(II) complex formation resulted in the higher catalytic activity compared with BC. Ten SMZ oxidative products and four transformation pathways was identified. This study provided an efficient and practical method to remove sulfonamide antibiotics and revealed its theoretical mechanism.