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1.
Chemosphere ; 364: 143107, 2024 Aug 14.
Artículo en Inglés | MEDLINE | ID: mdl-39151588

RESUMEN

Although dissolved oxygen plays an important role in electro-Fenton-like processes, few investigations have revealed its underlying effects in such processes. Herein, the effect of dissolved oxygen on peroxide activation in an electro-Fenton-like system comprising electrochemical cells and peroxymonosulfate (PMS) was investigated. Cobalt phosphide-modified carbon aerogel (Co/P/CA) was used as the cathode material owing to the high conductivity and catalytic activity of Co/P/CA. Several free radicals and their effects on organic pollutant removal were observed using electron paramagnetic resonance spectrometry and quenching experiments, respectively. The observations revealed that in the presence of O2, hydroxyl radical (·OH), superoxide (O2-·), and singlet oxygen (1O2) served as the primary active species in the PMS activation process, while in the presence of N2, ·OH and sulfate radical (SO4-·) served as the dominant active species in this process. The factor responsible for the difference in the PMS activation pathways available under O2 and N2 conditions was investigated using rotating disk electrode tests and free energy calculations. The tests indicated that O2 facilitates PMS activation to form ·OH instead of SO4-·. The dissolved oxygen subsequently underwent a single-electron-reduction reaction and was converted into O2-·, which could serve as a source of 1O2. When N2 was introduced, Co species, particularly Co(II), played a key role in activating PMS. The free radicals ·OH and SO4-· were generated during the PMS activation process. This study clearly demonstrates the mediating catalysis role of dissolved oxygen in electro-Fenton-like system through experimental data and theoretical calculations, thereby positively contributing to future studies regarding the continuous activation of peroxides in composite systems and improvement of the efficiency of waterbody remediation.

2.
Proc Natl Acad Sci U S A ; 121(33): e2407012121, 2024 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-39102537

RESUMEN

Water resources are indispensable basic resources and important environmental carriers; the presence of organic contaminants in wastewater poses considerable risks to the health of both humans and ecosystems. Although the Fenton-like reactions using H2O2 as the oxidant to destroy organic pollutants are attractive, there are still challenges in improving reaction activity under neutral or even alkaline conditions. Herein, we designed a H2O2 activation pathway with O2•- as the main active species and elucidated that the spin interaction between Fe sites and coordinated O atoms effectively promotes the generation of the key intermediate Fe-*OOH. Furthermore, we successfully captured and analyzed the Fe-*OOH intermediate by in situ Raman spectroscopy. When applying FBOB to a continuous-flow reactor, CIP removal efficiency remained at around 90% within 600 min of continuous operation, achieving excellent efficiency, stability, and pH tolerance in removing pollutants.

3.
Colloids Surf B Biointerfaces ; 243: 114133, 2024 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-39096622

RESUMEN

Achieving a desired whitening effect through short treatments without using peroxide and without compromising the integrity of tooth enamel remains a challenge in teeth whitening. Here, we developed a highly safe and efficient photodynamic therapy (PDT) strategy based on visible light-activated bismuth oxyiodide nanoparticles for nondestructive tooth whitening. The Bi7O9I3 nanoparticles (NPs) exhibited efficient photocatalytic activity owing to their narrow band gap, effectively harnessing the broad spectrum of visible light to generate ample electrons and holes. Meanwhile, the presence of oxygen vacancies, low oxidation state Bi3+ and the high specific surface area endow Bi7O9I3 NPs with effective electron-hole separation ability and potent redox potentials. Empowered by these characteristics, Bi7O9I3 NPs effectively catalyzed O2 into radicals (O2•-), facilitating the degradation of dental surface pigment molecules for tooth whitening. Concurrently, they eradicated oral bacteria and bacterial biofilms adhering to tooth surfaces, thereby having a positive effect on the effectiveness of tooth whitening. This PDT strategy with Bi7O9I3 NPs shows broad application prospects in tooth whitening.


Asunto(s)
Bismuto , Nanopartículas , Fotoquimioterapia , Blanqueamiento de Dientes , Bismuto/química , Bismuto/farmacología , Nanopartículas/química , Blanqueamiento de Dientes/métodos , Humanos , Biopelículas/efectos de los fármacos , Luz , Fármacos Fotosensibilizantes/farmacología , Fármacos Fotosensibilizantes/química , Tamaño de la Partícula , Yoduros/química , Yoduros/farmacología , Animales , Propiedades de Superficie
4.
J Hazard Mater ; 477: 135347, 2024 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-39084012

RESUMEN

Redox transformation of mercury (Hg) is critical for Hg exchange at the air-water interface. However, the superoxide radicals (O2•─) contribution of microalgal-fungal symbiotic systems in lake water to Hg(II) reduction is mainly unknown. Here, we studied the enhanced potential for O2•─ production by the coupling effect between microalgae and fungi. The relationships between microenvironment, microorganisms, and O2•─ production were also investigated. Furthermore, the implication of O2•─ for Hg(II) reduction was explored. The results showed that the coupling effect of microalgae and fungi enhanced O2•─ generation in the symbiotic systems, and the O2•─ generation peaked on day 4 in the lake water at 160.51 ± 13.06-173.28 ± 18.21 µmol/kg FW (fresh weight). In addition, O2•- exhibited circadian fluctuations that correlated with changes in dissolved oxygen content and redox potential on the inter-spherical interface of microalgal-fungal consortia. Partial least squares path modeling (PLS-PM) indicates that O2•─ formation was primarily associated with microenvironmental factors and microbial metabolic processes. The experimental results suggest that O2•─ in the microalgal-fungal systems could mediate Hg(II) reduction, promoting Hg conversion and cycling. The findings highlight the importance of microalgae and fungal symbiotic systems in Hg transformation in aquatic environments.


Asunto(s)
Mercurio , Microalgas , Oxidación-Reducción , Superóxidos , Simbiosis , Microalgas/metabolismo , Mercurio/metabolismo , Superóxidos/metabolismo , Hongos/metabolismo , Contaminantes Químicos del Agua/metabolismo , Lagos/microbiología
5.
Food Chem ; 452: 139459, 2024 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-38705121

RESUMEN

The current study analysed the antioxidant capacity of the main phenolics found in red fruits. In total, there were analysed the antioxidant activity against 1,1-diphenyl-2-picrylhydrazyl radical, nitric oxide and superoxide radicals (DPPH, NO and O2-, respectively) of 23 phenolics. Regarding DPPH, anthocyanins, (-)-epicatechin and kaempferol 3-O-rutinoside were the most active, while isorhamnetin 3-O-glucoside was the least active. Anthocyanins, (-)-epicatechin, quercetin 3-O-glucoside and caffeic acid showed the strongest potential against NO, while ρ-hydroxybenzoic acid was the less efficient. Regarding the O2- assay, quercetin aglycone and their derivatives were the best ones, while cyanidin aglycone did not show any potential to quench this radical. To deeper explore the biological potential of the most promising compounds, docking molecular and ADME studies were also done. The obtained data is another support regarding the biological potential of phenolics and might be useful in encouraging their use and incorporation in new products.


Asunto(s)
Antioxidantes , Frutas , Fenoles , Extractos Vegetales , Frutas/química , Fenoles/química , Antioxidantes/química , Extractos Vegetales/química , Extractos Vegetales/farmacología , Simulación del Acoplamiento Molecular , Simulación por Computador
6.
Chem Biol Interact ; 395: 111008, 2024 May 25.
Artículo en Inglés | MEDLINE | ID: mdl-38636791

RESUMEN

Oxidative protein damage involving carbonylation of respiratory tract proteins typically accompanies exposure to tobacco smoke. Such damage can arise via multiple mechanisms, including direct amino acid oxidation by reactive oxygen species or protein adduction by electrophilic aldehydes. This study investigated the relative importance of these pathways during exposure of a model protein to fresh cigarette emission extracts. Briefly, protein carbonyl adducts were estimated in bovine serum albumin following incubation in buffered solutions with whole cigarette emissions extracts prepared from either a single 1R6F research cigarette or a single "Heat-not-Burn" e-cigarette. Although both extracts caused concentration-dependent protein carbonylation, conventional cigarette extracts produced higher adduct yields than e-cigarette extracts. Superoxide radical generation by conventional and e-cigarette emissions was assessed by monitoring nitro blue tetrazolium reduction and was considerably lower in extracts made from "Heat-Not-Burn" e-cigarettes. The superoxide dismutase/catalase mimic EUK-134 strongly suppressed radical production by whole smoke extracts from conventional cigarettes, however, it did not diminish protein carbonyl adduction when incubating smoke extracts with the model protein. In contrast, edaravone, a neuroprotective drug with strong carbonyl-trapping properties, strongly suppressed protein damage without inhibiting superoxide formation. Although these findings require extension to appropriate cell-based and in vivo systems, they suggest reactive aldehydes in tobacco smoke make greater contributions to oxidative protein damage than smoke phase radicals.


Asunto(s)
Sistemas Electrónicos de Liberación de Nicotina , Carbonilación Proteica , Albúmina Sérica Bovina , Humo , Superóxidos , Productos de Tabaco , Superóxidos/metabolismo , Carbonilación Proteica/efectos de los fármacos , Humo/efectos adversos , Albúmina Sérica Bovina/química , Productos de Tabaco/efectos adversos , Bovinos , Animales , Nicotiana/química , Calor
7.
Microorganisms ; 12(2)2024 Feb 17.
Artículo en Inglés | MEDLINE | ID: mdl-38399806

RESUMEN

Since thermophilic microorganisms are valuable sources of thermostable enzymes, it is essential to recognize the potential toxicity of silver nanoparticles used in diverse industrial sectors. Thermophilic bacteria Geobacillus vulcani 2Cx, Bacillus licheniformis 3CA, Paenibacillus macerans 3CA1, Anoxybacillus ayderensis FMB1, and Bacillus paralicheniformis FMB2-1 were selected, and their MIC and MBC values were assessed by treatment with AgNPs in a range of 62.5-1500 µg mL-1. The growth inhibition curves showed that the G. vulcani 2Cx, and B. paralicheniformis FMB2-1 strains were more sensitive to AgNPs, demonstrating a reduction in population by 71.1% and 31.7% at 62.5 µg mL-1 and by 82.9% and 72.8% at 250 µg mL-1, respectively. TEM and FT-IR analysis revealed that AgNPs caused structural damage, cytoplasmic leakage, and disruption of cellular integrity. Furthermore, cell viability showed a significant decrease alongside an increase in superoxide radical (SOR; O2-) production. ß-galactosidase biosynthesis decreased to 28.8% level at 500 µg mL-1 AgNPs for G. vulcani 2Cx, 32.2% at 250 µg mL-1 for A. ayderensis FMB1, and 38.8% only at 62.5 µg mL-1, but it was completely inhibited at 500 µg mL-1 for B. licheniformis 3CA. Moreover, B. paralicheniformis FMB2-1 showed a significant decrease to 11.2% at 125 µg mL-1. This study is the first to reveal the toxic effects of AgNPs on thermophilic bacteria.

8.
Angew Chem Int Ed Engl ; 63(12): e202318783, 2024 03 18.
Artículo en Inglés | MEDLINE | ID: mdl-38258371

RESUMEN

We herein present an approach of photo-induced disproportionation for preparation of Type-I photodynamic agents. As a proof of concept, BODIPY-based photosensitizers were rationally designed and prepared. The photo-induced intermolecular electron transfer between homotypic chromophores leads to the disproportionation reaction, resulting in the formation of charged intermediates, cationic and anionic radicals. The cationic radicals efficiently oxidize the cellularimportant coenzyme, tetrahydrobiopterin (BH4 ), and the anionic radicals transfer electrons to oxygen to produce superoxide radicals (O2 - ⋅). One of our Type-I photodynamic agents not only self-assembles in water but also effectively targets the endoplasmic reticulum. It displayed excellent photocytotoxicity even in highly hypoxic environments (2 % O2 ), with a half-maximal inhibitory concentration (IC50 ) of 0.96 µM, and demonstrated outstanding antitumor efficacy in murine models bearing HeLa tumors.


Asunto(s)
Biopterinas/análogos & derivados , Fotoquimioterapia , Superóxidos , Ratones , Animales , Fármacos Fotosensibilizantes/farmacología , Especies Reactivas de Oxígeno , Oxígeno
9.
J Hazard Mater ; 460: 132259, 2023 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-37633018

RESUMEN

Photodegradation process plays an important role in the natural attenuation of petroleum hydrocarbons (PHs) in oil contaminated soil. The photodegradation characteristics of PHs (C10-C40) in topsoil of crude oil contaminated soil irradiated by simulated sunlight in 280 d without microbial action were investigated. The results showed that photodegradation rate of PHs was increased with increasing the light intensity and decreased with increasing the initial concentration of PHs. Moreover, the photodegradation capacity of tested PHs was relevant to the length of carbon chain. The photodegradation rates of C10-C20 were higher than that of C21-C40 in photoperiod. C21-C40 showed an obvious trend of photodegradation after 56 d, although their photodegradation rates were less than 20% at the early stage. And, the redundancy analysis indicated that lighting time was the primary factor for photodegradation of PHs under abiotic conditions. The photodegradation rate was well interpreted by a two-stage, first-order kinetic law with a faster initial photolysis rate. The EPR spectrums showed that simulated solar irradiation accelerated the generation of superoxide radicals, which could react with PHs in soil. Also, the function groups in PHs polluted soil were changed after light exposure, which might imply the possible photodegradation pathway of PHs.

10.
Biomolecules ; 13(7)2023 06 26.
Artículo en Inglés | MEDLINE | ID: mdl-37509077

RESUMEN

Numerous chemical probes have been used to measure or image oxidative, nitrosative and related stress induced by free radicals in biology and biochemistry. In many instances, the chemical pathways involved are reasonably well understood. However, the rate constants for key reactions involved are often not yet characterized, and thus it is difficult to ensure the measurements reflect the flux of oxidant/radical species and are not influenced by competing factors. Key questions frequently unanswered are whether the reagents are used under 'saturating' conditions, how specific probes are for particular radicals or oxidants and the extent of the involvement of competing reactions (e.g., with thiols, ascorbate and other antioxidants). The commonest-used probe for 'reactive oxygen species' in biology actually generates superoxide radicals in producing the measured product in aerobic systems. This review emphasizes the need to understand reaction pathways and in particular to quantify the kinetic parameters of key reactions, as well as measure the intracellular levels and localization of probes, if such reagents are to be used with confidence.


Asunto(s)
Oxidantes , Superóxidos , Especies Reactivas de Oxígeno/metabolismo , Oxidación-Reducción , Radicales Libres/química , Superóxidos/metabolismo , Antioxidantes/metabolismo , Colorantes , Estrés Oxidativo
11.
Adv Sci (Weinh) ; 10(24): e2301902, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-37357144

RESUMEN

Organic type-I photosensitizers (PSs) which produce aggressive reactive oxygen species (ROS) with less oxygen-dependent exhibit attractive curative effect for photodynamic therapy (PDT), as they adapt better to hypoxia microenvironment in tumors. However, the reported type-I PSs are limited and its exacted mechanism of oxygen dependence is still unclear. Herein, new selenium-containing type-I PSs of Se6 and Se5 with benzoselenadiazole acceptor has been designed and possessed aggregation-induced emission characteristic. Benefited from double heavy-atom-effect of selenium and bromine, Se6 shows a smaller energy gap (ΔEST ) of 0.03 eV and improves ROS efficiency. Interestingly, type-I radicals of both long-lived superoxide anion (O2 •‾ ) and short-lived hydroxyl (• OH) are generated from them upon irradiation. This may provide a switch-hitter of dual-radical with complementary lifetimes for PDT. More importantly, simultaneous processes to produce • OH are revealed, including disproportionation of O2 •‾ and reaction between excited PS and water. Actually, Se6 displays superior in-vitro PDT performance to commercial chlorin e6 (Ce6), under normoxia or hypoxia. After intravenous injection, a significantly in-vivo PDT performance is demonstrated on Se6, where tumor growth inhibition rates of 99% is higher than Ce6. These findings offer new insights about both molecular design and mechanism study of type-I PSs.


Asunto(s)
Neoplasias , Fotoquimioterapia , Selenio , Humanos , Fármacos Fotosensibilizantes/uso terapéutico , Especies Reactivas de Oxígeno , Superóxidos , Radical Hidroxilo , Neoplasias/tratamiento farmacológico , Oxígeno , Hipoxia , Microambiente Tumoral
12.
Chemosphere ; 313: 137564, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36526141

RESUMEN

Cobalt mediated perovskite oxides (Ca-Fe-Co-x) were prepared for heterogeneous Fenton-like, which exhibited excellent tetracycline (TC) degradation efficiency and wider pH suitability (3-11). Experimental results showed that Ca-Fe-Co-1.0 sample displayed the highest degradation rate could reach 80.5% under neutral conditions, and maintain at around 80% after four cycles. The analysis of degradation mechanism showed that the redox of Fe2+/Fe3+ and Co2+/Co3+ significant enhanced the activation of H2O2 to superoxide radical (∙O2-). Meanwhile, the hydroxyl radical (∙OH) was also detected by ESR analysis. In addition, the possible degradation pathway and mechanism of TC were deduced via UPLC-QTOF/MS analysis and density functional theory (DFT) calculations. The toxicity of TC and its intermediates were also evaluated by the ECOSAR software. The Ca-Fe-Co-1.0/nanocellulose aerogel (NCA) displayed highly removal efficiency of TC wastewater in the long-term operation conduction. This study provided a feasible method to design and synthesis heterogeneous Fenton-like catalysts for antibiotic degradation.


Asunto(s)
Peróxido de Hidrógeno , Superóxidos , Cobalto , Óxidos , Antibacterianos , Tetraciclina
13.
ACS Nano ; 16(12): 20238-20250, 2022 12 27.
Artículo en Inglés | MEDLINE | ID: mdl-36441924

RESUMEN

Every year, large quantities of plastics are produced and used for diverse applications, growing concerns about the waste management of plastics and their release into the environment. Plastic debris can break down into millions of pieces that adversely affect natural organisms. In particular, the photolysis of micro/nanoplastics can generate reactive oxygen species (ROS). However, their oxidative roles in initiating redox chemical reactions with heavy and transition metals have received little attention. In this study, we investigated whether the photolysis of polystyrene (PS) nanoplastics can induce the oxidation of Mn2+(aq) to Mn oxide solids. We found that PS nanoplastics not only produced peroxyl radicals (ROO•) and superoxide radicals (O2•-) by photolysis, which both play a role in unexpected Mn oxidation, but also served as a substrate for facilitating the heterogeneous nucleation and growth of Mn oxide solids and controlling the formation rate and crystalline phases of Mn oxide solids. These findings help us to elucidate the oxidative roles of nanoplastics in the oxidation of redox-active metal ions. The production of ROS from nanoplastics in the presence of light can endanger marine life and human health, and affect the mobility of the nanoplastics in the environment via redox reactions, which in turn may negatively impact their environmental remediation.


Asunto(s)
Poliestirenos , Contaminantes Químicos del Agua , Humanos , Poliestirenos/química , Microplásticos , Especies Reactivas de Oxígeno , Iluminación , Plásticos , Óxidos , Oxidación-Reducción , Estrés Oxidativo , Contaminantes Químicos del Agua/química
14.
ChemSusChem ; 15(19): e202201068, 2022 Oct 10.
Artículo en Inglés | MEDLINE | ID: mdl-35916074

RESUMEN

Photocatalysis is a promising technology for conversion of the glycerol into formic acid, but photocatalytic oxidation of C-C bonds in glycerol exhibits poor selectivity towards formic acid because the photogenerated radicals (e.g., hydroxyl radicals) further oxidize formic acid to CO2 . In this work, a synergy of photogenerated holes and superoxide radicals that achieved the selective oxidation of glycerol into formic acid over the TiO2 catalyst was revealed. The charge separation of pristine TiO2 was improved with the aid of oxygen, which resulted in efficient hole oxidation of the C-C bonds in glycerol to formic acid. Surface active species were controlled to prevent being converted to hydroxyl radicals on TiO2 by controlling the oxygen and water contents, which solved the problem of formic acid peroxidation without sophisticated catalyst modifications. Mechanism studies suggested that glyceraldehyde and glycolaldehyde were the intermediates to generate formic acid. This work provides a green and efficient approach to produce formic acid as a liquid hydrogen carrier from bio-based alcohols.


Asunto(s)
Glicerol , Superóxidos , Dióxido de Carbono , Formiatos , Gliceraldehído , Hidrógeno , Radical Hidroxilo , Oxígeno , Titanio , Agua
15.
ACS Appl Mater Interfaces ; 14(11): 13025-13037, 2022 Mar 23.
Artículo en Inglés | MEDLINE | ID: mdl-35285619

RESUMEN

A rapid increase in methicillin-resistant Staphylococcus aureus (MRSA) induced infection has been noticed in recent years and the biofilm formed by MRSA further delays wound healing, causing a high mortality rate. Hence, a safe and effective superoxide radical (O2•-) mediated self-synthesis strategy is developed to prepare Au-doped MoO3-x (Au/MoO3-x) plasmonic-semiconductor hybrid for the elimination of MRSA mediated wound infection. The synthesis mechanism of Au NPs is systematically investigated, proving that O2•- plays a key role in reduction of HAuCl4 into Au NPs in the presence of H2O and O2. Au-doped MoO3-x exhibits the improved photothermal conversion efficiency (∼52.40%) compared with MoO3-x (∼41.11%). Moreover, the peroxidase (POD)-like activity of Au/MoO3-x hybrid is higher than that of MoO3-x NPs, resulting in increased yield of highly toxic ·OH. In combination with the enhanced photothermal and POD-like properties, Au/MoO3-x hybrid achieves efficient elimination of MRSA bacteria with eradication ratio of ∼99.76%. Additionally, the as-prepared Au/MoO3-x NPs exhibit excellent biosafety, which is verified via in vitro and in vivo experiments. This study provides the basis for exploring MoO3-x-based hybrids via a green O2•--mediated self-synthesis approach.


Asunto(s)
Staphylococcus aureus Resistente a Meticilina , Antibacterianos/farmacología , Colorantes/farmacología , Peroxidasa/farmacología , Superóxidos/farmacología , Cicatrización de Heridas
16.
Environ Res ; 208: 112656, 2022 05 15.
Artículo en Inglés | MEDLINE | ID: mdl-34990609

RESUMEN

The Fenton reaction is regarded as highly efficient for the degradation of organic contaminants. However, the traditional Fenton reaction is still flawed in a narrow pH working range and low utilization efficiency of the reagents. Based on two striking features, a sustained release of H2O2 in-situ under the catalysis of glucose oxidase (GOX) and the rapid electron donation & transferability from green rust (GR), an adaptable biological Fenton-like system (GGGMFs) was established. The coupling roles of glucose, GOX and GR in the degradation of 3,4-dimethylaniline (3,4-DMA) and the types of reactive species were deduced by electron spin resonance (ESR), etc.. Results demonstrated that the suitable pH range of the system was optimized from acidic to circumneutral, which was favorable for practical application, owing to the heterogeneous formation of GR and the pH self-adjustable capacity of GOX-Glucose. Meanwhile, hydroxyl radical (·OH), superoxide radical (·O2-) and Fe (IV) were identified to be the main oxidizing reactive species. Taking different selectivity of the reactive species to certain pollutant functional groups into consideration, the degradation pathways of 3,4-DMA were proposed. Moreover, it was shown that GR not only acted as the activating substance of the Fenton-like reaction, but also enhanced the activity of GOX, resulting in the promotion of glucose conversion in GGGMFs. This study shed light on the enhancement mechanism consisting of two aspects: (i) the elimination of product inhibition (ii) the formation of a 2Fe(III)-FAD complex with FAD, the active center of GOX, which prompted the electronic transfer in the enzyme catalytic reaction.


Asunto(s)
Glucosa Oxidasa , Hierro , Glucosa , Glucosa Oxidasa/química , Glucosa Oxidasa/metabolismo , Peróxido de Hidrógeno/química , Concentración de Iones de Hidrógeno , Hierro/química , Oxidación-Reducción
17.
J Colloid Interface Sci ; 610: 504-517, 2022 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-34838311

RESUMEN

Oxygen vacancies (OVs) were introduced into Ni-based layered double hydroxides (LDHs) through Cu doping, and the catalytic performance of the resulting NixCu-LDHs were investigated for peroxymonosulfate (PMS) activation and methyl 4-hydroxybenzoate (MeP) degradation. Compared with that of Ni-LDH, the catalytic performance of NixCu-LDHs were significantly enhanced and increased with increasing OV content in the catalysts, indicating that Cu doping introduced OVs into NixCu-LDHs and greatly improved their catalytic activity with PMS. Quenching experiments and EPR analyses confirmed that oxidation processes dominated by superoxide radicals (O2•-) and singlet oxygen (1O2), rather than sulfate radicals (SO4•-) or hydroxyl radicals (•OH) used by traditional LDH catalysts, were responsible for MeP degradation by Ni15Cu-LDHs. In addition, quenching experiments with different systems showed the fate of reduced SO4•-and •OH, and demonstrated that O2•- and 1O2 concentrations grew with increasing OV content, confirming that the presence of OVs affected the process of PMS activation. Notably, O2•- mainly originated from adsorbed oxygen or dissolved oxygen (DO) by acquiring electrons from OVs in Ni15Cu-LDHs, since OVs possess abundant localized electrons. Consequently, an OV-mediated oxidative mechanism was proposed for Ni15Cu-LDHs/PMS. This study provides new clues for enhancing the catalytic performance of LDH catalysts by introducing OVs via metal doping in PMS-based AOPs systems.


Asunto(s)
Oxígeno , Superóxidos , Parabenos , Peróxidos
18.
Chemosphere ; 289: 133138, 2022 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-34863725

RESUMEN

The electrochemical disinfection efficiency of Pseudomons putida was studied using ruthenium iridium coated titanium (RICT) electrode as anode and carbonized orange peel biochar (OPB) or graphite as the cathode. The results indicated that RICT/OPB system induced 6.5 and 7.0 log of P. putia inactivation after 60 s at 2 V and 45 s at 10 V, respectively. RICT/OPB system showed better efficiency than RICT/graphite system. The energy consumption of OPB cathode (17.5 Wh m-3 per log) was significantly lower than that of graphite cathode (23.09 Wh m-3 per log). Both anode and cathode played great roles on the disinfection. The anode absorbed electric energy to generate electrical hole, which can oxidize chloride ions to chlorine free radicals. The continuous porous structure of OPB can provide more adsorption sites and reduce electrolyte transport resistance, resulting in more Cl· production. Moreover, P. putia was much easier adsorbed to the anode surface in the RICT/OPB system because of the stronger electrostatic repulsion between cells and OPB cathode. As a result, P. putia was more easily inactivated by the Cl· produced on the anode. Besides chlorine active species, superoxide radical (O2·ï¹£) produced on surface of cathode may also result in P. putia inactivation. The endogenous CuO in OPB can induce persistent free radicals (PFRs) production during pyrosis process. O2·ï¹£ can be produced by O2 activation through the function of Cu2O/CuO and PFRs existed in OPB cathode. The more superoxide radical production led to the better disinfection effect than the graphite cathode. As a consequence, OPB electrode showed high efficiency electrochemical disinfection of P. putida.


Asunto(s)
Carbón Orgánico , Citrus sinensis , Desinfección , Metales/farmacología , Pseudomonas putida/efectos de los fármacos , Carbón Orgánico/farmacología , Electrodos , Escherichia coli , Frutas
19.
J Am Heart Assoc ; 10(18): e021511, 2021 09 21.
Artículo en Inglés | MEDLINE | ID: mdl-34514847

RESUMEN

Background The loss of endothelial integrity increases the risk of intracerebral hemorrhage during ischemic stroke. Adjunct therapeutic targets for reperfusion in ischemic stroke are in need to prevent blood-brain barrier disruption. Recently, we have shown that endothelial permeability is mediated by lysophosphatidic acid (LPA), but the role of autotaxin, which produces LPA, remains unclear in stroke. We investigate whether autotaxin/LPA axis regulates blood-brain barrier integrity after cerebral ischemia. Methods and Results Ischemic stroke was induced in mice by middle cerebral artery occlusion for 90 minutes, followed by 24-hour reperfusion. The therapeutic efficacy of autotaxin/LPA receptor blockade was evaluated using triphenyl tetrazolium chloride staining, Evans blue permeability, infrared imaging, mass spectrometry, and XF24 analyzer to evaluate blood-brain barrier integrity, autotaxin activity, and mitochondrial bioenergetics. In our mouse model of ischemic stroke, the mRNA levels of autotaxin were elevated 1.7-fold following the cerebral ischemia and reperfusion (I/R) group compared with the sham. The enzymatic activity of autotaxin was augmented by 4-fold in the I/R group compared with the sham. Plasma and brain tissues in I/R group showed elevated LPA levels. The I/R group also demonstrated mitochondrial dysfunction, as evidenced by decreased (P<0.01) basal oxygen consumption rate, mitochondrial ATP production, and spare respiratory capacity. Treatment with autotaxin inhibitors (HA130 or PF8380) or autotaxin/LPA receptor inhibitor (BrP-LPA) rescued endothelial permeability and mitochondrial dysfunction in I/R group. Conclusions Autotaxin-LPA signaling blockade attenuates blood-brain barrier disruption and mitochondrial function following I/R, suggesting targeting this axis could be a new therapeutic approach toward treating ischemic stroke.


Asunto(s)
Barrera Hematoencefálica/fisiopatología , Isquemia Encefálica , Accidente Cerebrovascular Isquémico , Lisofosfolípidos/metabolismo , Mitocondrias/patología , Hidrolasas Diéster Fosfóricas/metabolismo , Animales , Isquemia Encefálica/tratamiento farmacológico , Isquemia Encefálica/metabolismo , Accidente Cerebrovascular Isquémico/tratamiento farmacológico , Accidente Cerebrovascular Isquémico/metabolismo , Ratones , Receptores del Ácido Lisofosfatídico/antagonistas & inhibidores
20.
Int J Mol Sci ; 22(16)2021 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-34445269

RESUMEN

Under stress conditions, elevated levels of cellular reactive oxygen species (ROS) may impair crucial cellular structures. To counteract the resulting oxidative damage, living cells are equipped with several defense mechanisms, including photoprotective functions of specific proteins. Here, we discuss the plausible ROS scavenging mechanisms by the enhanced green fluorescent protein, EGFP. To check if this protein could fulfill a photoprotective function, we employed electron spin resonance (ESR) in combination with spin-trapping. Two organic photosensitizers, rose bengal and methylene blue, as well as an inorganic photocatalyst, nano-TiO2, were used to photogenerate ROS. Spin-traps, TMP-OH and DMPO, and a nitroxide radical, TEMPOL, served as molecular targets for ROS. Our results show that EGFP quenches various forms of ROS, including superoxide radicals and singlet oxygen. Compared to the three proteins PNP, papain, and BSA, EGFP revealed high ROS quenching ability, which suggests its photoprotective role in living systems. Damage to the EGFP chromophore was also observed under strong photo-oxidative conditions. This study contributes to the discussion on the protective function of fluorescent proteins homologous to the green fluorescent protein (GFP). It also draws attention to the possible interactions of GFP-like proteins with ROS in systems where such proteins are used as biological markers.


Asunto(s)
Proteínas Fluorescentes Verdes/química , Fotoblanqueo , Oxígeno Singlete/química , Superóxidos/química , Espectroscopía de Resonancia por Spin del Electrón
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