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1.
Chemosphere ; 361: 142549, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38851501

RESUMO

Titanium dioxide nanoparticles (TiO2-NP) present in wastewater effluent are discharged into freshwater and saltwater (i.e., marine) systems. TiO2-NP can be solar-driven photoactivated by ultraviolet (UV)-light producing reactive oxygen species including hydroxyl radicals (·OH). ·OH are non-selective and react with a broad range of species in water. In other studies, photoactivation of TiO2-NP has been correlated with oxidative stress and ecotoxicological impacts on plant and animal biota. This study examined the photoactivation of TiO2-NP in freshwater and saltwater systems, and contrasted the oxidation potential in both systems using methylene blue (MB) as a reaction probe. Maximum MB loss (51.9%, n = 4; 95% confidence interval 49.4-54.5) was measured in salt-free, deionized water where ·OH scavenging was negligible; minimum MB loss (1%) was measured in saltwater due to significant ·OH scavenging, indicating the inverse correlation between MB loss and radical scavenging. A kinetic analysis of scavenging by seawater constituents indicated Cl- had the greatest impact due to high concentration and high reaction rate constant. Significant loss of MB occurred in the presence of Br- relative to other less aggressive scavengers present in seawater (i.e., HCO3-, HSO4-). This result is consistent with the formation of Bromate, a strong oxidant that subsequently reacts with MB. In freshwater samples collected from different water bodies in Oklahoma (n = 12), the average MB loss was 13.4%. Greater MB loss in freshwater systems relative to marine systems was due to lower ·OH scavenging by various water quality parameters. Overall, TiO2-NP photoactivation in freshwater systems has the potential to cause greater oxidative stress and ecotoxicological impacts than in marine systems where ·OH scavenging is a dominant reaction.


Assuntos
Sequestradores de Radicais Livres , Água Doce , Oxirredução , Água do Mar , Titânio , Poluentes Químicos da Água , Titânio/química , Titânio/toxicidade , Água Doce/química , Água do Mar/química , Sequestradores de Radicais Livres/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade , Radical Hidroxila/química , Nanopartículas/química , Nanopartículas/toxicidade , Raios Ultravioleta , Águas Residuárias/química , Azul de Metileno/química
2.
Environ Sci Technol ; 58(24): 10852-10862, 2024 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-38843408

RESUMO

The Cu(II)/H2O2 system is recognized for its potential to degrade recalcitrant organic contaminants and inactivate microorganisms in wastewater. We investigated its unique dual oxidation strategy involving the selective oxidation of copper-complexing ligands and enhanced oxidation of nonchelated organic compounds. L-Histidine (His) and benzoic acid (BA) served as model compounds for basic biomolecular ligands and recalcitrant organic contaminants, respectively. In the presence of both His and BA, the Cu(II)/H2O2 system rapidly degraded His complexed with copper ions within 30 s; however, BA degraded gradually with a 2.3-fold efficiency compared with that in the absence of His. The primary oxidant responsible was the trivalent copper ion [Cu(III)], not hydroxyl radical (•OH), as evidenced by •OH scavenging, hydroxylated BA isomer comparison with UV/H2O2 (a •OH generating system), electron paramagnetic resonance, and colorimetric Cu(III) detection via periodate complexation. Cu(III) selectively oxidized His owing to its strong chelation with copper ions, even in the presence of excess tert-butyl alcohol. This selectivity extended to other copper-complexing ligands, including L-asparagine and L-aspartic acid. The presence of His facilitated H2O2-mediated Cu(II) reduction and increased Cu(III) production, thereby enhancing the degradation of BA and pharmaceuticals. Thus, the Cu(II)/H2O2 system is a promising option for dual-target oxidation in diverse applications.


Assuntos
Cobre , Histidina , Peróxido de Hidrogênio , Oxirredução , Cobre/química , Histidina/química , Peróxido de Hidrogênio/química , Catálise , Ferro/química , Radical Hidroxila/química , Ácido Benzoico/química
3.
Water Sci Technol ; 89(10): 2783-2795, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38822614

RESUMO

Photocatalytically active ceramic flat sheet membranes based on a nanostructured titanium dioxide (TiO2) coating were produced for photocatalytic water treatment. The nano-TiO2 layer was produced by a novel combination of magnetron sputtering of a thin titanium layer on silicon carbide (SiC) membranes, followed by electrochemical oxidation (anodization) and subsequent heat treatment (HT). Characterization by Raman spectra and field emission scanning electron microscopy proved the presence of a nanostructured anatase layer on the membranes. The influence of the titanium layer thickness on the TiO2 formation process and the photocatalytic properties were investigated using anodization curves, by using cyclovoltammetry measurements, and by quantifying the generated hydroxyl radicals (OH•) under UV-A irradiation in water. Promising photocatalytic activity and permeability of the nano-TiO2-coated membranes could be demonstrated. A titanium layer of at least 2 µm was necessary for significant photocatalytic effects. The membrane sample with a 10 µm Ti/TiO2 layer had the highest photocatalytic activity showing a formation rate of 1.26 × 10-6 mmol OH• s-1. Furthermore, the membranes were tested several times, and a decrease in radical formation was observed. Assuming that these can be attributed to adsorption processes of the reactants, initial experiments were carried out to reactivate the photocatalyzer.


Assuntos
Compostos Inorgânicos de Carbono , Radical Hidroxila , Membranas Artificiais , Compostos de Silício , Titânio , Purificação da Água , Titânio/química , Radical Hidroxila/química , Purificação da Água/métodos , Catálise , Compostos de Silício/química , Compostos Inorgânicos de Carbono/química , Técnicas Eletroquímicas , Nanoestruturas/química , Processos Fotoquímicos
4.
Int J Nanomedicine ; 19: 5045-5056, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38832334

RESUMO

Background: Chemodynamic therapy (CDT) is a new treatment approach that is triggered by endogenous stimuli in specific intracellular conditions for generating hydroxyl radicals. However, the efficiency of CDT is severely limited by Fenton reaction agents and harsh reaction conditions. Methods: Bimetallic PtMn nanocubes were rationally designed and simply synthesized through a one-step high-temperature pyrolysis process by controlling both the nucleation process and the subsequent crystal growth stage. The polyethylene glycol was modified to enhance biocompatibility. Results: Benefiting from the alloying of Pt nanocubes with Mn doping, the structure of the electron cloud has changed, resulting in different degrees of the shift in electron binding energy, resulting in the increasing of Fenton reaction activity. The PtMn nanocubes could catalyze endogenous hydrogen peroxide to toxic hydroxyl radicals in mild acid. Meanwhile, the intrinsic glutathione (GSH) depletion activity of PtMn nanocubes consumed GSH with the assistance of Mn3+/Mn2+. Upon 808 nm laser irradiation, mild temperature due to the surface plasmon resonance effect of Pt metal can also enhance the Fenton reaction. Conclusion: PtMn nanocubes can not only destroy the antioxidant system via efficient reactive oxygen species generation and continuous GSH consumption but also propose the photothermal effect of noble metal for enhanced Fenton reaction activity.


Assuntos
Glutationa , Manganês , Platina , Espécies Reativas de Oxigênio , Animais , Platina/química , Platina/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Glutationa/química , Humanos , Manganês/química , Manganês/farmacologia , Terapia Fototérmica/métodos , Camundongos , Nanopartículas Metálicas/química , Peróxido de Hidrogênio/química , Linhagem Celular Tumoral , Radical Hidroxila/química , Antineoplásicos/química , Antineoplásicos/farmacologia , Ferro/química
5.
Colloids Surf B Biointerfaces ; 240: 113990, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38810468

RESUMO

Chemodynamic therapy (CDT), which employs intracellular H2O2 to produce toxic hydroxyl radicals to kill cancer cells, has received great attention due to its specificity to tumors. However, the relatively insufficient endogenous H2O2 and the short-lifetime and limited diffusion distance of •OH compromise the therapeutic efficacy of CDT. Mitochondria, which play crucial roles in oncogenesis, are highly vulnerable to elevated oxidative stress. Herein, we constructed a mitochondria-mediated self-cycling system to achieve high dose of •OH production through continuous H2O2 supply. Cinnamaldehyde (CA), which can elevate H2O2 level in the mitochondria, was loaded in Cu(II)-containing metal organic framework (MOF), termed as HKUST-1. After actively targeting mitochondria, the intrinsic H2O2 in mitochondria of cancer cells could induce degradation of MOF, releasing the initial free CA. The released CA further triggered the upregulation of endogenous H2O2, resulting in the subsequent adequate release of CA and the final burst growth of H2O2. The cycle process greatly promoted the Fenton-like reaction between Cu2+ and H2O2 and induced long-term high oxidative stress, achieving enhanced chemodynamic therapy. In a word, we put forward an efficient strategy for enhanced chemodynamic therapy.


Assuntos
Acroleína , Peróxido de Hidrogênio , Estruturas Metalorgânicas , Mitocôndrias , Estresse Oxidativo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Humanos , Peróxido de Hidrogênio/farmacologia , Peróxido de Hidrogênio/metabolismo , Acroleína/farmacologia , Acroleína/química , Acroleína/análogos & derivados , Estruturas Metalorgânicas/química , Estruturas Metalorgânicas/farmacologia , Cobre/química , Cobre/farmacologia , Animais , Sobrevivência Celular/efeitos dos fármacos , Camundongos , Radical Hidroxila/metabolismo , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Neoplasias/metabolismo , Antineoplásicos/farmacologia , Antineoplásicos/química , Tamanho da Partícula , Linhagem Celular Tumoral , Propriedades de Superfície
6.
Environ Sci Technol ; 58(23): 10175-10184, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38771930

RESUMO

The interplay between sulfur and iron holds significant importance in their atmospheric cycle, yet a complete understanding of their coupling mechanism remains elusive. This investigation delves comprehensively into the evolution of reactive oxygen species (ROS) during the interfacial reactions involving sulfur dioxide (SO2) and iron oxides under varying relative humidity conditions. Notably, the direct activation of water by iron oxide was observed to generate a surface hydroxyl radical (•OH). In comparison, the aging of SO2 was found to markedly augment the production of •OH radicals on the surface of α-Fe2O3 under humid conditions. This augmentation was ascribed to the generation of superoxide radicals (•O2-) stemming from the activation of O2 through the Fe(II)/Fe(III) cycle and its combination with the H+ ion to produce hydrogen peroxide (H2O2) on the acidic surface. Moreover, the identification of moderate relative humidity as a pivotal factor in sustaining the surface acidity of iron oxide during SO2 aging underscores its crucial role in the coupling of iron dissolution, ROS production, and SO2 oxidation. Consequently, the interfacial reactions between SO2 and iron oxides under humid conditions are elucidated as atmospheric processes that enhance oxidation capacity rather than deplete ROS. These revelations offer novel insights into the mechanisms underlying •OH radical generation and oxidative potential within atmospheric interfacial chemistry.


Assuntos
Espécies Reativas de Oxigênio , Dióxido de Enxofre , Dióxido de Enxofre/química , Compostos Férricos/química , Radical Hidroxila/química , Oxirredução , Peróxido de Hidrogênio/química , Umidade
7.
Bioresour Technol ; 403: 130863, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38772520

RESUMO

The OH production by adding magnetite (MGT) alone has been reported in composting. However, the potential of nitrilotriacetic acid (NTA) addition for magnetite-amended sludge composting remained unclear. Three treatments with different addition [control check (CK); T1: 5 % MGT; T2: 5 % MGT + 5 % NTA] were investigated to characterize hydroxyl radical, humification and bacterial community response. The NTA addition manifested the best performance, with the peak OH content increase by 52 % through facilitating the cycle of Fe(Ⅱ)/Fe(Ⅲ). It led to the highest organic matters degradation (22.3 %) and humic acids content (36.1 g/kg). Furthermore, NTA addition altered bacterial community response, promoting relative abundances of iron-redox related genera, and amino acid metabolism but decreasing carbohydrate metabolism. Structural equation model indicated that temperature and Streptomyces were the primary factors affecting OH content. The study suggests that utilizing chelators is a promising strategy to strengthen humification in sewage sludge composting with adding iron-containing minerals.


Assuntos
Compostagem , Óxido Ferroso-Férrico , Substâncias Húmicas , Radical Hidroxila , Ácido Nitrilotriacético , Esgotos , Ácido Nitrilotriacético/química , Óxido Ferroso-Férrico/química , Compostagem/métodos , Ferro/química
8.
Environ Sci Technol ; 58(24): 10623-10631, 2024 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-38781516

RESUMO

Iron minerals are widespread in earth's surface water and soil. Recent studies have revealed that under sunlight irradiation, iron minerals are photoactive on producing reactive oxygen species (ROS), a group of key species in regulating elemental cycling, microbe inactivation, and pollutant degradation. In nature, iron minerals exhibit varying crystallinity under different hydrogeological conditions. While crystallinity is a known key parameter determining the overall activity of iron minerals, the impact of iron mineral crystallinity on photochemical ROS production remains unknown. Here, we assessed the photochemical ROS production from ferrihydrites with different degrees of crystallinity. All examined ferrihydrites demonstrated photoactivity under irradiation, resulting in the generation of hydrogen peroxide (H2O2) and hydroxyl radical (•OH). The photochemical ROS production from ferrihydrites increased with decreasing ferrihydrite crystallinity. The crystallinity-dependent photochemical •OH production was primarily attributed to conduction band reduction reactions, with the reduction of O2 by conduction band electrons being the rate-limiting key process. Conversely, the crystallinity of iron minerals had a negligible influence on photon-to-electron conversion efficiency or surface Fenton-like activity. The difference in ROS productions led to a discrepant degradation efficiency of organic pollutants on iron mineral surfaces. Our study provides valuable insights into the crystallinity-dependent ROS productions from iron minerals in natural systems, emphasizing the significance of iron mineral photochemistry in natural sites with abundant lower-crystallinity iron minerals such as wetland water and surface soils.


Assuntos
Ferro , Minerais , Espécies Reativas de Oxigênio , Ferro/química , Espécies Reativas de Oxigênio/química , Minerais/química , Radical Hidroxila/química , Peróxido de Hidrogênio/química
9.
Bull Exp Biol Med ; 176(5): 617-619, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38730108

RESUMO

We studied the effect of the HSP27 inhibitor, 5-(5-ethyl-2-hydroxy-4-methoxyphenyl)-4-(4-methoxyphenyl)-isoxazole, at a final concentration of 0.1 µM and/or the apoptosis inducer dexamethasone at a final concentration of 10 µM on the content of hydroxyl radical, reduced and oxidized glutathione, HSP27, activity of glutathione reductase, glutathione peroxidase, caspase-3, and the number of Annexin+ Jurkat tumor cells. The involvement of HSP27 in apoptosis of Jurkat tumor cells was demonstrated. Simultaneous exposure to the HSP27 inhibitor and dexamethasone resulted in an increase in the level of HSP27 against the background of developing oxidative stress (increase in the concentration of hydroxyl radicals and changes in the state of the glutathione system).


Assuntos
Apoptose , Caspase 3 , Dexametasona , Glutationa , Proteínas de Choque Térmico HSP27 , Estresse Oxidativo , Humanos , Dexametasona/farmacologia , Células Jurkat , Apoptose/efeitos dos fármacos , Proteínas de Choque Térmico HSP27/metabolismo , Proteínas de Choque Térmico HSP27/genética , Glutationa/metabolismo , Caspase 3/metabolismo , Caspase 3/genética , Estresse Oxidativo/efeitos dos fármacos , Glutationa Redutase/metabolismo , Glutationa Peroxidase/metabolismo , Radical Hidroxila/metabolismo
10.
Bioresour Technol ; 402: 130806, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38718906

RESUMO

The study investigated the inactivation of Microcystis aeruginosa using a combined approach involving thermally activated peroxyacetic acid (Heat/PAA) and thermally activated persulfate (Heat/PDS). The Heat/PDS algal inactivation process conforms to first-order reaction kinetics. Both hydroxyl radical (•OH) and sulfate radical (SO4-•) significantly impact the disruption of cell integrity, with SO4-• assuming a predominant role. PAA appears to activate organic radicals (RO•), hydroxyl (•OH), and a minimal amount of singlet oxygen (1O2). A thorough analysis underscores persulfate's superior ability to disrupt algal cell membranes. Additionally, SO4-• can convert small-molecule proteins into aromatic hydrocarbons, accelerating cell lysis. PAA can accelerate cell death by diffusing into the cell membrane and triggering advanced oxidative reactions within the cell. This study validates the effectiveness of the thermally activated persulfate process and the thermally activated peroxyacetic acid as strategies for algae inactivation.


Assuntos
Microcystis , Oxirredução , Espécies Reativas de Oxigênio , Microcystis/efeitos dos fármacos , Microcystis/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Sulfatos/metabolismo , Sulfatos/farmacologia , Sulfatos/química , Ácido Peracético/farmacologia , Temperatura Alta , Radical Hidroxila/metabolismo , Cinética
11.
Environ Sci Technol ; 58(21): 9436-9445, 2024 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-38691809

RESUMO

Although electro-Fenton (EF) processes can avoid the safety risks raised by concentrated hydrogen peroxide (H2O2), the Fe(III) reduction has always been either unstable or inefficient at high pH, resulting in catalyst deactivation and low selectivity of H2O2 activation for producing hydroxyl radicals (•OH). Herein, we provided a strategy to regulate the surface dipole moment of TiO2 by Fe anchoring (TiO2-Fe), which, in turn, substantially increased the H2O2 activation for •OH production. The TiO2-Fe catalyst could work at pH 4-10 and maintained considerable degradation efficiency for 10 cycles. Spectroscopic analysis and a theoretical study showed that the less polar Fe-O bond on TiO2-Fe could finely tune the polarity of H2O2 to alter its empty orbital distribution, contributing to better ciprofloxacin degradation activity within a broad pH range. We further verified the critical role of the weakened polarity of H2O2 on its homolysis into •OH by theoretically and experimentally investigating Cu-, Co-, Ni-, Mn-, and Mo-anchored TiO2. This concept offers an avenue for elaborate design of green, robust, and pH-universal cathodic Fenton-like catalysts and beyond.


Assuntos
Peróxido de Hidrogênio , Titânio , Peróxido de Hidrogênio/química , Concentração de Íons de Hidrogênio , Titânio/química , Ferro/química , Radical Hidroxila/química , Catálise , Eletrodos
12.
Environ Pollut ; 351: 124090, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38697249

RESUMO

Indoor formaldehyde poses a significant carcinogenic risk to human health, making its removal imperative. Electro-Fenton degradation has emerged as a promising technology for addressing this concern. In the electro-Fenton system, ·OH is identified as the primary active species responsible for formaldehyde removal. Hence, its generation and utilization are pivotal for the system's effectiveness and economy. Experimental and quantum chemical methods were employed to investigate the effects and mechanisms of nitrogen doping on various aspects influencing ·OH generation and utilization. Results indicate that nitrogen doping synergistically enhances the generation and utilization of ·OH, leading to an improved formaldehyde removal efficiency in nitrogen-doped cathodic systems. The dominant nitrogen type influencing ·OH generation and utilization varies across different stages. Pyridinic nitrogen facilitates H2O2 adsorption through hydrogen bonding, while pyrrolic and graphitic nitrogen contribute to formaldehyde adsorption and catalyze the conversion of H2O2 to ·OH. Both pyridinic nitrogen and pyrrolic nitrogen boost the degradation of formaldehyde by ·OH. In comparison to the unmodified system, the modified system with NAC-GF/700C as cathode exhibits remarkable improvements. The formaldehyde removal efficiency has increased twofold, and energy consumption reduced by 73.45%. Furthermore, the system demonstrates excellent cyclic stability. These advancements can be attributed to the activation temperature, which leads to the appropriate types and high content of nitrogen elements in NAC-GF/700C. The research represents an important step towards more economical and efficient electro-Fenton technology for indoor formaldehyde removal.


Assuntos
Poluição do Ar em Ambientes Fechados , Carbono , Eletrodos , Formaldeído , Peróxido de Hidrogênio , Formaldeído/química , Peróxido de Hidrogênio/química , Carbono/química , Radical Hidroxila/química , Poluentes Atmosféricos/química , Ferro/química , Adsorção
13.
Environ Sci Technol ; 58(20): 8966-8975, 2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38722667

RESUMO

The absolute radical quantum yield (Φ) is a critical parameter to evaluate the efficiency of radical-based processes in engineered water treatment. However, measuring Φ is fraught with challenges, as current quantification methods lack selectivity, specificity, and anti-interference capabilities, resulting in significant error propagation. Herein, we report a direct and reliable time-resolved technique to determine Φ at pH 7.0 for commonly used radical precursors in advanced oxidation processes. For H2O2 and peroxydisulfate (PDS), the values of Φ•OH and ΦSO4•- at 266 nm were measured to be 1.10 ± 0.01 and 1.46 ± 0.05, respectively. For peroxymonosulfate (PMS), we developed a new approach to determine Φ•OHPMS with terephthalic acid as a trap-and-trigger probe in the nonsteady state system. For the first time, the Φ•OHPMS value was measured to be 0.56 by the direct method, which is stoichiometrically equal to ΦSO4•-PMS (0.57 ± 0.02). Additionally, radical formation mechanisms were elucidated by density functional theory (DFT) calculations. The theoretical results showed that the highest occupied molecular orbitals of the radical precursors are O-O antibonding orbitals, facilitating the destabilization of the peroxy bond for radical formation. Electronic structures of these precursors were compared, aiming to rationalize the tendency of the Φ values we observed. Overall, this time-resolved technique with specific probes can be used as a reliable tool to determine Φ, serving as a scientific basis for the accurate performance evaluation of diverse radical-based treatment processes.


Assuntos
Radical Hidroxila , Sulfatos , Sulfatos/química , Radical Hidroxila/química , Purificação da Água/métodos , Oxirredução , Peróxido de Hidrogênio/química
14.
Nat Commun ; 15(1): 4025, 2024 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-38740804

RESUMO

Intracellular membranes composing organelles of eukaryotes include membrane proteins playing crucial roles in physiological functions. However, a comprehensive understanding of the cellular responses triggered by intracellular membrane-focused oxidative stress remains elusive. Herein, we report an amphiphilic photocatalyst localised in intracellular membranes to damage membrane proteins oxidatively, resulting in non-canonical pyroptosis. Our developed photocatalysis generates hydroxyl radicals and hydrogen peroxides via water oxidation, which is accelerated under hypoxia. Single-molecule magnetic tweezers reveal that photocatalysis-induced oxidation markedly destabilised membrane protein folding. In cell environment, label-free quantification reveals that oxidative damage occurs primarily in membrane proteins related to protein quality control, thereby aggravating mitochondrial and endoplasmic reticulum stress and inducing lytic cell death. Notably, the photocatalysis activates non-canonical inflammasome caspases, resulting in gasdermin D cleavage to its pore-forming fragment and subsequent pyroptosis. These findings suggest that the oxidation of intracellular membrane proteins triggers non-canonical pyroptosis.


Assuntos
Inflamassomos , Proteínas de Membrana , Oxirredução , Piroptose , Humanos , Inflamassomos/metabolismo , Proteínas de Membrana/metabolismo , Estresse Oxidativo , Catálise , Estresse do Retículo Endoplasmático , Peróxido de Hidrogênio/metabolismo , Proteínas de Ligação a Fosfato/metabolismo , Radical Hidroxila/metabolismo , Mitocôndrias/metabolismo , Membranas Intracelulares/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Camundongos , Animais , Processos Fotoquímicos , Dobramento de Proteína , Caspases/metabolismo , Gasderminas
15.
Environ Sci Technol ; 58(22): 9669-9678, 2024 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-38771965

RESUMO

In subsurface environments, Fe(II)-bearing clay minerals can serve as crucial electron sources for O2 activation, leading to the sequential production of O2•-, H2O2, and •OH. However, the observed •OH yields are notably low, and the underlying mechanism remains unclear. In this study, we investigated the production of oxidants from oxygenation of reduced Fe-rich nontronite NAu-2 and Fe-poor montmorillonite SWy-3. Our results indicated that the •OH yields are dependent on mineral Fe(II) species, with edge-surface Fe(II) exhibiting significantly lower •OH yields compared to those of interior Fe(II). Evidence from in situ Raman and Mössbauer spectra and chemical probe experiments substantiated the formation of structural Fe(IV). Modeling results elucidate that the pathways of Fe(IV) and •OH formation respectively consume 85.9-97.0 and 14.1-3.0% of electrons for H2O2 decomposition during oxygenation, with the Fe(II)edge/Fe(II)total ratio varying from 10 to 90%. Consequently, these findings provide novel insights into the low •OH yields of different Fe(II)-bearing clay minerals. Since Fe(IV) can selectively degrade contaminants (e.g., phenol), the generation of mineral Fe(IV) and •OH should be taken into consideration carefully when assessing the natural attenuation of contaminants in redox-fluctuating environments.


Assuntos
Radical Hidroxila , Minerais , Radical Hidroxila/química , Minerais/química , Ferro/química , Argila/química , Oxigênio/química , Peróxido de Hidrogênio/química , Oxirredução , Silicatos de Alumínio/química , Bentonita/química
16.
Food Chem ; 452: 139567, 2024 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-38718456

RESUMO

In this study, a hydroxyl radical oxidation system was established to simulate the oxidation process in fermented meat products. This system was employed to examine the structural changes in myofibrillar proteins (MPs) resulting from tryptic hydrolysis after a hydroxyl radical oxidative regime. The effect of these changes on the ability of MPs to bind selected aldehydes (3-methyl butanal, pentanal, hexanal, and heptanal) was also investigated. Moderate oxidation (H2O2 ≤ 1.0 mM) unfolded the structure of MPs, facilitating trypsin-mediated hydrolysis and increasing their binding capacity for the four selected aldehydes. However, excessive oxidation (H2O2 ≥ 2.5 mM) led to cross-linking and aggregation of MPs, inhibiting trypsin-mediated hydrolysis. The oxidised MPs had the best binding capacity for heptanal. The interaction of the oxidised trypsin-hydrolysed MPs with heptanal was driven by hydrophobic interactions. The binding of heptanal affected the structure of the oxidised trypsin-hydrolysed MPs and reduced their α-helix content.


Assuntos
Aldeídos , Radical Hidroxila , Estresse Oxidativo , Radical Hidroxila/química , Radical Hidroxila/metabolismo , Aldeídos/química , Aldeídos/metabolismo , Hidrólise , Animais , Proteínas Musculares/química , Proteínas Musculares/metabolismo , Oxirredução , Miofibrilas/química , Miofibrilas/metabolismo , Tripsina/química , Tripsina/metabolismo , Suínos , Ligação Proteica , Produtos da Carne/análise
17.
Environ Pollut ; 353: 124153, 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-38750808

RESUMO

Isoproturon (IPU), a widely utilized phenylurea herbicide, is recognized as an emerging contaminant. Previous studies have predominantly attributed the degradation of IPU in natural waters to indirect photolysis by natural organic matter (NOM). Here, we demonstrate that nitrite (NO2-) also serves as an important photosensitizer that induces the photo-degradation of IPU. Through radical quenching tests, we identify hydroxyl radicals (•OH) and nitrogen dioxide radicals (NO2•) originating from NO2- photolysis as key players in IPU degradation, resulting in the generation of a series of hydroxylated and nitrated byproducts. Moreover, we demonstrate a synergistic effect on the photo-transformation of IPU when both NOM and NO2- are present in the reaction mixture. The observed rate constant (kobs) for IPU removal increases to 0.0179 ± 0.0002 min-1 in the co-presence of NO2- (50 µM) and NOM (2.5 mgC/L), surpassing the sum of those in the presence of each alone (0.0135 ± 0.0004 min-1). NOM exhibits multifaceted roles in the indirect photolysis of IPU. It can be excited by UV and transformed to excited triplet states (3NOM*) which oxidize IPU to IPU•+ that undergoes further degradation. Simultaneously, NOM can mitigate the reaction by reducing the IPU•+ intermediate back to the parent IPU. However, the presence of NO2- alters this dynamic, as IPU•+ rapidly couples with NO2•, accelerating IPU degradation and augmenting the formation of mono-nitrated IPU. These findings provide in-depth understandings on the photochemical transformation of environmental contaminants, especially phenylurea herbicides, in natural waters where NOM and NO2- coexist.


Assuntos
Herbicidas , Nitritos , Compostos de Fenilureia , Fotólise , Raios Ultravioleta , Poluentes Químicos da Água , Compostos de Fenilureia/química , Nitritos/química , Poluentes Químicos da Água/química , Herbicidas/química , Radical Hidroxila/química
18.
Chemosphere ; 359: 142304, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38734253

RESUMO

Toxic organic and heavy metal contaminants commonly exist in industrial waste stream(s) and treatment is of great challenge. In this study, a dielectric barrier discharge (DBD) non-thermal plasma technology was employed for the simultaneous treatment of two important contaminants, chloramphenicol (CAP) and Cr(VI) in an aqueous solution through redox transformations. More than 70% of CAP and 20% of TOC were degraded in 60 min, while Cr(VI) was completely removed in 10 min. The hydroxyl radicals were the main active species for the degradation. Meanwhile, the consumption of hydroxyl radicals was beneficial to the reduction of Cr(VI). The synergistic effect was investigated between CAP degradation and Cr(VI) reduction. The reduction of Cr(VI) would be enhanced in the presence of CAP with a low concentration and could be inhibited under a high concentration, because part of hydroxyl radicals could be consumed by the low-concentration CAP and the obtained intermediates with a higher kinetic rate. However, CAP with a high concentration could react with such reductive species as eaq- and •H, which could compete with Cr(VI) and inhibit the reduction. In addition, the presence of Cr(VI) enhanced the degradation and mineralization of CAP; the study of obtained intermediates indicated that the presence of Cr(VI) changed the degradation path of CAP as Cr(VI) would react with reductive species, enhance the generation of hydroxyl radicals, and cause more hydroxylation reactions. Moreover, the mechanism for the simultaneous redox transformations of CAP and Cr(VI) was illustrated. This study indicates that the DBD non-thermal plasma technology can be one of better solutions for simultaneous elimination of heavy metal and organic contaminants in aquatic environments.


Assuntos
Cloranfenicol , Cromo , Oxirredução , Poluentes Químicos da Água , Cloranfenicol/química , Cromo/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/análise , Gases em Plasma/química , Radical Hidroxila/química , Eliminação de Resíduos Líquidos/métodos
19.
Water Res ; 256: 121609, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38615601

RESUMO

Lingering inconsistencies in the global methane (CH4) budget and ambiguity in CH4 sources and sinks triggered efforts to identify new CH4 formation pathways in natural ecosystems. Herein, we reported a novel mechanism of light-induced generation of hydroxyl radicals (•OH) that drove the production of CH4 from aquatic dissolved organic matters (DOMs) under ambient conditions. A total of five DOM samples with different origins were applied to examine their potential in photo-methanification production under aerobic conditions, presenting a wide range of CH4 production rates from 3.57 × 10-3 to 5.90 × 10-2 nmol CH4 mg-C-1 h-1. Experiments of •OH generator and scavenger indicated that the contribution of •OH to photo-methanificaiton among different DOM samples reached about 4∼42 %. In addition, Fourier transform infrared spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry showed that the carbohydrate- and lipid-like substances containing nitrogen-bonded methyl groups, methyl ester, acetyl groups, and ketones, were the potential precursors for light-induced CH4 production. Based on the experimental results and simulated calculations, the contribution of photo-methanification of aquatic DOMs to the diffusive CH4 flux across the water-air interface in a typical eutrophic shallow lake (e.g., Lake Chaohu) ranged from 0.1 % to 18.3 %. This study provides a new perspective on the pathways of CH4 formation in aquatic ecosystems and a deeper understanding on the sources and sinks of global CH4.


Assuntos
Radical Hidroxila , Metano , Radical Hidroxila/química , Metano/química , Aerobiose
20.
Environ Sci Technol ; 58(17): 7505-7515, 2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38619820

RESUMO

The reaction of peracetic acid (PAA) and Fe(II) has recently gained attention due to its utility in wastewater treatment and its role in cloud chemistry. Aerosol-cloud interactions, partly mediated by aqueous hydroxyl radical (OH) chemistry, represent one of the largest uncertainties in the climate system. Ambiguities remain regarding the sources of OH in the cloud droplets. Our research group recently proposed that the dark and light-driven reaction of Fe(II) with peracids may be a key contributor to OH formation, producing a large burst of OH when aerosol particles take up water as they grow to become cloud droplets, in which reactants are consumed within 2 min. In this work, we quantify the OH production from the reaction of Fe(II) and PAA across a range of physical and chemical conditions. We show a strong dependence of OH formation on ultraviolet (UV) wavelength, with maximum OH formation at λ = 304 ± 5 nm, and demonstrate that the OH burst phenomenon is unique to Fe(II) and peracids. Using kinetics modeling and density functional theory calculations, we suggest the reaction proceeds through the formation of an [Fe(II)-(PAA)2(H2O)2] complex, followed by the formation of a Fe(IV) complex, which can also be photoactivated to produce additional OH. Determining the characteristics of OH production from this reaction advances our knowledge of the sources of OH in cloudwater and provides a framework to optimize this reaction for OH output for wastewater treatment purposes.


Assuntos
Aerossóis , Radical Hidroxila , Ácido Peracético , Radical Hidroxila/química , Ácido Peracético/química , Luz , Cinética , Ferro/química
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