Contrasting effects of NADPH oxidases on the fungal hyphae growth and immune responses in Pleurotus ostreatus.

Pleurotus ostreatus is one of the most consumed mushroom species, as it serves as a high-quality food, favors a rich secondary metabolism, and has remarkable adaptability to the environment and predators. In this study, we investigated the function of two key reactive oxygen species producing enzyme NADPH oxidase (PoNoxA and PoNoxB) in P. ostreatus hyphae growth, metabolite production, signaling pathway activation, and immune responses to different stresses. Characterization of the Nox mutants showed that PoNoxB played an important role in the hyphal formation of the multicellular structure, while PoNoxA regulated apical dominance. The ability of P. ostreatus to tolerate a series of abiotic stress conditions (e.g., osmotic, oxidative, membrane, and cell-wall stresses) and mechanical damage repair was enhanced with PoNoxA over-expression. PoNoxB had a greater responsibility in regulating the polysaccharide composition of the cell wall and methyl jasmonate and gibberellin GA1 biosynthesis, and improved mushroom resistance against Tyrophagus putrescentiae. Moreover, mutants were involved in the jasmonate and GA signaling pathway, and toxic protein defense metabolite production. Our findings shed light on how the oyster mushroom senses stress signals and responds to adverse environments by the complex regulators of Noxs.

Solar Light-Driven Molecular Oxygen Activation by BiOCl Nanosheets: Synergy of Coexposed {001}, {110} Facets and Oxygen Vacancies.

Single-crystalline BiOCl nanosheets with coexposed {001} and {110} facets, as well as oxygen vacancies, were synthesized using a simple method. These nanosheets have the ability to activate molecular oxygen, producing reactive superoxide radicals (77.8%) and singlet oxygen (22.2%) when exposed to solar light. The BiOCl demonstrated excellent photocatalytic efficiency in producing H2O2 under simulated solar light and in oxidatively hydroxylating phenylboronic acid under blue LED light. Our research highlights the significance of constructing coexposed {001} and {110} facets, as well as oxygen vacancies, in enhancing photocatalytic performance. The BiOCl nanosheets have the capability to produce H2O2 with a solar-to-chemical energy conversion efficiency of 0.11%.

Removal of Sb(V) from complex wastewater of Sb(V) and aniline aerofloat using Fe3O4-CeO2 absorbent enhanced by H2O2: Efficiency and mechanism.

Effective elimination of heavy metals from complex wastewater is of great significance for industrial wastewater treatment. Herein, bimetallic adsorbent Fe3O4-CeO2 was prepared, and H2O2 was added to enhance Sb(V) adsorption by Fe3O4-CeO2 in complex wastewater of Sb(V) and aniline aerofloat (AAF) for the first time. Fe3O4-CeO2 showed good adsorption performance and could be rapidly separated by external magnetic field. After five adsorption/desorption cycles, Fe3O4-CeO2 still maintained good stability. The maximum adsorption capacities of Fe3O4-CeO2 in single Sb(V), AAF + Sb(V), and H2O2+AAF + Sb(V) systems were 77.33, 70.14, and 80.59 mg/g, respectively. Coexisting AAF inhibited Sb(V) adsorption. Conversely, additional H2O2 promoted Sb(V) removal in AAF + Sb(V) binary system, and made the adsorption capacity of Fe3O4-CeO2 increase by 14.90%. H2O2 could not only accelerate the reaction rate, but also reduce the optimal amount of adsorbent from 2.0 g/L to 1.2 g/L. Meanwhile, coexisting anions had little effect on Sb(V) removal by Fe3O4-CeO2+H2O2 process. The adsorption behaviors of Sb(V) in three systems were better depicted by pseudo-second-order kinetics, implying that the chemisorption was dominant. The complexation of AAF with Sb(V) hindered the adsorption of Sb(V) by Fe3O4-CeO2. The complex Sb(V) was oxidized and decomposed into free state by hydroxyl radicals produced in Fe3O4-CeO2+H2O2 process. Then the free Sb(V) was adsorbed by Fe3O4-CeO2 mostly through outer-sphere complexation. This work provides a new tactic for the treatment of heavy metal-organics complex wastewater.

Variation of Chemical Microenvironment of Pores in Hydrazone-Linked Covalent Organic Frameworks for Photosynthesis of H2O2.

Photocatalytic synthesis of H2O2 is an advantageous and ecologically sustainable alternative to the conventional anthraquinone process. However, achieving high conversion efficiency without sacrificial agents remains a challenge. In this study, two covalent organic frameworks (COF-O and COF-C) were prepared with identical skeletal structures but with their pore walls anchored to different alkyl chains. They were used to investigate the effect of the chemical microenvironment of pores on photocatalytic H2O2 production. Experimental results reveal a change of hydrophilicity in COF-O, leading to suppressed charge recombination, diminished charge transfer resistance, and accelerated interfacial electron transfer. An apparent quantum yield as high as 10.3% (λ = 420 nm) can be achieved with H2O and O2 through oxygen reduction reaction. This is among the highest ever reported for polymer photocatalysts. This study may provide a novel avenue for optimizing photocatalytic activity and selectivity in H2O2 generation.

Materials Containing Single-, Di-, Tri-, and Multi-Metal Atoms Bonded to C, N, S, P, B, and O Species as Advanced Catalysts for Energy, Sensor, and Biomedical Applications.

Modifying the coordination or local environments of single-, di-, tri-, and multi-metal atom (SMA/DMA/TMA/MMA)-based materials is one of the best strategies for increasing the catalytic activities, selectivity, and long-term durability of these materials. Advanced sheet materials supported by metal atom-based materials have become a critical topic in the fields of renewable energy conversion systems, storage devices, sensors, and biomedicine owing to the maximum atom utilization efficiency, precisely located metal centers, specific electron configurations, unique reactivity, and precise chemical tunability. Several sheet materials offer excellent support for metal atom-based materials and are attractive for applications in energy, sensors, and medical research, such as in oxygen reduction, oxygen production, hydrogen generation, fuel production, selective chemical detection, and enzymatic reactions. The strong metal-metal and metal-carbon with metal-heteroatom (i.e., N, S, P, B, and O) bonds stabilize and optimize the electronic structures of the metal atoms due to strong interfacial interactions, yielding excellent catalytic activities. These materials provide excellent models for understanding the fundamental problems with multistep chemical reactions. This review summarizes the substrate structure-activity relationship of metal atom-based materials with different active sites based on experimental and theoretical data. Additionally, the new synthesis procedures, physicochemical characterizations, and energy and biomedical applications are discussed. Finally, the remaining challenges in developing efficient SMA/DMA/TMA/MMA-based materials are presented.

Catalyst-Free Extraction of U(VI) in Solution by Tribocatalysis.

Extraction of U(VI) in water is of great significance in energy and environmental fields. However, the traditional methods usually fail due to the indispensable extra addition of catalyst, adsorbent, precipitant, or sacrificial agents, which may lead to enhanced extraction costs and secondary pollution. Here, a new efficient uranium extraction strategy is proposed based on triboelectricity without adding a catalyst or other additives. It is found only under the friction between the microbubbles (generated under ultrasonication) and the water flow, that reactive oxygen species (ROS) can largely be generated, which thus contributes to the solidification of U(VI) from water. In addition, the magnetic field can affect the phase of the product. Under mechanical stirring, the product contains (UO2)O2·2H2O, while which contains UO2(OH)2 and (UO2)O2·4H2O under the magnetic stirring. Quenching experiments are also carried out to explore the influence of environmental factors. Most importantly, it shows great potential in the extraction of U(VI) from seawater. This work proposes a catalyst-free and light-free strategy toward the solidification of U(VI) from water, which avoids the secondary pollution of the catalyst to the environment and is low-cost, and has great potential in the real application.

Analysis of factors influencing on Electro-Fenton and research on combination technology (II): a review.

The principle of Fenton reagent is to produce ·OH by mixing H2O2 and Fe2+ to realize the oxidation of organic pollutants, although Fenton reagent has the advantages of non-toxicity and short reaction time, but there are its related defects. The Fenton-like technology has been widely studied because of its various forms and better results than the traditional Fenton technology in terms of pollutant degradation efficiency. This paper reviews the electro-Fenton technology among the Fenton-like technologies and provides an overview of the homogeneous electro-Fenton. It also focuses on summarizing the effects of factors such as H2O2, reactant concentration, reactor volume and electrode quality, reaction time and voltage (potential) on the efficiency of electro-Fenton process. It is shown that appropriate enhancement of H2O2 concentration, voltage (potential) and reaction volume can help to improve the process efficiency; the process efficiency also can be improved by increasing the reaction time and electrode quality. Feeding modes of H2O2 have different effects on process efficiency. Finally, a considerable number of experimental studies have shown that the combination of electro-Fenton with ultrasound, anodic oxidation and electrocoagulation technologies is superior to the single electro-Fenton process in terms of pollutant degradation.

Tandem Proton Transfer in Carboxylated Supramolecular Polymer for Highly Efficient Overall Photosynthesis of Hydrogen Peroxide.

Proton supply is as critical as O2 activation for artificial photosynthesis of H2O2 via two-electron oxygen reduction reaction (2e- ORR). However, proton release via water dissociation is frequently hindered because of the sluggish water oxidation reaction (WOR), extremely limiting the efficiency of photocatalytic H2O2 production. To tackle this challenge, carboxyl-enriched supramolecular polymer (perylene tetracarboxylic acid - PTCA) is elaborately prepared by molecular self-assembly for overall photosynthesis of H2O2. Interestingly, the interconversion between carboxyl as Brønsted acid and its conjugated base realizes rapid proton circulation. Through this efficient tandem proton transfer process, the spatial effect of photocatalytic reduction and oxidation reaction is greatly enhanced with reduced reaction barrier. This significantly facilitates 2e- photocatalytic ORR to synthesize H2O2 and in the meanwhile promotes 4e- photocatalytic WOR to evolve O2. Consequently, the as-developed PTCA exhibits a remarkable H2O2 yield of 185.6 µM h-1 in pure water and air atmosphere under visible light illumination. More impressively, an appreciable H2O2 yield of 78.6 µM h-1 can be well maintained in an anaerobic system owing to in-situ O2 generation by 4e- photocatalytic WOR. Our study presents a novel concept for artificial photosynthesis of H2O2 via constructing efficient proton transfer pathway to enable rapid proton circulation.

Hydrophobic-treated yolk-shell SnS2@CSs Z-scheme confinement reactor for solar-electro-driven hydrogen peroxide production in neutral media.

The diffusion and adsorption properties of the O2/H2O corpuscles at active sites play a crucial role in the fast photo-electrocatalytic reaction of hydrogen peroxide (H2O2) production. Herein, SnS2 nanosheets with abundant interfacial boundaries and large specific areas are encapsulated into hollow mesoporous carbon spheres (CSs) with flexibility, producing a yolk-shell SnS2@CSs Z-scheme photocatalyst. The nanoconfined microenvironment of SnS2@CSs could enrich O2/H2O in catalyst cavities, which allows sufficient internal O2 transfer, improving the surface chemistry of catalytic O2 to O2- conversion and increasing reaction kinetics. By shaping the mixture of SnS2@CSs and polytetrafluoroethylene (PTFE) on carbon felt (CF) using the vacuum filtration method, the natural air-breathing gas diffusion photoelectrode (AGPE) was prepared, and it can achieve an accumulated concentration of H2O2 about 12 mM after a 10 h stability test from pure water at natural pH without using electrolyte and sacrificial agents. The H2O2 product is upgraded through one downstream route of conversion of H2O2 to sodium perborate. The improved H2O2 production performance could be ascribed to the combination of the confinement effect of SnS2@CSs and the rich triple phase interfaces with the continuous hydrophobic layer and hydrophilic layer to synergistically modulate the photoelectron catalytic microenvironment, which enhanced the transfer of O2 mass and offered a stronger affinity to oxygen bubbles. The strategy of combining the confined material with the air-breathing gas diffusion electrode equips a wide practical range of applications for the synthesis of high-yield hydrogen peroxide.

Atmospheric H2O2 during haze episodes in a Chinese megacity: Concentration, source, and implication on sulfate production.

Atmospheric hydrogen peroxide (H2O2), as an important oxidant, plays a key role in atmospheric chemistry. To reveal its characteristics in polluted areas, comprehensive observations were conducted in Zhengzhou, China from February 22 to March 4, 2019, including heavy pollution days (HP) and light pollution days (LP). High NO concentrations (18 ± 26 ppbv) were recorded in HP, preventing the recombination reaction of two HO2• radicals. Surprisingly, higher concentrations of H2O2 were observed in HP (1.5 ± 0.6 ppbv) than those in LP (1.2 ± 0.6 ppbv). In addition to low wind speed and relative humidity, the elevated H2O2 in HP could be mainly attributed to intensified particle-phase photoreactions and biomass burning. In terms of sulfate formation, transition-metal ions (TMI)-catalyzed oxidation emerged as the predominant oxidant pathway in both HP and LP. Note that the average H2O2 oxidation rate increased from 3.6 × 10-2 in LP to 1.1 × 10-1 µg m-3 h-1 in HP. Moreover, the oxidation by H2O2 might exceed that of TMI catalysis under specific conditions, emerging as the primary driver of sulfate formation.

Stable detection of diazinon residues in vegetables by an electrochemiluminescent aptasensor based on the in-situ production of H2O2 from dual-catalytic glucose.

Stable detection of diazinon (DZN) residues in vegetables is important for food safety. In this work, an electrochemiluminescence (ECL) aptasensor with dual-catalytic glucose in-situ production of H2O2 was constructed for the stable detection of DZN in vegetables. Firstly, MWCNTs@MB was prepared using π-π stacking interactions between methylene blue (MB) and multi-walled carbon nanotubes (MWCNTs) to enhance the loading of MB on an electrode and thus catalyze the generation of H2O2 from glucose. Secondly, Cu2O@AuNPs was formed by loading AuNPs on the surface of Cu2O through spontaneous reduction reaction, which improved the interfacial charge transfer, Cu2O nano-enzyme had glucose oxidase mimicking activity and could further catalyze the production of more H2O2 from glucose. MWCNTs@MB and Cu2O@AuNPs played a key role in the in-situ generation of co-reacting reagent H2O2, which solved the problem of unstable detection caused by the easy decomposition of the H2O2 solution added to the luminescence system. In addition, the aptamer was immobilized on the electrode surface by forming Au-S bonds with Cu2O@AuNPs. As a result, the ECL aptasensor performed good linearity in 1.00 pg mL-1-1.00 µg mL-1 and a low limit of detection (LOD) to 0.39 pg mL-1 (S/N = 3). This work provided an effective method for the accurate and stable detection of DZN residues in vegetables, which was of great significance in ensuring food safety and assessing the environmental risk of DZN.

H2O2-mediated signaling in plant stress caused by herbicides: its role in metabolism and degradation pathways.

Systemic acquired acclimation and resistance are vital physiological mechanisms, essential for plants to survive challenging conditions, including herbicide stress. Harmonizing this adaptation involves a series of complex communication pathways. Hydrogen peroxide (H2O2) metabolism might play pivotal roles in orchestrating weeds' acclimation and defense responses. In the context of herbicide resistance, the interaction between H2O2 and key stress signaling pathways is crucial in understanding weed physiology and developing effective management strategies. This dynamic interplay might significantly influence how weeds develop resistance to the various challenges posed by herbicides. Moreover, the production and eradication of H2O2 can be highly compartmentalized, depending on the type of herbicide exposure. Till date there have been no studies aiming to explore/discuss these possibilities. Therefore, in this mini-review, our objective is to delve into the potentialities and recent advancements regarding H2O2-mediated signaling of transcriptomic changes during herbicide stress.

VUV coupled with low-dose H2O2 as pretreatment prior to UF: Performance, mechanisms, DBPs formation and toxicity evaluation.

Ultrafiltration (UF) is widely used in drinking water plants; however, membrane fouling is unavoidable. Natural organic matter (NOM) is commonly considered as an important pollutant that causes membrane fouling. Herein, we proposed VUV/H2O2 as a UF pretreatment and used UV/H2O2 for comparison. Compared to UV/H2O2, the VUV/H2O2 system presented superior NOM removal. In the VUV/H2O2 system, the steady-state concentration of HO• was approximately twice that in the UV/H2O2 system, which was ascribed to the promoting effect of the 185 nm photons. Specifically, 185 nm photons promoted HO• generation by decomposing mainly H2O at a low H2O2 dose or by decomposing mainly H2O2 at a high H2O2 dose. The VUV/H2O2 pretreatment also demonstrated better membrane fouling mitigation performance than did UV/H2O2. An increase in the H2O2 dose promoted HO• generation, thereby enhancing the performance of NOM degradation and membrane fouling alleviation and shifting the major membrane fouling mechanism from cake filtration to standard blocking. The VUV/H2O2 (0.60 mM) pretreatment effectively reduced disinfection byproducts (DBPs) formation during chlorine disinfection. Additionally, the oxidant H2O2 affected the membrane surface morphology and performance but had no evident effect on the mechanical properties. In actual water treatment, the VUV/H2O2 pretreatment exhibited better performance than the UV/H2O2 pretreatment in easing membrane fouling, ameliorating water quality, and reducing DBPs formation and acute toxicity.

Interactions of binary mixtures of metals on rainbow trout (Oncorhynchus mykiss) heart mitochondrial H2O2 homeodynamics.

For continuous pumping of blood, the heart needs a constant supply of energy (ATP) that is primarily met via oxidative phosphorylation in the mitochondria of cardiomyocytes. However, sustained high rates of electron transport for energy conversion redox reactions predisposes the heart to the production of reactive oxygen species (ROS) and oxidative stress. Mitochondrial ROS are fundamental drivers of responses to environmental stressors including metals but knowledge of how combinations of metals alter mitochondrial ROS homeodynamics remains sparse. We explored the effects and interactions of binary mixtures of copper (Cu), cadmium (Cd), and zinc (Zn), metals that are common contaminants of aquatic systems, on ROS (hydrogen peroxide, H2O2) homeodynamics in rainbow trout (Oncorhynchus mykiss) heart mitochondria. Isolated mitochondria were energized with glutamate-malate or succinate and exposed to a range of concentrations of the metals singly and in equimolar binary concentrations. Speciation analysis revealed that Cu was highly complexed by glutamate or Tris resulting in Cu2+ concentrations in the picomolar to nanomolar range. The concentration of Cd2+ was 7.2-7.5 % of the total while Zn2+ was 15 % and 21 % of the total during glutamate-malate and succinate oxidation, respectively. The concentration-effect relationships for Cu and Cd on mitochondrial H2O2 emission depended on the substrate while those for Zn were similar during glutamate-malate and succinate oxidation. Cu + Zn and Cu + Cd mixtures exhibited antagonistic interactions wherein Cu reduced the effects of both Cd and Zn, suggesting that Cu can mitigate oxidative distress caused by Cd or Zn. Binary combinations of the metals acted additively to reduce the rate constant and increase the half-life of H2O2 consumption while concomitantly suppressing thioredoxin reductase and stimulating glutathione peroxidase activities. Collectively, our study indicates that binary mixtures of Cu, Zn, and Cd act additively or antagonistically to modulate H2O2 homeodynamics in heart mitochondria.

Idebenone Antagonizes P53-Mediated Neuronal Oxidative Stress Injury by Regulating CD38-SIRT3 Protein Level.

Idebenone, an antioxidant used in treating oxidative damage-related diseases, has unclear neuroprotective mechanisms. Oxidative stress affects cell and mitochondrial membranes, altering Adp-ribosyl cyclase (CD38) and Silent message regulator 3 (SIRT3) protein expression and possibly impacting SIRT3's ability to deacetylate Tumor protein p53 (P53). This study explores the relationship between CD38, SIRT3, and P53 in H2O2-injured HT22 cells treated with Idebenone. Apoptosis was detected using flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining after determining appropriate H2O2 and Idebenone concentrations.In this study, Idebenone was found to reduce apoptosis and decrease P53 and Caspase3 expression in H2O2-injured HT22 cells by detecting apoptosis-related protein expression. Through bioinformatics methods, CD38 was identified as the target of Idebenone, and it further demonstrated that Idebenone decreased the expression of CD38 and increased the level of SIRT3. An increased NAD+/NADH ratio was detected, suggesting Idebenone induces SIRT3 expression and protects HT22 cells by decreasing apoptosis-related proteins. Knocking down SIRT3 downregulated acetylated P53 (P53Ac), indicating SIRT3's importance in P53 deacetylation.These results supported that CD38 was used as a target of Idebenone to up-regulate SIRT3 to deacetylate activated P53, thereby protecting HT22 cells from oxidative stress injury. Thus, Idebenone is a drug that may show great potential in protecting against reactive oxygen species (ROS) induced diseases such as Parkinson's disease, and Alzheimer's disease. And it might be able to compensate for some of the defects associated with CD38-related diseases.

Oxygen Functional Groups Regulate Cobalt-Porphyrin Molecular Electrocatalyst for Acidic H2O2 Electrosynthesis at Industrial-Level Current.

Electrosynthesis of hydrogen peroxide (H2O2) based on proton exchange membrane (PEM) reactor represents a promising approach to industrial-level H2O2 production, while it is hampered by the lack of high-efficiency electrocatalysts in acidic medium. Herein, we present a strategy for the specific oxygen functional group (OFG) regulation to promote the H2O2 selectivity up to 92% in acid on cobalt-porphyrin molecular assembled with reduced graphene oxide. In-situ X-ray adsorption spectroscopy, in-situ Raman spectroscopy and Kelvin probe force microscopy combined with theoretical calculation unravel that different OFGs exert distinctive regulation effects on the electronic structure of Co center through either remote (carboxyl and epoxy) or vicinal (hydroxyl) interaction manners, thus leading to the opposite influences on the promotion in 2e- ORR selectivity. As a consequence, the PEM electrolyzer integrated with the optimized catalyst can continuously and stably produce the high-concentration of ca. 7 wt% pure H2O2 aqueous solution at 400 mA cm-2 over 200 h with a cell voltage as low as ca. 2.1 V, suggesting the application potential in industrial-scale H2O2 electrosynthesis.

A Schottky/Z-Scheme Hybrid for Augmented Photocatalytic H2 and H2O2 Production.

The prodigious employment of fossil fuels to conquer the global energy demand is becoming a dreadful threat to the human society. This predicament is appealing for a potent photocatalyst that can generate alternate energy sources via solar to chemical energy conversion. With this interest, we have fabricated a ternary heterostructure of Ti3C2 nanosheet modified g-C3N4/Bi2O3 (MCNRBO) Z-scheme photocatalyst through self-assembly process. The morphological analysis clearly evidenced the close interfacial interaction between g-C3N4 nanorod, Bi2O3 and Ti3C2 nanosheets. The oxygen vacancy created on Bi2O3 surface, as suggested by XPS and EPR analysis, supported the Z-scheme heterojunction formation between g-C3N4 nanorod and Bi2O3 nanosheets. The collaborative effect of Z-scheme and Schottky junction significantly reduced charge transfer resistance promoting separation efficiency of excitons as indicated from PL and EIS analysis. The potential of MCNRBO towards photocatalytic application was investigated by H2O2 and H2 evolution reaction. A superior photocatalytic H2O2 and H2 production rate for MCNRBO is observed, which are respectively around 5 and 18 folds higher as compared to pristine CNR nanorod. The present work encourages for the development of a noble, eco-benign and immensely efficient dual heterojunction based photocatalyst, which can acts as saviour of human society from energy crisis.

Plasmonic Near-Infrared-Response S-Scheme ZnO/CuInS2 Photocatalyst for H2O2 Production Coupled with Glycerin Oxidation.

Solar fuel synthesis is intriguing because solar energy is abundant and this method compensates for its intermittency. However, most photocatalysts can only absorb UV-to-visible light, while near-infrared (NIR) light remains unexploited. Surprisingly, the charge transfer between ZnO and CuInS2 quantum dots (QDs) can transform a NIR-inactive ZnO into a NIR-active composite. This strong response is attributed to the increased concentration of free charge carriers in the p-type semiconductor at the interface after the charge migration between ZnO and CuInS2, enhancing the localized surface plasmon resonance (LSPR) effect and the NIR response of CuInS2. As a paradigm, this ZnO/CuInS2 heterojunction is used for H2O2 production coupled with glycerin oxidation and demonstrates supreme performance, corroborating the importance of NIR response and efficient charge transfer. Mechanistic studies through contact potential difference (CPD), Hall effect test, and finite element method (FEM) calculation allow for the direct correlation between the NIR response and charge transfer. This approach bypasses the general light response issues, thereby stepping forward to the ambitious goal of harnessing the entire solar spectrum.

Photodegradation of a Broad-Spectrum Antibiotic Azithromycin Using H2O2 under Ultraviolet Irradiation.

The photodegradation of azithromycin present was carried out in water using H2O2 under UV irradiation. The reaction variables considered in this study were the amount of H2O2 solution and the initial concentration of azithromycin to evaluate the performance of the photodegradation process. The azithromycin degradation was not observed in the dark during stirring for 20 min. The study showed an efficient photodegradation of azithromycin using H2O2 as an oxidant in the presence of UV irradiation. The azithromycin degradation was altered significantly by the pH of the irradiated solution. The degradation was low at an acidic pH and showed an increasing trend as the pH changed to basic. The azithromycin degradation increased with a higher amount (higher concentration) of H2O2. The degradation of azithromycin decreased with a higher concentration of azithromycin in the reacting solution. The highest degradation of AZT was achieved in 1 h using a 1.0 ppm AZT solution containing 3 mL of H2O2. The experimental data obtained were well-fitted to zero-order reaction kinetics. The results of this study were found quite excellent. They showed 100% degradation in 1 h when compared with those reported in the literature, both with photocatalysis using nanomaterials and photolysis using light irradiation and/or H2O2. The UV/H2O2 system was found to be quite efficient for the photodegradation of azithromycin, and this system can be applied to degrade other organic pollutants present in industrial wastewater.

Multifunctional N, Fe-doped carbon dots with peroxidase-like activity for the determination of H2O2 and ascorbic acid and cell protection against oxidation.

Multifunctional N, Fe-doped carbon dots (N, Fe-CDs) were synthesized by the one-step hydrothermal method using ferric ammonium citrate and dicyandiamide as raw materials. The N, Fe-CDs exhibited peroxidase-like (POD) activity by catalyzing the oxidization of 3,3',5,5'-tetramethylbenzidine (TMB) to the green oxidation state ox-TMB in the presence of hydrogen peroxide (H2O2). Subsequently, based on the POD activity of N, Fe-CDs, an efficient and sensitive colorimetric method for the detection of H2O2 and ascorbic acid (AA) was established with a limit of detection of 0.40 µM and 2.05 µM. The proposed detection method has been successfully applied to detect AA in fruit juice, vitamin C tablets, and human serum samples and has exhibited excellent application prospects in biotechnology and food fields. Furthermore, N, Fe-CDs also showed a protective effect on the cell damage caused by H2O2 and could be used as an antioxidant agent.