H2O2 Concentration Research Articles

Foamed calcium sulfoaluminate cement with controlled porous network for daily or seasonal heat storage in ettringite

Calcium sulfoaluminate (CSA) cement-based materials have high ettringite content enables heat storage, enhancing the thermal inertia of buildings. This study aims to optimize the porous network of foamed CSA material in terms of porosity, permeability and mechanical strength so that they can be effective in building applications as supporting structures with heat storage capacity. To achieve these goals, a foaming process method using hydrogen peroxide (H2O2) and surfactant was used to control the porous network. The H2O2 and surfactant contents varied from 0.5% to 1.2% and 0.01% to 0.05%, respectively, and generated a wide range of material densities from 589 to 1184 kg/m3 - and hence a wide range of properties in terms of porosity (43 - 70%), permeability (2.6 10-13 - 7.1 10-12 m2) and compressive strength (0.8 -9.4 MPa). Then, an abacus correlating material properties, found by surface fitting, linking porosity, gas permeability and compressive strength, allowed the material to be optimized in accordance with the needs of each building application. The CSA paste consisting of 1% H2O2 and 0.03% surfactant, with 66% porosity, 4.1 10-12 m2 permeability, and 1.8 MPa compressive strength, was the optimal mix-design for solar storage box applications (for short-term storage). The CSA paste consisting of 0.5% H2O2 and 0.01% surfactant, with 43% porosity, 5.6 10-13 m2 permeability, 9.4 MPa compressive strength, appeared to be optimal for self-supporting wall storing solar heat (long-term storage).

Engineering Robust Silver-Decorated calcium peroxide Nano-Antibacterial Platforms for chemodynamic enhanced sterilization

Calcium peroxide (CaO2) is commonly used as a hydrogen peroxide (H2O2) donor to eliminate bacterial infections. However, the rapid dissociation of CaO2 and the explosive release of H2O2 have limited the development of CaO2 in the antibacterial field. Therefore, a series of silver nanoparticles (AgNPs) functionalized bacteria-triggered smart hydrogels (CSA-H) that integrate sustained release of nanoparticles and localized chemodynamic sterilization were constructed. The pH-responsive hydrogel formed through the Schiff base reaction enables the responsive release of CaO2 nanoparticles while simultaneously regulating the concentration of H2O2 within the bacterial infection microenvironment. AgNPs are capable of reacting with H2O2 under mildly acidic conditions to produce hydroxyl radicals with enhanced antimicrobial activity. The antimicrobial results demonstrated that AgNPs functionalized silicon dioxide-coated calcium peroxide (CaO2@SiO2/AgNPs) nanoparticles exhibited enhanced bactericidal activity compared to AgNPs or CaO2 alone. Furthermore, CSA-H hydrogels exhibited significant antibacterial activity against S. aureus and E. coli under the dual effect of AgNPs and pH-driven Fenton-like reactions. This chemodynamic antibacterial platform is environmentally responsive and provides a promising strategy for creating multifunctional hydrogels loaded with nano-enzymes, thus advancing the development of AgNPs in chemodynamic-antibacterial related applications.

Protection effect of cis 9, trans 11-conjugated linoleic acid on oxidative stress and inflammatory damage in bovine mammary epithelial cells

The present study was conducted to observe the protective effects of c9, t11- conjugated linoleic acid (CLA) on oxidative stress and inflammation in bovine mammary epithelial cells (BMECs) exposed to H2O2. The BMECs were treated with different concentrations of H2O2 for 8 h, 600 µmol/L was determined to be the damage concentration. Using different concentrations of c9, t11-CLA to process BMECs for 24 h, 50 and 100 µmol/L were determined to be the effective concentrations for subsequent analyses. Thus, four BMEC groups were established: Control group; H2O2 group; 50 µmol/L c9, t11-CLA + H2O2 group; 100 µmol/L c9, t11-CLA + H2O2 group. We observed that the H2O2 group exhibited significantly lower total antioxidant activity (T-AOC), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities and significantly higher secretions of malondialdehyde (MDA), interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α and expressions of IL-1β, IL-6, and IL-8 than the control group (p < 0.05). Pretreatment with c9, t11-CLA enhanced SOD, CAT, and GPx activities and SOD mRNA expression and repressed IL-6 and IL-8 secretion and expression in H2O2-treated BMECs (p < 0.05). In conclusion, c9, t11-CLA treatment efficiently enhanced antioxidant capacity and decreased inflammation induced by H2O2 in BMECs.

Tsa1 is the dominant peroxide scavenger and a source of H2O2-dependent GSSG production in yeast

Hydrogen peroxide (H2O2) is an important biological molecule, functioning both as a second messenger in cell signaling and, especially at higher concentrations, as a cause of cell damage. Cells harbor multiple enzymes that have peroxide reducing activity in vitro. However, the contribution of each of these enzymes towards peroxide scavenging in vivo is less clear. Therefore, to directly investigate in vivo peroxide scavenging, we used the genetically encoded peroxide sensors, roGFP2-Tsa2ΔCR and HyPer7, to systematically screen the peroxide scavenging capacity of baker’s yeast thiol and heme peroxidase mutants. We show that the 2-Cys peroxiredoxin Tsa1 alone is responsible for almost all exogenous H2O2 and tert-butyl hydroperoxide scavenging. Furthermore, Tsa1 can become an important source of H2O2-dependent cytosolic glutathione disulfide production. The two catalases and cytochrome c peroxidase only produce observable scavenging defects at higher H2O2 concentrations when these three heme peroxidases are deleted in combination. We also analyzed the reduction of Tsa1 in vitro, revealing that the enzyme is efficiently reduced by thioredoxin-1 with a rate constant of 2.8×106 M–1s–1 but not by glutaredoxin-2. Tsa1 reduction by reduced glutathione occurs nonenzymatically with a rate constant of 2.9 M–1s–1. Hence, the observed Tsa1-dependent glutathione disulfide production in yeast probably requires the oxidation of thioredoxins. Our findings clarify the importance of the various thiol and heme peroxidases for peroxide removal and suggest that most thiol peroxidases have alternative or specialized functions in specific subcellular compartments.

Role of biosynthesized silver nanoparticles in mitigating hyperhydricity in micropropagated watermelon (Citrullus lanatus Thunb.) and assessment of genetic fidelity using RAPD and SCoT markers

Watermelon (Citrullus lanatus) is one of the five most consumed fresh fruits and is a commercially important horticulture crop. The consumer demand for seedless watermelons has considerably increased due to their superior taste and ease of consumption. Seedless watermelon plants are triploids hence plant tissue culture technology which is the cultivation of plant cells, tissues, or organs on specially formulated nutrient media can facilitate the rapid multiplication of seedless watermelon varieties. However, hyperhydricity has been reported as a frequent problem for in vitro growth and development of watermelon. Hence, the present study highlights the application of silver nanoparticles biosynthesized from Parthenium hysterophorus (PHAgNPs) for reversal of hyperhydricity and enhancing in vitro shoot production in watermelon. The biosynthesized PHAgNPs was characterized using UV–vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis and Transmission electron microscopy. Cotyledonary nodes used as explant and cultured in three types of cytokinins (BAP, TDZ and KIN) became hyperhydric, losing their ability to regenerate at high cytokinin concentrations (> 1.5 mg/L) irrespective of the cytokinin type. The optimum concentration of BAP (1.0 mg/L) fortified with PHAgNPs (15.0 mg/L) exhibited an improved response of 91 % and induced a maximum of 32.33 shoots with a maximum shoot length of 5.66 cm after 6 weeks. The incorporation of PHAgNPs reduced the percentage of hyperhydricity from 29 % to 1.33 % in regenerated shoots, which was confirmed by the reduction in relative water content (RWC) from 93.33 % to 80.33. Silver ions reduced H2O2 content by 50 % and increased photosynthetic pigments (chlorophyll a, b and carotenoids) by 50 %, which contributed to the formation of healthy regenerated shoots, with opened stomata compared to closed in hyperhydric shoots. Compared with those of hyperhydric shoots, the gene expression patterns of 1-aminocyclopropane-1-carboxylase synthase (ACS1) and 1-aminocyclopropane-1-carboxylic acid oxidase (ACO1) decreased after the retroversion of shoots to 15 mg/L PHAgNP medium. The relative gene expression profiles of ACS1 and ACO1 in hyperhydric shoots were 8.8- and 1.8-fold greater than those in normal shoots, respectively. Profuse root growth was observed in MS basal media supplemented with IBA (1.0 mg/L) and PHAgNPs (10.0 mg/L), which resulted in the greatest number of roots (12.33), with an average root length of 4.33 cm and a response of 89.33 %. The genotoxic effect of PHAgNPs evaluated using RAPD and SCoT molecular markers, showed that the addition of low levels of silver nanoparticles to the medium did not cause any genetic variation. The efficient regeneration protocol standardized in this study provides a solution to solve the problem of hyperhydricity in watermelon regeneration.

Unveiling the influences of P fertilization on bioactive compounds and antioxidant activity in grains of four sorghum cultivars.

Phosphorus is a critical nutrient in agriculture, influencing plant growth and nutritional quality. This study, uniquely designed to investigate the effects of phosphorus (P) fertilization levels, sorghum cultivars, and growing locations on phytochemical content and antioxidant activity in sorghum grains, employed four sorghum cultivars (Hakeka, P954063, Tabat, and Tetron) grown under three P levels (0P, 1P, 2P) in two locations (Gezira and White Nile) in Sudan. In this study, four sorghum cultivars were grown in two distinct locations in Sudan, employing a split-plot design with three (P) fertilization levels. P was applied as triple super phosphate directly with the seeds, and additional fertilization included urea applied in two split doses. At physiological maturity, representative sorghum panicles were harvested, processed, and analyzed for bioactive compounds and antioxidant activities using standard extraction and quantification techniques such as Folin-Ciocalteu for phenolics and colorimetric flavonoid assays. Antioxidant activities were assessed through various assays, including DPPH and FRAP. Statistical analyses were performed using a three-way ANOVA to examine the effects of cultivar, P level, and location on the measured parameters, supplemented by multivariate analysis to further elucidate the interactions between these factors. Significant interactions (p<0.001) were observed among cultivars, P levels, and locations for total phenolic content (TPC), total flavonoid content (TFC), carotenoids, tannins, and various antioxidant activity measures (DPPH, FRAP, ABTS, TRP, H2O2). P fertilization significantly increased all measured phytochemicals and antioxidant activities compared to non-treated cultivars, except for H2O2, which decreased with P application. Among cultivars, Hakeka consistently exhibited the highest TFC, carotenoid content, and antioxidant activities (DPPH, FRAP, TRP, ABTS), particularly at the 2P level. P954063 showed the highest TPC and tannin concentrations. Tetron generally had the lowest phytochemical and antioxidant levels. White Nile showed higher TPC, carotenoids, DPPH, FRAP, TRP, and ABTS levels, while Gezira had higher TFC, tannins, and H2O2 concentrations. The impact of phosphorus fertilization often varies between locations. Strong positive correlations were found between TPC and all antioxidant assays (r = 0.68-0.90) and total carotenoids and antioxidant activities (r = 0.73-0.93). This study recommended cultivating the Tabat variety with 2P doses in Gezira. In addition, the Hakeka cultivar showed the highest increases in total flavonoid content, carotenoids, and antioxidant activities, particularly under the highest P level (2P). The findings highlight that P plays a critical role in enhancing sorghum's nutritional and health-promoting qualities, which are essential for leveraging this staple crop for food and nutrition security strategies in semi-arid regions.

Dynamic Rare-Earth Metal-Organic Frameworks Based on Molecular Rotor Linkers with Efficient Emissions and Ultrasensitive Optical Sensing Performance.

4,4',4″-Triphenylamine tricarboxylate (TPA-COOH) with a distinct molecular rotor structure was reacted with rare-earth (RE) metal ions to obtain seven dynamic RE-based luminescent MOFs (RE-LMOFs) (i.e., emission colors in the blue, yellow-green, red, and near-infrared regions and emission peak wavelengths between 400 and 1600 nm) via the effective transfer of absorbed energy from TPA-COOH to the RE metal ions through the antenna effect. Due to the large energy level difference between RE ions, it was rare in the early days to use the same ligand to construct energy-level matching RE-LMOF homologues with multiple RE metal centers. The uncoordinated oxygen atoms on the molecular rotor linkers in RE-LMOFs provide active sites that can specifically capture highly toxic metal ions and strong oxidative pollutants. The limit of detection (LOD) of RE-LMOF for Al(III) ions is far below the maximum concentration of Al(III) ions in drinking water stipulated by the U.S. Environmental Protection Agency (USEPA) and that for H2O2 is much lower than the H2O2 content in cancer cells, showing excellent application potential for diagnosing early cell cancelation.

Accelerated Proton‐Coupled Electron Transfer via Engineering Palladium Sub‐Nanoclusters for Scalable Electrosynthesis of Hydrogen Peroxide

AbstractElectrosynthesis of H2O2 from oxygen reduction reaction via a two‐electron pathway is vital as an alternative for the energy‐intensive anthraquinone process. However, this process is largely hindered in neutral and alkaline conditions due to sluggish kinetics associated with the transformation of intermediate O2* into OOH* via proton‐coupled electron transfer sourced from slow water dissociation. Herein, we developed Pd sub‐nanoclusters on the nickel ditelluride nanosheets (Pd SNCs/NiTe2) to enhance the performance of H2O2 electrosynthesis. The newly‐developed Pd SNCs/NiTe2 exhibited a H2O2 selectivity of as high as 99 % and a positive shift of onset potential up to 0.81 V. Combined theoretical calculations and experimental studies (e.g., X‐ray absorption and attenuated total reflectance‐Fourier transform infrared spectra measurements) revealed that the Pd sub‐nanoclusters supported by NiTe2 nanosheets efficiently reduced the energy barrier of water dissociation to generate more protons, facilitating the proton feeding kinetics. When used in a flow cell, Pd SNCs/NiTe2 cathode efficiently produced H2O2 with a maximum yield rate of 1.75 mmol h−1 cm−2 and a current efficiency of 95 % at 100 mA cm−2. Further, an accumulated H2O2 concentration of 1.43 mol L−1 was reached after 10 hours of continuous electrolysis, showing the potential for practical H2O2 electrosynthesis.

Removal of tetracycline antibiotic from aqueous solution using bimetallic CuCo-ZIFs as an efficient catalyst in the presence of hydrogen peroxide

Antibiotics play an important role in disease treatment; however, they are also a threat to public health and the ecosystem. Therefore, a bimetallic CuCo-ZIFs catalyst was manufactured through the ultrasonic-assisted solvothermal method to activate H2O2 towards the removal of tetracycline (TC) in an aqueous environment, a polluting broad-spectrum antibiotic model. PXRD, SEM, TEM, EDX, TGA, FT-IR, and BET analyses indicated that CuCo-ZIFs cubic crystals were successfully synthesized with high crystallinity, large specific surface area, and ideal thermal stability. Factors affecting the TC removal were investigated, including CuCo-ZIFs dosage, H2O2 concentration, treatment time, initial TC concentration, and reaction temperature. The results showed that the CuCo-ZIFs/H2O2 catalytic system was capable of effectively handling TC, with about 93.9% of TC removed in the presence of 0.3 g.L-1 CuCo-ZIFs, 0.01 mol.L-1 H2O2 at room temperature within 30 min. Conclusively, this study contributes to expanding the application potential of bimetallic CuCo-ZIFs materials to eliminate antibiotic residues in an aqueous environment and inspire research on environmental improvement.

Selective and durable H2O2 electrosynthesis catalyst in acid by selenization induced straining and phasing

Developing efficient electrocatalysts for acidic electrosynthesis of hydrogen peroxide (H2O2) holds considerable significance, while the selectivity and stability of most materials are compromised under acidic conditions. Herein, we demonstrate that constructing amorphous platinum–selenium (Pt–Se) shells on crystalline Pt cores can manipulate the oxygen reduction reaction (ORR) pathway to efficiently catalyze the electrosynthesis of H2O2 in acids. The Se2‒Pt nanoparticles, with optimized shell thickness, exhibit over 95% selectivity for H2O2 production, while suppressing its decomposition. In flow cell reactor, Se2‒Pt nanoparticles maintain current density of 250 mA cm−2 for 400 h, yielding a H2O2 concentration of 113.2 g L−1 with productivity of 4160.3 mmol gcat−1 h−1 for effective organic dye degradation. The constructed amorphous Pt–Se shell leads to desirable O2 adsorption mode for increased selectivity and induces strain for optimized OOH* binding, accelerating the reaction kinetics. This selenization approach is generalizable to other noble metals for tuning 2e‒ ORR pathway.

Comparative transcriptome analysis of B. oleracea L. var. italica and B. macrocarpa Guss. genotypes under drought stress: de novo vs reference genome assembly

Drought stress influences plant growth and development affecting some physiological processes during the growing cycle. The improvement of the drought stress resistance of the plant will allow the reduction of the water requirements of the crops, representing the new frontier for agriculture, as consequence of the ongoing climatic changes. The individuation of genetic features useful for enhancing the reduction of water use and the plant drought resistance will be one of the key strategy for providing enough food for the foreseen increment of the global population. Nowadays, the cultivars used for modern agriculture show a narrow genetic diversity due to the domestication process carried out of each crop, resulting with a less adaptation to the environmental conditions affected by both antropic activities and the climatic change in act. Among the several grown species, Brassica oleracea L. (n = 9) crops are particularly vulnerable to the adverse effects of water deficiency. Transcriptomic analysis is a powerful tool that allows researchers to identify genes and pathways, that are activated or repressed in response to each specific stress, elucidating the complex regulatory networks that underlie the correspondent response. To individuate the differentially expressed genes we compared two drought-sensitive B. oleracea L. var. botritis x italica Sicilian landraces and two drought-tolerant B. macrocarpa Guss populations grown in ordinary irrigation regimes and in water deficit conditions. Their transcriptome was obtained by a RNAseq approach. The individuated sensible and tolerant drought stress genotypes showed significant difference for H2O2 content, leaf area and SPAD index (Soil Plant Analysis Development). For better identify crucial genes and pathways associated with drought stress response of both the sensible and tolerant genotypes a thorough evaluation of both de novo assembly and reference B. oleracea var. italica genome-based assembly was conducted. The comparison of the transcriptomes allowed to identify the crucial genes and pathways associated with tolerance to drought stress in Brassica oleracea L. crops. As main results, we individuated one gene coding transcription factor showing opposite behavior in the sensitive and tolerant signatures. The adoption of two transcriptome assembly methods provided a more comprehensive dataset, enabling an unbiased interpretation of the outcomes.

By-product distribution and cytotoxicity assessment of ZnO-assisted photocatalytic degradation of reactive blue 250 dye

This research examined the effectiveness and feasibility of utilizing ultraviolet (UV) assisted photo-catalysis to treat wastewater effluents from textile production containing reactive blue 250 (RB 250) dye. Molecular oxygen and active species like O2•−, HO2•, H2O2 and •OH play crucial roles in the degradation process. Additionally, the degradation of dyes is influenced by several factors, including dye concentration, duration of UV irradiation, pH levels, concentration of H2O2, and the catalyst. The concentration of H2O2 and catalyst dose for the decolorization was studied at 0.6 mL and 0.5 g respectively. The discoloration was higher at low dye concentration, high H2O2 concentration, acidic conditions and high catalyst concentration. The maximum degradation (97 %) of RB 250 dye was obtained in the presence of zinc oxide nanoparticles within 90 min. The extent of decolorization of the dye was determined by UV–Vis spectroscopy. Fourier transform infrared spectroscopy (FTIR) was employed to analyze the changes in functionalities after degradation. The disappearance of characteristic peaks associated with specific groups within the dye molecule confirmed the extensive degradation of RB 250 dye. LCMS analysis was conducted to examine the intermediates and a mechanistic degradation pathway was subsequently proposed. The cytotoxicity of the irradiated dye samples was evaluated through a hemolytic test both pre and post-treatment. The findings suggest that the UV/H2O2/ZnO treatment represents a promising approach for effectively degrading RB 250 dye.

Indices of carbohydrate metabolism and antioxidant system state during germination of aged wheat and triticale seeds treated with H(2)S donor

Hydrogen sulfide is a gasotransmitter molecule involved in the realization of many functions of the plant organism, including seed germination. Aging of seeds is shown to be accompanied by oxidative stress and reduced germination. The effect of exogenous hydrogen sulfide on the germination of aged cereal seeds has not been studied. The aim of the work was to estimate the effect of priming with NaHS as an H2S donor on wheat and triticale seeds previously subjected to natural aging. Seeds of winter wheat (Triticum aestivum) and winter ×Triticosecale were stored indoors for 4 years at fluctuating temperature and humidity. Aged seeds were treated with 0.2-5 mM NaHS solution for 3 h and germinated in Petri dishes for 3 days. The hydropriming­ treatment was used as a control. Amylase activity in grains, the biomass of shoots and roots, the content of total sugars, H2O2, lipid peroxidation products and anthocyanin, and the activity of antioxidant enzymes in seedlings were determined. It was shown that after the treatment with H2S donor, the activities of catalase and guaiacol peroxidase, as well as the content of anthocyanins were increased only in triticale seedlings. Nevertheless, treatment of seeds of both cereal species was followed by enhanced growth of shoots and roots, increase in amylase and superoxide dismutase activities, decrease in H2O2 and MDA contents, and elevated accumulation of sugars in shoots. It is concluded that the increase in germination of aged cereal seeds under the influence of H2S donor is caused by increased mobilization of reserve carbohydrates and modulation of antioxidant system activity. Such treatment can be considered as an effective tool to improve seedling growth. Keywords: amylase, antioxidant system, hydrogen sulfide, oxidative stress, seeds aging, total sugar, Triticosecale, Triticum aestivum

Molecular characterization of a novel thioredoxin-related transmembrane protein gene AcTMX3 that plays important roles in antioxidant defence in Arma chinensis diapause.

Protein disulphide isomerase (PDI) possesses disulphide isomerase, oxidoreductase and molecular chaperone activities, and is involved in regulating various physiological processes. However, there are few studies on the function in insect diapause. In this study, we cloned one novel member PDI family (TMX3, thioredoxin-related transmembrane protein 3) in Arma chinensis. The AcTMX3 encodes 426 amino acids that contains a predicted N-terminal signal sequence, a thioredoxin-like domain with the CXXC active site and a potential transmembrane region, which are typical sequence features of TMX3. RT-qPCR results showed that AcTMX3 was mainly expressed in the head under non-diapause conditions, while AcTMX3 was highly expressed in the fat body (central metabolic organ) under diapause conditions. Moreover, temporal expression profile showed that compared with non-diapause conditions, diapause conditions significantly induced AcTMX3 expression, and the expression of AcTMX3 was enhanced at 15°C. Silencing AcTMX3 in A. chinensis significantly inhibited the expression of antioxidant genes (AcTrx2 and AcTrx-like), increased the content of H2O2 and ascorbate and reduced the survival rate of A. chinensis under diapause conditions. Our results suggested that AcTMX3 played an important role in the resistance of A. chinensis to oxidative stress under diapause conditions.

OsAAH confers salt tolerance in rice seedlings.

Soil salinization is becoming a great threat that reduces crop productivity worldwide. In this study, we found that rice allantoate amidohydrolase (OsAAH) expression was significantly upregulated by salt stress, and its overexpression conferred salt tolerance at the seedling stage. Compared to wild type (WT), the contents of ureides (allantoin and allantoate) were significantly increased in Osaah mutants and reduced in OsAAH overexpression lines both before and after salt treatments. Exogenous allantoin significantly promoted salt tolerance in OsAAH overexpression, but not in Osaah mutants. Subcellular localization showed that OsAAH was also localized to the peroxisomes in addition to the previously reported endoplasmic reticulum (ER). The differential expression of peroxisome-related genes was identified between Osaah mutants and WT. Furthermore, the contents of H2O2 and malondialdehyde (MDA) were significantly accumulated in Osaah mutants and reduced in OsAAH overexpression lines. The activities of antioxidant enzymes were significantly reduced in Osaah mutants and enhanced in OsAAH overexpression under NaCl treatment. The transcription factor OsABI5 could directly bind to OsAAH promoter and activate OsAAH expression. Our findings reveal that OsAAH could be induced by salt stress through the activation of OsABI5 and then confer salt tolerance by enhancing the scavenging capacity of reactive oxygen species (ROS), which contributes to rice breeding in salt tolerance.

Bimetallic FeCo metal–organic framework based cascade reaction system: Enhanced peroxidase activity for antibacterial performance

Metal-organic frameworks (MOFs), as a peroxidase (POD), can catalyze the conversion of H2O2 to reactive oxygen species (ROS) for antibacterial application. To achieve strong antibacterial activity, it is necessary to improve the enzyme-like activity of MOFs. In this study, FexCoMOF was synthesized by incorporating Co(II) to improve the electron transfer of Fe(III)/Fe(II), which enhanced its redox capacity as a nanozyme and further promoted the generation of hydroxyl radical (⋅OH), exhibiting higher POD activity. Doping with different amounts of Co(II) altered the particle size, specific surface area, and surface defects of FexCoMOF, thus exhibiting differential enzyme-like activities. Additionally, a glucose-responsive enzyme cascade reaction system based on Fe4CoMOF/glucose oxidase (GOx) was established. In the presence of glucose, the in situ-generated substrate H2O2 was in contact with the catalytic site and the generated gluconic acid enabled Fe4CoMOF to maintain maximum enzyme activity under physiological pH conditions, avoiding damage caused by the use of exogenous high concentrations of H2O2. In the in vitro antibacterial experiment, the minimum inhibitory concentration (MIC) of Fe4CoMOF/GOx was 10 μg mL−1 for Escherichia coli (E. coli) and 5 μg mL−1 for Staphylococcus aureus (S. aureus) (∼108 CFU mL−1). The increase in enzyme activity resulted in a considerable reduction in the dose of the antibacterial agent, which was conducive to improving bio-safety. The in vivo experiment in mice demonstrated that the glucose-responsive Fe4CoMOF-based cascade reaction system had excellent antibacterial properties and remarkably promoted wound healing. The antibacterial agent based on bimetallic MOF developed in this work provides a new idea for cascade catalytic antibacterial therapy and will have remarkable application prospects in biomaterials and nanomedicine.

Degradation of ciprofloxacin by hydrogen peroxide activated with pyrite under simulated sunlight

Ciprofloxacin (CIP) residues in the environment pose risks to both human health and ecosystems. In this study, we explored the effect of hydrogen peroxide (H2O2) on CIP degradation, activated by pyrite (FeS2) under simulated sunlight. XRD, XRF, EDS, XSP, DRS, and PL tests confirmed the high purity of FeS2 and its photocatalytic properties. With [CIP] = 30 μM, [FeS2] = 0.2 g/L, [H2O2] = 0.2 mM, CIP removal reached 87.6 %. The removal rate of TOC reached 55.3 % after 60 min of light exposure, and hydroxyl radicals (OH) contributed 72.7 % to the process. H2O2 utilization was 67.5 %, and the system operated effectively across a pH range of 2.00 to 8.00. CIP removal in river water reached 87.9 % after 3 h of light exposure, though the degradation was slower than in ultrapure water. Cl−, SO42−, and NO3− had little effect on degradation, whereas H2PO4−, CO32−, and HCO3− significantly inhibited the process as their concentrations increased. In livestock wastewater, the simulated sunlight-FeS2/H2O2 system was less effective, but after diluting the wastewater 100 times, CIP removal reached 87.6 % after 60 min. The degraded solutions showed no significant toxicity. These findings suggest that FeS2, combined with simulated sunlight, can effectively catalyze low concentrations of H2O2 to produce OH radicals, removing antibiotics from livestock wastewater.

Reaction kinetics of molybdenum dissolution by hydrogen peroxide in acidic and alkaline solutions using tartaric acid and sodium hydroxide: A semi‐empirical model with rotating disc method

AbstractMolybdenum is an amphoteric metal that dissolves in both acidic and alkaline solutions. This fundamental study explores a sustainable process for the dissolution of molybdenum, focusing on the reaction kinetics in H2O2, H2O2‐NaOH, and H2O2‐C4H6O6 solutions. A rotating disc method was applied with the Levich's equation. Semi‐empirical models with activation energy were developed for the H2O2‐NaOH and H2O2‐C4H6O6 solutions. The study examined the effects of rotating speed, disc surface area, temperature, H2O2, NaOH, and C4H6O6 concentrations, along with rotating speed, disc surface area, and temperature. Hydrogen peroxide significantly impacted molybdenum dissolution rates across all three solutions. The reaction order of hydrogen peroxide concentration in the H2O2 solution was greater than that of the H2O2‐NaOH and H2O2‐C4H6O6 solutions. The complex of molybdenum peroxo was formed in H2O2 and H2O2‐NaOH solutions but decomposed at a temperature ≥50°C. The activation energies were determined to be 49.90, 43.60, and 41.10 kJ/mol for the H2O2, H2O2‐NaOH, and H2O2‐C4H6O6 solutions.

Nanozymes as Antibacterial Agents: New Concerns in Design and Enhancement Strategies.

Nanozymes exhibiting natural enzyme-mimicking catalytic activities as antibacterial agents present several advantages, including high stability, low cost, broad-spectrum antibacterial activity, ease of preparation and storage, and minimal bacterial resistance. Consequently, they have attracted significant attention in recent years. However, the rapid expansion of antimicrobial nanozyme research has resulted in pioneering reviews that do not comprehensively address emerging concerns and enhancement strategies within this field. This paper first summarizes the factors influencing the intrinsic activity of nanozymes; subsequently, we outline new research considerations for designing antibacterial nanozymes with enhanced functionality and biosafety features such as degradable, imageable, targeted, and bacterial-binding nanozymes as well as those capable of selectively targeting pathogenic bacteria while sparing normal cells and probiotics. Furthermore, we review novel enhancement strategies involving external physical stimuli (light or ultrasound), the introduction of extrinsic small molecules, and self-supplying H2O2 to enhance the activity of antibacterial nanozymes under physiological conditions characterized by low concentrations of H2O2 and O2. Additionally, we present non-redox nanozymes that operate independently of highly toxic reactive oxygen species (ROS) alongside those designed to combat less common pathogenic bacteria. Finally, we discuss current issues, challenges faced in the field, and future prospects for antibacterial nanozymes.

Accelerated In Vitro Oxidative Degradation Testing of Ultra-High Molecular Weight Polyethylene (UHMWPE).

Nonabsorbable polymers used in biomedical applications are assumed to be permanently stable based on short-term testing, but some may be susceptible to oxidative degradation over several years of implantation. Traditional in vitro oxidative degradation screenings employ hydrogen peroxide (H2O2) solutions. However, the inherent instability of H2O2 can compromise the consistency of oxidative conditions, especially over extended periods and at elevated temperatures used for accelerated testing. In this study, an automated reactive accelerated aging (aRAA) system, which integrates an electrochemical detection method and a feedback loop, was utilized to ensure precise control of H2O2 concentrations during polymer oxidative degradation testing. The reproducibility of the aRAA system was evaluated by comparing four identical setups. Its efficacy as an oxidation challenge was demonstrated on (i) medical-grade vitamin E (VE) blended ultra-high molecular weight polyethylene (UHMWPE) and (ii) highly crosslinked (HXL) UHMWPE as model materials. The aRAA-aged VE-UHMWPE and HXL-UHMWPE samples were also compared against samples aged via an existing accelerated aging standard, ASTM F2003-02(2022). Samples were analyzed using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy to calculate their oxidation index per ASTM F2102-17. We observed that the aRAA system was more effective in oxidizing VE-UHMWPE and HXL-UHMWPE than the traditional ASTM F2003-02(2022) method. By providing a standardized and reliable approach to assess polymer oxidative degradation, the aRAA system could enhance the accuracy of long-term stability predictions for nonresorbable polymers in medical devices.