Peroxidation Products Research Articles

Response of Mycobacterium avium subsp. paratuberculosis isolates to reactive oxygen stress generated by treatment with copper ions

Copper (Cu) ions have been recognized for their efficacy in inactivating bacteria, including Mycobacterium avium subsp. paratuberculosis (MAP), the causative agent of Johne’s disease (JD) known for its resilience to unfavorable conditions. However, the response of MAP isolates isolated from cows to Cu exposure remains inadequately understood, as their responses may differ from those of laboratory-adapted reference strains. In this study, we examined the response of MAP isolates obtained from MAP-infected and affected cows to Cu ion treatment, comparing that with the response of the reference strain ATCC 19698 to the same treatment. Three MAP field isolates and the MAP reference strain were exposed to Cu ions, and their viability, protein/lipid damage, ROS production, and gene expression were evaluated in triplicate. Survival differed among isolates, with an isolate from a cow with clinical JD exhibiting increased tolerance to Cu exposure. While Cu treatment induced lipid peroxidation and ROS production across all isolates, genes associated with Cu detoxification and virulence were upregulated, particularly in the reference strain. Whole genome sequencing analysis revealed that, despite genomic similarities between field isolates and the reference strain ATCC 19698, there were differences regarding the presence/absence of genes related with certain virulence factors. Further research on Cu exposure with larger numbers of MAP isolates is needed to explain the stress-induced responses that influence MAP survival during natural infections and in challenging environments.

Zn-O-Sn covalency interface governs the intrinsic activity of the Zn2SnO4/SnO2 heterostructure for boosting hydrogen peroxide production

Electrocatalytic production of hydrogen peroxide (H2O2) from oxygen is vital for sustainable clean fuel. Developing highly active, stable, and inexpensive catalysts for H2O2 remains a top priority but is still challenging. In this study, an atomic-shared heterointerface was constructed between Zn2SnO4 and SnO2 via a self-templating co-precipitation method. Theoretical and experimental analysis confirms the delocalization effects of electrons within the Zn2SnO4/SnO2 spinel structure. The resulting Zn-O-Sn bridge (asymmetric sites) modulates electronic transport at the interface, and the intensified Zn-O bond facilitates proton adsorption and transfer kinetics. Moreover, strong interface coupling between Zn2SnO4 and SnO2 enhances electron transfer, which effectively promotes the *OOH intermediate favorable for H2O2 production, boosting H2O2 selectivity of nearly 97 %. The high production rate of 8.19 mol gcat−1 h−1 and excellent stability during long-term operation over 24 h. This work provides strategic insights into developing efficient H2O2 catalysts and other catalytic applications.

Novel insights on ecological responses of short- and long-chain perfluorocarboxylic acids in constructed wetlands coupled with modified basalt fiber bio-nest

The first investigation based on constructed wetlands coupled with modified basalt fiber bio-nest (MBF-CWs) was performed under exposure of short- and long-chain perfluorocarboxylic acids (PFCAs). In general, both perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA) caused significant decline of chemical oxygen demand removal by 10.83 % and 4.73 %. However, only PFOA led to marked inhibition on total phosphorus removal by 12.51 % in whole duration. Suppression of removal performance resulted from side impacts on microbes by PFOA. For instance, activities of key enzymes like dehydrogenase (DHA), urease (URE), and phosphatase (PST) decreased by 52.77 %, 40.70 %, and 56.94 % in maximum under PFOA stress, while URE could alleviate over time. By contrast, distinct inhibition was only found on PST in later phases with PFBA exposure. PFCAs had adverse influence on alpha diversity of MBF-CWs, particularly long-chain PFOA. Both PFCAs caused enrichment of Proteobacteria, owing to increase of Gammaproteobacteria and Plasticicumulans by 22.04–35.79 % and 22.91–219.77 %. Nevertheless, some dominant phyla (like Bacteroidota and Acidobacteriota) and genera (like SC-I-84, Thauera, Subgroup_10, and Ellin6067) were only suppressed by PFOA, causing more hazards to microbial decontamination than PFBA did. As for plants, chlorophyll contents tend to decrease with PFOA treatment. Whereas, higher antioxidase activities and more lipid peroxidation products were uncovered in PFOA group, demonstrating more reactive oxygen species brought by long-chain PFCAs. This work offered new findings about ecological effects of MBF-CWs under PFCAs exposure, evaluating stability and sustainability of MBF-CW systems to treat sewage containing complex PFCAs.

Developing three-dimensional hydrophobic photocatalysts to enhance mass transfer for promoting hydrogen peroxide production

Photocatalytic oxygen reduction reaction (ORR) is a promising approach for hydrogen peroxide (H2O2) production to alternative conventional anthraquinone process. However, the slow O2 diffusion and low-efficiency water oxidation reaction (WOR, limitation of protons) pathways have restricted the H2O2 production efficiency of organic photocatalysts. Therefore, a promising strategy to develop photocatalysts with three-dimensional (3D) architectures possessing high O2 diffusion, high-efficiency WOR pathway, and quick H2O2 desorption is desirable. Herein, a hydrophobic two-dimensional porous organic polymer (2D-POP) based on tetraphenylethylene (TPE) was synthesized as the building block. 3D-POPs (TPE-2 and TPE-3) were subsequently developed through the Friedel-Crafts alkylation reaction to regulate the O2 adsorption and optical properties. The 3D architectures allow O2 to diffuse into the interlayers, leading to efficient extraction of O2 from air, thus an excellent H2O2 production rate of 2.57 mmol g−1 h−1has been achieved by TPE-2 in air and without sacrificial agents, which only decreases by 4% compared to that in O2 due to a suitable specific surface area, good photoelectric properties, and excellent mass transfer of O2, H+, and H2O2. Furthermore, the H2O2 production rate of TPE-2 reaches 2.67 mmol g−1 h−1 in a triphasic system in air, which is higher than that in a traditional diphasic system, and the concentration of H2O2 reaches 1.80 mmol L−1 h−1. Additionally, by adding external Fe2+ or Fe3+ to make the utmost of photogenerated H2O2 and trigger the in-situ Fenton reaction for the formation of ·OH, TPE-2 exhibits extraordinary photodegradation efficiency toward representative organic pollutants, reaching > 99% removal within 60 min for bisphenol A and 2,4-dichlorophenoxyacetic acid with high concentrations (200 ppm).

Glucose-responsive carboxymethyl chitosan/ sodium alginate film protects against mechanical wound on postharvest blueberry

Fresh fruits and vegetables, particularly berries, are highly susceptible to mechanical damage, which results in nutrient loss, reduced quality, and increased decay from microbial infections, ultimately leading to significant losses. Here, a biodegradable polysaccharide film was employed to encapsulate glucose oxidase (Gox), thereby creating a glucose/wounding-responsive active package that reduced fruit respiration, promoted healing and protected blueberry wounds from mold infection. The combination of carboxymethyl chitosan and sodium alginate resulted in the formation of the polysaccharides film CSF that effectively restricted the permeation of oxygen, water, and carbon dioxide around the surface of the fruit. The encapsulation of Gox in the CSF film (CSFG) reduced glucose levels through enzymatic reaction in surface wounds of the fruit, thereby competing for glucose to establish a starvation-like microenvironment for the pathogenic fungus Botrytis cinerea. The enzymatic reaction also facilitated the production of hydrogen peroxide, which functioned as a fungicide that inhibits the growth of B. cinerea and served as a secondary messenger in fruit immunity. The CSFG film increased beta-glucanase activity, and decreased lipid peroxidation in wounds of blueberries. Therefore, this glucose-responsive CSFG barrier significantly reduced the decay rates of gray mold, caused by B. cinerea in wounded blueberries, by 66.7% compared to the control at 6 d of storage. Taken together, the glucose-responsive active packaging film provides an alternative package for safeguarding blueberries against mechanical damage.

Green synthesis of In2S3-supported Ni-MOF: Bifunctional photocatalyst for sustainable H2O2 production and 2,4,6-trinitrophenol photoreduction

This study describes a unique and sustainable strategy for synthesizing a highly effective photocatalyst using solvothermal synthesis to combine bioderived In2S3 and Nickel Metal-Organic Framework (Ni-MOF) forming In2S3/Ni-MOF. Bioderived In2S3 was produced using Azadirachta indica (neem) leaf extract, providing a green and sustainable source for semiconductor material synthesis. The synergistic interaction of In2S3 with Ni-MOF led to better charge transfer kinetics, a wider band gap, and reduced charge recombination, all contributing to increased photoactivity. The constructed photocatalyst performed admirably under visible light irradiation in producing hydrogen peroxide (H2O2) with an impressive 1528.5 μmol/g.h yield. Furthermore, the photocatalyst demonstrated extraordinary effectiveness in reducing 2,4,6-trinitrophenol (2,4,6-TNP), with a reduction efficiency of 96.31 % in 20 min and high reusability in both applications. The observed results highlight the importance of the collaborative impact between In2S3 and Ni-MOF, demonstrating the promise of this green-synthesized material as a highly efficient photocatalyst with dual uses in various environmental settings. Using renewable neem leaf extract to manufacture In2S3 adds an environmentally beneficial component to the entire strategy, helping to build sustainable and efficient photocatalytic materials.

LncRNA-HMG incites colorectal cancer cells to chemoresistance via repressing p53-mediated ferroptosis

Upon chemotherapy, excessive reactive oxygen species (ROS) often lead to the production of massive lipid peroxides in cancer cells and induce cell death, namely ferroptosis. The elimination of ROS is pivotal for tumor cells to escape from ferroptosis and acquire drug resistance. Nevertheless, the precise functions of long non-coding RNAs (lncRNAs) in ROS metabolism and tumor drug-resistance remain elusive. In this study, we identify LncRNA-HMG as a chemoresistance-related lncRNA in colorectal cancer (CRC) by high-throughput screening. Abnormally high expression of LncRNA-HMG predicts poorer prognosis in CRC patients. Concurrently, we found that LncRNA-HMG protects CRC cells from ferroptosis upon chemotherapy, thus enhancing drug resistance of CRC cells. LncRNA-HMG binds to p53 and facilitates MDM2-mediated degradation of p53. Decreased p53 induces upregulation of SLC7A11 and VKORC1L1, which contribute to increase the supply of reducing agents and eliminate excessive ROS. Consequently, CRC cells escape from ferroptosis and acquire chemoresistance. Importantly, inhibition of LncRNA-HMG by anti-sense oligo (ASO) dramatically sensitizes CRC cells to chemotherapy in patient-derived xenograft (PDX) model. LncRNA-HMG is also a transcriptional target of β-catenin/TCF and activated Wnt signals trigger the marked upregulation of LncRNA-HMG. Collectively, these findings demonstrate that LncRNA-HMG promotes CRC chemoresistance and might be a prognostic or therapeutic target for CRC.

Energy Recovery from Hexavalent Chromium Reduction for In Situ Electrocatalytic Hydrogen Peroxide Production.

Recovering chemical energy embedded in pollutants is significant in achieving carbon-neutral industrial wastewater treatment. Considering that industrial wastewater is usually treated in a decentralized manner, in situ utilization of chemical energy to achieve waste-to-treasure should be given priority. Herein, the chemical energy released by the electroreduction of Cr(VI) was used to enhance on-site H2O2 generation in a stacked flow-through electrochemical system. The driving force of water flow efficiently coupled O2 evolution with 2-e O2 reduction to facilitate H2O2 generation by transporting anode-produced O2 to the cathode. Meanwhile, the chemical energy released by Cr(VI) promoted O2 evolution and impeded H2 evolution by regulating the electrode potentials, accounting for the enhanced H2O2 generation. The system could completely reduce 10-100 ppm of Cr(VI), reaching the maximum H2O2 concentration of 2.41 mM. In particular, the H2O2 concentrations in the Cr(VI)-containing electrolyte were 10.6-88.1% higher than those in the Cr(VI) free electrolyte at 1.8-2.5 V. A 24-day continuous experiment demonstrated the high efficiency and stability of the system, achieving a 100% reduction efficiency for 100 ppm of Cr(VI) and producing ∼1.5 mM H2O2 at 1.8 V. This study presents a feasible strategy for Cr(VI) detoxification and synchronous on-site H2O2 generation, providing a new perspective for innovative Cr(VI) wastewater treatment toward resource utilization.

Synergistic Active Heterostructure Design for Enhanced Two Electron Oxygen Reduction via Chemical and Electrochemical Reconstruction of Heterosulfides.

Transition metal sulfides, particularly heterostructures, represent a promising class of electrocatalysts for two electron oxygen reduction (2e- ORR), however, understanding the dynamic structural evolution of these catalysts during alkaline ORR remains relatively unexplored. Herein, NiS2/In2.77S4 heterostructure was synthesized as a precatalyst and through a series of comprehensive ex situ and in situ characterizations, including X-ray absorption spectroscopy, Raman spectroscopy, transient photo-induced voltage measurements, electron energy loss spectroscopy, and spherical aberration-corrected electron microscopy, it was revealed that nickel/indium (oxy)hydroxides (NiOOH/In(OH)3) could be evolved from the initial NiS2/In2.77S4 via both electrochemical and chemical-driven methods. The electrochemical-driven phase featured abundant bridging oxygen-deficient [NiO6]-[InO6] units at the interfaces of NiOOH/In(OH)3, facilitating a synergistic effect between active Ni and In sites, thus enabling an enhanced alkaline 2e- ORR capability than that of chemical-driven process. Remarkably, electrochemically induced NiOOH/In(OH)3 exhibited exceptional performance, achieving H2O2 selectivity of >90 % across the wide potential window (up to 0.4 V) with a peak selectivity of >99 %. Notably, within the three-electrode flow cell, a current density of 200 mA cm-2 was sustained over 20 h, together with an impressive Faradaic efficiency of ~90 % during the whole cycle process.

Iron-based magnetic nanocomplexes for combined chemodynamic and photothermal cancer therapy through enhanced ferroptosis

Chemodynamic therapy (CDT) guided by Fenton chemistry and iron-containing materials can induce ferroptosis as a prospective cancer treatment method, but the inefficient Fe3+/Fe2+ conversion restricts the monotherapeutic performances. Here, an iron-based nanoplatform (Fe3O4-SRF@FeTA) including a magnetic core and a reductive film is developed for combined CDT and photothermal therapy (PTT) through ferroptosis augmentation. The inner iron oxide core serves as a photothermal transducer, a magnet-responsive module, and an iron reservoir for CDT. The coated Fe3+-tannic acid film (FeTA) provides extra iron and reductants for Fe3+/Fe2+ conversion acceleration, and functions as a door keeper for the pH- and light-responsive release of the embedded ferroptosis inducer sorafenib (SRF). The in vitro results demonstrate that the iron-based nanocomplexes promote the production of lipid peroxide through the amplified Fenton activity, and downregulate glutathione involved in lipid peroxide repair system through the responsively released SRF. Upon accumulation in tumor by magnetic targeting and sequential laser irradiation locoregionally, Fe3O4-SRF@FeTA nanocomplexes present prominent in vivo anticancer efficacy by leveraging PTT and CDT-enhanced ferroptosis.

Photoelectrochemical Synthesis of Hydrogen Peroxide from Saline Water via the Two-Electron Water Oxidation Reaction.

Hydrogen peroxide (H2O2) production on the anode is more valuable than oxygen and chlorine evolution for photoelectrochemical saline water splitting. In this work, by the introduction of bicarbonate (HCO3-), H2O2 is produced from saline water (2 M KHCO3 + 0.5 M NaCl aqueous solution) via the two-electron water oxidation reaction by a photoanode of bismuth vanadate (BiVO4). Furthermore, the Faradaic efficiency (FE) and accumulation for H2O2 are improved by coating antimony tetroxide (Sb2O4) on BiVO4. A H2O2 FE of 26% at 1.54 V vs RHE is obtained by Sb2O4/BiVO4 and 49 ppm of H2O2 is accumulated after a 135 min chronoamperometry. Similar to that in KHCO3 pure water solution, infrared spectroscopy and electrochemical analysis confirm that HCO3- plays a surface-mediating role in the formation of H2O2 in KHCO3 saline water solution. The presence of HCO3- in the electrolyte is able to not only increase the photocurrent density but also effectively inhibit the chlorine evolution reaction.

At least five: Benefit origins of potassium and sodium co-doping on carbon nitride for integrating pharmaceuticals degradation and hydrogen peroxide production

Benefit origins of potassium (K+) and sodium (Na+) co-doping on carbon nitride for integrating pharmaceutical degradation and hydrogen peroxide (H2O2) production was investigated. K+ and Na+ co-doped carbon nitride (CN-K/Na) with modified crystallinity and surface structure was synthesized by ionothermal polymerization of urea. The CN-K/Na exhibited an apparent quantum yield of 26.2% in H2O2 photosynthesis at 400nm (isopropanol as proton donor), and it was better at extracting proton from pharmaceutical-laden wastewater to produce H2O2 than pristine carbon nitride. These superior performances are attributed to the benefits directly or indirectly caused by the co-doping: i) Na+ optimizes in-plane charge transfer, ii) K+ builds channel for interplane charge transfer, iii) cyano group as Lewis acid site adsorbs and activates oxygen, iv) amino group as Lewis base site extracts and releases protons, v) increased visible-light absorption. This work offers significant insights into designing polymeric photocatalysts for environmental management and energy conservation.

Unveiling O2 adsorption on non-metallic active site for selective photocatalytic H2O2 production

Photocatalytic oxygen reduction reaction (ORR) offers a promising pathway for sustainable hydrogen peroxide (H2O2) production but faces challenges in developing catalysts with good ORR selectivity. Herein, we report that tailoring O2 adsorption on non-metallic active sites can optimize ORR selectivity. This concept is demonstrated on three carbon nitrides with different atomic configurations: polymeric carbon nitride (PCN), lithium-poly triazine imide (Li-PTI), and sodium-poly heptazine imide (Na-PHI). Na-PHI emerges as a strong candidate for H2O2 production due to the end-on adsorption mode and suitable adsorption strength with O2. Synthesized Na-PHI, PCN, and Li-PTI are characterized, with Na-PHI showing superior light absorption, charge carrier separation, and remarkable selectivity (92 %) for two-electron ORR. Consequently, Na-PHI achieves a high H2O2 generation rate of 3.48 mmol g−1 h−1, surpassing Li-PTI and PCN by 9.2 and 33 times, respectively. This study underscores the importance of O2 adsorption on non-metallic active sites for selective photocatalytic H2O2 generation.

Impaired arterial dilation and increased NOX2 generated oxidative stress in subjects with ataxia-telangiectasia mutated (ATM) kinase

BackgroundSubjects with mutations in the Ataxia-Telangiectasia mutated (ATM) gene encoding for ATM kinase have a greater predisposition to develop atherosclerosis, but the mechanism behind this phenomenon is not yet understood. NADPH oxidase type 2 may play a role in this process, leading to endothelial dysfunction and an increased susceptibility to thrombosis. The purpose of this study was to assess the redox state in individuals with ATM mutations and determine its impact on endothelial function. MethodsIn this cross-sectional study, twenty-seven children with ataxia telangiectasia (AT) (13 males and 14 females, mean age 15.1 ± 7.6 years) were compared with 27 controls (13 males and 14 females, mean age 14.6 ± 8.4 years) matched for age and gender. Additionally, 29 AT parents with heterozygous mutation of ATM (h-ATM) gene, and 29 age- and gender-matched controls were included. Endothelial function was evaluated through brachial flow-mediated dilation (FMD) and the assessment of nitric oxide (NO) bioavailability. Oxidative stress was evaluated by measuring serum activity of soluble NOX2-dp (sNOX2-dp), hydrogen peroxide (H2O2) production, and hydrogen breakdown activity (HBA). Thrombus formation was assessed through the Total Thrombus Formation Analysis System (T-TAS). ResultsAT children and parents with heterozygous ATM mutations exhibited significantly lower FMD, HBA, and NO bioavailability as compared to age and gender matched controls. AT children and ATM carrier of heterozygous ATM mutations had significantly higher concentrations of sNOX2-dp and H2O2 as compared to controls. Compared to the respective controls, AT children and their parents, who carried heterozygous ATM mutation, showed an accelerated thrombus growth as revealed by reduced occlusion time. Multivariable linear regression analysis revealed that sNOX2 (standardized coefficient β: −0.296; SE: 0.044; p = 0.002) and NO bioavailability (standardized coefficient β: 0.224; SE: 0.065; p = 0.02) emerged as the only independent predictive variables associated with FMD (R2: 0.44). ConclusionsThis study demonstrates that individuals with ATM mutations experience endothelial dysfunction, increased oxidative stress, and elevated thrombus formation. These factors collectively contribute to the heightened susceptibility of these individuals to develop atherosclerosis.

Hermetic effect of Moringa oleifera leaf extract mitigates salinity stress in maize by modulating photosynthetic efficiency, and antioxidant activities

Salinity poses a significant constraint to cereal productivity particularly in arid and semiarid regions. The application of allelochemical has shown promising results in mitigating the intensity of abiotic stresses. A pot experiment was conducted to assess the efficacy of different concentrations of aqueous allelopathic extract derived from moringa leaves in mitigating the adverse impacts of salinity on the germination and growth of maize cultivars via seed priming. The study involved three variables: two cultivars of maize, ‘Pioneer 30Y87’ (salt tolerant) and ‘Pioneer 30T60’ (salt sensitive) e seed priming with moringa leaf extract (MLE) at varying concentrations of 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, and hydro-priming as control; and different salinity levels of 0, 6, and 12 dS m-1. Salinity had a negative impact on the germination process, leading to delayed and suboptimal growth of seedlings. Additionally, salinity reduced the synthesis of photosynthetic pigments (20-50%), photosynthesis, transpiration, internal carbon, and stomatal conductance. Further, MLE also improved the antioxidant activities (catalase: CAT and peroxidase: POD) by 22-56% which reduced the hydrogen peroxide production. Moreover, ‘P-30Y87’ exhibited favorable performance in terms of better germination, growth, photosynthesis and antioxidant activities. The application of moringa leaf extract (3%) resulted in a more notable hermetic effect in elevating salinity stress thereby enhancing germination, growth, photosynthesis and antioxidant activities. In the conclusion, application of MLE (3%) is a promising approach to mitigate the adverse impacts of salinity by improving germination, growth, photosynthesis and antioxidant activities.

Salicylic Acid Treatment Ameliorates Postharvest Quality Deterioration in 'France' Prune (Prunus domestica L. 'Ximei') Fruit by Modulating the Antioxidant System.

The potential of salicylic acid (SA) in delaying postharvest fruit senescence has been extensively documented; nevertheless, its effect on antioxidant activity and quality of 'France' prune fruit is largely unknown. The study investigated the effects of SA (0.5 mM) on postharvest quality deterioration of 'France' prune fruit. Results indicated that SA impeded the increase in respiration rate and weight loss, and mitigated the decrease of soluble solids content (SSC), titratable acidity (TA) content, firmness, and hue angle. SA sustained the ascorbate-glutathione cycle by inducing the production of ascorbic acid (AsA) and glutathione (GSH) and attenuates flavonoids, total phenols, and anthocyanins degradation by inhibiting polyphenol oxidase (PPO) activity and PdPPO. Moreover, SA significantly improved superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), and glutathione reductase (GR) activities and gene expression levels, sustained higher 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging capacity, ferric reducing antioxidant power (FRAP), and hydroxyl radical (·OH) inhibition capacity, and impeded the production of hydrogen peroxide (H2O2) and superoxide anion (O2•-). Overall, SA improved the antioxidant capacity by inducing the synthesis of defense response-related substances and promoting antioxidant enzyme activities to sustain the storage quality of 'France' prune fruit.

Copper Single-Atom Nanozyme Mimicking Galactose Oxidase with Superior Catalytic Activity and Selectivity.

Due to the low stability and high cost of some natural enzymes, nanozymes have been developed as enzyme-imitating nanomaterials. Single-atom nanozymes are a class of nanozymes with metal centers that mimic the structure of metal-based natural enzymes. Herein, Cu-N-C single-atom nanozyme (SAN) is synthesized with excellent peroxidase- and enhanced oxidase-like activities to mimic the action of natural galactose oxidase. Cu-SAN demonstrates stereospecific activity akin to that of natural galactose oxidase by oxidizing D-galactose and primary alcohol but not L-Galactose or other carbohydrates. The SAN can catalyze the oxidation of galactose in the presence of oxygen, producing hydrogen peroxide as a sub-product. The produced hydrogen peroxide then oxidizes 3,3',5,5'-tetramethylbenzidine catalyzed by the SAN, yielding the typical blue product. The relationship between absorbance and galactose concentration is linear in the 1-60µm range with a detection limit as low as 0.23µm. This strategy can be utilized in the diagnosis of galactosemia disorder and detection of galactose in some dairy and other commercial products. DFT calculations clarify the high activity of the Cu sites in the POD-like reaction and explain the selectivity of the Cu-SAN oxidase-like reaction toward D-galactose.

Unprecedented Photocatalytic Hydrogen Peroxide Production via Covalent Triazine Frameworks Constructed from Fused Building Blocks

Covalent organic frameworks (COFs) have garnered attention for their potential in photocatalytic hydrogen peroxide (H2O2) production. However, their photocatalytic efficiency is impeded by insufficient exciton dissociation and charge carrier transport. Constructing COFs with superior planarity is an effective way to enhance the π‐conjugation degree and facilitate electron‐hole separation. Nonetheless, the conventional linear linkers of COFs inevitably introduce torsional strain that disrupts coplanarity.Herein, we address this issue by introducing inherently coplanar triazine rings as linkers and fused building blocks as monomers to create covalent triazine frameworks (fused CTFs) with superior coplanarity. Both experimental and theoretical calculations confirm that CTFs constructed from fused building blocks significantly enhance the electron‐hole separation efficiency and improve the photocatalytic performance, compared to the CTFs constructed with non‐fused building blocks. The frontier molecular orbitals and electrostatic potentials (ESP) revealed that the ORR is preferentially facilitated by the triazine rings, with the WOR likely occurring at the thiophene‐containing moiety. Remarkably, CTF‐BTT achieved an exceptional H2O2 production rate of 74956 μmol g−1 h−1 when employing 10% benzyl alcohol (V/V) as a sacrificial agent in an O2‐saturated atmosphere, surpassing existing photocatalysts by nearly an order of magnitude.

Unprecedented Photocatalytic Hydrogen Peroxide Production via Covalent Triazine Frameworks Constructed from Fused Building Blocks.

Covalent organic frameworks (COFs) have garnered attention for their potential in photocatalytic hydrogen peroxide (H2O2) production. However, their photocatalytic efficiency is impeded by insufficient exciton dissociation and charge carrier transport. Constructing COFs with superior planarity is an effective way to enhance the π-conjugation degree and facilitate electron-hole separation. Nonetheless, the conventional linear linkers of COFs inevitably introduce torsional strain that disrupts coplanarity.Herein, we address this issue by introducing inherently coplanar triazine rings as linkers and fused building blocks as monomers to create covalent triazine frameworks (fused CTFs) with superior coplanarity. Both experimental and theoretical calculations confirm that CTFs constructed from fused building blocks significantly enhance the electron-hole separation efficiency and improve the photocatalytic performance, compared to the CTFs constructed with non-fused building blocks. The frontier molecular orbitals and electrostatic potentials (ESP) revealed that the ORR is preferentially facilitated by the triazine rings, with the WOR likely occurring at the thiophene-containing moiety. Remarkably, CTF-BTT achieved an exceptional H2O2 production rate of 74956 μmol g-1 h-1 when employing 10% benzyl alcohol (V/V) as a sacrificial agent in an O2-saturated atmosphere, surpassing existing photocatalysts by nearly an order of magnitude.

Aquaporin CmPIP2; 3 links H2O2 signal and antioxidation to modulate trehalose-induced cold tolerance in melon seedlings.

Cold stress severely restricts the growth and development of cold-sensitive crops. Trehalose (Tre), known as the 'sugar of life', plays key roles in regulating plant cold tolerance by triggering antioxidation. However, the relevant regulatory mechanism remains unclear. Here, we confirmed that Tre triggers apoplastic hydrogen peroxide (H2O2) production and thus plays key roles in improving the cold tolerance of melon (Cucumis melo var. makuwa Makino) seedlings. Moreover, Tre treatment can promote the transport of apoplastic H2O2 to the cytoplasm. This physiological process may depend on aquaporins. Further studies showed that a Tre-responsive plasma membrane intrinsic protein 2; 3 (CmPIP2; 3) had strong H2O2 transport function and that silencing CmPIP2; 3 significantly weakened apoplastic H2O2 transport and reduced the cold tolerance of melon seedlings. Yeast library and protein-DNA interaction technology were then used to screen two Tre-responsive transcription factors, abscisic acid responsive element (ABRE)-binding factor 2 (CmABF2) and abscisic acid responsive element (ABRE)-binding factor 3 (CmABF3), which can bind to the ABRE motif of the CmPIP2; 3 promoter and activate its expression. Silencing of CmABF2 and CmABF3 further dramatically increased the ratio of apoplastic H2O2/cytoplasm H2O2 and reduced the cold tolerance of melon seedlings. This study uncovered that Tre treatment induces CmABF2/3 to positively regulate CmPIP2; 3 expression. CmPIP2; 3 subsequently enhances the cold tolerance of melon seedlings by promoting the transport of apoplastic H2O2 into the cytoplasm for conducting redox signals and stimulating downstream antioxidation.