Low Concentrations Of H2O2 Research Articles

Food Polyphenols as Preventive Medicine.

Reactive oxygen species (ROS) are the initiators in foods and in the stomach of oxidized dietary lipids, proteins, and lipid-oxidation end-products (ALEs), inducing in humans the development of several chronic diseases and cancer. Epidemiological, human clinical and animal studies supported the role of dietary polyphenols and derivatives in prevention of development of such chronic diseases. There is much evidence that polyphenols/derivatives at the right timing and concentration, which is critical, acts mostly in the aerobic stomach and generally in the gastrointestinal tract as reducing agents, scavengers of free radicals, trappers of reactive carbonyls, modulators of enzyme activity, generators of beneficial gut microbiota and effectors of cellular signaling. In the blood system, at low concentration, they act as generators of electrophiles and low concentration of H2O2, acting mostly as cellular signaling, activating the PI3K/Akt-mediated Nrf2/eNOS pathways and inhibiting the inflammatory transcription factor NF-κB, inducing the cells, organs and organism for eustress, adaptation and surviving.

Hydrogen peroxide preoxidation as a strategy for enhanced antimicrobial photodynamic action against methicillin-resistant Staphylococcus aureus.

Antimicrobial photodynamic treatment (aPDT) is a photooxidative process based on the excitation of a photosensitizer (PS) in the presence of molecular oxygen, under specific wavelengths of light. It is a promising method for advanced treatment of water and wastewater, particularly targeting disinfection challenges, such as antibiotic-resistant bacteria (ARB). Research in improved aPDT has been exploring new PS materials, and additives in general. Hydrogen peroxide (H2O2) a widely applied disinfectant, mostly in the food industry and clinical settings, present environmentally negligible residuals at the usually applied concentrations, making it friendly for the water and wastewater sectors. Here, we explored the effects of preoxidation with H2O2 followed by blue light-mediated (450 nm) aPDT using curcumin (a natural-based PS) against methicillin-resistant Staphylococcus aureus (MRSA). Results of the sequential treatment pointed to a slight hampering in aPDT efficiency at very low H2O2 concentrations, followed by an increasing cooperative effect up to a deleterious point (≥7 log10 inactivation in CFU mL-1), suggesting a synergistic interaction of preoxidation and aPDT. The increased performance in H2O2-pretreated aPDT encourages studies of optimal operational conditions for the assisted technology and describes potentials for using the described strategy to tackle the issue of ARB spread.

Exogenous control of dormancy and chemical regulation of germination in Texas wintergrass (Nassella leucotricha (Trin. & Rupr.) Pohl) seeds

AbstractTexas wintergrass (Nassella leucotricha (Trin. & Rupr.) Pohl) has potential as a cool‐season forage but has not been used for such purpose due to its poor seed germination. This study focused on understanding the determinants of dormancy and identifying means of inducing maximum germination in Texas wintergrass toward making it more readily available for grazing systems. Scarification using sulfuric acid resulted in a significant improvement (≥50%) in the overall germination performance of the seeds. Chemical profiling of the seed coat identified diverse phenolic compounds, primarily in the form of flavonoids, which have been previously reported to induce seed dormancy in other plant species. Together, these results indicate the presence of exogenous dormancy in Texas wintergrass that prevents it from germinating even under optimum conditions. Treatment with low hydrogen peroxide (H2O2) titers in combination with scarification further increased seed germination up to 85%. This positive germination response is attributed to H2O2‐induced weakening of the seed coat that makes it semipermeable, oxidation and leaching of phenolic inhibitors of germination, and hydrolysis of H2O2 that provides seeds with access to more water and O2. Additionally, treatment with low H2O2 concentrations within the first 24 h of water uptake downregulated abscisic aldehyde oxidase (AAO3) and upregulated abscisic 8′ hydroxylase (A8H1) expression. AAO3 converts abscisic aldehyde into abscisic acid (ABA), whereas A8H1 breaks down ABA to produce phaseic acid. Treatment with the phytohormones gibberellic acid (GA) and 6‐benzylaminopurine (BAP) in combination with scarification also improved the germination performance of Texas wintergrass, with BAP producing better results than GA.

Effect of heterogeneous fenton-like pretreatment on semi-permeable membrane-covered co-composting: Humification and microbial community succession

This study focused on the impacts of heterogeneous Fenton-like pretreatment on the humification and bacterial community during co-composting of wheat straw with cattle dung covered with a semi-permeable membrane. In this study, FeOCl and low concentration of H2O2 were used for pretreatment and composting, which lasted for 39 days. The results showed that the pretreatment promoted the humification process, with degree of polymerization and percentage of humic acid increasing by 53.2 % and 7.3 %, respectively. Furthermore, the diversity and structure of bacterial communities were altered by pretreatment. During the thermophilic phase, pretreatment considerably promoted the metabolism of carbohydrate. According to redundancy analysis, C/N, moisture and organic matter were the key environmental factors that dominated the microbial community. In summary, heterogeneous Fenton-like pretreatment provided a novel idea for improving the humic acid content and maturity of the compost pile.

Low-temperature acclimation related with developmental regulations of polyamines and ethylene metabolism in wheat recombinant inbred lines

Winter survival is determined by complicated developmental regulations enabling wheat to adjust their transcriptome and metabolome to develop low temperature (LT) tolerance. The aim of the study was to clarify the metabolic responses developmentally regulated in six F6 recombinant inbred lines from a cross between Pishtaz (spring parent) and Mironovskaya 808 (winter parent). Spring genotypes, including pishtaz, RILs 4006 and 4014 showed lower LT tolerance, PAs (except the spermin), GABA and proline contents and DPPH• scavenging capacity. In these genotypes, genes and enzymes involved in the pathways of PAs and GABA degradation and ethylene biosynthesis were more active than other genotypes. RILs 4012 and 4016 with short vernalization displayed higher tolerance and lower H2O2 content compared to Pishtaz. Strong vernalization requirements in winter and facultative genotypes (Mironovskaya 808 parent and RILs 4003 and 4005) results in up-regulation of the metabolites and genes involved in PAs and GABA biosynthesis pathways (particularly when vernalization fulfillment occurred) to establish high tolerance as compared to genotypes without vernalization requirement. LT tolerance in all genotypes significantly decreased after vernalization fulfillment in February. Results indicated that LT tolerance was partly validated from developmental regulation of PAs, GABA, and ethylene metabolism during venalization and LT acclimation.

Optimizing porosity of the catalyst for hydrogen peroxide based thrusters

The texture of the catalyst support is a crucial factor for H2O2 decomposition due to the expansion of H2O2 in monopropellant thrusters, which can lead to overpressure and catalyst breakage. Therefore, alumina supports with 5 wt%, 10 wt%, and 15 wt% microcrystalline cellulose templates were studied to create macropores. MIP and SEM analysis showed that microcrystalline cellulose template increases the macropore fraction. Low-concentration H2O2 decomposition experiments revealed that over 10 wt% microcrystalline cellulose prevented catalyst breakage. Additionally, the thermal durability of the catalyst was studied at different calcination temperatures. Alumina with 15 wt% microcrystalline cellulose and a 900 °C calcination temperature exhibited the highest fracture strength and suitable reaction kinetics. The catalysts were tested in high-concentration H2O2 monopropellant thruster. The results demonstrated enhancement in catalyst size retention, pressure stability, and pressure drop. Introducing macropores through microcrystalline cellulose addition overcomes unstable thruster performance and it extends catalyst lifespan in H2O2 monopropellant thrusters’ applications.

Expression of Cowpea VuWRKY21 and VuWRKY87 Genes in Arabidopsis thaliana Confers Plant Tolerance to Salt Stress

WRKY transcription factors play a pivotal role in regulating stress signaling pathways, including those associated with salt stress response. The present work characterized the effects of two WRKY genes from Vigna unguiculata, namely VuWRKY21 and VuWRKY87, on enhancing plant salinity tolerance. Under salt stress conditions, Arabidopsis lines expressing VuWRKY21 or VuWRKY87 showed elevated expression of genes participating in saline stress response pathways and reduced oxidative stress induced by reactive oxygen species (ROS). Among the salt-responsive genes in Arabidopsis, AtP5CS1, AtNHX1, AtRD29A, AtSOS3, AtSOS2, and AtSOS1 exhibited modulated expression levels after stress imposition. Furthermore, compared to wild-type plants, at most evaluated times, transgenic lines, on average, presented lower H2O2 content while displaying higher content of SOD (EC: 1.15.1.1) and CAT (EC: 1.11.1.6) at early stages of salt stress. These findings suggest that the expression of both VuWRKY genes in Arabidopsis, particularly VuWRKY21, activated genes involved in salinity tolerance.

Optical hydrogen peroxide sensor for measurements in flow

An optical hydrogen peroxide (H2O2) sensor is presented. The sensor is based on catalytic degradation of H2O2 and the detection of produced oxygen (O2) with a phosphorescent sensor. A novel aspect of the sensor is removal O2 from the analyte solution in flow. This allows the use of a more sensitive O2 sensor. Thereby, a better resolution at lower H2O2 concentrations is achieved. Sensor spots are integrated in a flow-through cell, and H2O2 is measured in flow between 10 and 80 µL/min. The catalytic activities of previously reported catalyst are tested. RuO2 and silica supported platinum nanoparticles are applied in the sensor with limit of detections of 0.16 and 0.17 µM H2O2, respectively. The sensor can measure reliably between 1 and 200 µM H2O2. The concentration range can be extended to 1000 µM H2O2 by exchanging the O2 sensor. Interfering species (NaONOO, NaOCl, t-BuOOH, and ascorbic acid) are tested and show only minor cross-sensitivities. The sensor is applied at-line in a model batch reactor with glucose oxidase to showcase production of H2O2 from glucose.

Can atypical response in endothelial dysfunction-related genes and microRNAs arise from low hydrogen peroxide exposure?

Vascular endothelium is a tissue in which several vasoactive substances are produced and secreted. Reactive oxygen species can cause endothelial dysfunction (ED). miRNAs can be implicated in the oxidative stress-related ED during vascular disease pathogeneses. Our aim is to investigate effect of H2O2-induced oxidative stress on expression levels of genes and miRNAs that are key players in ED. H2O2 effect on cell viability of human umbilical-vein endothelial cells (HUVEC) at 24-hour was measured with MTT. Low sub-cytotoxic H2O2 concentrations (25, 50µM) were selected to analyze their oxidative stress-inducing capacities with MDA assay and their effects on EDN1, NOS3, VCAM1, SERPINE1, miR21, miR22, miR126, and miR146a levels with RT-qPCR. Each tested H2O2 concentration reduced HUVEC cell viability. Fifty µM H2O2 augmented cellular MDA levels. Intriguingly, EDN1, VCAM1, and SERPINE1 and all analyzed miRNAs' levels attenuated upon H2O2 treatment whereas there was no change in NOS3 levels compared to control. There was a positive correlation between miR-21 and VCAM1. Rather than individual alterations in analyzed parameters, consistent changes in our findings i.e., parallel decreases in EDN1, VCAM1, SERPINE1 mRNA levels as well as miRNAs, suggests that H2O2 concentration-dependent modulation of expression patterns can bring about various impacts on ED (Tab. 1, Fig. 5, Ref. 63).

Phytoplankton interspecific interactions modified by symbiotic fungi and bacterial metabolites under environmentally relevant hydrogen peroxide concentrations stress

Hydrogen peroxide (H2O2), which accumulates in water and triggers oxidative stress for aquatic microbes, has been shown to have profound impacts on planktonic microbial community dynamics including cyanobacterial bloom formation. Yet, potential effects of H2O2 on interspecific relationships of phytoplankton-microbe symbiotic interactions remain unclear. Here, we investigated effects of environmentally relevant H2O2 concentrations on interspecific microbial relationships in algae-microbe symbiosis. Microbes play a crucial role in the competition between M. aeruginosa and Chlorella vulgaris at low H2O2 concentrations (∼400 nM), in which fungi and bacteria protect Microcystis aeruginosa from oxidative stress. Moreover, H2O2 stimulated the synthesis and release of extracellular microcystin-LR from Microcystis aeruginosa, while intracellular microcystin-LR concentrations remained at a relatively constant level. In the presence of H2O2, loss of organoheterocyclic compounds, organic acids and ketones contributed to the growth of M. aeruginosa, but the reduction of vitamins inhibited it. Regulation of interspecific relationships by H2O2 is achieved by its action on fungal species and bacterial secretory metabolites. This study explored the response of phytoplankton interspecific relationships in symbiotic phytoplankton-microbe interactions to environmentally relevant H2O2 concentrations stress, providing a theoretical basis for understanding the formation of harmful-algae blooming and impact of photochemical properties of water on aquatic ecological safety and stability.

Assessment of solar water disinfection enhancement with H2O2 and dissolved oxygen on inactivating different waterborne pathogens

Water scarcity has been growing for the last decades and one feasible solution for water-deprived areas is the storage and treatment of roof-harvested rainwater. Solar disinfection (SODIS) is a proven water treatment procedure, but several drawbacks still need assessing, such as increasing the output volume of treated water, reducing the treatment time and/or increasing the inactivation efficiency performance. In this study, the addition of low concentrations (1–5 mg/L) of H2O2 and/or the increment of dissolved oxygen (DO) has been tested at a pilot plant scale using a solar Compound Parabolic Collector photo-reactor with the aim of enhancing the disinfection efficiency of SODIS. Their performance has been assessed against a consortium of five pathogens normally found in rainwater: E. coli, E. faecalis, S. enteritidis, P. aeruginosa and MS2 bacteriophage. The addition of DO and/or H2O2 to solar photo-inactivation (SP-I) proved to enhance pathogens’ inactivation kinetics. Results have shown that O2 supply affects E. coli, P, aeruginosa and E. faecalis as their kinetic constants increase 1.48, 1.17 and 1.6 times, respectively. On the other hand, H2O2 addition enhances the inactivation of all pathogens. being the most noteworthy MS2 inactivation as > 5 Log Reduction Values (LRV) were reduced for all concentrations between 99% and 95% of the energy required for SP-I. Finally, the combination of both agents is also effective but can only be noted in E. faecalis inactivation, which is better than with only H2O2 addition. The findings obtained in this study show that from the perspective of implementing solar technologies in the field, the addition of DO sparging can be discarded due to a slightly enhanced disinfection performance, while the use of low H2O2 concentrations can be envisaged due to both, the enhancement of the disinfection performance and the competitive cost estimated (0.0025 €/L) in comparison with only SODIS (0.002 €/L).

Effect of H2O2 Concentration on Morphology, Reflectivity and Wettability of Si Nanowalls Prepared by Metal Assisted Chemical Etching

A facile and low cost method, metal assisted chemical etching was used to prepare silicon (Si) nanowalls atop the Si wafer, where the effect of etchant solution concentration (H2O2 concentration) on the morphology, reflectivity and wettability of the fabricated Si nanowalls is investigated. The morphological and structural studies by scanning and transmission electron microscopy revealed the Si nanowalls prepared at both low and high H2O2 concentration are smooth, nonporous and single crystalline, where the increase of H2O2 concentration only changes the morphology from isolated nanowall structure to agglomerated nanowall structure. The height of nanowalls also increases with increase in H2O2 concentration and follows a linear behaviour with an etching rate of 5697 nm/M. The reflectance study shows that the reflectance is extremely low over broad wavelength range (300-1100 nm) for Si nanowalls, compared to that of planar Si wafer. The increase of H2O2 concentration significantly changes the wavelength dependence of the reflectance spectrum. The wettability studies show that SiNWs prepared at low H2O2 concentration exhibit hydrophobicity in contrast to the hydrophilicity of planar Si wafer, where the increase of H2O2 concentration to very high value changes the hydrophobicity of SiNWs to hydrophilicity as similar to planar Si wafer.

Redox Modification of PKA-Cα Differentially Affects Its Substrate Selection.

The cyclic AMP-dependent protein kinase (PKA) plays an essential role in the regulation of many important cellular processes and is dysregulated in several pervasive diseases, including diabetes, cardiovascular disease, and various neurodegenerative disorders. Previous studies suggest that the alpha isoform of the catalytic subunit of PKA (PKA-Cα) is oxidized on C199, both in vitro and in situ. However, the molecular consequences of these modifications on PKA-Cα's substrate selection remain largely unexplored. C199 is located on the P + 1 loop within PKA-Cα's active site, suggesting that redox modification may affect its kinase activity. Given the proximity of C199 to the substrate binding pocket, we hypothesized that oxidation could differentially alter PKA-Cα's activity toward its substrates. To this end, we examined the effects of diamide- and H2O2-dependent oxidation on PKA-Cα's activity toward select peptide and protein substrates using a combination of biochemical (i.e., trans-phosphorylation assays and steady-state kinetics analysis) and biophysical (i.e., surface plasmon resonance and fluorescence polarization assays) strategies. These studies suggest that redox modification of PKA-Cα differentially affects its activity toward different substrates. For instance, we found that diamide-mediated oxidation caused a marked decrease in PKA-Cα's activity toward some substrates (e.g., Kemptide and CREBtide) while having little effect on others (e.g., Crosstide). In contrast, H2O2-dependent oxidation of PKA-Cα led to an increase in its activity toward each of the substrates at relatively low H2O2 concentrations, with differential effects at higher peroxide concentrations. Together, these studies offer novel insights into crosstalk between redox- and phosphorylation-dependent signaling pathways mediated by PKA. Likewise, since C199 is highly conserved among AGC kinase family members, they also lay the foundation for future studies designed to elucidate the role of redox-dependent modification of kinase substrate selection in physiological and pathological states.

Comparison of Electro-Fenton and Photoelectro-Fenton for removal of Acrylonitrile Butadiene Styrene (ABS) from petrochemical wastewater

The purpose of this study was the evaluation the Electro-Fenton (EF) and Photo Elecro-Fennton (PEF) efficiencies to remove of some pollution indicators from effluents of Acrylonitrile Butadiene Styrene (ABS) petrochemical industries affected by the operational parameters such as operation time, pH, current density, and concentration of H2O2. The EF and PEF reactors were made and a batch study was performed to optimize the operational parameters. The optimum operating conditions were determined as pH 5, reaction time 60 min, H2O2 concentration 50 mmol/lit and current density 20 mA/cm2 for EF process and pH 5, operation time 30 min, H2O2 concentration 25 mmol/lit, current density of 20 mA/cm2 for PEF process. The highest removal efficiencies of COD (chemical oxygen demand), turbidity, total kejaldahl nitrogen (TKN) and total suspended solids (TSS) by EF and PEF processes under optimal conditions were obtained 86.7, 88.1, 67.9 and 64.1% for EF and 92.4, 93.7, 70.5 and 67.2% for PEF process, respectively. The PEF process resulted in higher removal efficiencies than that of the EF process to remove COD and TKN especially. Also, the amount of energy consumption for EF and PEF were obtained 10.1 and 9.3 kW h/m3, respectively. The PEF process was more capable to remove the pollutants from wastewater, than the EF process in a shorter time and with a lower H2O2 concentration due to the presence of UV radiation, which causes the photocatalytic decomposition of organic pollutants.

Inactivation kinetics of horseradish peroxidase (HRP) by hydrogen peroxide

In recent years, the peroxidase enzymes have generated wide interest in several industrial processes, such as wastewater treatments, food processing, pharmaceuticals, and the production of fine chemicals. However, the low stability of the peroxidases in the presence of hydrogen peroxide (H2O2) has limited its commercial use. In the present work, the effect of H2O2 on the inactivation of horseradish peroxidase (HRP) was evaluated. Three states of HRP (E0, E2, and E3) were identified. While in the absence of H2O2, the resting state E0 was observed, in the presence of low and high concentrations of H2O2, E2, and E3 were found, respectively. The results showed that HRP catalyzed the H2O2 decomposition, forming the species Ex, which was catalytically inactive. Results suggest that this loss of enzymatic activity is an intrinsic characteristic of the studied HRP. A model from a modified version of the Dunford mechanism of peroxidases was developed, which was validated against experimental data and findings reported by the literature.

Cationic Cu(I)-covalent organic framework as self-enhanced synergetic Photothermal/Phtodynamic/Cationic/Enzymatic antibacterial agent

Combination therapy, functioned by the integration of two or more therapies, simultaneously, into one platform, have gained wide popularity to combat antibiotic-resistant bacteria in both the clinical trials and fundamental researches. Here, a multifunctional cationic Cu(I)-covalent organic framework (COF), denoted as HLVCu, which could realize the joint action of photothermal/photodynamic/cationic/enzymatic therapies was facilely fabricated as an antimicrobial therapy platform. This material enables an amplified synergistic therapeutic effects to combat bacteria. The intrinsic photothermal activity could enhance the enzymatic activity, which is closely related to temperature to effectively catalyze the generation of toxic hydroxyl radical (•OH) from low concentration H2O2 to synergize with photothermal therapy. The positive charged skeleton structure allows the material to interact better with the bacterial membrane, which could decrease the diffusion distance of reactive oxygen species (ROS), realizing the quickly and effectively killing of bacteria. Under the laser irradiation, the present HLV-Cu could act as a broad-spectrum antibacterial agent, delivering an extremely high sterilization efficiency of 100% towards the gram positive (S. aureus) and gram negative (E. coli) model microorganisms, simultaneously, at a low dose of agents. Altogether, this work offers a new and safe antibiotic-free treatment option for high-efficiency combination antimicrobial therapy.

A mesophilic phosphotriesterase-like lactonase shows high stability and proficiency as quorum quenching enzyme

The problem of biofilm formation is a serious concern under various pathological conditions such as extensive burns, wounds in diabetic patients, bedsores, cystic fibrosis, nosocomial infections from implantable medical devices such as catheters, valves, etc.Environmental diffusion of biofilm (in pools, wet floors, industrial food plants) that could represent a reservoir of antibiotic resistant bacteria constitues an additional issue.In this work is described a lactonase from Rhodococcus erythropolis, a phosphotriesterase-like lactonase (PLL) enzyme, which has already been studied in the past and can be used for containment of biofilm formation. The protein is 28% and 40% identical with respect to the Pseudomonas diminuta PTE and the thermostable Saccharolobus solfataricus SsoPox respectively. The protein was obtained starting from a synthetic His-tagged gene, expressed in E. coli, purified and further characterized. New properties, not previously known or deducible from its sequence, have been highlighted. These properties are: the enzyme is thermophilic and thermostable even though it originates from a mesophilic bacterium; the enzyme has a long (months) shelf life at 4 °C; the enzyme is not only stable to low concentrations of the oxidant H2O2 but even activated by it at high concentrations; the enzyme proved to be a proficient quorum quenching enzyme, able to hydrolase acyl-homoserine lactones 3oxoC12-HSL and C4-HSL, and can inhibit up to 60% the formation of Pseudomonas aeruginosa (PAO1) biofilm.These different properties make the lactonase useful to fight resistant bacteria that induce inflammatory and infectious processes mediated by the quorum sensing mechanism.

Removal of 4-Chlorophenoles from Simulated Wastewater by Advanced Oxidation Processes

The degradation and mineralization of 4-chlorophenol (4-CP) by advanced oxidation processes (AOPs) was investigated in this work, using both of UV/H2O2 and photo-Fenton UV/H2O2/Fe+3 systems.The reaction was influenced by the input concentration of H2O2, the amount of the iron catalyst, the type of iron salt, the pH and the concentration of 4-CP. A colored solution of benzoquinon can be observed through the first 5 minutes of irradiation time for UV/H2O2 system when low concentration (0.01mol/L) of H2O2 was used. The colored solution of benzoquinon could also be observed through the first 5 minutes for the UV/H2O2/Fe+3 system at high concentration (100ppm) of 4-CP. The results have shown that adding Fe+3 to the UV/H2O2 system enhanced the rate of 4-CP oxidation at a molar ratio of H2O2/Fe+3/4-CP equals to 13/0.4/1 by a factor of 7. This reduced the consumption of H2O2 by a factor of 6 and the irradiation time required for complete degradation was reduced by a factor of 6. The experimental results have shown that the optimum reagents for a complete degradation of 4-CP(50ppm) were H2O2.=0.005mol/L, Fe+3=0.16*10-3 mol/L under acidic condition (pH=3) and irradiation time of 15 min for the UV/H2O2/Fe+3 system with a molar ratio of H2O2/Fe+3/4-CP equals to 13/0.4/1.

Ferrocene-based porous polymer as advanced environmental remediation material for self-enhanced synergetic photothermal-enzymatic antibacterial and reversible iodine capture

Water pollution, associated with both the modern productions and pathogen contamination, has become a worldwide safety concern, seriously threatening the health of living beings. Herein, a multifunctional porous polymer, denoted as Fc-PP-POP, composed by porphyrin (PP) and Ferrocene (Fc) unites, capable of self-enhanced synergetic antibacterial effect, as well as reversible capture of iodine pollutants, was facilely prepared through the simple but efficient Alder-Longo method via direct polymerization of pyrrole with Ferrocene dialdehyde. Fc-PP-POP integrated the features of Porphyrin (photoactivity) and Ferrocene (enzymatic activity), simultaneously, can serve as a broad-spectrum antibacterial agent, which could not only realize the rapidly and efficiently converting of light energy into local thermal energy for photothermal therapy (PTT), but also the transformation of low concentration of H2O2 into toxic hydroxyl radical (•OH) for the enzyme therapy. The as-generated local heat could further improve the enzymatic activity, displaying a remarkably enhanced synergistic therapeutic effect, realizing the efficient sterilization at low concentrations (300 μg/mL). In vivo assay revealed Fc-PP-POP can significantly promote the healing of infected wounds. Meanwhile, Fc-PP-POP can function as an efficient adsorbent, capturing the iodine contaminants from the environment. This work opens up a new mean for the application of low-cost POPs in the field of environmental remediation and public health.

H2O2-activated transcription factor MdERF4 negatively regulates ethylene biosynthetic during fruit ripening by suppressing MdACS1 transcription

Ethylene is essential for the ripening of climacteric fruit. The accumulation of reactive oxygen species (ROS) in apples can accelerate fruit ripening. Although ethylene signaling has been extensively studied, the transcriptional regulation of ethylene biosynthesis combined with ROS signaling remains limited. Hydrogen peroxide (H2O2) is one of the most abundant ROS involved in fruit development, ripening and senescence. Therefore, we treated apple fruit with different concentrations of H2O2 and found that low concentrations of H2O2 stimulated the activities of antioxidant enzymes, improved the scavenging ability of ROS, and reduced ethylene production·H2O2, as a signaling molecule, activated the expression of MdERF4, which can directly bind to proMdACS1 and suppress its expression, thereby inhibiting ethylene synthesis. Moreover, H2O2 indirectly attenuated the expression of MdACS1 and reduced ethylene production, thereby prolonging the storage period of the fruit by indirectly promoting the inhibitory effect of the ethylene inhibitor MdERF4 on proMdERF3. Our findings provide insights into the transcriptional regulation of ethylene biosynthesis during fruit ripening.