Hydrogen peroxide (H2O2) is an endogenous reactive oxygen species that contributes to oxidative stress directly as a molecular oxidant and indirectly through free radical generation. Topically ...applied 1% to 45% H2O2 can be used for a range of clinical purposes, which will be reviewed here in addition to its safety. In concentrations from 1% to 6%, H2O2 has antimicrobial properties and can act as a debriding agent through its effervescence, making low-concentration H2O2 useful for wound care. H2O2 has also been shown to promote venous insufficiency ulcer healing, but studies in other wound types are needed. In 1% formulations, H2O2 is used outside the United States to treat acne and has shown efficacy similar to or greater than benzoyl peroxide, with reduced side effects. In a concentration of 40%, H2O2 is US Food and Drug Administration–approved to treat seborrheic keratoses and may cause fewer pigmentary changes than cryotherapy, although elimination often requires 2 to 4 treatments. However, H2O2 should be used with caution, as exposure can cause adverse effects through its oxidant capabilities. Low H2O2 concentrations cause only transient symptoms (blanching and blistering), but exposure to 9% to 45% H2O2 can cause more severe skin damage, including epidermal necrosis leading to erythema and bullae. Overall, H2O2 has numerous therapeutic uses, and novel indications, such as treating actinic keratoses and skin cancers, continue to be explored.
Hydrogen peroxide (H₂O₂) is produced, via superoxide and superoxide dismutase, by electron transport in chloroplasts and mitochondria, plasma membrane NADPH oxidases, peroxisomal oxidases, type III ...peroxidases and other apoplastic oxidases. Intracellular transport is facilitated by aquaporins and H₂O₂ is removed by catalase, peroxiredoxin, glutathione peroxidase-like enzymes and ascorbate peroxidase, all of which have cell compartment-specific isoforms. Apoplastic H₂O₂ influences cell expansion, development and defence by its involvement in type III peroxidase-mediated polymer cross-linking, lignification and, possibly, cell expansion via H₂O₂-derived hydroxyl radicals. Excess H₂O₂ triggers chloroplast and peroxisome autophagy and programmed cell death. The role of H₂O₂ in signalling, for example during acclimation to stress and pathogen defence, has received much attention, but the signal transduction mechanisms are poorly defined. H₂O₂ oxidizes specific cysteine residues of target proteins to the sulfenic acid form and, similar to other organisms, this modification could initiate thiol-based redox relays and modify target enzymes, receptor kinases and transcription factors. Quantification of the sources and sinks of H₂O₂ is being improved by the spatial and temporal resolution of genetically encoded H₂O₂ sensors, such as HyPer and roGFP2-Orp1. These H₂O₂ sensors, combined with the detection of specific proteins modified by H₂O₂, will allow a deeper understanding of its signalling roles.
Hydrogen peroxide (H
O
) is an important green oxidizing agent for environmental protection and chemical production. In comparison to the traditional anthraquinone method, photosynthesis is a green ...and energy-saving process for H
O
production. To improve the stability and practical application value of the H
O
synthesized by photocatalysis, the H
O
photosynthesis should be conducted in pure water without involving any sacrificial reagents. In this regard, organic semiconducting catalysts pose as a suitable candidate for photocatalytic H
O
synthesis owing to their metal-free nature to prevent H
O
decomposition by the metal ions. In this Perspective, the H
O
photosynthesis history is firstly introduced, followed by a review of the organic semiconductor photocatalysts reported to date. Finally, the main problems to thwart the advances of current pure H
O-to-H
O
photosynthesis are discussed, followed by proposed solutions to address these issues in order to pave new ways for the development of highly efficient metal-free organic photocatalysts for sustainable pure H
O-to-H
O
conversion.
Powdery mildew is an apple disease caused by the obligate trophic fungus Podosphaera leucotricha. Basic helix-loop-helix (bHLH) transcription factors play important roles in plant development and ...stress responses, and they have been widely studied in model plants such as Arabidopsis thaliana. However, their role in the stress response of perennial fruit trees remains unclear. Here, we investigated the role of MdbHLH093 in the powdery mildew of apples. The expression of MdbHLH093 was significantly induced during the infection of apples with powdery mildew, and the allogenic overexpression of MdbHLH093 in A. thaliana enhanced the resistance to powdery mildew by increasing the accumulation of hydrogen peroxide (Hsub.2Osub.2) and activating the salicylic acid (SA) signaling pathway. The transient overexpression of MdbHLH093 in apple leaves increased the resistance to powdery mildew. Conversely, when MdbHLH093 expression was silenced, the sensitivity of apple leaves to powdery mildew was increased. The physical interaction between MdbHLH093 and MdMYB116 was demonstrated by yeast two-hybrid, bi-molecular fluorescence complementation, and split luciferase experiments. Collectively, these results indicate that MdbHLH093 interacts with MdMYB116 to improve apple resistance to powdery mildew by increasing the accumulation of Hsub.2Osub.2 and activating the SA signaling pathway, as well as by providing a new candidate gene for resistance molecular breeding.
The electrochemical production of hydrogen peroxide (H
O
) by 2-electron oxygen reduction reaction (ORR) is an attractive alternative to the present complex anthraquinone process. The objective of ...this paper is to provide a state-of-the-arts review of the most important aspects of this process. First, recent advances in H
O
production are reviewed and the advantages of H
O
electrogeneration via 2-electron ORR are highlighted. Second, the selectivity of the ORR pathway towards H
O
formation as well as the development process of H
O
production are presented. The cathode characteristics are the decisive factors of H
O
production. Thus the focus is shifted to the introduction of commonly used carbon cathodes and their modification methods, including the introduction of other active carbon materials, hetero-atoms doping (i.e., O, N, F, B, and P) and decoration with metal oxides. Cathode stability is evaluated due to its significance for long-term application. Effects of various operational parameters, such as electrode potential/current density, supporting electrolyte, electrolyte pH, temperature, dissolved oxygen, and current mode on H
O
production are then discussed. Additionally, the environmental application of electrogenerated H
O
on aqueous and gaseous contaminants removal, including dyes, pesticides, herbicides, phenolic compounds, drugs, VOCs, SO
, NO, and Hg
, are described. Finally, a brief conclusion about the recent progress achieved in H
O
electrogeneration via 2-electron ORR and an outlook on future research challenges are proposed.
Due to the significance of hydrogen peroxide (H(2)O(2)) in biological systems and its practical applications, the development of efficient electrochemical H(2)O(2) sensors holds a special attraction ...for researchers. Various materials such as Prussian blue (PB), heme proteins, carbon nanotubes (CNTs) and transition metals have been applied to the construction of H(2)O(2) sensors. In this article, the electrocatalytic H(2)O(2) determinations are mainly focused on because they can provide a superior sensing performance over non-electrocatalytic ones. The synergetic effect between nanotechnology and electrochemical H(2)O(2) determination is also highlighted in various aspects. In addition, some recent progress for in vivo H(2)O(2) measurements is also presented. Finally, the future prospects for more efficient H(2)O(2) sensing are discussed.
Accumulating data indicate that strigolactones (SLs) are implicated in the response to environmental stress, implying a potential effect of SLs on stomatal response and thus stress acclimatization. ...In this study, we investigated the molecular mechanism underlying the effect of SLs on stomatal response and their interrelation with abscisic acid (ABA) signaling.
The impact of SLs on the stomatal response was investigated by conducting SL-feeding experiments and by analyzing SL-related mutants. The involvement of endogenous ABA and ABA-signaling components in SL-mediated stomatal closure was physiologically evaluated using genetic mutants. Pharmacological and genetic approaches were employed to examine hydrogen peroxide (H2O2) and nitric oxide (NO) production.
SL-related mutants exhibited larger stomatal apertures, while exogenous SLs were able to induce stomatal closure and rescue the more widely opening stomata of SL-deficient mutants. The SL-biosynthetic genes were induced by abiotic stress in shoot tissues. Disruption of ABA-biosynthetic genes, as well as genes that function in guard cell ABA signaling, resulted in no impairment in SL-mediated stomatal response. However, disruption of MORE AXILLARY GROWTH2 (MAX2), DWARF14 (D14), and the anion channel gene SLOW ANION CHANNEL-ASSOCIATED 1 (SLAC1) impaired SL-triggered stomatal closure. SLs stimulated a marked increase in H2O2 and NO contents, which is required for stomatal closure.
Our results suggest that SLs play a prominent role, together with H2O2/NO production and SLAC1 activation, in inducing stomatal closure in an ABA-independent mechanism.
To date, the significant anti-cancer capacity of cold atmospheric plasma (CAP) on dozens of cancer cell lines has been demonstrated in vitro and in mice models. Conventionally, CAP was directly ...applied to irradiate cancer cells or tumor tissue. Over past three years, the CAP irradiated media was also found to kill cancer cells as effectively as the direct CAP treatment. As a novel strategy, using the CAP stimulated (CAPs) media has become a promising anti-cancer tool. In this study, we demonstrated several principles to optimize the anti-cancer capacity of the CAPs media on glioblastoma cells and breast cancer cells. Specifically, using larger wells on a multi-well plate, smaller gaps between the plasma source and the media, and smaller media volume enabled us to obtain a stronger anti-cancer CAPs media composition without increasing the treatment time. Furthermore, cysteine was the main target of effective reactive species in the CAPs media. Glioblastoma cells were more resistant to the CAPs media than breast cancer cells. Glioblastoma cells consumed the effective reactive species faster than breast cancer cells did. In contrast to nitric oxide, hydrogen peroxide was more likely to be the effective reactive species.
Summary
Medical devices are an important and growing aspect of healthcare provision and are increasing in complexity to meet established and emerging patient needs. Terminal sterilization plays a ...vital role in the provision of safe medical devices. While terminal sterilization technologies for medical devices include multiple radiation options, ethylene oxide remains the predominant nonthermal gaseous option, sterilizing c. 50% of all manufactured devices. Vaporized hydrogen peroxide (abbreviated VH2O2 by the International Organization for Standardization) is currently deployed for clinical sterilization applications, where its performance characteristics appear aligned to requirements, constituting a viable alternative low‐temperature process for terminal processing of medical devices. However, VH2O2 has operational limitations that create technical challenges for industrial‐scale adoption. This timely review provides a succinct overview of VH2O2 in gaseous sterilization and addresses its applicability for terminal sterilization of medical devices. It also describes underappreciated factors such as the occurrence of nonlinear microbial inactivation kinetic plots that may dictate a need to develop a new standard approach to validate VH2O2 for terminal sterilization of medical devices.
The presence of emerging contaminants such as pharmaceuticals in natural waters has raised increasing concern due to their frequent appearance and persistence in the aquatic ecosystem and the threat ...to health and safety of aquatic life, even at trace concentrations. Conventional water treatment processes are known to be generally inadequate for the elimination of these persistent contaminants. Therefore, the use of advanced oxidation processes (AOPs) which are able to efficiently oxidize organic pollutants has attracted a great amount of attention. The main limitation of AOPs lies in their high operating costs associated with the consumption of energy and chemicals. Fenton-based processes, which utilize nontoxic and common reagents and potentially can exploit solar energy, will considerably reduce the removal cost of recalcitrant contaminants. The disadvantages of homogeneous Fenton processes, such as the generation of high amounts of iron-containing sludge and limited operational range of pH, have prompted much attention to the use of heterogeneous Fenton processes. In this review, the impacts of some controlling parameters including the H2O2 and catalyst dosage, solution pH, initial contaminants concentrations, temperature, type of catalyst, intensity of irradiation, reaction time and feeding mode on the removal efficiencies of hetero/homogeneous Fenton processes are discussed. In addition, the combination of Fenton-type processes with biological systems as the pre/post treatment stages in pilot-scale operations is considered. The reported experimental results obtained by using Fenton and photo-Fenton processes for the elimination of pharmaceutical contaminants are also compiled and evaluated.
•Safe, environmentally-benign and relatively cheap reagents of Fenton-type reactions.•Comprehensive review of controlling parameters on the Fenton-type reactions.•Narrow pH range and iron-containing sludge as the homogenous Fenton limitations.•The slow reaction kinetics is the major drawback of heterogeneous Fenton reaction.•Recent strategies to address these limitations are presented.
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