Reactive Oxygen Species Species Research Articles

Ozonolysis of Terpene Flavor Additives in Vaping Emissions: Elevated Production of Reactive Oxygen Species and Oxidative Stress.

The production of e-cigarette aerosols through vaping processes is known to cause the formation of various free radicals and reactive oxygen species (ROS). Despite the well-known oxidative potential and cytotoxicity of fresh vaping emissions, the effects of chemical aging on exhaled vaping aerosols by indoor atmospheric oxidants are yet to be elucidated. Terpenes are commonly found in e-liquids as flavor additives. In the presence of indoor ozone (O3), e-cigarette aerosols that contain terpene flavorings can undergo chemical transformations, further producing ROS and reactive carbonyl species. Here, we simulated the aging process of the e-cigarette emissions in a 2 m3 FEP film chamber with 100 ppbv of O3 exposure for an hour. The aged vaping aerosols, along with fresh aerosols, were collected to detect the presence of ROS. The aged particles exhibited 2- to 11-fold greater oxidative potential, and further analysis showed that these particles formed a greater number of radicals in aqueous conditions. The aging process induced the formation of various alkyl hydroperoxides (ROOH), and through iodometric quantification, we saw that our aged vaping particles contained significantly greater amounts of these hydroperoxides than their fresh counterparts. Bronchial epithelial cells exposed to aged vaping aerosols exhibited an upregulation of the oxidative stress genes, HMOX-1 and GSTP1, indicating the potential for inhalation toxicity. This work highlights the indirect danger of vaping in environments with high ground-level O3, which can chemically transform e-cigarette aerosols into new particles that can induce greater oxidative damage than fresh e-cigarette aerosols. Given that the toxicological characteristics of e-cigarettes are mainly associated with the inhalation of fresh aerosols in current studies, our work may provide a perspective that characterizes vaping exposure under secondhand or thirdhand conditions as a significant health risk.

Superoxide Radicals in Uranyl Peroxide Solids: Lasting Signatures Identified by Electron Paramagnetic Resonance Spectroscopy

AbstractU(VI) peroxide phases (studtite and meta‐studtite) are found throughout the nuclear fuel cycle and exist as corrosion products in high radiation fields. Peroxides are part of a family of reactive oxygen species (ROS) that include hydroperoxyl and superoxide species and are produced during alpha radiolysis of water. While U(VI) peroxides have been thoroughly investigated, the incorporation and stability of ROS species within studtite have not been validated. In the current study, electron paramagnetic resonance (EPR) spectroscopy was used to identify the presence of free radicals within a series of U(VI) peroxide samples containing depleted, highly enriched, and natural uranium. Density functional theory calculations indicated that the predicted EPR signals matched well with a superoxide (O2−⋅) species incorporated into the studtite structure, confirming the presence of ROS in the material. Further analysis of samples that were synthesized between 1945 and 2023 indicated that there is a correlation between the radical signal and the product of specific activity multiplied by age of the sample.

Superoxide Radicals in Uranyl Peroxide Solids: Lasting Signatures Identified by Electron Paramagnetic Resonance Spectroscopy.

U(VI) peroxide phases (studtite and meta-studtite) are found throughout the nuclear fuel cycle and exist as corrosion products in high radiation fields. Peroxides are part of a family of reactive oxygen species (ROS) that include hydroperoxyl and superoxide species and are produced during alpha radiolysis of water. While U(VI) peroxides have been thoroughly investigated, the incorporation and stability of ROS species within studtite have not been validated. In the current study, electron paramagnetic resonance (EPR) spectroscopy was used to identify the presence of free radicals within a series of U(VI) peroxide samples containing depleted, highly enriched, and natural uranium. Density functional theory calculations indicated that the predicted EPR signals matched well with a superoxide (O2 -⋅) species incorporated into the studtite structure, confirming the presence of ROS in the material. Further analysis of samples that were synthesized between 1945 and 2023 indicated that there is a correlation between the radical signal and the product of specific activity multiplied by age of the sample.

Quantitative Factors Introduced in the Feasibility Analysis of Reactive Oxygen Species (ROS)-Sensitive Triggers.

Reactive oxygen species (ROS) are critical for cellular signaling. Various pathophysiological conditions are also associated with elevated levels of ROS. Hence, ROS-sensitive triggers have been extensively used for selective payload delivery. Such applications are predicated on two key functions: (1) a sufficient magnitude of concentration difference for the interested ROS between normal tissue/cells and intended sites and (2) appropriate reaction kinetics to ensure a sufficient level of selectivity for payload release. Further, ROS refers to a group of species with varying reactivity, which should not be viewed as a uniform group. In this review, we critically analyze data on the concentrations of different ROS species under various pathophysiological conditions and examine how reaction kinetics affect the success of ROS-sensitive linker chemistry. Further, we discuss different ROS linker chemistry in the context of their applications in drug delivery and imaging. This review brings new insights into research in ROS-triggered delivery, highlights factors to consider in maximizing the chance for success and discusses pitfalls to avoid.

Regulatory role of peroxynitrite in advanced glycation end products mediated diabetic cardiovascular complications.

The Advanced Glycation End Products (AGE) binding with its receptor can increase reactive oxygen species (ROS) generation through specific signaling mediators. The effect of superoxide (O2-) and O2- mediated ROS and reactive nitrogen species depends on their concentration and location of formation. Nitric oxide (NO) has anti-inflammatory and anticoagulant properties and a vasodilation effect, but NO can be deactivated by reacting with O2-. This reaction between NO and O2- produces the potent oxidant ONOO-. Therefore, ONOO-'s regulatory role in AGEs in diabetic cardiovascular complications must considered as a regulator of cardiovascular complications in diabetes.

Oxidative Stress and Cerebral Vascular Tone: The Role of Reactive Oxygen and Nitrogen Species.

The brain's unique characteristics make it exceptionally susceptible to oxidative stress, which arises from an imbalance between reactive oxygen species (ROS) production, reactive nitrogen species (RNS) production, and antioxidant defense mechanisms. This review explores the factors contributing to the brain's vascular tone's vulnerability in the presence of oxidative damage, which can be of clinical interest in critically ill patients or those presenting acute brain injuries. The brain's high metabolic rate and inefficient electron transport chain in mitochondria lead to significant ROS generation. Moreover, non-replicating neuronal cells and low repair capacity increase susceptibility to oxidative insult. ROS can influence cerebral vascular tone and permeability, potentially impacting cerebral autoregulation. Different ROS species, including superoxide and hydrogen peroxide, exhibit vasodilatory or vasoconstrictive effects on cerebral blood vessels. RNS, particularly NO and peroxynitrite, also exert vasoactive effects. This review further investigates the neuroprotective effects of antioxidants, including superoxide dismutase (SOD), vitamin C, vitamin E, and the glutathione redox system. Various studies suggest that these antioxidants could be used as adjunct therapies to protect the cerebral vascular tone under conditions of high oxidative stress. Nevertheless, more extensive research is required to comprehensively grasp the relationship between oxidative stress and cerebrovascular tone, and explore the potential benefits of antioxidants as adjunctive therapies in critical illnesses and acute brain injuries.

Genome-wide analysis of respiratory burst oxidase homolog (Rboh) genes in Aquilaria species and insight into ROS-mediated metabolites biosynthesis and resin deposition.

Respiratory burst oxidase homolog (Rboh) generates reactive oxygen species (ROS) as a defense response during biotic and abiotic stress. In Aquilaria plants, wounding and fungal infection result in biosynthesis and deposition of secondary metabolites as defense responses, which later form constituents of fragrant resinous agarwood. During injury and fungal invasion, Aquilaria tree generates ROS species via the Rboh enzymes. Despite the implication of Rboh genes in agarwood formation, no comprehensive genomic-level study of the Rboh gene family in Aquilaria is present. A systematic illustration of their role during stress and involvement in initiating signal cascades for agarwood metabolite biosynthesis is missing. In this study, 14 Rboh genes were retrieved from genomes of two Aquilaria species, A. agallocha and A. sinensis, and were classified into five groups. The promoter regions of the genes had abundant of stress-responsive elements. Protein-protein network and in silico expression analysis suggested their functional association with MAPK proteins and transcription factors such as WRKY and MYC2. The study further explored the expression profiles of Rboh genes and found them to be differentially regulated in stress-induced callus and stem tissue, suggesting their involvement in ROS generation during stress in Aquilaria. Overall, the study provides in-depth insight into two Rboh genes, AaRbohC and AaRbohA, highlighting their role in defense against fungal and abiotic stress, and likely during initiation of agarwood formation through modulation of genes involved in secondary metabolites biosynthesis. The findings presented here offer valuable information about Rboh family members, which can be leveraged for further investigations into ROS-mediated regulation of agarwood formation in Aquilaria species.

Dye-augmented bandgap engineering of a degradable cascade nanoreactor for tumor immune microenvironment-enhanced dynamic phototherapy of breast cancer

Non-invasive precision tumor dynamic phototherapy has broad application prospects. Traditional semiconductor materials have low photocatalytic activity and low reactive oxygen species (ROS) production rate due to their wide band gap, resulting in unsatisfactory phototherapy efficacy for tumor treatment. Employing the dye-sensitization mechanism can significantly enhance the catalytic activity of the materials. We develop a multifunctional nanoplatform (BZP) by leveraging the benefits of bismuth-based semiconductor nanomaterials. BZP possesses robust ROS generation and remarkable near-infrared photothermal conversion capabilities for improving tumor immune microenvironment and achieving superior phototherapy sensitization. BZP produces highly cytotoxic ROS species via the photocatalytic process and cascade reaction, amplifying the photocatalytic therapy effect. Moreover, the simultaneous photothermal effect during the photocatalytic process facilitates the improvement of therapeutic efficacy. Additionally, BZP-mediated phototherapy can trigger the programmed death of tumor cells, stimulate dendritic cell maturation and T cell activation, modulate the tumor immune microenvironment, and augment the therapeutic effect. Hence, this study demonstrates a promising research paradigm for tumor immune microenvironment-improved phototherapy. Statement of significanceThrough the utilization of dye sensitization and rare earth doping techniques, we have successfully developed a biodegradable bismuth-based semiconductor nanocatalyst (BZP). Upon optical excitation, the near-infrared dye incorporated within BZP promptly generates free electrons, which, under the influence of the Fermi energy level, undergo transfer to BiF3 within BZP, thereby facilitating the effective separation of electron–hole pairs and augmenting the catalytic capability for reactive oxygen species (ROS) generation. Furthermore, a cascade reaction mechanism generates highly cytotoxic ROS, which synergistically depletes intracellular glutathione, thereby intensifying oxidative stress. Ultimately, this dual activation strategy, combining oxidative and thermal damage, holds significant potential for tumor immunotherapy.

Boosted Photocatalytic Degradation of Atrazine Using Oxygen-Modified g-C3N4: Investigation of the Reactive Oxygen Species Interconversion.

Elaborating the specific reactive oxygen species (ROS) involved in the photocatalytic degradation of atrazine (ATZ) is of great significance for elucidating the underlying mechanism. This study provided conclusive evidence that hydroxyl radicals (·OH) were the primary ROS responsible for the efficient photocatalytic degradation of ATZ, thereby questioning the reliability of widely adopted radical quenching techniques in discerning authentic ROS species. As an illustration, oxygen-modified g-C3N4 (OCN) was prepared to counteract the limitations of pristine g-C3N4 (CN). Comparative assessments between CN and OCN revealed a remarkable 10.44-fold improvement in the photocatalytic degradation of ATZ by OCN. This enhancement was ascribed to the increased content of C-O functional groups on the surface of the OCN, which facilitated the conversion of superoxide radicals (·O2-) into hydrogen peroxide (H2O2), subsequently leading to the generation of ·OH. The increased production of ·OH contributed to the efficient dealkylation, dechlorination, and hydroxylation of ATZ. Furthermore, toxicity assessments revealed a significant reduction in ATZ toxicity following its photocatalytic degradation by OCN. This study sheds light on the intricate interconversion of ROS and offers valuable mechanistic insights into the photocatalytic degradation of ATZ.

Redox Active Zn@MOFs as Spontaneous Reactive Oxygen Species Releasing Antimicrobials.

The rapid development of antimicrobial resistance (AMR) among infectious pathogens has become a major threat and challenge in healthcare systems globally. A strategy distinct from minimizing the overuse of antimicrobials involves the development of novel antimicrobials with a mode of action that prevents the development of AMR microbial strains. Reactive oxygen species (ROS) are formed as a natural byproduct of the cellular aerobic metabolism. However, it becomes pathological when ROS is produced at excessive levels. Exploiting this phenomenon, research on redox-active bactericides has been demonstrated to be beneficial. Materials that release ROS via photodynamic, thermodynamic, and photocatalytic interventions have been developed as nanomedicines and are used in various applications. However, these materials require external stimuli for ROS release to be effective as biocides. In this paper, we report novel zinc-based metal organic framework (Zn@MOF) particles that promote the spontaneous release of active ROS species. The synthesized Zn@MOF spontaneously releases superoxide anions and hydrogen peroxide, exhibiting a potent antimicrobial efficacy against various microbes. Zn@MOF-incorporated plastic films and coatings show excellent, long-lasting antimicrobial potency even under continuous microbial challenge and an aging process. These disinfecting surfaces maintain their antimicrobial properties even after 500× surface wipes. Zn@MOF is also biocompatible and safe on the skin, illustrating its broad potential applications in medical technology and consumer care applications.

The generation pathways of OH and H2O2 by plasma-liquid interactions

Plasma-liquid interactions (PLIs) are a rich source providing many reactive oxygen species (ROS). These ROS species, such as OH and H2O2, feature powerful oxidative properties, which are excellent utilization for bacterial killing, water treatment, and other applications. Lifetime and reaction pathways of ROS species from plasma into the bulk liquid are complex. Understanding these behaviors is essential for the applications of the ROS species. In this work, we presented two pathways for generation of OH radicals and H2O2 from the plasma into the bulk liquid. Firstly, OH radicals are mainly produced via the dissociation of water molecules by free electrons in the plasma. Generated radicals then quickly recombine into H2O2. These species with a high Henry constant easily absorb and disperse into the bulk liquid. In a second way, OH radicals and H2O2 are also generated by the reaction of O3 with H2O molecules. At first, O3 is absorbed into the bulk liquid and reacts with H2O2 molecules to generate H2O2. Next, O3 continues reacting with this generated H2O2 to produce OH radicals.

Dual‐Functional Artificial Peroxidases with Ferriporphyrin Centers for Amplifying Tumor Immunotherapies via Immunogenic Cell Death

AbstractConstructing highly effective sonosensitizers that integrate tumor microenvironment (TME)‐adaptive and ultrasound (US)‐controllable production of reactive oxygen species (ROS) to amplify tumor immunotherapies is extremely desirable but remains challenging. Here, inspired by the coordination structure and biocatalytic effects of Fe‐based peroxidase, a dual‐functional artificial peroxidase is synthesized with ferriporphyrin networks (FePorNW‐DAP) to serve a TME‐adaptive and US‐controllable ROS‐generator for amplifying tumor immunotherapies in breast cancer via immunogenic cell death. Owing to the structural advantages of the ferriporphyrin‐based large d–π‐conjugated networks with the monatomic Fe─N4 coordination center, moderate interaction with H2O2, and decreased bandgap, the FePorNW‐DAP displays efficient dual‐functional ROS production capabilities to combat tumor cells and amplify the tumor immunotherapies, 1) utilize locally produced H2O2 in the TME to catalytically generate potent •OH and other ROS species; simultaneously, 2) external US irradiation can further boost the generation of •OH and 1O2. This work provides not only critical evidence that the proposed dual‐functional artificial peroxidases can induce a strong antitumor immune response and immune memory but also offers essential guidance for creating a high‐performance and biocompatible strategy to regulate the immunosuppression TME and enhance the antitumor immune responses of breast cancer.

Red blood cell membrane biomimetic nanoprobes for ratiometric imaging of reactive oxygen species level in atherosclerosis

Atherosclerosis (AS) is a major pathological factor to cardiovascular diseases, wherein reactive oxygen species (ROS) serve as the initiating link for the development of AS. However, direct and accurate assessment of ROS levels in AS plaque sites remains challenging. Herein, by embedding a ROS-responsive fluorescent small molecule (HDB with positive response or Cy7 with negative response) and a stable ROS-independent fluorescent dye CH1055 into red blood cell membrane (RBCM)-biomimetic liposomes, two biomimetic nanoprobes (R-Lipo@HDB/CH1055 and R-Lipo@Cy7/CH1055) were developed for indicating the existence of AS plaques and direct in situ ratiometric imaging of ROS at plaque sites. The fused RBCM endows the nanoprobes with attractive immune escape properties and the ability to accumulate at the AS sites. They not only can indicate the presence of plaques by the second near-infrared (NIR-II) fluorescence of CH1055, but also enable the accurate response to ROS levels through the upward or downward ratiometric fluorescence of HDB or Cy7 to CH1055, avoiding the interference of probe accumulation fluctuation or metabolism at the disease site and thus allowing for more accurate imaging compared to traditional monochromatic imaging. Via the specific responses of HDB and Cy7 to different species of ROS, we verified the upregulation of these ROS at the AS site using these two nanoprobes, and demonstrated their potential to assess the therapeutic effect of AS drugs. This study paves a feasible way to construct a ratiometric imaging platform using RBCM biomimetic liposomes to simultaneously encapsulate several functional molecules, achieving the disease diagnosis, pathological analysis and drug effect evaluation.

Construction of Z-scheme NiO/BiOBr heterojunction for facilitating photocatalytic degradation of oxytetracycline and 2-mercaptobenzothiazole

Z-scheme NiO/BiOBr heterojunction was prepared by mechanical ball milling method and applied for the photodegradation removal of oxytetracycline (OTC) and 2-mercaptobenzothiazole (MBT). The Z-scheme electron transport pathway optimizes the separation of photogenerated carriers, thereby significantly increasing the generation capacity of reactive oxygen species (ROS). The photocatalytic degradation experiments demonstrate that the optimized OTC and MBT removal efficiency of NiO/BiOBr (NBOB) composites could reach 72.6% (120 min) and 97.7% (9 min), respectively. Photoluminescence (PL) spectra and PL decay curves indicate that NBOB-2 composites exhibit low photoinduced electron-hole recombination rate and accelerated electron separation efficiency. In addition, ESR spectra confirm that the Z-scheme NiO/BiOBr heterojunction can generate a larger quantity of ROS species. The possible photodegradation pathways and toxicity analysis for the OTC and MTB photodegradation intermediates are elucidated by HPLC-MS measurement and T.E.S.T. application. The manuscript provides a reference for the macro-preparation of bismuth-based photocatalysts with superior performance and high stability.

Electrocatalytic reduction of hydrogen peroxide in solution in the presence of polyacrylic acid and copper ions: Application for gaseous hydrogen peroxide detection

A comprehensive voltammetric investigation into the electrocatalytic electrode mechanism for the reduction of hydrogen peroxide in an aqueous polyacrylic acid solution, in the presence of Cu2+ ions, is presented. The primary objective is to lay the groundwork for the development of a straightforward electrochemical sensor for the detection of gaseous H2O2. Various electrode reaction pathways have been observed depending on the potential applied to the glassy carbon electrode. At potentials approximately −0.400 V vs. Ag/AgCl (3 mol L−1 KCl), an electrochemical reduction of H2O2 occurs. In this context, the Cu2+/Cu+ redox couple, stabilized by polyacrylic acid, acts as a redox mediator, following the EC’ reaction scheme. Additionally, a complex Fenton-like spontaneous redox chemistry takes place between Cu2+/Cu+ and H2O2 within the bulk of the polyacrylic aqueous solution. This results in the generation of a variety of reactive oxygen species (ROS), with the superoxide anion and hydroxyl radical being the most probable intermediates. The electrochemical reduction of ROS species effectively recycles H2O2 near the electrode surface, constituting an electrocatalytic mechanism of the second order. This particular electrocatalytic process is evident as a prominent reduction current tail at potentials more negative than −0.400 V. This, in conjunction with the adsorption and stabilizing influence of polyacrylic acid, facilitates exceptional analytical sensitivity for the detection of gaseous H2O2. The sensor exhibits the capability to detect concentrations of gaseous H2O2 as low as 10−11 mol L−1, accomplished through the utilization of square-wave voltammetry and other advanced voltammetric techniques.

Unravelling the Mechanistic Understanding of Metal Nanoparticle-Induced Reactive Oxygen Species Formation: Insights from a Cu Nanoparticle Study.

Humans can be exposed to engineered and nonintentionally formed metal and metal oxide nanoparticles (Me NPs) in occupational settings, in public transportation areas, or by means of contact with different consumer products. A critical factor in the toxic potency of Me NPs is their ability to induce oxidative stress. It is thus essential to assess the potential reactive oxygen species (ROS) formation properties of Me NPs. A common way to assess the relative extent of ROS formation in vitro is to use fluorescence spectroscopy with the DCFH-DA (2',7'-dichlorofluorescein diacetate) probe, with and without HRP (horseradish peroxidase). However, this method does not provide any information about specific ROS species or reaction mechanisms. This study investigated the possibility of using complementary techniques to obtain more specific information about formed ROS species, both the type and reaction mechanisms. Cu NPs in PBS (phosphate buffered saline) were chosen as a test system to have the simplest (least interference from other components) aqueous solution with a physiologically relevant pH. ROS formation was assessed using fluorescence by means of the DCFH-DA method (information on relative amounts of oxygen radicals without selectivity), the Ghormley's triiodide method using UV-vis spectrophotometry (concentrations of H2O2), and electron paramagnetic resonance with DMPO as the spin-trap agent (information on specific oxygen radicals). This approach elucidates that Cu NPs undergo ROS-generating corrosion reactions, which previously have not been assessed in situ. In the presence of H2O2, and based on the type of oxygen radical formed, it was concluded that released copper participates in Haber-Weiss and/or Fenton reactions rather than in Fenton-like reactions. The new combination of techniques used to determine ROS induced by Me NPs provides a way forward to gain a mechanistic understanding of Me NP-induced ROS formation, which is important for gaining crucial insight into their ability to induce oxidative stress.

Abstract 14665: Cybrid Analysis Delineates Nuclear and Mitochondrial Contributions to Oxidative Stress in Pulmonary Arterial Hypertension

Rationale : Heritable pulmonary arterial hypertension (HPAH) is a serious vasculopathy caused by remodeling of pulmonary arterioles. It is inherited in an autosomal dominant pattern with reduced penetrance, suggesting additional triggers are needed for disease development. Past study shows increased DNA damage and total reactive oxygen species (ROS) in lymphoblastoid cells (LCL) from PAH patients and unaffected relatives, indicating a potential genetic component. Hypothesis: Increased oxidative stress is an independent genetically-determined modifier of PAH susceptibility. Methods: LCL from patients, relatives and unrelated controls were analyzed for total and mitochondrial (mt) ROS and mt function (Seahorse). Untargeted metabolomics were performed by Metabolon. Nuclear vs mt gene contribution was studied using cybrids created by transferring the mitochondria from high (HC) and low ROS LCL (LC) to mt negative 143B Rho0 cells. Results: Metabolomics revealed significant differences between PAH and control LCL in the TCA cycle and glutathione metabolism relating to oxidative stress. HPAH LCL showed significant upregulation of both ROS species compared to controls. LCL from relatives clustered into two groups, one with increased mtROS, the other comparable to controls . Like PAH lung vascular cells, LCL with increased mtROS had reduced spare respiratory capacity (SRC) suggesting dysfunctional mitochondria, but no glycolytic switch. Cybrid analysis revealed that HCs had significantly higher basal respiration (p=0.02), with SRC trending higher compared to LCs, indicating a functional electron transport chain. These cells also had elevated mtROS (p=0.04), suggesting reduced antioxidants. Conclusions: HPAH is a complex disease, and mutation status alone doesn’t determine its susceptibility. Patient LCL recapitulate some of the metabolomic pathways dysregulated in lung vascular cells. Oxidative stress in LCL extends to some unaffected relatives, suggesting this is an independent genetic trait that modifies PAH risk. Our cybrid analysis, novel in PAH highlights the importance of nuclear-mt crosstalk. WGS is underway to identify nuclear variants that could affect the mt, and act as potential modifiers and second hits in PAH pathogenesis.

Magnetically recyclable Cu2+ doped Fe3O4@biochar for in-situ inactivation of Microcystis aeruginosa: Performance and reusability

Harmful cyanobacterial blooms in eutrophic water bodies have frequently occurred worldwide and become a major environmental concern. Therefore, it is imperative to develop a stable and efficient algaecide to solve this issue. In this study, our purpose was to investigate the efficacy and mechanism of a newly developed Cu2+ doped Fe3O4@Biochar magnetic composite (Cu-Mag-BC) in in-situ inactivation of Microcystis aeruginosa (M. aeruginosa). We successfully synthesized the Cu-Mag-BC by coating Cu2+ onto Fe3O4@Biochar. Cu-Mag-BC exhibited superparamagnetic behavior and was uniformly impregnated by Cu2+. Cu-Mag-BC (5 mg/L), rapidly inactivated chlorophyll-a (Chl-a) in M. aeruginosa with low Fe and Cu leaching, during which time the OD264 value and malondialdehyde (MDA) content increased, while the activities of superoxide dismutase (SOD) and catalase (CAT) first increased and then decreased, due to oxidative stress induced by over-generated reactive oxygen species (ROS). Quantitative results showed that ·O2− and ·OH were the main ROS species produced from Cu-Mag-BC. Inactivation efficiency was maintained at approximately 80 % after three consecutive runs and total Chl-a removal efficiency reached 2.84 g/g, indicating good reusability and stability. A possible inactivation mechanism is proposed; amino groups and adipose chain were the primary oxidation sites. Thus, Cu-Mag-BC shows potential as a candidate for simultaneously inactivating harmful cyanobacteria and preventing secondary pollution.

In Vitro Antioxidant and In Vivo Antigenotoxic Features of a Series of 61 Essential Oils and Quantitative Composition-Activity Relationships Modeled through Machine Learning Algorithms.

The antioxidant activity of essential oils (EOs) is an important and frequently studied property, yet it is not sufficiently understood in terms of the contribution of EOs mixtures' constituents and biological properties. In this study, a series of 61 commercial EOs were first evaluated as antioxidants in vitro, following as closely as possible the cellular pathways of reactive oxygen species (ROS) generation. Hence, EOs were assessed for the ability either to chelate metal ions, thus interfering with ROS generation within the respiratory chain, or to neutralize 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and lipid peroxide radicals (LOO•), thereby halting lipid peroxidation, as well as to neutralize 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid cation radicals (ABTS•+) and hydroxyl radicals (OH•), thereby preventing the ROS species from damaging DNA nucleotides. Showing noteworthy potencies to neutralize all of the radicals at the ng/mL level, the active EOs were also characterized as protectors of DNA double strands from damage induced by peroxyl radicals (ROO•), emerging from 2,2'-azobis-2-methyl-propanimidamide (AAPH) as a source, and OH•, indicating some genome protectivity and antigenotoxicity effectiveness in vitro. The chemical compositions of the EOs associated with the obtained activities were then analyzed by means of machine learning (ML) classification algorithms to generate quantitative composition-activity relationships (QCARs) models (models published in the AI4EssOil database available online). The QCARs models enabled us to highlight the key features (EOSs' chemical compounds) for exerting the redox potencies and to define the partial dependencies of the features, viz. percentages in the mixture required to exert a given potency. The ML-based models explained either the positive or negative contribution of the most important chemical components: limonene, linalool, carvacrol, eucalyptol, α-pinene, thymol, caryophyllene, p-cymene, eugenol, and chrysanthone. Finally, the most potent EOs in vitro, Ylang-ylang (Cananga odorata (Lam.)) and Ceylon cinnamon peel (Cinnamomum verum J. Presl), were promptly administered in vivo to evaluate the rescue ability against redox damage caused by CCl4, thereby verifying their antioxidant and antigenotoxic properties either in the liver or in the kidney.

Enhanced Antibacterial Activity at Ag-Cu Nanojunctions: Unveiling the Mechanism with Simple Surfaces of CuNPs-on-Ag Films.

Deposition of CuNPs on silver film gives rise to the formation of active Ag-Cu interfaces leading to dramatic enhancements in antibacterial activity against Escherichia coli. Transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDAX) analyses reveal that CuNPs are covered in a thin Cu2O shell, while X-ray photoelectron spectroscopy measurements (XPS) reveal that the Ag film samples contain significant amounts of Ag2O. XPS analyses show that the deposition of CuNPs on Ag films leads to the formation of a photoactive Ag2O-Cu2O heterostructure. Following a Z-scheme mechanism, electrons from the conduction band of Ag2O recombine with photogenerated holes from the valence band of Cu2O. Consequently, electrons at Cu2O's conduction band render Cu reduced and cause reductive activation of surface oxygen species on Cu forming reactive oxygen species (ROS). Interaction between metallic Cu and ROS species leads to the formation of a Cu(OH)2 phase. Both ROS and Cu(OH)2 species have previously been reported to lead to enhanced antibacterial properties. Holes on Ag2O produce a highly oxidized AgO phase, a phase reported to exhibit excellent antibacterial properties. Quantitative analysis of Cu and Ag high-resolution X-ray photoelectron spectroscopy (HR-XPS) spectra directly reveals several-fold increases in these active phases in full agreement with the observed increase in antibacterial activities. This study provides insight and surface design parameters by elucidating the important roles of Ag and Cu's bifunctionality as active antibacterial materials.