Stable Peroxide Research Articles

Insight on the generation of reactive oxygen species in the CaO2/Fe(II) Fenton system and the hydroxyl radical advancing strategy

Calcium peroxide (CaO2) is a stable hydrogen peroxide (H2O2) carrier, and the CaO2/Fe(II) system has been applied for treatment of various pollutants. It is commonly reported in the literature that hydroxyl radical (HO) and superoxide radical anions (O2−) are the two main reactive oxygen species (ROSs) generated in the CaO2/Fe(II) system. However, many of the reported results were deduced from degradation performance rather than specific testing of radical generation. Thus, the specific generation of ROSs and the influence of system conditions on ROSs yield are still unclear. To our knowledge, this is the first study specifically focusing on the generation of HO and O2− in the CaO2/Fe(II) system. Experimental conditions were optimized to investigate the production of HO and O2−. The results showed the influences of CaO2, Fe(II), and solution pH on HO and O2− generation, and the HO generation efficiency was reported for the first time. In addition, the ROSs generation pathways in the CaO2/Fe(II) system were elucidated. A strategy for enhancing HO yield is developed, based on the continuously dosing Fe(II). This proposed strategy has implications for the effective application of in situ chemical oxidation employing CaO2/Fe(II) for groundwater remediation.

Efficient hydrogen peroxide generation using reduced graphene oxide-based oxygen reduction electrocatalysts

Electrochemical oxygen reduction has garnered attention as an emerging alternative to the traditional anthraquinone oxidation process to enable the distributed production of hydrogen peroxide. Here, we demonstrate a selective and efficient non-precious electrocatalyst, prepared through an easily scalable mild thermal reduction of graphene oxide, to form hydrogen peroxide from oxygen. During oxygen reduction, certain variants of the mildly reduced graphene oxide electrocatalyst exhibit highly selective and stable peroxide formation activity at low overpotentials (<10 mV) under basic conditions, exceeding the performance of current state-of-the-art alkaline catalysts. Spectroscopic structural characterization and in situ Raman spectroelectrochemistry provide strong evidence that sp2-hybridized carbon near-ring ether defects along sheet edges are the most active sites for peroxide production, providing new insight into the electrocatalytic design of carbon-based materials for effective peroxide production. Electrochemical routes for the production of hydrogen peroxide would reduce the waste inherent in the current anthraquinone process, and also make distributed and on-site production more feasible. Here, inexpensive reduced graphene oxide is proven to be a stable and selective catalyst for oxygen reduction at remarkably low overpotentials.

Iron-Catalyzed Batch/Continuous Flow C-H Functionalization Module for the Synthesis of Anticancer Peroxides.

Iron-catalyzed dehydrogenative cross-coupling of carbonyl compounds with aliphatic peroxide was developed under mild conditions. A library of linear alkylated and arylated peroxides are synthesized in good to excellent yield. This method is highly selective and general for a range of biologically important derivatives of 2-oxindole, barbituric acid, and 4-hydroxy coumarin with a good functional group tolerance and without the cleavage of the peroxide bond. This peroxidation reaction is upscalable to grams and also synthesizable in continuous flow with increased safety in short duration. Mechanistic investigation reveals Fe-(II) undergoes redox type process to generate the radical intermediates, which subsequently recombine selectively to form the stable peroxides. The potential of peroxides is evaluated by cell viability assay and found to exhibit the good anticancer activity with minimum IC50= 5.3 μM.

Highly sensitive, stable and selective hydrogen peroxide amperometric biosensors based on peroxidases from different sources wired by Os-polymer: A comparative study

A comparison was made between two plant peroxidases, cationic horseradish peroxidase (HRP) and anionic tobacco peroxidase (TOP), combined with a highly cationic osmium polymer [Os(4,4′-dimethyl-2,2′-bipyridine)2poly(N-vinylimidazole)10Cl]+2/+ ([Os(dmp)PVI]+/2+) to develop highly sensitive, stable and selective hydrogen peroxide biosensors. The two different plant peroxidases were individually immobilized onto graphite rod (G) electrodes by a three steps drop-casting procedure consisting of the subsequent deposition of an aqueous solution of ([Os(dmp)PVI]+/2+), followed by a solution of poly(ethyleneglycol) diglycidyl ether (PEGDGE), used as a cross linking agent and finally an aliquot of a solution of cationic HRP or anionic TOP to make HRP/PEGDGE/[Os(dmp)PVI]+/2+/G and TOP/PEGDGE/[Os(dmp)PVI]+/2+/G based electrodes, respectively. Electrochemical experiments were carried out to investigate the influence of the surface charge of the enzyme and the charge of the polymer on the efficiency of the electron transfer (ET) between the enzyme and the wiring redox polymer and the efficiency for electrocatalytic reduction of H2O2. In the case of HRP a decrease in the ET rate was observed due to the repulsion between this enzyme and the polymer, both positively charged, whereas with TOP there was an enhanced ET rate due to the attraction between the anionic enzyme and the cationic polymer. The effects of enzyme loading and pH were investigated. Both peroxidase modified electrodes exhibited a wide dynamic response range (1–500μM H2O2) and a low detection limit (0.3μM H2O2). The TOP based electrode showed a higher sensitivity (470nAμM−1cm−2) compared to that of the HRP based electrode (300nAμM−1cm−2) and an improved long-term stability (decrease in 17.3% upon 30days compared with 50% for HRP). Both enzyme electrodes showed a response time of 3s. The HRP based sensor was more sensitive to the presence of phenolic compounds acting as alternative electron donors, whereas the TOP based sensor was virtually interference free. Both HRP and TOP based electrodes were successfully tested in contact lens cleaning samples and real “spiked” samples from different sources such as tap water, milk and dairy products.

Oxygen Sensing in the Pulmonary Circulation

Since the original description of hypoxic pulmonary vasoconstriction (HPV) by Von Euler and Liljestrand in 1946, where they concluded, “breathing of pure oxygen lowered the pulmonary arterial pressure and oxygen-lack raised it,”1 the precise oxygen-sensing mechanism within the lungs has remained an enigma. Nevertheless, there seems to be some agreement to an overall mechanism for HPV: the primary oxygen sensor is the pulmonary artery smooth muscle cells (PASMC) mitochondrial electron transport chain (ETC); the ETC-produced superoxide/reactive oxygen species (ROS) is the mediator; and redox-sensitive plasma membrane voltage-gated potassium (Kv) channels are the effectors.2 Intriguingly, a similar sensor-mediator-effector model seems to operate in other areas where oxygen is sensed in the body, such as the ductus arteriosus or the carotid body.2 But many controversies exist. Although several groups, including ours, show that acute hypoxia decreases superoxide production from ETC complexes I and III, others find that hypoxia increases superoxide production.2,3 Regardless, most agree that it is the more stable and diffusible hydrogen peroxide (H2O2), produced from superoxide via the mitochondrial MnSOD (manganese superoxide dismutase) that eventually reaches the cell membrane to regulate Kv channels.2,3 However, once again controversy exists. Many groups, including ours, show that decreased levels of H2O2 (a reducing signal) directly inhibits Kv channels (like Kv1.5),2,3 depolarizing the plasma membrane, increasing Ca2+ influx through L-type Ca2+ channels, and causing PASMC contraction2,3 (Kv channels are intrinsically redox sensitive and animals lacking Kv1.5 lack HPV4). Others suggest that increased levels of H2O2 (an oxidative signal) primarily result in an endoplasmic reticulum-mediated calcium release, with K+ channel inhibition as a downstream effect.3 Much has been written about the first controversy, which tends to …

Extraction, radical scavenging activities and physicochemical fingerprints of black pepper (Piper nigrum) extract

Black pepper (Piper nigrum) is an essential tropical crop which doubled as spice in food industries and medicine in the treatment of free radical related disorders. For this study, microwave reflux method was employed in the extraction of bioactive oleoresin from black peppercorns. Extraction parameters such as irradiation time, microwave power, feed particle size and molar ratio were optimized. The effects of these parameters on the oleoresin yield and antiradical activities were investigated using a multi-level Taguchi methodology. The results obtained placed the optimum extraction condition at 120 min irradiation time, 350 W microwave power, 0.105 mm feed particle size and 12 g/ml molar ratio. Under this optimal condition, the oleoresin yield was obtained as 5.64% (w/w). However, the optimum percentage inhibitions of the extracted spice oleoresins on the stable DPPH and hydrogen peroxide radicals were estimated to be 88.75 and 90.31%, respectively. Moreover, the Fourier transform infrared (FTIR) analysis confirmed the presence of unsaturated amide groups, which validated the antioxidant potential of the black pepper extract. The scanning electronic microscopy (SEM) further elucidated the structural transformation of black pepper from the pulsed microwave heating effect.

Highly Stable Hydrogen Peroxide Biosensor Based on Gelatin-Hierarchical Porous Carbon Obtained from Fish Scales Modified Glassy Carbon Electrode

Highly Stable Hydrogen Peroxide Biosensor Based on Gelatin-Hierarchical Porous Carbon Obtained from Fish Scales Modified Glassy Carbon Electrode

Biological Properties of Polyphenols Extracts from Agro Industry’s Wastes

Processing and selection of fruits and vegetables generate high amounts of wastes that represent an economical and environmental issue for the agroindustry sector. Nevertheless, according to so called “biorefinery” approach, this waste biomass can be exploited for the recovery of value added molecules. In this paper the residues of industrial processing of fennels, carrots, lemons and tomatoes were used as sources of polyphenols. In order to optimize the recovery of polyphenols, different extraction techniques (maceration, ultrasound and microwave assisted extraction) were used in combination with different extraction media (water, ethanol, methanol and their mixtures). The polyphenols’ fractions were tested for their chemical and biological properties. All the obtained phenol fractions showed high antioxidant power and scavenging ability towards stable radical species and hydrogen peroxide. Moreover, the isolated polyphenol mixtures (containing remarkable compounds like quercetin, kaempferol, naringin, hesperetin) also displayed potential activities as anti-cancer, anti-microbial and acetylcholinesterase inhibiting agents. Overall the obtained results showed that the residual matter produced by the industrial processing of fruits and vegetables contain high amounts of polyphenols. These polyphenolic fractions still retain their biological and antioxidant properties and therefore could be further exploited for other industrial applications.

Pressure-Induced Stable Beryllium Peroxide.

Beryllium oxides, at ambient pressure, have been extensively studied due to their unique chemical bonds and applications. However, the long-desirable target beryllium peroxide (BeO2) has not been reported, thus far. Currently, the application of pressure has become a powerful tool in finding unusual stoichiometric compounds with exotic properties. Here, swarm structural searches in combination with first-principles calculations disclosed that the reaction of BeO and oxygen, at pressures above 89.6 GPa, yields BeO2. Interestingly, this reaction pressure is lower than the phase transition pressure (106 GPa) of pure BeO. BeO2 crystallizes in FeS2-type structure, whose remarkable feature is that it contains peroxide group (O22-) with an O-O distance of 1.40 Å at 100 GPa. Notably, O22- is maintained in the pressure range of 89.6-300 GPa. The chemical bonding analysis shows that the uniformly distributed ionic Be-O and covalent O-O bonding network plays a key role in determining its structural stability. BeO2 is a direct band gap nonmetal, and its band gap becomes larger with increase of pressure, which is in sharp contrast with BaO2. Moreover, phase diagram of Be-O binary compounds with various BexOy (x = 1-3, y = 1-6) compositions at pressures of up to 300 GPa was reliably built. Our results are also important for enriching the understanding of beryllium oxides.

Abstract 13280: Localized Hydrogen Peroxide Production and Differential Activation of Redox-sensitive Transcription Factors Involved in Atherogenesis

Reactive oxygen species modulate key physiological responses, yet ROS are also implicated in vascular disease states. At low concentrations, the stable ROS hydrogen peroxide (H 2 O 2 ) activates eNOS and enhances vascular barrier function. Yet at higher concentrations, vascular ROS lead to oxidative stress, increase permeability and promote atherosclerosis. The molecular events underlying the transition from “physiological” to “pathological” ROS in the endothelium are incompletely understood. Laminar shear stress activates “atheroprotective” redox-modulated transcription factors whereas turbulent/oscillatory flow activates “atherogenic” transcription factors that are sensitive to cellular redox state. In these studies, we constructed differentially-targeted HyPer biosensors for H 2 O 2 to identify the intracellular organelles and pathways responsible for dynamic mechanochemical regulation of endothelial H 2 O 2 metabolism. We discovered that laminar (physiological) shear stress increases H 2 O 2 in the endothelial cell nucleus much more than in the cytosol. By contrast, oscillatory (pathological) shear increases H 2 O 2 in the cytosol significantly more than in the nucleus. We next generated H 2 O 2 in specific subcellular locales in endothelial cells using recombinant constructs expressing a D-amino acid oxidase (DAAO) that robustly generates H 2 O 2 upon addition of D-alanine to the cells. By transfecting a series of differentially targeted DAAO constructs into endothelial cells, we discovered that generation of H 2 O 2 in distinct subcellular compartments differentially modulates transcriptional activation. Generation of H 2 O 2 by DAAO expressed in the endothelial cell nucleus led to enhanced transcription of Nrf2-modulated genes, whereas generation of H 2 O 2 by DAAO targeted to the cytosol instead activated NF-κB-regulated genes. This differential transcriptional response regulated by H 2 O 2 generated in distinct subcellular locales provides new insights into the roles of ROS and eNOS in mechanochemical coupling. Taken together, these findings have important implications for our understanding of flow-responsive genes in the normal blood vessel as well as in disease states associated with disordered blood flow and oxidative stress.

Cyclic voltammetry, square wave voltammetry, electrochemical impedance spectroscopy and colorimetric method for hydrogen peroxide detection based on chitosan/silver nanocomposite

In this paper, we demonstrate a promising method to fabricate a non-enzymatic stable, highly sensitive and selective hydrogen peroxide sensor based on a chitosan/silver nanoparticles (CS/AgNPs) hybrid. Using this composite, we elaborated both electrochemical and colorimetric sensors for hydrogen peroxide detection. The colorimetric sensor is based on a homogenous reaction which fades the color of CS/AgNPs solutions from red-orange to colorless depending on hydrogen peroxide concentration. For the electrochemical sensor, CS/AgNPs were immobilized on glassy carbon electrodes and hydrogen peroxide was measured using cyclic voltammetry, square wave voltammetry and electrochemical impedance spectroscopy. The response time is less than 10s and the detection limit is 5μM.

REDUCING RESISTANCE TO ACID HEMOLYSIS BY IRON-CONTAINED DRUG INCREASES THE LEVEL OF HEMOGLOBIN IN THE ERYTHROCYTES OF AGING ANIMALS.

In experiments in vivo we studied the effect of chronic iron-contained drug (Urfuhem) supplemention on the level of hemoglobin (Hb) in the blood of aging rats. To establish the biochemical mechanisms of drug action it were determined the parameters of oxidative/nitrosative stress and the hydrogei sulfide level in plasma and erythrocytes, the level of non-heme iron in plasma and erythrocytes sensitivity to acid hemolysis. It was found that in aging rats the drug significantly increases the Hb content of red blood cells and reduces its resistance to acid hemolysis. After the drug supplemention the rate of superoxide anion-radical (*0(2)(-)) generation in erythrocytes and stable hydrogen peroxide (H(2)0(2)) content both in plasma and erythrocytes, were down-regulated. The drug did not reduce the high levels of generation of the hydroxyl radical (*OH) and high levels of excess NO de novo synthesis by iNOS in erythrocytes but reduced the pools of nitrate anion(NO(3)(-))a its reutilization for NO synthesis. After thei drug supplemention the rate of constitutine NO synthesis by cNOS in aging rats plasma was up-regulated perhaps by cNOS coupling. The results indicate that the reason for increasing the permeability of the proton (H*) in red blood cells that causes the acid hemolysis in aging fats after the drug supplemention can be change in the balance of levels of oxidative and nitrosative stress in red blood cells in favor of the latter, and that toxic, OH generation is not at the expense of the classical Fenton reaction in the presence of iron ions (Fe(2+)); but due to the formation and decomposition of peroxynitrie (ON0O(-)).

Preparation and Characterization of Hemoglobin Immobilized on Graphene Quantum Dots-Chitosan Nanocomposite as a Sensitive and Stable Hydrogen Peroxide Biosensor

Preparation and Characterization of Hemoglobin Immobilized on Graphene Quantum Dots-Chitosan Nanocomposite as a Sensitive and Stable Hydrogen Peroxide Biosensor

Impact of tomato lycopene on the chemical and physical properties for beef burger, which was preserved by cooling for 3 weeks.

Each of concentrated extract of tomato by-products with addition ratio 0.1, 0.2, 0.3 and 0.4%, signed as T1, T2, T3 and T4, respectively and crude tomato by-products with addition ratio 3, 4.5, 6 and 7.5%, respectively, signed as T5, T6, T7 and T8, respectively as additives in beef burger manufacture. Results of sensory evaluation of manufactured samples did detect any significantly differences between them in studies characters whereas T8 was the highest in color, treatments T1 and T8 showed its strike in flavor and the juiciness character was relevant in treatments T2 and T8. Tenderness was high for temperature T2 and T8, general acceptance in treatments T2, T7 and T8 and odor was not affected by treatments. Study of chemical and physical characters of manufacture burger through storing times which is ranged between 0-3 weeks confirmed in that samples T5-T8 maintained hydrogen number not more than 6.12 comparing samples T0 , T1, T2 , T3 and T4 which in their hydrogen numbers was increase to higher than 7.28 in the first week from storage. Water holding capacity (WHC) in samples T1, T4 and improved by 7.44% as compared with control sample (T0) which lost 12.56%. From WHC. The WHC in samples T5-T8 increased with adding percent of crude by-products and reached 7.67%. Also, the results showed that free fat acids (FFA) increased in control sample (T0) more than in other samples that increased in its peroxide value discriminately but less share; the most stable sample peroxide value was the treatment T8 that included the highest proportion of by-products 7.5%. Results of peroxide value and thiobarbituric acid value insured free fat acids tests. Whereas all samples showed stability in peroxide value and thiobarbituric acid with special superiority of samples T6, T7 and T8. For lycopene and concentration test all samples maintained saved at concentrations of lycopene and which increased with addition value. According to this, T8 had higher concentration 20.760 mg. g-1 than control sample (T0) which reached 1.285 mg. g-1 of lycopene.

Vertical α-FeOOH nanowires grown on the carbon fiber paper as a free-standing electrode for sensitive H2O2 detection

Highly sensitive, selective, and stable hydrogen peroxide (H2O2) detection using nanozyme-based catalysts are desirable for practical applications. Herein, vertical α-FeOOH nanowires were successfully grown on the surface of carbon fiber paper (CFP) via a low-temperature hydrothermal procedure. The formation of vertical α-FeOOH nanowires is ascribed to the structure-directing role of sodium dodecyl sulfate. The resulting free-standing electrode with one-dimensional (1D) nanowires offers oriented channels for fast charge transfer, excellent electrical contact between the electrocatalyst and the current collector, and good mechanical stability and reproducibility. Thus, it can serve as an efficient electrocatalyst for the reduction and sensitive detection of H2O2. The relation of the oxidation current of H2O2 with the concentration is linear from 0.05 to 0.5 mM with a sensitivity of −0.194 mA/(mM·cm2) and a low detection limit of 18 μM. Furthermore, the portability in the geometric tailor and easy device fabrication allow extending the general applicability of this free-standing electrode to chemical and biological sensors.

Stable Boron Peroxides with a Subporphyrinato Ligand.

Subporphyrin B-peroxides have been synthesized in good yields by acid-catalyzed exchange reactions of subporphyrin B-methoxide with the corresponding hydroperoxides. Thermal dimerization of the subporphyrin B-hydroperoxide provided the peroxo-bridged bis(subporphyrin) quantitatively. These subporphyrin B-peroxides are fairly stable under ambient conditions, which allowed their isolation and full characterization as the first examples of structurally authenticated boron hydroperoxides, acyclic boron organylperoxides, and neutral peroxo-bridged diboron species. The subporphyrin B-peroxides thus prepared were investigated through their crystal structures, IR spectra, and cyclic voltammograms as well as by DFT calculations. The subporphyrin B-hydroperoxide oxidizes triphenylphosphine quantitatively to triphenylphosphine oxide.

Stable Boron Peroxides with a Subporphyrinato Ligand

AbstractSubporphyrin B‐peroxides have been synthesized in good yields by acid‐catalyzed exchange reactions of subporphyrin B‐methoxide with the corresponding hydroperoxides. Thermal dimerization of the subporphyrin B‐hydroperoxide provided the peroxo‐bridged bis(subporphyrin) quantitatively. These subporphyrin B‐peroxides are fairly stable under ambient conditions, which allowed their isolation and full characterization as the first examples of structurally authenticated boron hydroperoxides, acyclic boron organylperoxides, and neutral peroxo‐bridged diboron species. The subporphyrin B‐peroxides thus prepared were investigated through their crystal structures, IR spectra, and cyclic voltammograms as well as by DFT calculations. The subporphyrin B‐hydroperoxide oxidizes triphenylphosphine quantitatively to triphenylphosphine oxide.

Facile preparation of a three-dimensional macroporous graphene wrapped cuprous oxide composite by one-step hydrothermal assembly for stable and sensitive hydrogen peroxide detection

A facile one-pot hydrothermal assembly approach was developed to prepare a novel three-dimensional macroporous graphene wrapped Cu2O composite (3D-p-rGO–Cu2O) for the electrochemical detection of H2O2.

Stable magnesium peroxide at high pressure.

Rocky planets are thought to comprise compounds of Mg and O as these are among the most abundant elements, but knowledge of their stable phases may be incomplete. MgO is known to be remarkably stable to very high pressure and chemically inert under reduced condition of the Earth’s lower mantle. However, in exoplanets oxygen may be a more abundant constituent. Here, using synchrotron x-ray diffraction in laser-heated diamond anvil cells, we show that MgO and oxygen react at pressures above 96 GPa and T = 2150 K with the formation of I4/mcm MgO2. Raman spectroscopy detects the presence of a peroxide ion (O22−) in the synthesized material as well as in the recovered specimen. Likewise, energy-dispersive x-ray spectroscopy confirms that the recovered sample has higher oxygen content than pure MgO. Our finding suggests that MgO2 may be present together or instead of MgO in rocky mantles and rocky planetary cores under highly oxidized conditions.

Novel macromolecules derived from coumarin: synthesis and antioxidant activity.

The rational design of 4-hydroxycoumarins with tailor-made antioxidant activities is required nowadays due to the wide variety of pharmacologically significant, structurally interesting of coumarins and researcher orientation toward green chemistry and natural products. A simple and unique coumarins have been achieved by reaction of 4-hydroxycoumarin with aromatic aldehyde accompanied with the creation of a macromolecules have 2-aminothiazolidin-4-one. The molecular structures of the compounds were characterized by the Fourier transformation infrared and Nuclear magnetic resonance spectroscopies, in addition to CHN analysis. The scavenging abilities of new compounds against stable DPPH radical (DPPH•) and hydrogen peroxide were done and the results show that the compounds exhibited high antioxidant activates.