Generation of hydroxyl radicals from reactions between a dimethoxyhydroquinone and iron oxide nanoparticles

Lyngsie, Gry; Krumina, Lelde; Tunlid, Anders; Persson, Per

doi:10.1038/s41598-018-29075-5

Cited by 110 publications

(64 citation statements)

References 54 publications

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“…Therefore, this provides another reason why the complex shows improved antibacterial activity reported and discussed in the following sections. 44 − 46 In this regard, it should however be mentioned (as correctly pointed out by one reviewer while reviewing this manuscript) that although we consider formation of the hydroxyl radical (HO • ) as logically formed from H 2 O 2 and use it to explain the better performance of the complex in comparison to curcumin, it would have been nice had we shown its actual formation by the deoxyribose assay, which, for more than one reason, could not be included in our study. 47 , 48 …”

Section: Results and Discussionmentioning

confidence: 99%

Multitargeting Antibacterial Activity of a Synthesized Mn²⁺ Complex of Curcumin on Gram-Positive and Gram-Negative Bacterial Strains

et al. 2020

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Curcumin is an important molecule with a plethora of pharmacological activities and therapeutic potentials. Despite its efficacy, it remained a potential drug candidate owing to hydrolytic instability and poor aqueous solubility. To overcome the limitations related to low solubility, low bioavailability, and the fact that curcumin is never present in solution as a “single unit”, its complex was prepared with Mn II with the idea that binding to a metal ion might help to resolve these issues. The complex was characterized by elemental and spectral analysis. The structure of the complex was determined by density functional theory calculations. The complex was stable at physiological buffer conditions, unlike curcumin. It did not have any detrimental effect on mammalian cells. There was a significant enhancement in the antibacterial activity of the complex compared to curcumin against both Gram-positive ( Staphylococcus aureus ) and Gram-negative ( Escherichia coli ) bacteria. It showed a strong affinity for deoxyribonucleic acid (DNA) evident from a high binding constant value with calf thymus DNA and also from the retarded electrophoretic mobility of bacterial plasmid DNA. The complex showed “superoxide dismutase-like” activity leading to the generation of reactive oxygen species (ROS). The complex caused bacterial membrane perturbation evident from calcein leakage assay, which was further corroborated by scanning and transmission electron microscopic experiments. Overall, the present study shows improved stability and antibacterial potency of a nontoxic complex over curcumin. Its multitargeting mode of action such as ROS-production, effective binding with DNA, and permeabilization of bacterial membrane together allows it to be an effective antibacterial agent that could be taken further for therapeutic use against bacterial infections.

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Section: Results and Discussionmentioning

confidence: 99%

Multitargeting Antibacterial Activity of a Synthesized Mn²⁺ Complex of Curcumin on Gram-Positive and Gram-Negative Bacterial Strains

et al. 2020

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“…The oxygen vacancy peak indicates the defects in the material, which are the reaction sites for photoelectrochemical catalyzing water oxidation. The hydroxyl group or the OH radical on the surface can accelerate water oxidation kinetics [30–32] . The Ti 2p spectrum shows Ti 2p 2/3 and Ti 2p 1/2 peaks respectively at 458.2 and 463.7 eV, indicating the alloy‐bonding between the Ti and O for Mg−Fe 2 O 3 /Ti−Fe 2 O 3 electrode, no the formation of TiO 2 since there is no peak fitting the standard pattern for TiO 2 the XRD pattern (Figure 2).…”

Section: Resultsmentioning

confidence: 99%

“…The hydroxyl group or the OH radical on the surface can accelerate water oxidation kinetics. [30][31][32] The Ti 2p spectrum shows Ti 2p 2/3 and Ti 2p 1/2 peaks respectively at 458.2 and 463.7 eV, indicating the alloy-bonding between the Ti and O for MgÀ Fe 2 O 3 /TiÀ Fe 2 O 3 electrode, no the formation of TiO 2 since there is no peak fitting the standard pattern for TiO 2 the XRD pattern (Figure 2). Last, Mg 2p spectrum shows MgO/Mg peak at 50.0 eV.…”

Section: Physical Analysis Of Fe 2 O 3 Tià Fe 2 O 3 and Mgà Fe 2 O mentioning

confidence: 99%

Heteroatom Doping Strategy for Establishing Hematite Homojunction as Efficient Photocatalyst for Accelerating Water Splitting

Tao

Chung

Lin

2020

Chemistry An Asian Journal

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Hematite (α-Fe 2 O 3) is one of the promising photocatalysts for water oxidation, owing to its stable, abundant and visible-light responsive features. Enhancing electrical conductivity and accelerating oxidation evolution kinetics are expected to improve photocatalytic ability of hematite toward water oxidation. In this work, strategies of doping heteroatoms and developing pn homojunction are adopted to enhance the photocatalytic ability of hematite electrodes. The Ti and Mg dopants are separately incorporated in two layers of hematite electrodes via two-step hydrothermal reaction and one-step annealing process. The effect of regrowth time for synthesizing Mg-doped hematite on the photoelectrochemical performance of Mg-doped and Tidoped hematite (MgÀ Fe 2 O 3 /TiÀ Fe 2 O 3) electrode is studied. The size of rod-like structure and gaps in-between play important roles on the photocatalytic ability of MgÀ Fe 2 O 3 / TiÀ Fe 2 O 3. The optimized MgÀ Fe 2 O 3 /TiÀ Fe 2 O 3 electrode is prepared by using merely 10 min for synthesizing the Mgdoped hematite top layer, which shows the highest photocurrent density of 2.83 mA/cm 2 at 1.60 V RHE along with the highest carrier density of 5.89 × 10 16 cm À 3 and the smallest charge-transfer resistance. This largely improved photoelectrochemical performance is attributed to the more donor generation with heteroatom-doping and more efficient charge cascade with homojunction establishment. Other ptype metals are encouraged to dope in hematite as the second layer to couple with the n-type Ti-doped hematite for developing efficient pn homojunction and improve the photocatalytic ability of hematite in the near future.

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“…Goethite was synthesized as described previously (59). The goethite had a needle shape with an estimated width of 10 to 20 nm and an estimated length of several hundred nanometers (60). The specific surface area was estimated to be 62 m 2 g −1 using the N 2 Brunauer–Emmett–Teller (BET) method (61).…”

Section: Methodsmentioning

confidence: 99%

Influence of Ammonium on Formation of Mineral-Associated Organic Carbon by an Ectomycorrhizal Fungus

Wang

Tian

Tunlid

et al. 2019

Appl Environ Microbiol

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The interactions between dissolved organic matter (DOM) and mineral particles are critical for the stabilization of soil organic matter (SOM) in terrestrial ecosystems. The processing of DOM by ectomycorrhizal fungi contributes to the formation of mineral-stabilized SOM by two contrasting pathways: the extracellular transformation of DOM (ex vivo pathway) and the secretion of mineral-surface-reactive metabolites (in vivo pathway). In this study, we examined how changes in nitrogen (N) availability affected the formation of mineral-associated carbon (C) from these two pathways. DOM was extracted from forest soils. The processing of this DOM by the ectomycorrhizal fungus Paxillus involutus was examined in laboratory-scale studies with different levels of ammonium. At low levels of ammonium (i.e., under N-limited conditions), the DOM components were slightly oxidized, and fungal C metabolites with iron-reducing activity were secreted. Ammonium amendments decreased the amount of C metabolites, and no additional oxidation of the organic matter was detected. In contrast, the hydrolytic activity and the secretion of N-containing compounds increased, particularly when high levels of ammonium were added. Under these conditions, C, but not N, limited fungal growth. Although the overall production of mineral-associated organic C was not affected by ammonium concentrations, the observed shifts in the activities of the ex vivo and in vivo pathways affected the composition of organic matter adsorbed onto the mineral particles. Such changes will affect the properties of organic matter-mineral associations and, thus, ultimately, the stabilization of SOM. IMPORTANCE Nitrogen (N) availability plays a critical role in the cycling and storage of soil organic matter (SOM). However, large uncertainties remain in predicting the net effect of N addition on soil organic carbon (C) storage due to the complex interactions between organic matter, microbial activity, and mineral particles that determine the formation of stable SOM. Here, we attempted to disentangle the effects of ammonium on these interactions in controlled microcosm experiments including the ectomycorrhizal fungus P.involutus and dissolved organic matter extracted from forest soils. Increased ammonium levels affected the fungal processing of the organic material as well as the secretion of extracellular metabolites. Although ammonium additions did not increase the net production of mineral-adsorbed C, changes in the decomposition and secretion pathways altered the composition of the adsorbed organic matter. These changes may influence the properties of the organic matter-mineral associations and, thus, the stabilization of SOM.

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Generation of hydroxyl radicals from reactions between a dimethoxyhydroquinone and iron oxide nanoparticles

Cited by 110 publications

References 54 publications

Multitargeting Antibacterial Activity of a Synthesized Mn²⁺ Complex of Curcumin on Gram-Positive and Gram-Negative Bacterial Strains

Multitargeting Antibacterial Activity of a Synthesized Mn²⁺ Complex of Curcumin on Gram-Positive and Gram-Negative Bacterial Strains

Heteroatom Doping Strategy for Establishing Hematite Homojunction as Efficient Photocatalyst for Accelerating Water Splitting

Influence of Ammonium on Formation of Mineral-Associated Organic Carbon by an Ectomycorrhizal Fungus

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Generation of hydroxyl radicals from reactions between a dimethoxyhydroquinone and iron oxide nanoparticles

Cited by 110 publications

References 54 publications

Multitargeting Antibacterial Activity of a Synthesized Mn2+ Complex of Curcumin on Gram-Positive and Gram-Negative Bacterial Strains

Multitargeting Antibacterial Activity of a Synthesized Mn2+ Complex of Curcumin on Gram-Positive and Gram-Negative Bacterial Strains

Heteroatom Doping Strategy for Establishing Hematite Homojunction as Efficient Photocatalyst for Accelerating Water Splitting

Influence of Ammonium on Formation of Mineral-Associated Organic Carbon by an Ectomycorrhizal Fungus

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Multitargeting Antibacterial Activity of a Synthesized Mn²⁺ Complex of Curcumin on Gram-Positive and Gram-Negative Bacterial Strains

Multitargeting Antibacterial Activity of a Synthesized Mn²⁺ Complex of Curcumin on Gram-Positive and Gram-Negative Bacterial Strains