Fenton Reaction Research Articles

Tailoring the Oxidizing Intermediate in the Fenton Reaction, OH⋅ or FeIV=Oaq, by Modifying the pKa of the (H2O)5FeII(H2O2) Complex, and the Case of PDS - a DFT Study.

A DFT analysis of the Fenton and Fenton-like reactions points out that the pH effect on the nature of the oxidizing intermediate formed is due to a pKa of the peroxide when hydroperoxides are used. When S2O8 2- is used, the pH effect is due to the pKa of one of the water ligands of the central iron cation. The results suggest that the choice of the hydroperoxide and the ligands present affects the pH at which the transition from the formation of hydroxyl radicals to the formation of FeIV=Oaq occurs.

Exploring freeze-injury mechanism through ion-specific analysis of leachate from reversibly versus irreversibly injured spinach (Spinacia oleracea L.) leaves

The present study analyzed four cations (K+, Ca2+, Mg2+, Fe2+) in leachate from freeze-injured spinach (Spinacia oleracea L. ‘Reflect’) leaves exposed for four freezing-durations (FDs) (0.5, 3.0, 5.5, 10.5 h) at −4.8 °C. Comparison of electrolyte leakage from right-after-thaw with that after 6-d recovery revealed that injury at 0.5 or 3 h FDs was recoverable but irreversible at 5.5 or 10.5 h FDs. Data suggests leakage of K+, the most abundant cation in leachate, can serve as a proxy for total electrolyte-leakage in determining plant freezing-tolerance and an ionic marker discerning moderate vs. severe injury. Quantitative correspondence between Ca2+- and K+-leakage supports earlier proposition that leaked K+ induces loss of membrane-Ca2+, which, in turn, promotes further K+-leakage due to weakened membrane. Reduced/undetectable Fe2+ in leachate at longer FDs suggests activation of Fenton reaction converting soluble Fe2+ into insoluble Fe3+. Enhanced Mg2+-leakage at greater freeze-injury suggests structural/functional impairment of chlorophyll/chloroplast complex.

8-weeks aerobic exercise ameliorates cognitive deficit and mitigates ferroptosis triggered by iron overload in the prefrontal cortex of APP Swe/PSEN 1dE9 mice through Xc-/GPx4 pathway.

Alzheimer's disease (AD) is a degenerative disorder of the central nervous system characterized by notable pathological features such as neurofibrillary tangles and amyloid beta deposition. Additionally, the significant iron accumulation in the brain is another important pathological hallmark of AD. Exercise can play a positive role in ameliorating AD, but the mechanism is unclear. The purpose of the study is to explore the effect of regular aerobic exercise iron homeostasis and lipid antioxidant pathway regarding ferroptosis in the prefrontal cortex (PFC) of APP Swe/PSEN 1dE9 (APP/PS1) mice. Eighty 6-month-old C57BL/6 J and APP/PS1 mice were divided equally into 8-weeks aerobic exercise groups and sedentary groups. Subsequently, Y-maze, Morris water maze test, iron ion detection by probe, Western Blot, ELISA, RT-qPCR, HE, Nissle, Prussian Blue, IHC, IF, and FJ-C staining experiments were conducted to quantitatively assess the behavioral performance, iron levels, iron-metabolism-related proteins, lipid antioxidant-related proteins and morphology in each group of mice. In APP/PS1 mice, the increase in heme input proteins and heme oxygenase lead to the elevated levels of free iron in the PFC. The decrease in ferritin content by ferritin autophagy fails to meet the storage needs for excess free iron within the nerve cells. Ultimately, the increase of free ferrous iron triggers the Fenton reaction, may lead to ferroptosis and resulting in cognitive impairment in APP/PS1 mice. However, 8-weeks aerobic exercise induce upregulation of the Xc-/GPx4 pathway, which can reverse the lipid peroxidation process, thereby inhibiting ferroptosis in APP/PS1 mice. 8 weeks aerobic exercise can improve learning and memory abilities in AD, upregulate GPx4/Xc- pathway in PFC to reduce ferroptosis induced by AD.

Stress-Induced Sulfide Production by Bacillus subtilis and Bacillus megaterium.

It was previously discovered that, in the Gram-negative bacterium Escherichia coli growing on a minimal medium with sulfate, stress-induced growth arrest is accompanied by the release of hydrogen sulfide. The source of the sulfide is the desulfurization of intracellular cysteine as one of the ways of maintaining it at a safe level. The danger of excess cysteine is associated with its participation in the Fenton reaction, leading to the formation of highly toxic hydroxyl radicals. Using electrochemical sensors, we identified stress-induced sulfide production in the Gram-positive bacteria Bacillus subtilis and Bacillus megaterium, growing on a minimal medium with sulfate, and changes in physiological parameters such as Eh, pH, and oxygen and potassium consumption. Sulfide production was observed during growth arrest due to the depletion of glucose, ammonium or antibiotic action. The use of sensors allowed to continuously record, in growing cultures, even small changes in parameters. There were significant differences in the amount and kinetics of sulfide production between Bacillus and E. coli. These differences are thought to be due to the lack of glutathione in Bacillus. It is suggested that stress-induced sulfide production by Bacillus under the described conditions may be one of the previously unknown sources of hydrogen sulfide in nature.

Indole-3-Butyric Acid, a Natural Auxin, Protects against Fenton Reaction-Induced Oxidative Damage in Porcine Thyroid.

We present results on the potential protective antioxidant properties of indole-3-butyric acid. Indole-3-butyric acid is an indole derivative defined as an auxin and widely known as a plant growth regulator. It naturally occurs in Arabidopsis thaliana, which is applied as a model plant in genetic studies. Oxidative damage to membrane lipids (lipid peroxidation; LPO) in porcine thyroid homogenates was induced by Fenton reaction substrates (Fe2+ + H2O2). Iron (Fe2+) was used in very high concentrations of 1200, 600, 300, 150, 75, 37.5, 18.75, 9.375, 4.687, and 2.343 µM. Indole-3-butyric acid (10.0, 5.0, 2.5, 1.25, and 0.625 mM) was applied to check whether it prevents the above process. The LPO level, expressed as malondialdehyde + 4-hydroxyalkenals (MDA + 4-HDA) concentration, was measured spectrophotometrically. Expectedly, Fenton reaction substrates, in a Fe2+ concentration-dependent manner, increased LPO level, with the lowest effective concentration of iron being 9.375 µM. In the case of almost all concentrations of indole-3-butyric acid, this auxin has exhibited very promising antioxidant protection, with the most effective concentrations being 10.0 and 5.0 mM; however, as low concentrations of indole-3-butyric acid at 1.25 mM was still effective. Indole-3-butyric acid used alone did not change the basal level of LPO, which is a favourable effect. To summarise, indole-3-butyric acid has protective antioxidant properties against experimentally induced oxidative damage to membrane lipids in the thyroid, and this is for the first time documented in the literature. This compound can be considered a natural protective agent present in plants, which can serve as a dietary nutrient.

Apoptosis and cuproptosis Co-activated Copper-based metal-organic frameworks for cancer therapy

Lung cancer, predominantly non-small cell lung cancer (NSCLC), remains a significant global health challenge, with limited therapeutic options for patients with KRAS-mutated tumors. Herein, a copper-based metal-organic framework (Cu-MOF) was applied as a novel cuproptosis-mediated nanoplatform for lung cancer therapy. Cu-MOF would disassemble and liberate copper ions under the acidic microenvironment of lysosomes of cancer cells, initiating a cascade of cellular events. The released copper ions catalyzes the Fenton reaction, generating hydroxyl radicals that induce oxidative damage, leading to cytoskeletal disruption and activation of caspase-3, ultimately triggering apoptosis. Simultaneously, with the mediation of the key regulatory factor FDX1, we found that the copper ions binding to the mitochondrial protein DLAT could result in the loss of iron-sulfur cluster proteins and aggregation of lipoylated proteins, which culminated in proteotoxic stress-induced cuproptosis. The pronounced anti-tumor effects of Cu-MOF with apoptosis and cuproptosis were confirmed both in vitro and in vivo experiments. Such dual induction of apoptosis and cuproptosis by Cu-MOF presents a promising therapeutic strategy for NSCLC, particularly for KRAS-mutated tumors, and expands potential applications of Cu-based nanomateirals for other cancers.

Application of metal-based catalysts for Fenton reaction: from homogeneous to heterogeneous, from nanocrystals to single atom

Application of metal-based catalysts for Fenton reaction: from homogeneous to heterogeneous, from nanocrystals to single atom

Enhanced hydroxyl radical generation by zero-valent iron/ethylenediamine tetramethylene phosphonic acid for Cr(VI) reduction and 2,4-dichlorophenol degradation

Zero-valent iron (ZVI) has emerged as a promising material for water remediation in recent years. However, the formation of a passivation layer on the surface of ZVI significantly reduces its reactivity. Ethylenediamine tetramethylene phosphonic acid (EDTMPA), a chelating agent, aids in the prevention and passivation of ZVI. This chelating agent has been used in combination with ZVI to remove 2,4-dichlorophenol (2,4-DCP) and hexavalent chromium (Cr(VI)) simultaneously. In this study, the addition of EDTMPA significantly enhanced the removal efficiencies of Cr(VI) and 2,4-DCP by 7.7–10 times compared to ZVI, reaching complete removal of Cr(VI) and 80 % removal of 2,4-DCP within 120 min. Quenching and probing experiments have shown that hydroxyl radicals (•OH) serve as the predominant reactive species responsible for the degradation of 2,4-DCP. Meanwhile, pristine ZVI effectively reduced Cr(VI) to the less hazardous Cr(III) and reacted with oxygen in water to generate Fe(II) and hydrogen peroxide (H2O2), both critical for initiating the subsequent Fenton reaction. The addition of EDTMPA effectively mitigated the formation of the passivation layer on the surface of the ZVI, maintaining its reactivity. The ZVI/EDTMPA system offers an effective method for simultaneous remediation of Cr(VI) and 2,4-DCP by optimizing the application of ZVI.

Hyaluronic acid-covered ferric ion-rich nanobullets with high zoledronic acid payload for breast tumor-targeted chemo/chemodynamic therapy

Due to the heterogeneity of the tumor microenvironment, the clinical efficacy of tumor treatment is not satisfied, highlighting the necessity for new strategies to tackle this issue. To effectively treat breast tumors by tumor-targeted chemo/chemodynamic therapy, herein, the Fe3+-rich MIL-88B nanobullets (MNs) covered with hyaluronic acid (HA) were fabricated as vehicles of zoledronic acid (ZA). The attained ZA@HMNs showed a high ZA payload (ca 29.6 %), outstanding colloidal stability in the serum-containing milieu, and accelerated ZA as well as Fe3+ release under weakly acidic and glutathione (GSH)-rich conditions. Also, the ZA@HMNs consumed GSH by GSH-mediated Fe3+ reduction and converted H2O2 into OH via Fenton or Fenton-like reaction with pH reduction. After being internalized by 4T1 cells upon CD44-mediated endocytosis, the ZA@HMNs depleted intracellular GSH and degraded H2O2 into OH, thus eliciting lipid peroxidation and mitochondria damage to suppress cell proliferation. Also, the ZA@HMNs remarkably killed macrophage-like RAW 264.7 cells. Importantly, the in vivo studies and ki67 and GPX4 staining of tumor sections demonstrated that the ZA@HMNs efficiently accumulated in 4T1 tumors to hinder tumor growth via ZA chemotherapy combined with OH-mediated ferroptosis. This work presents a practicable strategy to fabricate ZA@HMNs for breast tumor-targeted chemo/chemodynamic therapy with potential clinical translation.

Photothermal and ROS-mediated cellular apoptosis using copper-driven Prussian blue analog nanoparticles with bimetallic reaction centres

The development of chemodynamic therapy (CDT) agents derived from copper and iron is crucial due to their ability to their biological safety, biocompatibility, and bio-specificity to only kill cancer cells. This study investigates bimetallic copper/iron-Prussian blue coordination analogs nanoparticles (CuxFey-PBAs, x = 15, 11, 7, 4, 0; y = 0, 4, 8, 11, 15), which exhibit photothermally enhanced bimetallic central catalytic activity for effective cancer treatment. By adjusting the Cu2+/Fe2+ ratio, CuxFey-PBAs demonstrated remarkable photothermal properties (from 1.9 % to 39.75 %) and exceptional reactive oxygen species (ROS) activity (k: 0.077 min−1, R2: 0.97), leading to mitochondrial dysfunction and subsequent tumour cell death. Density functional theory (DFT) calculations highlighted that the most critical factors influencing photothermal properties are carrier concentration and electron transition. The electronic structure of the bimetallic centre was found to significantly correlate with the reaction pathway and ROS activity. In vitro experiments showed that CuxFey-PBAs can enter cancer cells via endocytosis, induce mitochondrial dysfunction, and cause cancer cell death through apoptosis. Compared to conventional ROS-mediated systems, CuxFey-PBAs with photothermal properties exhibit superior ROS catalytic activity, facilitating photothermally enhanced CDT. These findings represent a significant advancement in synergistic photothermal-enhanced Fenton reaction with bimetallic reaction centres, offering a novel strategy for CDT enhancement.

Ferritin Hinders Ferroptosis in Non-Tumorous Diseases: Regulatory Mechanisms and Potential Consequences.

Ferritin, as an iron storage protein, has the potential to inhibit ferroptosis by reducing excess intracellular free iron concentrations and lipid reactive oxygen species (ROS). An insufficient amount of ferritin is one of the conditions that can lead to ferroptosis through the Fenton reaction mediated by ferrous iron. Consequently, upregulation of ferritin at the transcriptional or posttranscriptional level may inhibit ferroptosis. In this review, we have discussed the essential role of ferritin in ferroptosis and the regulatory mechanism of ferroptosis in ferritin-deficient individuals. The description of the regulatory factors governing ferritin and its properties in regulating ferroptosis as underlying mechanisms for the pathologies of diseases will allow potential therapeutic approaches to be developed.

Construction of heterojunction superparamagnetic Cd0.5Ag0.5Fe2O4 nanocomposite photocatalyst for simulated textile effluent oxidation

Abstract Significant attempts have been recently made regarding nanomaterials due to their several environmental applications especially in wastewater treatment technologies. Among the available nanoparticles, ferrite based substances are gaining a special interest since their superior characteristics such as their magnetic nature, high adsorption capacity and large specific surface area. In this regard, Cd0.5Ag0.5Fe2O4 was prepared using the green simple co-precipitation route. Then, the sample is characterized via Scanning Electron Microscopy (SEM) that proved the produced material’s surface morphology. The substance is then employed as a catalyst source for Fenton reaction to oxidize textile effluent solution containing Rhodamine B (Rh-B 6G) dye. The oxidation experiment conducted under ultraviolet (UV) light with the ferrite-based Fenton catalyst supplemented with hydrogen peroxide showed an exceptional removal rate of up to 94% removals. Notably, the oxidation system is significantly impacted by the operational variables. The oxidation efficiency of the dye was maximized at pH 3.0 and 50 mg/L and 1600 mg/L for ferrite-based Fenton catalyst and H2O2, respectively. The impacts of the operational factors, i.e. initial pH value, initial dye concentration, catalyst, and H2O2 concentrations were also investigated. This perspective introduces the role of a superparamagnetic material to be a recyclable sustained catalyst.

A Zwitterionic Hydrogel-Based Heterogeneous Fenton Catalyst for Water Treatment.

Persistent organic pollutants (POPs), including xenoestrogens and polyfluoroalkyl substances (PFAS), demand urgent global intervention. Fenton oxidation, catalyzed by iron ions, offers a cost-effective means to degrade POPs. However, numerous challenges like acid dependency, catalyst loss, and toxic waste generation hinder practical application. Efforts to create long-lasting heterogeneous Fenton catalysts, capable of simultaneously eliminating acid requirements, sustaining rapid kinetics, and retaining iron efficiently, have been unsuccessful. This study introduces an innovative heterogeneous zwitterionic hydrogel-based Fenton catalyst, surmounting these challenges in a cost-effective and scalable manner. The hydrogel, hosting individually complexed iron ions in a porous scaffold, exhibits substantial effective surface area and kinetics akin to homogeneous Fenton reactions. Complexed ions within the hydrogel can initiate Fenton degradation at neutral pH, eliminating acid additions. Simultaneously, the zwitterionic hydrogel scaffold, chosen for its resistance to Fenton oxidation, forms strong bonds with iron ions, enabling prolonged reuse. Diverging from existing designs, the catalyst proves compatible with UV-Fenton processes and achieves rapid self-regeneration during operation, offering a promising solution for the efficient and scalable degradation of POPs. The study underscores the efficacy of the approach by demonstrating the swift degradation of three significant contaminants-xenoestrogens, pesticides, and PFAS-across multiple cycles at traceconcentrations.

Cyclic catalysis of intratumor Fe3+/2+ initiated by a hollow mesoporous iron sesquioxide nanoparticle for ferroptosis therapy of large tumors

Numerous nanoparticles have been utilized to deliver Fe2+ for tumor ferroptosis therapy, which can be readily converted to Fe3+via Fenton reactions to generate hydroxyl radical (•OH). However, the ferroptosis therapeutic efficacy of large tumors is limited due to the slow conversion of Fe3+ to Fe2+via Fenton reactions. Herein, a strategy of intratumor Fe3+/2+ cyclic catalysis is proposed for ferroptosis therapy of large tumors, which was realized based on our newly developed hollow mesoporous iron sesquioxide nanoparticle (HMISN). Cisplatin (CDDP) and Gd-poly(acrylic acid) macrochelates (GP) were loaded into the hollow core of HMISN, whose surface was modified by laccase (LAC). Fe3+, CDDP, GP, and LAC can be gradually released from CDDP@GP@HMISN@LAC in the acidic tumor microenvironment. The intratumor O2 can be catalyzed into superoxide anion (O2•-) by LAC, and the intratumor NADPH oxidases can be activated by CDDP to generate O2•-. The O2•- can react with Fe3+ to generate Fe2+, and raise H2O2 level via the superoxide dismutase. The generated Fe2+ and H2O2 can be fast converted into Fe3+ and •OH via Fenton reactions. The cyclic catalysis of intratumor Fe3+/2+ initiated by CDDP@GP@HMISN@LAC can be used for ferroptosis therapy of large tumors.

A manganese-doped layered double hydroxide loaded with lactate oxidase and DNA repair inhibitors for synergistically enhanced tumor immunotherapy

Tumor immunotherapy has gained more and more attention in tumor treatment. However, the accumulation of lactic acid in tumor tissue inhibits the response of immune cells to form an immunosuppressive microenvironment (ISME). To reverse the ISME, an acid-responsive nanoplatform (termed as MLLN@HA) is reported for synergistically enhanced tumor immunotherapy. MLLN@HA is constructed by the co-loading of lactate oxidase (LOX) and DNA repair inhibitor (NU7441) in a manganese-doped layered double hydroxide (Mn-LDH), and then modified with hyaluronic acid (HA) for tumor-targeted delivery. After endocytosis by tumor cells, MLLN@HA decomposes and releases LOX, NU7441 and Mn2+ ions in the acidic tumor microenvironment. The released LOX catalyzes the conversion of lactic acid into hydrogen peroxide (H2O2), which not only alleviates the ISME, but also provides reactants for the Mn2+-mediated Fenton-like reaction to enhance chemodynamic therapy (CDT). Released NU7441 prevents CDT-induced DNA damage from being repaired, thereby increasing double-stranded DNA (dsDNA) fragments within tumor cells. Importantly, the released Mn2+ ions enhance the sensitivity of cyclic GMP-AMP synthase (cGAS) to dsDNA fragments, and activate the stimulator of interferon genes (STING) to induce an anti-tumor immune response. Such an orchestrated immune-boosting strategy ultimately achieves effective tumor growth inhibition and prevents tumor lung metastasis. Statement of significanceTo improve the efficacy of tumor immunotherapy, an innovative acid-responsive MLLN@HA nanoplatform was developed for synergistically enhanced tumor immunotherapy. The MLLN@HA actively targets to tumor cells through the interaction of HA with CD44, and then degrades to release LOX, NU7441 and Mn2+ ions in the acidic tumor microenvironment. The released LOX generates H2O2 for the Mn2+-mediated Fenton reaction and reverses the ISME by consuming lactate. NU7441 prevents DNA damage repair, leading to an increased concentration of free DNA fragments, while Mn2+ ions activate the cGAS-STING pathway, enhancing the systemic anti-tumor immune response. The orchestrated immune-boosting nanoplatform effectively inhibits tumor growth and lung metastasis, presenting a promising strategy for cancer treatment.

Investigation of structural, optical, and magnetic properties of NiFe2O4 for efficient photocatalytic degradation of organic pollutants through photo fenton reactions

Nowadays, water pollution generated from textile effluents is one of the major problems for the human race and ecology. Hence, development of sustainable strategies to lower the water pollution level has become a burning need. In this regard, the present study focuses on the preparation of nano catalyst NiFe2O4 to catalyze the chemical reactions on industrial organic dyes for their fast cleansing from water. By sol-gel auto-combustion technique, NiFe2O4 nanoparticles were synthesized and exposed to thermal process at temperatures of 400, 600, and 800 °C. Highly crystalline phase with spinel cubic structured NiFe2O4 was formed with a crystal size of 18.71 nm, which was confirmed by XRD analysis. The FTIR spectra showed two fundamental absorption bands in the range 597.80–412.59 cm−1, which are the characteristics of tetrahedral M − O and octahedral M − O bond in NiFe2O4. The surface morphology of calcined NiFe2O4 was investigated by scanning electron microscope (SEM). The nanoparticle size analyzer exhibited that the synthesized NiFe2O4 nanoparticles had an average particle size of ∼ 291.3 nm. Three stage decomposition patterns were observed for NiFe2O4, which was analyzed by a temperature programmed STA. Zeta potential analyzer showed that the synthesized sample S1 and S2 were stable in the dispersion medium. Also, NiFe2O4 exhibited optical band gap energies for direct band transitions within the visible spectrum measured to be 1.43–1.45 eV, rendering them effective as photocatalysts under sunlight. The samples showed magnetic measurements by VSM with saturation magnetization, coercivity, remnant magnetization value of 66.81 emu/g, 4.13 Oe and 12.94 emu/g, respectively. The synthesized photocatalyst, NiFe2O4, at 400 °C, significantly degraded three toxic organic pollutants—Methylene blue, Rhodamine B, and Congo Red—under visible light through ‘Photo-Fenton’ reaction mechanisms. Among the three dyes, Methylene Blue exhibited the highest degradation percentage with a rate constant of 0.0149 min−1 and followed pseudo-first-order kinetic model.

NIR responsive scaffold with multistep shape memory and photothermal-chemodynamic properties for complex tissue defects repair and antibacterial therapy

Complex tissue damage accompanying with bacterial infection challenges healthcare systems globally. Conventional tissue engineering scaffolds normally generate secondary implantation trauma, mismatched regeneration and infection risks. Herein, we developed an easily implanted scaffold with multistep shape memory and photothermal-chemodynamic properties to exactly match repair requirements of each part from the tissue defect by adjusting its morphology as needed meanwhile inhibiting bacterial infection on demand. Specifically, a thermal-induced shape memory scaffold was prepared using hydroxyethyl methacrylate and polyethylene glycol diacrylate, which was further combined with the photothermal agent iron tannate (FeTA) to produce NIR light-induced shape memory property. By varying ingredients ratios in each segment, this scaffold could perform a stepwise recovery under different NIR periods. This process facilitated implantation after shape fixing to avoid trauma caused by conventional methods and gradually filled irregular defects under NIR to perform suitable tissue regeneration. Moreover, FeTA also catalyzed Fenton reaction at bacterial infections with abundant H2O2, which produced excess ROS for chemodynamic antibacterial therapy. As expected, bacteriostatic rate was further enhanced by additional photothermal therapy under NIR. The in vitro and vivo results showed that our scaffold was able to perform high efficacy in both antibiosis, inflammation reduction and wound healing acceleration, indicating a promising candidate for the regeneration of complex tissue damage with bacterial infection.

BioTemplated Fe3+-Doped g-C3N4 Heterojunction Micromotors for the Degradation of Tetracycline through the Photo-Fenton Reaction

The excessive discharge of antibiotics into aquatic systems is a major issue in many countries worldwide and poses a threat to human health and the sustainable development of society. Hence, developing efficient treatment methods and purification technologies to degrade antibiotics is essential. Herein, we present the synthesis of low-cost, self-propelled tubular Fe3+-incorporated graphitic carbon nitride (g-C3N4-Fe@KF) micromotors using kapok fibers (KFs) as templates and their application as photo-catalysts for the photo-Fenton degradation of tetracycline (TC) under visible-light irradiation. The g-C3N4-Fe@KF micromotors moved rapidly when being propelled by oxygen bubbles generated in a hydrogen peroxide (H2O2) solution as a result of a photo-assisted Fenton reaction. The motion behavior of the g-C3N4-Fe@KF micromotors was dependent on the concentration of H2O2 and the length of the micromotors. The propulsion mechanism was discussed in detail. The micromotors efficiently degraded antibiotics via the photo-Fenton process. Photo-Fenton degradation efficiency was attributed to the synergistic effects of the doped Fe3+ and g-C3N4 under visible-light irradiation and self-propulsion of the micromotors. In addition, the micromotors possessed good reusability, thereby efficiently realizing multiple cycles of degradation. The current work offers an avenue for the design of micromotors, using inexpensive approaches, for various potential environmental applications.

Novel two-dimensional FeB nanosheets for photoacoustic imaging-guided NIR-photothermal therapy

The development of biosafe near infrared (NIR)-photothermal nanomaterials is meaningful for tumor-targeted photothermal therapy and photoacoustic imaging for high-performance theranostics, but still challenging. Herein, we propose a new ultrasound-assisted chemical etching method based on the Fenton reaction to synthesize a novel kind of two-dimensional iron boride nanosheets (FBN) as NIR-photothermal nanomaterials. The developed FBN theranostic agent exhibits high NIR adsorption and NIR-photothermal conversion efficiencies, realizing biosafe and high efficacy of photoacoustic imaging-guided tumor-targeted NIR-photothermal therapy of tumor mice.

Involvement of PG1037 in the repair of 8-oxo-7,8-dihydroguanine caused by oxidative stress in Porphyromonas gingivalis.

The PG1037 gene is part of the uvrA-PG1037-pcrA operon in Porphyromonas gingivalis. It encodes for a protein of unknown function upregulated under hydrogen peroxide (H2O2)-induced oxidative stress. Bioinformatic analysis shows that PG1037 has a zinc-finger motif, two peroxidase motifs, and one cytidylate kinase domain. The aim of this study is to characterize further the role of the PG1037 recombinant protein in the unique 8-oxoG repair system in P. gingivalis. PG1037 recombinant proteins with deletions in the zinc-finger or peroxidase motifs were created. Electrophoretic mobility shift assays were used to evaluate the ability of the recombinant proteins to bind 8-oxoG-containing oligonucleotides. Zinc binding, peroxidase, and Fenton reaction assays were used to assess the functional roles of the rPG1037 protein. A bacterial adenylate cyclase two-bride assay was used to identify the partner protein of PG1037 in the repair of 8-oxoG. The recombinant PG1037 (rPG1037) protein carrying an N-terminal His-tag demonstrated an ability to recognize and bind 8-oxoG-containing oligonucleotide. In contrast to the wild-type rPG1037 protein, the zinc-finger motif deletion resulted in the loss of zinc and 8-oxoG binding activities. A deletion of the peroxidase motif-1 showed a decrease in peroxidase activity. Using a bacterial adenylate cyclase two-hybrid system, there was no observed protein-protein interaction of PG1037 with UvrA (PG1036), PcrA (PG1038), or mismatch repair system proteins. Taken together, the results show that PG1037 is an important member of a novel mechanism that recognizes and repairs oxidative stress-induced DNA damage in P. gingivalis.