Oxygen Species Research Articles

Ginsenoside Rk1 prevents 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinson's disease via activating silence information regulator 3-mediated Nrf2/HO-1 signaling pathway.

Objectives:Ginsenoside Rk1, a novel ginsenoside isolated from red ginseng, has anti-inflammatory and anti-tumor activities. This study was designed to elucidate therole of RK1 in an in vitro1-methyl-4-phenylpyridinium (MPP+) cell model and an in vivo1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) of Parkinson's disease (PD).Methods: The grasping test, pole-climbing test,androtarod testwere performed to measure the effects of RK1 on MPTP-induced motor disorders.The expression of tyrosine hydroxylase (TH) and IBA-1were evaluated by western blotting.CCK-8 and flow cytometry assays were utilized to assess cell viability and apoptosis.Reactive oxygen species (ROS), Lactate dehydrogenase (LDH), and superoxide dismutase (SOD) were detected to analyze the effects of RK1 on oxidative stress. The levels of inflammatory cytokines were evaluated byenzyme-linked immunosorbent assay (ELISA).Results: The results showed that RK1 allayed motor deficitelicited by MPTP in a mouse model.RK1 administration augmented tyrosine hydroxylase (TH) expression in the brain striatum and substantia nigra (SN) of MPTP-treated mice.Moreover, RK1pretreatment promotedviability and suppressed apoptosis in MPP+-induced PC-12cells. Further, RK1 also attenuated MPP+-stimulatedoxidative stressand inflammatory response in PC-12 cells. Besides,RK1 augmented thelevel of SIRT3, and SIRT3 deletion counteracted RK1-induced repression on MPP+-elicited apoptosis, oxidative stress, and inflammatory response in PC-12 cells via modulating the Nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway.Conclusions: RK1mightexertneuroprotective effectsagainst MPP+/MPTP-induced neurotoxicity via activating SIRT3-mediated Nrf2/HO-1 signaling.RK1 might be a promising candidate against PD.

Engineering the electronic structure of PtCo sites via electron injection to CoNC boosts acidic oxygen electroreduction

Inadequate performance of oxygen reduction reaction (ORR) hinders the commercialization of proton exchange membrane fuel cells (PEMFCs). Herein, we report an ORR catalyst consisting of intermetallic PtCo nanoparticles and atomically dispersed CoNC sites, exhibiting outstanding performance in the RDE test (E1/2 = 0.906 V vs. RHE, 7 mV loss after 20,000 cycles, 0.63 A mg−1Pt of mass activity at 0.9 V). The enhancement of activity and durability is attributed to the unique structure that Pt atoms are modified by the smaller transition metal atoms Co to form PtCo intermetallic and further regulated by CoNC, the dual electronic engineering results appropriate binding energy between Pt and oxygen species. In addition, enhanced PtCo–CoNC interaction impedes the agglomeration of nanoparticles, which enables the formation of sub-5 nm PtCo intermetallic and enhances the stability. This synthesis method provides an idea for further regulating the electronic structure of Pt alloy and synthesize uniform and small intermetallic particles.

BCAA insufficiency leads to premature ovarian insufficiency via ceramide‐induced elevation of ROS

Premature ovarian insufficiency (POI) is a disease featured by early menopause before 40 years of age, accompanied by an elevation of follicle‐stimulating hormone. Though POI affects many aspects of women's health, its major causes remain unknown. Many clinical studies have shown that POI patients are generally underweight, indicating a potential correlation between POI and metabolic disorders. To understand the pathogenesis of POI, we performed metabolomics analysis on serum and identified branch‐chain amino acid (BCAA) insufficiency‐related metabolic disorders in two independent cohorts from two clinics. A low BCAA diet phenotypically reproduced the metabolic, endocrine, ovarian, and reproductive changes of POI in young C57BL/6J mice. A mechanism study revealed that the BCAA insufficiency‐induced POI is associated with abnormal activation of the ceramide‐reactive oxygen species (ROS) axis and consequent impairment of ovarian granulosa cell function. Significantly, the dietary supplement of BCAA prevented the development of ROS‐induced POI in female mice. The results of this pathogenic study will lead to the development of specific therapies for POI.

Efficient toluene low‐temperature elimination over manganese oxides: Unveiling the decisive role of lattice oxygen

Manganese oxide catalysts are considered to be active in the catalytic purification of volatile organic compounds based on two theories. According to one view, defects are mainly constructed to increase the amount of adsorbed oxygen and, consequently, the catalytic activity, whereas the opposite view suggests that the mobility of lattice oxygen is the main reason for determining the catalytic performance. In order to investigate which form of oxygen is the key factor controlling the catalytic performance of manganese oxides, a series of manganese oxide octahedral molecular sieves (OMS‐2) with different adsorption and lattice oxygen properties were synthesized in this study, and the catalytic oxidation performance of the catalysts for toluene was examined. The impact of various oxygen species on the catalytic activity of OMS‐2 was investigated in depth by characterization by Raman, X‐ray diffraction, scanning electron microscope, Brunauer–Emmett–Teller, O2 temperature‐programmed desorption, H2 temperature‐programmed reduction, X‐ray photoelectron spectroscopy, and so forth. It was discovered that OMS‐2‐150 exhibits excellent catalytic activity for toluene purification due to its higher Mn4+ and lattice oxygen as well as low‐temperature reducibility. In addition, in situ diffuse reflectance, infrared Fourier transform spectroscopy also verified that lattice oxygen dominates the reaction and improves the catalytic performance. As such, in contrast to previous investigations, this study found that lattice oxygen migration was more important than adsorbed oxygen content for manganese oxides in the field of volatile organic compounds purification. This brings a new perspective to the preparation of manganese‐based catalysts with promising catalytic behaviors.

Curcumin-Functionalized Graphene Oxide Strongly Prevents Candida parapsilosis Adhesion and Biofilm Formation.

Candida parapsilosis is the major non-C. albicans species involved in the colonization of central venous catheters, causing bloodstream infections. Biofilm formation on medical devices is considered one of the main causes of healthcare-associated infections and represents a global public health problem. In this context, the development of new nanomaterials that exhibit anti-adhesive and anti-biofilm properties for the coating of medical devices is crucial. In this work, we aimed to characterize the antimicrobial activity of two different coated-surfaces, graphene oxide (GO) and curcumin-graphene oxide (GO/CU) for the first time, against C. parapsilosis. We report the capacity of GO to bind and stabilize CU molecules, realizing a homogenous coated surface. We tested the anti-planktonic activity of GO and GO/CU by growth curve analysis and quantification of Reactive Oxigen Species( ROS) production. Then, we tested the antibiofilm activity by adhesion assay, crystal violet assay, and live and dead assay; moreover, the inhibition of the formation of a mature biofilm was investigated by a viability test and the use of specific dyes for the visualization of the cells and the extra-polymeric substances. Our data report that GO/CU has anti-planktonic, anti-adhesive, and anti-biofilm properties, showing a 72% cell viability reduction and a decrease of 85% in the secretion of extra-cellular substances (EPS) after 72 h of incubation. In conclusion, we show that the GO/CU conjugate is a promising material for the development of medical devices that are refractory to microbial colonization, thus leading to a decrease in the impact of biofilm-related infections.

Morphology-dependent activation of hydrogen peroxide with Cu2O for tetracycline hydrochloride degradation in bicarbonate aqueous solution

The design of efficient heterogeneous catalysts in bicarbonate-activated hydrogen peroxide systems (BAP) is a hot topic in wastewater treatment. In this work, Cu2O nanoparticles with different morphologies including cubic shape (c-Cu2O), octahedron shape (o-Cu2O) and spherical shape (s-Cu2O), were applied in BAP for the first time to degrade tetracycline hydrochloride (TC). Compared with Cu2+ ions and CuO, TC degradation was boosted in the presence of Cu2O in the BAP system, with the degradation rate following the order c-Cu2O > o-Cu2O > s-Cu2O. The morphology-dependent effects could be linearly correlated with the ratio of surface oxygen species (OS), but not with the surface area or Cu(I) ratio. The c-Cu2O catalyst with exposure of (100) facets contained 76.6% OS as the active site for H2O2 adsorption and activation, while the value was much lower for o-Cu2O and s-Cu2O with dominant (111) facets. The presence of HCO3− enhanced the interactions among Cu2O, H2O2 and TC, leading to facile oxidation of Cu(I) to Cu(II) by H2O2, and the formation of various reactive species such as hydroxyl radicals and Cu(III) contributed to TC degradation. This work provides a new method for enhancing H2O2 activation with heterogeneous catalysts by crystal facet engineering.

A hint from phosphine complex: The π back-bonding in cobalt-phosphorene composite enables enhanced electrocatalytic performance

Regulating the electronic structure of the metal electrocatalyst is fundamental for its performance optimizing. The electronic states of the active metal centers are highly dependent on their coordination environment, especially when bonding is formed. The π back-bonding can induce great electron density redistribution around metals, yet it is barely applied in electrocatalyst design. Herein we electrodeposited metallic cobalt on black phosphorus (BP) nanosheets, forming BP-Co with a unique π back-bonding on the interfaces. The BP-Co exhibited high electrocatalytic activity and stability for hydrogen evolution reaction in alkaline electrolyte. The electrochemical and spectroscopic characterizations demonstrated that the BP acted as σ donor and π acceptor to coordinate with electron-rich metallic Co, similar to the phosphine complex. The directional σ bond strengthen the relationship between BP and Co, while the non-directional π bond accelerated the in-plane electron transfer. The π back donation also decreased the oxophilicity of Co to make BP-Co resist the poison from oxygen species. This study can intrigue new thinking prospective for the electrocatalyst design.

Iron-based and BRD4-downregulated strategy for amplified ferroptosis based on pH-sensitive/NIR-II-boosted nano-matchbox.

Ferroptosis (FPT), a novel form of programmed cell death, is characterized by overwhelming iron/reactive oxygen species (ROS)-dependent accumulation of lipid peroxidation (LPO). However, the insufficiency of endogenous iron and ROS level limited the FPT therapeutic efficacy to a large extent. To overcome this obstacle, the bromodomain-containing protein 4 (BRD4)-inhibitor (+)-JQ1 (JQ1) and iron-supplement ferric ammonium citrate (FAC)-loaded gold nanorods (GNRs) are encapsulated into the zeolitic imidazolate framework-8 (ZIF-8) to form matchbox-like GNRs@JF/ZIF-8 for the amplified FPT therapy. The existence of matchbox (ZIF-8) is stable in physiologically neutral conditions but degradable in acidic environment, which could prevent the loaded agents from prematurely reacting. Moreover, GNRs as the drug-carriers induce the photothermal therapy (PTT) effect under the irradiation of near-infrared II (NIR-II) light owing to the absorption by localized surface plasmon resonance (LSPR), while the hyperthermia also boosts the JQ1 and FAC releasing in the tumor microenvironment (TME). On one hand, the FAC-induced Fenton/Fenton-like reactions in TME can simultaneously generate iron (Fe3+/Fe2+) and ROS to initiate the FPT treatment by LPO elevation. On the other hand, JQ1 as a small molecule inhibitor of BRD4 protein can amplify FPT through downregulating the expression of glutathione peroxidase 4 (GPX4), thus inhibiting the ROS elimination and leading to the LPO accumulation. Both invitro and invivo studies reveal that this pH-sensitive nano-matchbox achieves obvious suppression of tumor growth with good biosafety and biocompatibility. As a result, our study points out a PTT combined iron-based/BRD4-downregulated strategy for amplified ferrotherapy which also opens the door of future exploitation of ferrotherapy systems.

Opening the door to nitrogen fixation in oxygenic phototrophs

Conveying biological nitrogen fixation (BNF) to photosynthetic species may be the next agricultural revolution, yet poses major engineering challenges. Liu et al. created a diazotrophic strain of a previously non-nitrogen-fixing species, the cyanobacterium Synechocystis sp. PCC 6803, and uncovered critical aspects of nitrogen fixation in an oxygenic species.

Mycobacterium tuberculosis Rv1324 Protein Contributes to Mycobacterial Persistence and Causes Pathological Lung Injury in Mice by Inducing Ferroptosis.

Mycobacterium tuberculosis (Mtb) is the pathogenic agent of tuberculosis (TB). Intracellular survival plays a central role in the pathogenesis of Mtb, a process that depends on an array of virulence factors for Mtb to colonize and proliferate within a host. Reactive nitrogen and oxygen species (RNS and ROS) are among the most effective antimycobacterial molecules generated by the host during infection. However, Mtb has evolved a number of proteins and enzymes to detoxify ROS and RNS. Secretory protein Rv1324, as a possible thioredoxin, might also have oxidoreductase activity against ROS and RNS during Mtb infection, and it is a potential virulence factor of Mtb. In this study, we investigated the biochemical properties of Mtb Rv1324 and its role in mycobacterial survival and virulence. The results showed that the Rv1324 protein had antioxidant activity and increased the survival of M. smegmatis that was exposed to ROS and RNS. In addition, Rv1324 enhanced the colonization ability of M. smegmatis in the lungs of mice. Further, mice infected with M. smegmatis harboring Rv1324 exhibited pathological injury and inflammation in the lung, which was mediated by ferroptosis. In summary, this study advances our understanding of the mechanisms of mycobacterial survival and pathogenesis, and it reveals a novel target for TB treatment. IMPORTANCE The intracellular survival of M. tuberculosis (Mtb) plays a crucial role in its pathogenesis, which depends on various Mtb oxidoreductases that are resistant to reactive oxygen and nitrogen species (ROS and RNS) that are generated by the host during Mtb infection. Secretory protein Rv1324 is a potential virulence factor of Mtb and is a possible thioredoxin that has oxidoreductase activity against ROS and RNS during Mtb infection. We investigated the biochemical properties of Mtb Rv1324 and its role in mycobacterial survival and virulence. It was confirmed that the Rv1324 protein had antioxidant activity and an increased mycobacterial resistance to ROS and RNS. In addition, Rv1324 enhanced mycobacterial persistence and induced pathological injury and inflammation in the lungs of mice by activating ferroptosis. This study advances our understanding of the mechanisms of mycobacterial survival and pathogenesis, and it reveals a novel target for TB treatment.

Chronic exposure to lipopolysaccharides as an in vitro model to simulate the impaired odontogenic potential of dental pulp cells under pulpitis conditions.

Simulating a bacterial-induced pulpitis environment in vitro may contribute to exploring mechanisms and bioactive molecules to counteract these adverse effects. To investigate the chronic exposure of human dental pulp cells (HDPCs) to lipopolysaccharides (LPS) aiming to establish a cell culture protocol to simulate the impaired odontogenic potential under pulpitis conditions. HDPCs were isolated from four healthy molars of different donors and seeded in culture plates in a growth medium. After 24 h, the medium was changed to an odontogenic differentiation medium (DM) supplemented or not with E. coli LPS (0 - control, 0.1, 1, or 10 µg/mL) (n=8). The medium was renewed every two days for up to seven days, then replaced with LPS-free DM for up to 21 days. The activation of NF-κB and F-actin expression were assessed (immunofluorescence) after one and seven days. On day 7, cells were evaluated for both the gene expression (RT-qPCR) of odontogenic markers (COL1A1, ALPL, DSPP, and DMP1) and cytokines (TNF, IL1B, IL8, and IL6) and the production of reactive nitrogen (Griess) and oxygen species (Carboxy-H2DCFDA). Cell viability (alamarBlue) was evaluated weekly, and mineralization was assessed (Alizarin Red) at 14 and 21 days. Data were analyzed with ANOVA and post-hoc tests (α=5%). After one and seven days of exposure to LPS, NF-κB was activated in a dose-dependent fashion. LPS at 1 and 10 µg/mL concentrations down-regulated the gene expression of odontogenic markers and up-regulated cytokines. LPS at 10 µg/mL increased both the production of reactive nitrogen and oxygen species. LPS decreased cell viability seven days after the end of exposure. LPS at 1 and 10 µg/mL decreased hDPCs mineralization in a dose-dependent fashion. The exposure to 10 µg/mL LPS for seven days creates an inflammatory environment that is able to impair by more than half the odontogenic potential of HDPCs in vitro, simulating a pulpitis-like condition.

Accelerated formation of iodine vacancies in CH3NH3PbI3 perovskites: The impact of oxygen and charges

AbstractDefects in CH3NH3PbI3 perovskites, oxygen species in the air, and local charges play a significant role in the long‐term stability of perovskites. However, the interplay of these factors are complex and their role in the degradation of perovskites at the atomistic level is not well understood. By using density functional theory calculations and chemical bonding analysis, we study the effect of oxygen and local charges on the degradation of perovskites. We find that the easier formation of I vacancies upon oxygen and the accelerated degradation of CH3NH3PbI3 by excess electrons via the formation of peroxide species. The creation of peroxide disintegrates the lattice of perovskites on the surfaces and possibly induces a cascade of degradation reactions that eventually destruct the perovskite lattices. We further demonstrate that the addition of holes are beneficial to prevent the formation of the peroxide, therefore can potentially improve the stability of the perovskites.image

Applicability and antibacterial activity of polycyclic aromatic compound derivatives used as photocatalysts for water oxidation

Water is oxidized using 5,8-dicyano[5]phenacene, a thin-film catalyst supported on a silica plate by vacuum deposition; hydrogen peroxide is produced under visible-light irradiation. Despite the high hydrogen peroxide production rate during the initial reaction stage, the rate decreases after 12 h, and the reaction is almost terminated after 24 h, possibly because hydrogen peroxide undergoes self-decomposition. The self-decomposition rate of hydrogen peroxide increases with increasing concentration, and attains equilibrium. Additionally, Escherichia coli is efficiently sterilized using this catalyst under visible-light; the antibacterial effect is exhibited even under indoor light. Among several polycyclic aromatic derivatives, 9,10-dicyanoanthracene exhibits the highest hydrogen peroxide production rate and antibacterial activity against E. coli. Its antibacterial efficiency is approximately 16 times higher than that of 5,8-dicyano[5]phenacene. The oxygen species causing these antibacterial effects is investigated using trapping reagents. superoxide anion radicals and hydroxyl radicals induce antibacterial effects; hydroxyl radicals are particularly effective.

UV–vis-enhanced photothermal catalytic reforming of biomass model tar via LaMnxNi1-xO3 perovskite catalyst

Tar formation during biomass gasification reduces energy efficiency and poses a negative impact on downstream applications. A photothermal steam reforming (PTR) system based on LaMnxNi1-xO3 (0 ≤ x ≤ 1) perovskite was developed to convert tar into combustible gas. The effects of Mn substitution, temperature, and the steam to carbon ratio on PTR activity were investigated. Mn substitution increased the content of surface adsorbed oxygen and maintained the perovskite structure of LaMn0.4Ni0.6O3 (LM4N6). Moreover, LM4N6 showed improved optical absorption and electron-hole separation properties. LM4N6 presented 90 % carbon conversion during PTR at 400 °C. Due to the introduction of ultraviolet–visible light (UV–vis), LM4N6 obtained better catalytic activity and stability in PTR than in the thermal catalytic reforming process. Detailed characterization and experiments proved that UV–vis effectively activated Ni sites and the oxygen species on LM4N6 and formed a photothermal synergistic effect, which inhibited carbon deposition and improved catalytic activity and stability. This work provides a novel concept for the conversion and utilization of biomass tar at low temperatures.

An Organic Redox Mediator with a Defense‐Donor for Lithium Anode in Lithium–Oxygen Batteries

Lithium-oxygen batteries (LOBs) suffer from large charge overpotential and unstable Li metal interface, which can be attributed to the inefficient charge transport at the insulating Li2 O2 /cathode interface and the severe oxygen corrosion issue on the Li anode surface. The use of soluble redox mediators (RMs) can effectively enhance the charge transport between Li2 O2 and cathode, thus greatly reducing the charge overpotential. However, oxidized RMs will also shuttle to the anode side and react with the Li metal, which not only results in the loss of both the RMs and the electrical energy efficiency but also exacerbates the Li anode corrosion. Herein, an organic compound-acetylthiocholine iodide (ATCI), in which a big cation group is contained, is proposed as a defense-donor RM for lithium anode in LOBs to simultaneously address the above issues. During charge, it can accelerate the oxidation kinetics of Li2 O2 via its iodide anion redox couple (I- /I3 - ). Meanwhile, its cation segment (ATC+ ) can move to the anode surface via electric attraction and in situ forms a protective interfacial layer, which prevents the Li anode from the attack of oxidized RM and oxygen species. Consequently, the ATCI-containing LOBs can achieve both a low charge potential (≈3.49V) and a long cycle life (≈190 cycles).

Comparison of three commercial photosensitizers for efficiency of inducing immunogenic cell death in anti-tumor immunotherapy

To compare 3 commercial immunogenic cell death (ICD) inducers, namely Chlorin e6 (Ce6), Neutral Red (NR), and Rose Bengal Sodium salt (RB), for their photosensitive properties, efficacy for photodynamic therapy (PDT) and ICD induction efficiency in antitumor immunotherapy. Reactive oxygen species (ROS) probes were used to evaluate the photosensitivity of the 3 ICD inducers, and their capacity for inducing intracellular ROS production was evaluated using a DCFH-DA probe. The cytotoxicity and biocompatibility of the 3 photosensitizers were compared using a CCK-8 kit, and their ICD-inducing efficiency was assessed by detecting the levels of surface-exposed calreticulin (ecto-CRT), high mobility group protein 1 (HMGB1) and adenosine triphosphate (ATP). In the animal experiment, BALB/c mouse models bearing 4T1 cellderived subcutaneous tumor were given intratumoral injection of Ce6 or NR solution (30 μL, 5 mg/mL), followed 2 h later by white light irradiation for 10 min (400 mW/cm2). Body weight and tumor size changes of the mice were monitored, and the percentage of CD8+ T cells in the tumor and IFN-γ+ CD8+ T cells in the spleen were analyzed by flow cytometry 14 days after the treatment. HE and TUNEL staining was used to analyze tumor cell apoptosis in the mice. Among the 3 photosensitizers, Ce6 exhibited the strongest ROS-inducing capability and killing effect on the tumor cells. The results of ectoCRT, HMGB1 and ATP level detection all demonstrated a stronger ICD induction ability of Ce6. In the tumor-bearing mice, the tumor growth in Ce6 and NR groups was significantly inhibited after the treatment. The percentages of CD8+ T cells and IFN-γ+ CD8+ T cells were 12.7% and 7.1% in Ce6 group, respectively, significantly higher than those in NR group (6.1% and 2.8%, respectively; P < 0.05). HE and TUNEL staining revealed obvious tumor cell apoptosis in the tumor tissues in both Ce6 and NR groups, but the therapeutic effect was more prominent in Ce6 group. Among the 3 photosensitizers, Ce6 has the highest efficiency for inducing ROS production with the strongest PDT efficacy and ICD induction capability. Ce6 can also increase the number and function of CD8+ T cells in anti-tumor immunotherapy to initiate robust adaptive immune response.

Heterogeneous photocatalytic activation of electrogenerated chlorine for the production of reactive oxygen and chlorine species: A new approach for Bisphenol A degradation in saline wastewater

UV-E-chlorination/hematite nanoparticles (UV/E-Cl/HNs) as a heterogeneous photocatalytic activation of electrogenerated chlorine was assessed for the degradation of bisphenol A (BPA) as a new approach based on the generation of reactive chlorine and oxygen species. The prepared sample was characterized using multiple techniques, such as XRD, FTIR, FESEM, EDS, and BET-BJH. An excellent decontamination efficiency of 99.4% was achieved within 40 min of electrolysis under optimum conditions (pH of 5, HNs dosage 100 mg/L, current density of 20 mA/cm2, and NaCl concentration of 50 mM). The HOCl content was reduced more swiftly in the presence of ultraviolet (UV) irradiation and hematite, resulting in the production of oxidative radicals (i.e., •OH, Cl•, and Cl2•−). The scavenging experiments also verified the vital role of these radicals in oxidative treatment. The UV/E-Cl/HNs process is readily supplied with hydroxyl radicals through several mechanisms. Bicarbonate ions showed a noticeable inhibitory impact, whereas nitrate and sulfate anions only slightly affected BPA degradation. The HNs were a recoverable and stable catalyst for six cycles. Furthermore, the ECOSAR program predicted that the UV/E-Cl/HNs can be labeled as an environmental-friendly process. Eventually, reasonable degradation pathways were proposed based on the identified by-products through experimental and theoretical approaches.

Kinetics-Based Quantification of Peroxynitrite Using the Oxidative Decarbonylation of Isatin.

Peroxynitrite and its radical decomposition products are highly reactive nitrogen and oxygen species that can influence the balance between health and disease in multiple organ systems. Despite vigorous research activity, real-time quantitative monitoring of peroxynitrite generated by donor compounds remains challenging. Here, we report a kinetics-based fluorescence method for quantitative tracking of peroxynitrite generation using the oxidative decarbonylation of isatin to form anthranilic acid as a fluorescent probe. This method relies on knowledge of the rate of the reaction of peroxynitrite with the probe, which we measure using stopped-flow fluorescence techniques. To the best of our knowledge, this is the first optical method capable of providing real-time quantitative measures of peroxynitrite concentrations generated from donor compounds, as demonstrated herein for SIN-1 and Angeli's salt.

Uncovering the effect of surface basicity on the carbon deposition of Ni/CeO2 catalyst modified by oxides in DRM

The acidity and basicity of Ni based catalysts play very important role in the catalytic performance during dry reforming of methane. Hence, the effects of surface basicity regulated by adding the oxides (CaO, MgO, ZnO and La2O3) in Ni/CeO2 catalysts on the catalytic behavior were systematically investigated, and the characterization methods and DFT calculations were performed to reveal the underlying mechanism. It was found that the addition of basic oxides could improve the activity and stability due to these oxides could increase the adsorbed oxygen, reduce the size of Ni particle and improve the interaction between Ni and support, in particular, the MgO interacts with Ni to form MgNiO2 spinel, which contribute to promote Ni dispersion and inhibit Ni aggregation. Moreover, the results suggested that the resistance to carbon deposition has something to do with the surface basicity. To a certain degree, the increasing the amount of basic site and enhancing alkaline strength could suppress the carbon deposition of Ni based catalysts. This is mainly because that the basic site is beneficial to CO2 adsorption and activation based the DFT calculations, which could accelerate the elimination of carbon deposition by provide more oxygen species. These results could provide some useful information to the design and synthesis of Ni-based catalysts.

Comprehensive analysis of ERCC3 prognosis value and ceRNA network in AML.

Acute myeloid leukemia (AML) is a hematological malignancy with high molecular and clinical heterogeneity, and is the most common type of acute leukemia in adults. Due to limited treatment options, AML is prone to relapse and has a poor prognosis. Excision repair cross-complementing 3 (ERCC3) is an important member of nucleotide excision repair (NER) that is overexpressed in types of solid cancers and potentially regarded as a prognostic factor. However, its role in AML remains unclear. The purpose of this study was to explore ERCC3 expression and functions in AML. The Cancer Genome Atlas (TCGA) and GEO (Gene Expression Omnibus) were used to test the accuracy of ERCC3 expression levels for AML diagnosis. Using online databases and R packages, we also explored the signaling pathway, epigenetic regulation, infiltration of immune cells, clinical prognostic value, and ceRNA network in AML. Our results revealed that ERCC3 expression was increased in AML and that high ERCC3 expression had good value for disease-free survival and overall survival in AML patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT). We found that ERCC3 and co-expressed genes were mainly involved in chemical carcinogenesis/reactive oxygen species, ubiquitin-mediated protein degradation and oxidative phosphorylation. In addition, almost all the m6A-related coding genes (except GF2BP1) were positively associated with ERCC3 expression. We also constructed a ceRNA regulatory network containing ERCC3 in AML and identified 6 pairs of ceRNA networks, indicating that ERCC3 expression is regulated by a noncoding RNA system. This study demonstrated that ERCC3 was overexpressed in AML and that high ERCC3 expression can be considered a biomarker conducive to allo-HSCT in AML patients.