Oxide Species Research Articles

Thrombopoietin ameliorates doxorubicin-induced toxicities in H9c2 myocardiocytes by inhibiting oxidative stress through the SIRT1/p38 MAPK signaling pathway

Objective: To explore whether thrombopoietin can exert a protective effect against doxorubicin-induced cardiotoxicity by modulating the sirtuin 1 (SIRT1) signaling pathway. Methods: H9c2 cell viability was determined by CCK-8 and cardiomyocyte apoptosis was detected by TUNEL assay. The protein expressions of SIRT1 and p38 MAPK were measured by Western blot. RT-qPCR was also used to determine S1RT1 mRNA expression. In addition, intracellular reactive oxygen species levels and antioxidant enzyme activities were evaluated. Results: Thrombopoietin treatment reversed doxorubicin-induced decline in H9c2 cell viability. It also increased SIRT1 and decreased p-p38 MAPK protein expressions. In addition, thrombopoietin significantly attenuated doxorubicin-induced apoptosis and oxidative stress, and enhanced antioxidant enzyme activities. However, silencing S1RT1 abrogated the protective effects of thrombopoietin, as evidenced by reduced cell viability and increased oxidative stress and reactive oxygen species levels. Conclusions: Thrombopoietin alleviates doxorubicin-induced cardiomyocyte injury by reducing oxidative stress and apoptosis via the SIRT1/p38 MAPK pathway. However, its protective effects need to be further verified in animal tests.

S-nitrosoglutathione (GSNO) induces necroptotic cell death in K562 cells: Involvement of p73, TSC2 and SIRT1

BackgroundNitric oxide and Reactive Nitrogen Species are known to effect tumorigenicity. GSNO is one of the main NO carrying signalling moiety in cell. In the current study, we tried to delve into the effect of GSNO induced nitrosative stress in three different myelogenous leukemic K562, U937 and THP-1 cell lines. MethodWST-8 assay was performed to investigate cell viability. RT-PCR and western-blot analysis were done to investigate mRNA and protein expression. Spectrophotometric and fluorimetric assays were done to investigate enzyme activities. ResultWe found that GSNO exposure led to reduced cell viability and the mode of cell death in K562 was non apoptotic in nature. GSNO promoted impaired autophagic flux and necroptosis. GSNO treatment heightened phosphorylation of AMPK and TSC2 and inhibited mTOR pathway. We observed increase in NAD+/ NADH ratio following GSNO treatment. Increase in both SIRT1 m-RNA and protein expression was observed. While total SIRT activity remained unaltered. GSNO increased tumor suppressor TAp73/ oncogenic ∆Np73 ratio in K562 cells which was correlated with cell mortality. Surprisingly, GSNO did not alter cellular redox status or redox associated protein expression. However, steep increase in total SNO and PSNO content was observed. Furthermore, inhibition of autophagy, AMPK phosphorylation or SIRT1 exacerbated the effect of GSNO. Altogether our work gives insights into GSNO mediated necroptotic event in K562 cells which can be excavated to develop NO based anticancer therapeutics. ConclusionOur data suggests that GSNO could induce necroptotic cell death in K562 through mitochondrial dysfunctionality and PTM of different cellular proteins.

Chronic Administration of Red Yeast Rice Mitigates Endothelial Dysfunction in Spontaneously Hypertensive Rats by Inhibiting Oxidative Stress and Endothelial Nitric Oxide Synthase Uncoupling.

Hypertension is associated with endothelial dysfunction. An imbalance in the production of Nitric Oxide (NO) and Reactive Oxygen Species (ROS), leading to impaired NO-cyclic Guanosine Monophosphate (cGMP) pathway, contributes to this disorder. Red Yeast Rice (RYR), produced from the fermentation of rice with Monascus purpureus, is a traditional functional food originating from China. Although recognized for its anti-dyslipidemia properties, there has been growing evidence regarding the anti-hypertensive effects of RYR. However, these studies only focused on its direct and short-term effects. This study aims to investigate the vasoprotective effects of chronic oral RYR administration using Spontaneously Hypertensive Rats (SHR). SHR were randomly divided into 3 groups: SHR - Control; SHR - RYR extract (100 mg/kg/day); SHR - lovastatin (10 mg/kg/day). Wistar-Kyoto Rats (WKY) were used as normotensive controls. All animals were treated for 12 weeks by oral gavage. Systolic Blood Pressure (SBP) was measured weekly (tail-cuff method). Vascular reactivity was determined using isolated rat aortic rings in an organ bath. Aortic ROS, NO, tetrahydrobiopterin (BH4), and cGMP levels were evaluated. Administration of RYR attenuated SBP elevation and enhanced endothelium-dependent vasodilation in aortic rings. In addition, RYR decreased ROS production and significantly improved the level of vascular NO, BH4, and cGMP. In an SHR model, treatment with RYR for 12 weeks exerts an SBP lowering effect that can be attributed to improved vascular function via reduction of oxidative stress, decreased endothelial NO Synthase (eNOS) uncoupling and enhanced NO-cGMP pathway.

Potential Role of Oxidative Stress in the Pathophysiology of Neurodegenerative Disorders.

Neurodegeneration causes premature death in the peripheral and central nervous system. Neurodegeneration leads to the accumulation of oxidative stress, inflammatory responses, and the generation of free radicals responsible for nervous disorders like amyotrophic lateral sclerosis, Alzheimer's disease, Parkinson's disease, and Huntington's disorders. Therefore, focus must be diverted towards treating and managing these disorders, as it is very challenging. Furthermore, effective therapies are also lacking, so the growing interest of the global market must be inclined towards developing newer therapeutic approaches that can intercept the progression of neurodegeneration. Emerging evidences of research findings suggest that antioxidant therapy has significant potential in modulating disease phenotypes. This makes them promising candidates for further investigation. This review focuses on the role of oxidative stress and reactive oxygen species in the pathological mechanisms of various neurodegenerative diseases, amyotrophic lateral sclerosis, Alzheimer's disease, Parkinson's disease, and Huntington's disorders and their neuroprotection. Additionally, it highlights the potential of antioxidant-based therapeutics in mitigating disease severity in humans and improving patient compliance. Ongoing extensive global research further sheds light on exploring new therapeutic targets for a deeper understanding of disease mechanisms in the field of medicine and biology targeting neurogenerative disorders.

An electron paramagnetic resonance time-course study of oxidative stress in the plasma of electronic cigarette exposed rats.

The long-term consequences of electronic cigarette (Ecig) use in humans are not yet known, but it is known that Ecig aerosols contain many toxic compounds of concern. We have recently shown that Ecig exposure impairs middle cerebral artery (MCA) endothelial function and that it takes 3days for MCA reactivity to return to normal. However, the sources contributing to impairment of the endothelium were not investigated. We hypothesized that the increased levels of oxidative stress markers in the blood are correlated with impaired MCA reactivity. We used electron paramagnetic resonance (EPR) spectroscopy to examine plasma from 4-month-old male Sprague-Dawley rats that were exposed to either air (n=5) or 1h Ecig exposure, after which blood samples were collected at varying times after exposure (i.e., 1-4, 24, 48 and 72h postexposure, n=4 or 5 in each time group). The EPR analyses were performed using the redox-sensitive hydroxylamine spin probe 1-hydroxy-3-carboxymethyl-2,2,5,5-tetramethyl-pyrrolidine (CMH) to measure the level of reactive oxidant species in the plasma samples. We found that EPR signal intensity from the CM• radical was significantly increased in plasma at 1-4, 24 and 48h (P<0.05, respectively) and returned to control (air) levels by 72h. When evaluating the EPR results with MCA reactivity, we found a significant negative correlation (Pearson's P=0.0027). These data indicate that impaired cerebrovascular reactivity resulting from vaping is associated with the oxidative stress level (measured by EPR from plasma) and indicate that a single 1h vaping session can negatively influence vascular health for up to 3 days after vaping. HIGHLIGHTS: What is the central question of this study? Does the time course of oxidative stress triggered by electronic cigarette exposure follow the cerebral vascular dysfunction? What is the main finding and its importance? Electron paramagnetic resonance analysis shows that the oxidative stress induced after a single 1h exposure to electronic cigarette aerosol takes ≤72h to return to normal, which mirrors the time course for vascular dysfunction in the middle cerebral artery that we have reported previously.

Nanozyme Decorated Metal-Organic Framework Nanosheet for Enhanced Photodynamic Therapy Against Hypoxic Tumor.

Photodynamic therapy (PDT) has attracted increasing attention in the clinical treatment of epidermal and luminal tumors. However, the PDT efficacy in practice is severely impeded by tumor hypoxia and the adverse factors associated with hydrophobic photosensitizers (PSs), including low delivery capacity, poor photoactivity and limited ROS diffusion. In this study, Pt nanozymes decorated two-dimensional (2D) porphyrin metal-organic framework (MOF) nanosheets (PMOF@HA) were fabricated and investigated to conquer the obstacles of PDT against hypoxic tumors. PMOF@HA was synthesized by the coordination of transition metal iron (Zr4+) and PS (TCPP), in situ generation of Pt nanozyme and surface modification with hyaluronic acid (HA). The abilities of hypoxic relief and ROS generation were evaluated by detecting the changes of O2 and 1O2 concentration. The cellular uptake was investigated using flow cytometry and confocal laser scanning microscopy. The SMMC-7721 cells and the subcutaneous tumor-bearing mice were used to demonstrate the PDT efficacy of PMOF@HA in vitro and in vivo, respectively. Benefiting from the 2D structure and inherent properties of MOF materials, the prepared PMOF@HA could not only serve as nano-PS with high PS loading but also ensure the rational distance between PS molecules to avoid aggregation-induced quenching, enhance the photosensitive activity and promote the rapid diffusion of generated radical oxide species (ROS). Meanwhile, Pt nanozymes with catalase-like activity effectively catalyzed intratumoral overproduced H2O2 into O2 to alleviate tumor hypoxia. Additionally, PMOF@HA, with the help of externally coated HA, significantly improved the stability and increased the cell uptake by CD44 overexpressed tumor cells to strengthen O2 self-supply and PDT efficacy. This study provided a new strategy of integrating 2D porphyrin MOF nanosheets with nanozymes to conquer the obstacles of PDT against hypoxic tumors.

Plasma 8-Hydroxydeoxyguanosine, 4-Hydroxynonenal and Selenium in Hepatitis B Virus-Infected Adults in Ibadan, Nigeria

Introduction: Hepatitis B Virus (HBV) infection is a significant global health challenge, particularly in Sub-Saharan Africa, including Nigeria. Reactive oxidative species (ROS) generated during HBV replication contribute to redox imbalance, leading to oxidative stress. However, data on the levels of oxidative stress markers in Nigerians infected with HBV is scarce. This study aimed to investigate plasma levels of oxidative stress markers [8-hydroxydeoxyguanosine (8-OHdG) and 4-hydroxynonenal (4-HNE)] and the trace element, selenium, in HBV-infected adults in Ibadan, Nigeria. Materials and Methods: In a case-control study, 40 HBV-infected patients served as cases, and 40 HBV-uninfected patients served as controls. Anthropometric data were collected, and plasma 8-OHdG and 4-HNE were determined using the ELISA method. Selenium was determined using atomic absorption spectrophotometry. Data were analysed using descriptive, t-test, and Pearson correlation statistics at p = 0.05. Results: The mean ages of HBV-infected and uninfected individuals were 35.3±1.5 and 36.0±1.5 years, respectively. The level of 4-HNE was not significantly different between HBV-infected (2.2±1.7 ng/ml) and uninfected (1.8±1.3 ng/ml). There was also no significant difference in 8-OHdG levels between HBV-infected (4.1±2.4 ng/ml) and uninfected (3.6±1.8 ng/ml). However, in HBV-infected patients, 8-OHdG levels showed a significant positive correlation with 4-HNE (r =0.320, p =0.044). Selenium levels were also significantly higher in HBV-infected (78.4±25.4 ug/dl) than uninfected (35.6±11.4 ug/dl). Conclusion: The levels of markers of lipid peroxidation and DNA oxidation were similar in HBV-infected and uninfected participants, but selenium, the key component of the potent antioxidant glutathione peroxidase was more than double in the infected group. It is plausible that the protective effect of Se may have spared the other markers of oxidative damage. Further studies are needed to elucidate these preliminary findings.

Visible-light-driven photocatalytic oxidation of furfural to furoic acid over Ag/g-C3N4

Furoic acid (FA) is a useful bio-chemicals, which can be used in the production of pharmaceuticals, food additives, flavors, industrial chemicals, biofuels, etc. Oxidation of furfural to FA has been carried out by a thermal catalytic method, but photocatalytic oxidation protocol has not been reported yet. Here, g-C3N4-supported Ag nanoparticles (Ag NPs) catalysts with different Ag loading were synthesized and used for the photocatalytic oxidation of furfural to FA under visible light irradiation. The physicochemical and photoelectrochemical properties of the catalysts were systematically investigated by XRD, TEM, XPS, UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), photoluminescence, etc. Compared with the pristine g-C3N4, Ag-CN(N2 + H2) was found to have better photocatalytic performances in the aerobic oxidation of furfural under visible light irradiation, and the conversion can reach 82 % with a FA yield of 30 %. Importantly, the loading of Ag NPs has a significant effect on the photoelectrochemical properties. Specifically, 0.5 % Ag NPs loading maximized the photocurrent response, indicating that the loading of Ag NPs enhances charge separation and migration under visible light excitation. The introduction of Ag NPs also led to a significant decrease in electrochemical impedance, which promoted the rate of electron transfer at the interface, further confirming the improved photocatalytic efficiency. The addition of Ag NPs broadens the solar absorption and promotes the separation/transport of photo-generated carriers to form “hot electrons”, and provides the active species for furfural oxidation. The reasonable reaction mechanism of the photocatalytic oxidation of furfural to FA was elucidated. This work offers a novel method for the oxidation of furfural to FA in a mild and green way.

Electrochemical treatment on a pilot scale of a mixture with high concentrations of dyes from the tanning/textile industry

Violet LR (VLR), Brown RD (BRD), and Green A (GA) dyes are widely used in the tannery industry for dyeing leather. These types of compounds can be toxic and, in many cases, carcinogenic. In this context, electrochemical oxidation (EO) and electro-Fenton (EF) processes are the most popular electrochemical advanced oxidation processes (EAOPs) to degrade persistent/toxic water pollutants. The efficiency of these processes largely depends on the nature of the electrode materials, among other operation parameters. This study evaluates Ti/IrO2-SnO2-Sb2O and BDD anodes for dye degradation in a pilot plant of 4.0 L of total volume. It was found that DSA IrO2-SnO2-Sb2O performed better than BDD for the discoloration of a mixture of the dyes (kDSA=0.0970 min−1 and kBDD=0.0370 min−1) in a medium containing 50 mM NaCl and 10 mM Na2SO4 (j = 50 mA cm−2, Q=12 L min−1 and pH 3). Such an effect was due to the combined production of heterogeneous •OH at the anode surface by H2O oxidation and reactive chlorinated species in the bulk solution via Cl- oxidation. In addition, •OH quantification showed a higher production by DSA ([BDD(•OH)] = 3,8 × 10-15 M vs [DSA(•OH)] = 6.6 × 10-15 M). The efficiency was enhanced when applying EF (BDD cathode promoting H2O2 production) in the presence of Fe2+ ions under similar experimental conditions. The color was almost totally removed in 50 min with kEF-DSA=0.1584 min−1, while COD was removed by 80 % in 80 min. The EC was 0.082 kWh (g COD)-1. Such results highlight the potential of EO and EF with accessible Ti/IrO2-SnO2-Sb2O anodes as a pretreatment unit within a treatment train for tanning or textile wastewater management.

Mechanical and statistical pathway for the experimental investigation of the dairy industry effluent using non-thermal plasma

Globally, there is still a demand for effective removal of industrial pollutants using modern treatment technologies. Therefore, to achieve industrial implementation, treatment efficiency and energy demand, at present the new Non-Thermal Plasma (NTP) technology is adopted to treat the dairy industry pollutants. Falling Film Dielectric Barrier Discharge reactor (FF-DBD) is developed whereas the reactor is further characterized by the various operating parameters including electric field, gas source, flow rate and pH for the removal of COD and lactose content for different experimental conditions. In this present study, experimental works are carried out in ‘lab-scale experimental hardware to analyze the degradation efficiency of dairy effluent based on COD and lactose. For the maximum of 68 % and 75.56 % of COD and lactose removal is achieved at the maximum voltage of 30 k,Vp-p. Moreover, the interaction between COD and lactose is analyzed by using ANOVA and the p-value is < 0.001. Comparing to the air, oxygen as a discharge gas in a DBD reactor gives more treatment efficiency because it produces more oxygen-based oxidative species. Further the 2D - simulation model is employed to find the velocity profile of effluent inside the FF-DBD reactor.

Tailored small molecule for inflammation treatment: Dual scavenger targeting nitric oxide and reactive oxygen species

Inflammation-related diseases are often marked by elevated levels of nitric oxide (NO) and reactive oxygen species (ROS), which play important roles in the modulation of inflammation. However, the development of organic materials effective in managing NO/ROS levels has remained a challenge. This study introduces a novel organic compound, NmeGA, engineered to scavenge both NO and ROS. NmeGA ingeniously integrates N-methyl-1,2,-phenylenediamine (Nme), a NO scavenger, with gallic acid (GA), a ROS scavenger, through an amide bond, endowing it with enhanced scavenging capabilities over its individual component. This compound exhibits reduced toxicity and increased lipophilicity value, underlining its increased biological applicability and highlighting its potential as an inflammation management tool. Through in vitro studies on lipopolysaccharide (LPS)-stimulated RAW 264.7 cells, NmeGA displayed remarkable scavenging efficiency for NO and ROS, coupled with significant anti-inflammatory effects. In an LPS-induced peritonitis model, administration of NmeGA substantially decreased mortality rates, NO and ROS levels, and inflammatory cytokine concentrations. These findings highlight NmeGA's versatility as a therapeutic agent against various inflammatory diseases.

Untangling the Uncertain Role of Overactivation of the Renin-Angiotensin-Aldosterone System with the Aging Process Based on Sodium Wasting Human Models.

Every individual at some point encounters the progressive biological process of aging, which is considered one of the major risk factors for common diseases. The main drivers of aging are oxidative stress, senescence, and reactive oxygen species (ROS). The renin-angiotensin-aldosterone system (RAAS) includes several systematic processes for the regulation of blood pressure, which is caused by an imbalance of electrolytes. During activation of the RAAS, binding of angiotensin II (ANG II) to angiotensin II type 1 receptor (AGTR1) activates intracellular nicotinamide adenine dinucleotide phosphate (NADPH) oxidase to generate superoxide anions and promote uncoupling of endothelial nitric oxide (NO) synthase, which in turn decreases NO availability and increases ROS production. Promoting oxidative stress and DNA damage mediated by ANG II is tightly regulated. Individuals with sodium deficiency-associated diseases such as Gitelman syndrome (GS) and Bartter syndrome (BS) show downregulation of inflammation-related processes and have reduced oxidative stress and ROS. Additionally, the histone deacetylase sirtuin-1 (SIRT1) has a significant impact on the aging process, with reduced activity with age. However, GS/BS patients generally sustain higher levels of sirtuin-1 (SIRT1) activity than age-matched healthy individuals. SIRT1 expression in GS/BS patients tends to be higher than in healthy age-matched individuals; therefore, it can be assumed that there will be a trend towards healthy aging in these patients. In this review, we highlight the importance of the hallmarks of aging, inflammation, and the RAAS system in GS/BS patients and how this might impact healthy aging. We further propose future research directions for studying the etiology of GS/BS at the molecular level using patient-derived renal stem cells and induced pluripotent stem cells.

Enhanced Tomato Seed Germination and Seedling Growth Through Oxidative Stress Using Biogenic Silver Nanoparticles

In this study, silver nanoparticles (AgNP) were successfully biosynthesized from Larrea tridentata leaf extract. X-ray Dif fraction (XRD) and Transmission Electron Microscopy (TEM) analysis confirmed that AgNP are crystalline and hemispherical, with sizes between 4 and 26 nm. In addition, the ef fect of nanoparticles on tomato (Solanum lycopersicum) seed germination and seedling growth was examined. Seeds were pre-soaked with dif ferent concentrations of AgNP (0, 4.03, 6.72, 18.66, 51.84, and 86.4 mg L-1). Up to 90% seed germination was achieved at a concentration of at least 4.03 mg L-1, while the control reached below 60%. The highest vigor was obtained at a concentration of 51.84 mg L-1, 2.67 times higher than the vigor of untreated seeds. The synthesized nanoparticles induced activation of tomato seedlings’ defense system against reactive oxidative species, increasing CAT and APX enzyme activities and seedling’s growth. Plumule and radicle length rose 1.49 and 1.98-fold compared to the control. The seedlings were susceptible at 86.4 mg L-1 of AgNP, which af fected all growth parameters and induced oxidative stress response through increased hydrogen peroxide (H2O2) formation and proline content. These provide further insight into the ef fects of biogenic silver nanoparticles on plants during their initial stages of development, demonstrating that these nanoparticles can promote early germination.

Cold plasma/alkaline pretreatment facilitates corn stalk fractionation and valorization towards zero-waste approach

The present study employed alkaline hydrogen peroxide pretreatment coupled with cold plasma for corn stalk’s complex biopolymers fractionation and valorization through enzymatic hydrolysis. This hurdle approach enables the prolonged generation of reactive oxidative species, initiating chemical reactions otherwise hardly possible under ambient conditions. A delignification rate between 76±1 and 86±2 % was obtained under different process parameters in a significantly shorter time compared to conventional alkaline pretreatment. Up to 94±4 % of cellulose in treated biomass was converted to glucose after enzymatic hydrolysis, achieving around 3.5 times higher glucose yield than the raw biomass. Different spectroscopic analyses confirmed specific alterations in the structure of the lignin-rich fraction caused by cold plasma. Micro- and nanoscale lignin particles obtained were rich in total phenolic content, reaching up to 140±20 and 107±12 µg gallic acid equivalents (GAE) per mg of lignin, respectively. The proposed concept of corn stalk fractionation through biorefinery can open new opportunities for valorizing different agricultural waste types.

NOX1-mediated oxidative stress induces chondrocyte ferroptosis by inhibiting the Nrf2/HO-1 pathway

Osteoarthritis (OA) is a common joint disease associated with the aging of the population, and it reduces the quality of life of patients. It is characterized by the destruction of articular cartilage and the secretion of inflammatory cytokines. Owing to the unclear pathogenesis of OA, current treatment methods have significant limitations. Oxidative stress has been revealed to play an important role in the development of OA. Our experiments indicated that the levels of GSH decreased and the level of MDA increased in chondrocytes, which induced ferroptosis in chondrocytes in OA. We also revealed that ferroptosis was the main mechanism of cartilage destruction caused by the addition of the ferroptosis activator erastin and the ferroptosis inhibitor ferrostatin-1. NOX1 is the main modulator of oxidative stress by increasing the generation of reactive oxidative species (ROS). We suppressed the expression of NOX1 in chondrocytes through cell transfection. The expression of collagen II and MMP13, and the secretion of IL-1β and TNF-α were reversed. An increase in the mitochondrial membrane potential and a decrease in the level of intracellular ROS indicate an improvement in oxidative damage. Additionally, we determined the effect of the Nrf2/HO-1 pathway on NOX1-mediated chondrocyte injury. We found that NOX1 inhibited the expression of Nrf2/HO-1, but the activation of Nrf2 improved the oxidative damage to chondrocytes in vivo and vitro. This study revealed that NOX1-mediated oxidative stress induces chondrocyte ferroptosis by inhibiting the Nrf2/HO-1 pathway. Our findings contribute to revealing the pathogenesis of OA, providing targets for drug design and optimizing the clinical treatment of OA.

In Situ Formation of B═O Bond in Oxidative Dehydrogenation of Propane and as a Hunter for Alkoxyl Radicals: A Computational Study.

B═O multiple bonds are fundamentally important owing to the unique property of B and its potential as a tool in catalysis. Herein by means of DFT calculations, we investigated the in situ generation of transient -B═O species in the nonmetallic inorganic boron oxides and demonstrated its superior ability to capture alkoxyl radicals under the conditions of oxidative dehydrogenation of propane (ODHP). Boron-containing materials are emerging as promising catalysts for ODHP, while an extensive understanding of the underlying mechanisms remains challenging. Through systematic mechanistic and characterization calculations, we show the feasibility for the presence of -B═O species under ODHP conditions and propose that its π nature dictates its inertness in the C-H activation of propane (ΔG⧧ = 57 kcal/mol) but offers its strong ability in capturing alkoxyl radicals (barrierless with ΔG = -30 kcal/mol), which can then transform to the ·C3H6OH radical. This explains the observation of enol in the experimental study. This specific behavior of the -B═O species makes it one of the key players in the complex reaction network of ODHP and also implicates the rational design of scavengers for reactive oxygen species (ROS) and other active oxygenated species.

Boosting photocatalytic multi-VOCs decontamination over COF-based heterojunction via targeted construction of Ov–M–N charge channel (M = Ti, Zn, W, Ce) and –NH2 functionalization

Covalent organic frameworks (COF) based materials have exhibited excellent gas and visible light absorption capability, yet are very difficult to generate strong oxidative species for photocatalytic mineralization of volatile organic compounds (VOCs). Here, a facile in situ modulation protocol developed could enable the growth of MOx (M = Ti, Zn, W, Ce) with oxygen vacancy (Ov) on –NH2-functionalized COF surfaces to construct NH2–COF/Ov–MOx Z–scheme heterojunctions of excellent stability and efficiency (98.3 %) in photo-oxidation of formaldehyde, acetaldehyde, and acetone. The –NH2 functionalization enhanced VOC chemisorption via H-bond interaction. Moreover, the constructed fast charge transfer channel (Ov–M–N) at the interface not only promoted directional migration of photo-excited carrier, activated adsorbed O2 and H2O to quickly generate strong •OH, but also effectively inhibited injurant formation to realize the precise control of the conversion path. These findings offer new insights into customizing the interfacial structure of COF for indoor air purification.

Manganese oxide for heterogeneous Fenton treatment: Catalyst or inhibitor?

Manganese oxide species have been frequently used for Fenton catalyst design, but their role in reaction with hydrogen peroxide (H2O2) is still in debate. We here revealed the different routes of manganese oxide/H2O2 interactions occurring at bulk surfaces to that at nanopore-confined surfaces, which have been overlooked in literatures. Briefly, particulate manganese oxide species cause a fast H2O2 decomposition influenced by the valence of manganese and solution pH, but without generation of reactive oxygen species (•OH, •O2-, or 1O2) for water treatment; in contrast, manganese oxide/H2O2 interaction under nanopore confinement (ca. 1 nm) led to the production of radicals (mainly •OH and •O2-) and the removal of organic pollutants. We gained insights into the differed reaction routes based on experimental and computational study. Our findings provide caveats on the indiscriminate pursuit of manganese in Fenton catalyst development, against a nullified H2O2 decomposition and impractically slow radical production.

Self-Regulated Assembly and Disassembly of Gold Nanoparticles for Low-Temperature Time Indication.

The color-changing self-assembly and autonomous disassembly of colloidal gold nanoparticles (AuNPs) is reported by simply mixing negatively charged phosphine ligand-capped AuNPs with partially oxidized polyethylene glycol (PEG). The assembly of AuNPs is initiated by PEG adsorption, which disrupts the hydration layer of AuNPs, leading to depletion attraction and reduction of hydration repulsion among the AuNPs. The oxidative species in PEG subsequently oxidize and remove the charged ligands from the AuNP surface, resulting in a decrease and reversal of the negative surface charge. This causes the PEG to adsorb on AuNPs in a tighter and more direct manner, providing strong steric shielding to the AuNPs, thereby triggering the disassembly of the AuNP assemblies. The self-regulated assembly-disassembly process can be tuned widely by controlling chemical conditions of PEG, nanoparticle concentration, and the environmental conditions, suggesting potential applications as colorimetric time-temperature indicators for food and medicine storage conditions. As a proof of concept, it is demonstrated that the lifetime of the color-changing assembly-disassembly process can be extended from tens of minutes to weeks when subjected to a refrigerated environment, with tunability achievable through varying polymer conditions and storage atmospheres.

Triangle CeO2/g-C3N4 heterojunctions: Enhanced light-driven photocatalytic degradation of methylparaben

In this work, an efficient photocatalytic system for methylparaben (MP) removal, using solar (λ > 360 nm) and visible (λ > 420 nm) light-driven CeO2/g-C3N4 (CeO2/CN) heterojunctions is reported for the first time. The physicochemical properties of pure CeO2, CN, and CeO2/CN composites were investigated using characterization techniques, such as XRD, FESEM-EDS, TEM, UV–Vis, PL, XPS, and electrochemical spectroscopy. Among the catalysts with different mass ratios of CeO2, 10 %CeO2/CN showed the best photocatalytic performance. This is attributed to the enhanced charge carrier’s separation because of the proper band-edge alignment between CN and CeO2 components, and the strong visible light absorbance. The photocatalytic degradation of MP followed the first-order kinetics, and the 10 %CeO2/CN catalyst exhibited a 3.8- and 11.3-times higher reaction rate (k) constant than that of pure CN, investigated under solar and visible light illumination, respectively. Further, scavenger trapping experiments confirmed that hydroxyl radicals (OH.) and dissolved oxygen are the predominant active species in MP oxidation over 10 %CeO2/CN composite catalyst. 1H NMR and LCMS-HPLC results and observations showed complete degradation of MP (0.1 g/L) to CO2 and H2O after 7 h of solar irradiation, due to the absence of the representative peaks of MP and its organic degradation products (e.g. phenols, benzoates).