Redox Interactions Research Articles

Enhanced gaseous benzene degradation by bimetallic MIL-101(Fe, Cu) activated persulfate system: Efficiency and mechanism

Persulfate oxidation is a promising technology for air pollution control but still suffers from degrading refractory volatile organic compounds (VOCs) under mild conditions. Metal-doped metal-organic frameworks (MOFs) offer a novel strategy to enhance persulfate activation and VOCs degradation. Herein, a novel bimetallic MIL-101 (Fe, Cu) is prepared for more effective degradation of gaseous benzene via persulfate activation. Under optimal conditions (Fe/Cu ratio of 1:4, persulfate concentration of 7 mM/L, pH of 5, and reaction temperature of 70 °C), the MIL-101(Fe1, Cu4) activated persulfate system achieves a benzene degradation efficiency of 79.1 %, a value significantly higher than that of MIL-101(Fe) (20.1 %). The enhanced performance can be attributed to the synergistic effect of Fe²⁺/Fe³⁺ and Cu²⁺/Cu⁺ redox interactions facilitating the activation of persulfate and generation of radical species. Density functional theory (DFT) calculations indicate an increase in the adsorption energy of MIL-101(Fe) in the presence of Cu doping from −3.46 eV to −5.92 eV along with a rise in the Fermi energy level from 0.5 eV to 1.33 eV, enhancing the electron density and mobility. A reaction energy diagram is provided to illustrate the reaction pathways and transition states involved in the degradation of benzene. Overall, the incorporation of Cu in MOFs significantly enhances the efficiency of persulfate-based oxidation systems toward VOCs degradation.

Pomegranate peel extract for green synthesis of magnetite (Fe3O4) nanozymes as a colorimetric probe for determination of diclofenac

A nanozyme based on Fe3O4 was constructed for colorimetric detection of diclofenac in pharmaceutical formulations. Firstly, an eco-friendly, rapid, and simple green approach was introduced to synthesize magnetite (Fe3O4) nanoparticles. Pomegranate peel extract was employed as a green reducing and stabilizing agent. The synthesized magnetite NPs were characterized by field emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, ultraviolet–visible spectroscopy, energy-dispersive X-ray spectroscopy, BET, X-ray diffraction, and zeta potential (Ƶ) techniques and have an average size of 14.24 nm. In the presence of hydrogen peroxide, a redox interaction takes place, and the resulting hydroxyl promotes a colorimetric conversion from colorless to blue in the presence of 3,3′,5,5′-tetra-methyl-benzidine (TMB). In addition, diclofenac can inhibit colorimetric conversion once it competes with TMB’s interaction with hydroxyl. There is a relationship between the colorimetric distinction and the target amount. It is also obvious that there is a colorimetric distinction between diclofenac and TMB due to their competition. The signal responses to diclofenac are linear in the range of 0.1–75 mg/L, and the limit of detection is 0.01 mg/L. In practical assays of diclofenac in pharmaceutical formulations, the relative standard deviation of the sample tests is 0.51 %, and the recovery for the spiked assays is 96.93 % with an RSD of 1.68 %. The effects of different interferences were studied with recovery ranging from 95.02 to 99.93 %.

Mediterranean Diet and Olive Oil Redox Interactions on Lactate Dehydrogenase Mediated by Gut Oscillibacter in Patients with Long-COVID-19 Syndrome.

Chronic viral inflammation is associated with oxidative stress and changes in gut microbiota. The Mediterranean diet (MD), with recognized anti-inflammatory and antioxidant properties, modulates gut microorganisms, specifically on the interaction between extra virgin olive oil, a key component of the MD with well-documented antioxidant effects. This study investigated the influence of adherence to MD and antioxidant-rich foods (extra virgin olive oil) on biochemical, inflammatory, and microbiota profiles in patients with chronic inflammation defined as a prolonged inflammatory response due to immune dysregulation following the acute phase of the viral infection. Participants were classified into low (n = 54) and high (n = 134) MD adherence groups (cut-off of 7 points based on previous studies utilizing the same threshold in the assessment of MD adherence). Gut microbiota was sequenced using the 16S technique, and the adherence to MD was assessed using a validated questionnaire for a Spanish population. High adherence to the MD was linked to significant improvements in inflammatory and oxidative stress markers, including reductions in LDL-cholesterol, glucose, and lactate dehydrogenase (LDH) levels, an indicative of redox balance, as well as a significant higher consumption of antioxidant foods. Moreover, gut microbiota analysis revealed distinct compositional shifts and a lower abundance of the Oscillibacter genus in the high adherence group. Notably, a significant interaction was observed between MD adherence and extra virgin olive oil consumption, with Oscillibacter abundance influencing LDH levels, suggesting that the MD antioxidant properties may modulate inflammation through gut microbiota-mediated mechanisms. These findings provide new evidence that adherence to the Mediterranean diet can reduce inflammatory markers in patients with long-COVID-19, a population that has not been extensively studied, while also highlighting the potential role of the bacterial genus Oscillibacter in modulating this effect.

Electrochemical Sensing Strategies for Synthetic Orange Dyes.

This review explores electrochemical sensing strategies for synthetic orange dyes, addressing the growing need for sensitive and selective detection methods in various industries. We examine the fundamental principles underlying the electrochemical detection of these compounds, focusing on their redox behavior and interaction with electrode surfaces. The review covers a range of sensor designs, from unmodified electrodes to advanced nanomaterial-based platforms. Chemically modified electrodes incorporating polymers and molecularly imprinted polymers are discussed for their enhanced selectivity. Particular attention is given to nanomaterial-based sensors, including those utilizing carbon nanotubes, graphene derivatives, and metal nanoparticles, which have demonstrated exceptional sensitivity and wide linear ranges. The potential of biological-based approaches, such as DNA interaction sensors and immunosensors, is also evaluated. Current challenges in the field are addressed, including matrix effects in complex samples and long-term stability issues. Emerging trends are highlighted, including the development of multi-modal sensing platforms and the integration of artificial intelligence for data analysis. The review concludes by discussing the commercial potential of these sensors in food safety, environmental monitoring, and smart packaging applications, emphasizing their importance in ensuring the safe use of synthetic orange dyes across industries.

Harnessing in-situ oxidation of nanostructured mxene to modulate the electronic structure for improved selectivity for electrochemical carbon dioxide reduction

The electrochemical CO2 reduction reaction (CO2RR) is a promising approach to valorizing CO2. Ti3C2TX as a support material has received significant interest in enhancing CO2RR performance for tuning the electronic structure. However, there has been relatively less focus on changes to the Ti3C2TX electronic structure induced by loading catalysts onto the Ti3C2TX. Because Ti3C2TX has an intrinsic activity for both CO2RR and the competitive hydrogen evolution reaction (HER), electronic structure changes can affect the balance between CO2RR and HER selectivity. Therefore, tuning the electronic structure of Ti3C2TX can control the competition between CO2RR and HER and tune the selectivity and activity. Herein, we report that Ti3C2TX’s electronic structure can be tuned by the Ag+ loading method via redox interactions, tuning the reaction selectivity and activity for CO2RR. To illustrate this effect, we compare the CO2RR performance of in-situ formed Ag nanoparticles (NPs) on Ti3C2TX (0.9Ag-IS-Ti3C2TX) with physically mixed Ag NPs and Ti3C2TX (0.9Ag/P/Ti3C2TX). Here, ‘0.9’ refers to the molar ratio between Ag precursor and Ti3C2Tx, and ‘IS’ vs. ‘P’ refers to in-situ formed vs. physically mixed Ag NPs. 0.9Ag-IS-Ti3C2TX demonstrates a higher oxidation state for Ti and a higher proportion of Ti-O bonds than 0.9Ag/P/Ti3C2TX. Compared to 0.9Ag/P/Ti3C2TX, 0.9Ag-IS-Ti3C2TX exhibits higher CO Faradaic efficiency (FE), rising from 8.1 % with a partial current density of −2.0 mA cm−2 to 49.6 % with a partial current density of −20.1 mA cm−2 at −1.4 V vs. RHE (reversible hydrogen electrode). To harness this effect, we demonstrate control over the CO: H2 ratio of syngas formed from CO2RR over our Ti3C2TX-supported catalysts. Further electrochemical anodic oxidation experiments reveal the critical oxidation potential of Ti3C2TX (0.8 V vs. RHE) and show that HER can be partially suppressed by partial oxidation of Ti3C2TX. This work highlights the importance of considering the changes in Ti3C2TX (and other) supports when supporting catalysts for CO2RR and other electrochemical reactions.

Interactive impacts of organic-inorganic modifiers on surface characteristics of Cu+-doped activated carbon for stable CO-adsorptive separation from CO2

Conventional Cu+-doped activated carbon (C) materials are problematic in carbon monoxide (CO)-selective adsorption from carbon dioxide (CO2) due to their CO2-friendly surface basicity and microporosity. In this study, boehmite (AlOOH) film modified-carbon composite (AlC) was hydrothermally synthesized to dope with 30 wt% Cu+ ions by the impregnation-calcination method. The functional hydroxyl groups of Boehmite behaved as metallic anchoring sites for better Cu+ ion dispersion, enhancing the CO adsorption uptake to 38.84 cm3/g at 25 °C and ∼ 100 kPa in isotherm analysis. Additionally, the improved Lewis acidity of AlC surface interface together with pore widening impact reduced the CO2 uptake to 14 cm3/g, around half that of Cu+-doped activated carbon, by undergoing Lewis acid-acid repelling interaction between boehmite film and CO2. However, to address rapid oxidation of Cu+ ions in the hygroscopic AlC structure, iron (II) chloride (FeCl2) surface modification on the Cu+-doped AlC composite created a Fe3+-Cu+ bimetallic interface with high Cu+ immobilization, enriching the CO adsorption stability to 92 % even after 30 day-air exposure. Noticeably, pre-complexation of FeCl2 with thiourea (NH2CSNH2) before its dispersion over the doped Cu+ ions led to distinct Cu+ stabilization mechanisms without bimetallic redox interaction. This involves developing auto-redoxable iron (II) sulfides as barrier coatings for Cu+ species against oxidation and raising the Cu2+ reducibility via cyanide-ligands of thiourea. These combined preservation effects for Cu+ ions ensured CO adsorption stability of 91 %, underlining higher CO adsorption uptake (39.38 cm3/g) and CO/CO2 selectivity (67.49 at 0.2 kPa and 3.09 at ∼ 100 kPa) than modification effects of boehmite and FeCl2.

A complex and dynamic redox network regulates oxygen reduction at photosystem I in Arabidopsis.

Thiol-dependent redox regulation of enzyme activities plays a central role in regulating photosynthesis. Besides the regulation of metabolic pathways, alternative electron transport is subjected to thiol-dependent regulation. We investigated the regulation of O2 reduction at photosystem I. The level of O2 reduction in leaves and isolated thylakoid membranes depends on the photoperiod in which plants are grown. We used a set of Arabidopsis (Arabidopsis thaliana) mutant plants affected in the stromal, membrane, and lumenal thiol network to study the redox protein partners involved in regulating O2 reduction. Light-dependent O2 reduction was determined in leaves and thylakoids of plants grown in short-day and long-day conditions using a spin-trapping electron paramagnetic resonance assay. In wild-type samples from short-day conditions, reactive oxygen species generation was double that of samples from long-day conditions, while this difference was abolished in several redoxin mutants. An in vitro reconstitution assay showed that thioredoxin m, NADPH-thioredoxin reductase C, and NADPH are required for high O2-reduction levels in thylakoids from plants grown in long-day conditions. Using isolated photosystem I, we also showed that reduction of a photosystem I protein is responsible for the increase in O2 reduction. Furthermore, differences in the membrane localization of m-type thioredoxins and 2-Cys peroxiredoxin were detected between thylakoids of short-day and long-day plants. Overall, we propose a model of redox regulation of O2 reduction according to the reduction power of the stroma and the ability of different thiol-containing proteins to form a network of redox interactions.

Adapalene as a chemical sensor for sensitive determination of manganese

ABSTRACT The work describes the use of 6-[3-(1-adamantyl)-4-methoxyphenyl]-2- naphthoic acid, or Adapalene (ADP) as a fluorescence tagging reagent, in a straightforward and very specific spectrofluorometric approach for the trace measurement of manganese (VII) in water. The process is based on the redox interaction of ADP with manganese (VII) in an acidic solution, which forms the complex [Mn (II)-ADP] and causes fluorescence at λex max/λem max = 323/400 nm. High-intensity fluorescence at 400 nm was seen in the fluorescence spectra of the formed complex ion association, Mn (II)-ADP, at pH 4. 1.55 µg mL−1 was the quantification limit, and 0.51 µg mL−1 was the detection limit and the correlation coefficient (R2) was 0.9863. 1.2173 L mol−1 was determined to be the Stern-Volmer. Spectrofluorometric technique is used to validate the approach in environmental water samples, yielding reasonable recovery percentages (89–93%). The current approach is advised to be used for reliable and accurate assessment of manganese (VII) in all wastewater and seawater samples, without the need for complex instrumentation and lengthy procedures.

A fluorimetric and colorimetric dual-mode sensor based on N, S co-doped carbon dots functionalized silver nanoparticles for glucose detection

A fluorescent-colorimetric dual-signal platform, N, S co-doped carbon dots functionalized silver nanoparticles (NS-CDs-AgNPs), was designed in situ by reducing AgNO3 in the presence of N, S co-doped carbon dots (NS-CDs) under the assistance of microwave irradiation for glucose determination. With the formation of silver nanoparticles (AgNPs), the intrinsic fluorescence of NS-CDs was quenched, showing the fluorescence state was off. Whereas the fluorescence of NS-CDs can be switched on when a trace amount of H2O2 was added. Based on this novel phenomenon, the peroxidase-like activity of NS-CDs-AgNPs by using 3,3′,5,5′-tetramethylbenzidine (TMB) chromogen and H2O2 as substrates was evaluated. The Km values of the prepared probe for H2O2 and TMB were 0.84 mM and 0.01 mM with the Vm of 6.65 × 10−8 M S−1 and 3.01 × 10−8 M S−1, respectively. The results showed that NS-CDs-AgNPs had good peroxidase-like activity and strong affinity to TMB and H2O2. It confirmed that there is a redox interaction between AgNPs and H2O2, and H2O2 can oxidize Ag to produce Ag+, which is the main reason that the fluorescence of NS-CDs-AgNPs can be activated by H2O2. The hydroxyl radical (·OH) was formed in the process of reaction, which can further oxidize TMB for color reaction. Meanwhile, glucose can be oxidized to produce H2O2 in the presence of glucose oxidase (GOx). Based on the phenomenon, a fluorimetric and colorimetric dual-mode sensor for glucose detection was established. Satisfactory results were obtained with the linear range of 0.1–80 μM for fluorimetric mode and 0.5–5 μM for colorimetric mode, respectively. Additionally, the LOD was below 0.32 μM and 0.21 μM, respectively. The method was successfully applied to determine the glucose in human serum with satisfactory recovery and RSD.

Redox interaction between mitochondria and safranin in the absence of oxygen

Redox interaction between mitochondria and safranin in the absence of oxygen

Enhanced degradation of sulfonamides by copper and cuprous oxides activated ferrate (VI) synergistically: Mechanism and applicability

Sulfonamides are extensively utilized for their affordability and effectiveness, leading to their significant accumulation in the environment, and posing a potential threat to human health. In this study, we introduced a novel system utilizing copper and cuprous oxides (CuxO) to activate ferrate (Ⅵ) (Fe (Ⅵ)) for the degradation of sulfamethazine (SMT), achieving a reaction rate 15 times higher than using Fe (Ⅵ) alone. Various experiments have shown that the primary active species in the CuxO/Fe (Ⅵ) system were Fe (V) and Fe (Ⅳ), predominantly formed via the redox interaction between Cu (I) and Fe (Ⅵ). Additionally, this system exhibited remarkable degradation efficiency even in seawater, with negligeable disruption from surrounding substances. This research developed a novel strategy for Fe (Ⅵ) activation, offering a promising approach for sulfonamide degradation in seawater.

Selective recovery of noble metals from electronic waste leachates via coral-like adsorbents

Coral-like adsorbents (BCTC@PEI) with polyethyleneimine backbones and a crosslinked network are engineered to selectively recover gold, palladium, and platinum, from synthetic E-waste leachates. These adsorbents exhibit high maximum adsorption capacities (qmax) according to the Langmuir isotherm: 2405, 1084, and 1153 mg/g for Au, Pd, and Pt, respectively (at 25 °C). The adsorption processes fit well with the pseudo-second-order kinetics (R2 > 0.99), with rapid equilibrium (te) achieved within 5 and 10 min for Au and Pd, respectively. The coral-like morphologies and macroporous structure facilitate intraparticle diffusion, resulting in a bulk diffusion-controlled kinetics. By combining experimental design and systematic characterizations, the adsorption mechanism is confirmed to involve synergetic forces, including electrostatic, chelation, and redox interactions (excluding redox interactions for Pd recovery). Furthermore, a significant separation factor (103–106) is realized among noble metals and competing metals, with effective adsorption (>89 % recovery) maintained over eight regeneration/reuse cycles. Over 90 % of Au recovery is also realized with real E-waste leachates. With their high adsorption capacity, rapid kinetics, high selectivity, and robust stability, these coral-like adsorbents hold great potential for selectively recovering noble metals from E-waste leachates.

Structure and molecular-level transformation for oxidation of effluent organic matters by manganese oxides

As important organic components in water environments, effluent organic matters (EfOMs) from wastewater treatment plants are widely present in Mn-rich environments or engineered treatment systems. The redox interaction between manganese oxides (MnOx) and EfOMs can lead to their structural changes, which are crucial for ensuring the safety of water environments. Herein, the reactivities of MnOx with EfOMs were evaluated, and it was found that MnOx with high specific surface area, active high-valent manganese content and lattice oxygen content (i.e., amorphous MnO2) possessed stronger oxidizing ability towards EfOMs. Accompanying by EfOMs oxidation, Mn(IV) and Mn(III) were reduced into Mn(II), with Mn(III) as the significant active species. Through molecular-level transformation analysis by ultrahigh mass spectrometry (FT-ICR MS), the highly reactive compounds in EfOMs were clearly determined to be that with more aromatic and unsaturated structures, especially lignin-like compounds (the highest content in EfOMs (over 60 %)). EfOMs were oxidized by amorphous MnO2 into products with lower humification index (0.60 vs. 0.46), smaller apparent molecular weight (386.94 Da vs. 368.68 Da), and higher biodegradability (BOD5/COD: 0.12 vs. 0.78). This finding suggested that redox reactions between MnOx and EfOMs might alter their abiotic and biotic behaviors in receiving water environments.

Dual-Site Chemosensor for Visualizing •OH-GSH Redox and Tracking Ferroptosis-Inducing Pathways In Vivo.

Oxidative stress, characterized by an imbalance between oxidative and antioxidant processes, results in excessive accumulation of intracellular reactive oxygen species. Among these responses, the regulation of intracellular hydroxyl radicals (•OH) and glutathione (GSH) is vital for physiological processes. Real-time in situ monitoring these two opposing bioactive species and their redox interactions is essential for understanding physiological balance and imbalance. In this study, we developed a dual-site fluorescence chemosensor OG-3, which can independently image both exogenous and endogenous •OH and GSH in separate channels both within cells and in vivo, eliminating issues of spatiotemporal inhomogeneous distribution and cross-interference. With its imaging capabilities of monitoring •OH-GSH redox, OG-3 elucidated two different pathways for ferroptosis induction: (i) inhibition of system xc- to block cystine uptake (extrinsic pathway) and (ii) GPX4 inactivation, leading to the loss of antioxidant defense (intrinsic pathway). Moreover, we assessed the antiferroptotic function and effects of ferroptosis inhibitors by monitoring •OH and GSH fluctuations during ferroptosis. This method provides a reliable platform for identifying potential ferroptosis inhibitors, contributing to our understanding of relevant metabolic and physiological mechanisms. It shows potential for elucidating the regulation of ferroptosis mechanisms and investigating further strategies for therapeutic applications.

Redox Synergy: Enhancing Gas Sensing Stability in 2D Conjugated Metal-Organic Frameworks via Balancing Metal Node and Ligand Reactivity.

Two-dimensional conjugated metal-organic frameworks (2D c-MOFs) have emerged as promising candidates in gas sensing, owing to their tunable porous structure and conductivity. Nevertheless, the reported gas sensing mechanisms heavily relied on electron transfer between metal nodes and gas molecules. Normally, the strong interaction between the metal sites and target gas molecule would result poor recovery and thus bad recycling property. Herein, we propose a redox synergy strategy to overcome this issue by balancing the reactivity of metal sites and ligands. A 2D c-MOF, Zn3(HHTQ)2, was prepared for nitrogen dioxide (NO2) sensing, which was constructed from active ligands (hexahydroxyltricycloquinazoline, HHTQ) and inactive transition-metal ions (Zn2+). Substantial characterizations and theoretical calculations demonstrated that by utilizing only the redox interactions between ligands and NO2, not only high sensitivity and selectivity, but also excellent cycling stability in NO2 sensing could be achieved. In contrast, control experiments employing isostructural 2D c-MOFs with Cu/Ni metal nodes exhibited irreversible NO2 sensing. Our current work provides a new design strategy for gas sensing materials, emphasizing harnessing the redox activity of only ligands to enhance the stability of MOF sensing materials.

Redox Potential Based Self-Powered Electrochromic Devices for Smart Windows.

Energy-efficient glass windows are pivotal in modern infrastructure striving toward the "Zero energy" concept. Electrochromic (EC) energy storage devices emerge as a promising alternative to conventional glass, yet their widespread commercialization is impeded by high costs and dependence on external power sources. Addressing this, redox potential-based self-powered electrochromic (RP-SPEC) devices are introduced leveraging established EC materials like tungsten oxide (WO3) and vanadium-doped nickel oxide (V-NiO) along with aluminum (Al) as an anode. These devices produce open circuit voltages (OCV) exceeding ±0.3V, enabling autonomous operation for multiple cycles. The WO3 film exhibits 1% transmission and 88% modulation in the colored state at 550nm with a mere 260nm thickness. The redox interactions facilitate coloring and bleaching cycles without external power, while photo-charging rejuvenates the system. Notably, the inherent voltages of the RP-SPEC device offer dual functionality, powering electronic devices for up to 81h. Large-area (≈28 cm2) device feasibility is demonstrated, paving the way for industrial adoption. The RP-SPEC device promises to revolutionize smart window technology by offering both energy efficiency and autonomous operation, thus advancing sustainable infrastructure.

Surface-Roughened Graphene Oxide Microfibers Enhance Electrochemical Reversibility.

Here, we provide an optimized method for fabricating surface-roughened graphene oxide disk microelectrodes (GFMEs) with enhanced defect density to generate a more suitable electrode surface for dopamine detection with fast-scan cyclic voltammetry (FSCV). FSCV detection, which is often influenced by adsorption-based surface interactions, is commonly impacted by the chemical and geometric structure of the electrode's surface, and graphene oxide is a tunable carbon-based nanomaterial capable of enhancing these two key characteristics. Synthesized GFMEs possess exquisite electronic and mechanical properties. We have optimized an applied inert argon (Ar) plasma treatment to increase defect density, with minimal changes in chemical functionality, for enhanced surface crevices to momentarily trap dopamine during detection. Optimal Ar plasma treatment (100 sccm, 60 s, 100 W) generates crevice depths of 33.4 ± 2.3 nm with high edge plane character enhancing dopamine interfacial interactions. Increases in GFME surface roughness improve electron transfer rates and limit diffusional rates out of the crevices to create nearly reversible dopamine electrochemical redox interactions. The utility of surface-roughened disk GFMEs provides comparable detection sensitivities to traditional cylindrical carbon fiber microelectrodes while improving temporal resolution ten-fold with amplified oxidation current due to dopamine cyclization. Overall, surface-roughened GFMEs enable improved adsorption interactions, momentary trapping, and current amplification, expanding the utility of GO microelectrodes for FSCV detection.

Manganese- and Platinum-Driven Oxidative and Nitrosative Stress in Oxaliplatin-Associated CIPN with Special Reference to Ca4Mn(DPDP)5, MnDPDP and DPDP.

Platinum-containing chemotherapeutic drugs are efficacious in many forms of cancer but are dose-restricted by serious side effects, of which peripheral neuropathy induced by oxidative-nitrosative-stress-mediated chain reactions is most disturbing. Recently, hope has been raised regarding the catalytic antioxidants mangafodipir (MnDPDP) and calmangafodipir [Ca4Mn(DPDP)5; PledOx®], which by mimicking mitochondrial manganese superoxide dismutase (MnSOD) may be expected to overcome oxaliplatin-associated chemotherapy-induced peripheral neuropathy (CIPN). Unfortunately, two recent phase III studies (POLAR A and M trials) applying Ca4Mn(DPDP)5 in colorectal cancer (CRC) patients receiving multiple cycles of FOLFOX6 (5-FU + oxaliplatin) failed to demonstrate efficacy. Instead of an anticipated 50% reduction in the incidence of CIPN in patients co-treated with Ca4Mn(DPDP)5, a statistically significant increase of about 50% was seen. The current article deals with confusing differences between early and positive findings with MnDPDP in comparison to the recent findings with Ca4Mn(DPDP)5. The POLAR failure may also reveal important mechanisms behind oxaliplatin-associated CIPN itself. Thus, exacerbated neurotoxicity in patients receiving Ca4Mn(DPDP)5 may be explained by redox interactions between Pt2+ and Mn2+ and subtle oxidative-nitrosative chain reactions. In peripheral sensory nerves, Pt2+ presumably leads to oxidation of the Mn2+ from Ca4Mn(DPDP)5 as well as from Mn2+ in MnSOD and other endogenous sources. Thereafter, Mn3+ may be oxidized by peroxynitrite (ONOO-) into Mn4+, which drives site-specific nitration of tyrosine (Tyr) 34 in the MnSOD enzyme. Conformational changes of MnSOD then lead to the closure of the superoxide (O2•-) access channel. A similar metal-driven nitration of Tyr74 in cytochrome c will cause an irreversible disruption of electron transport. Altogether, these events may uncover important steps in the mechanism behind Pt2+-associated CIPN. There is little doubt that the efficacy of MnDPDP and its therapeutic improved counterpart Ca4Mn(DPDP)5 mainly depends on their MnSOD-mimetic activity when it comes to their potential use as rescue medicines during, e.g., acute myocardial infarction. However, pharmacokinetic considerations suggest that the efficacy of MnDPDP on Pt2+-associated neurotoxicity depends on another action of this drug. Electron paramagnetic resonance (EPR) studies have demonstrated that Pt2+ outcompetes Mn2+ and endogenous Zn2+ in binding to fodipir (DPDP), hence suggesting that the previously reported protective efficacy of MnDPDP against CIPN is a result of chelation and elimination of Pt2+ by DPDP, which in turn suggests that Mn2+ is unnecessary for efficacy when it comes to oxaliplatin-associated CIPN.

Integrating Tide‐Driven Wetland Soil Redox and Biogeochemical Interactions Into a Land Surface Model

AbstractRedox processes, aqueous and solid‐phase chemistry, and pH dynamics are key drivers of subsurface biogeochemical cycling and methanogenesis in terrestrial and wetland ecosystems but are typically not included in terrestrial carbon cycle models. These omissions may introduce errors when simulating systems where redox interactions and pH fluctuations are important, such as wetlands where saturation of soils can produce anoxic conditions and coastal systems where sulfate inputs from seawater can influence biogeochemistry. Integrating cycling of redox‐sensitive elements could therefore allow models to better represent key elements of carbon cycling and greenhouse gas production. We describe a model framework that couples the Energy Exascale Earth System Model (E3SM) Land Model (ELM) with PFLOTRAN biogeochemistry, allowing geochemical processes and redox interactions to be integrated with land surface model simulations. We implemented a reaction network including aerobic decomposition, fermentation, sulfate reduction, sulfide oxidation, methanogenesis, and methanotrophy as well as pH dynamics along with iron oxide and iron sulfide mineral precipitation and dissolution. We simulated biogeochemical cycling in tidal wetlands subject to either saltwater or freshwater inputs driven by tidal hydrological dynamics. In simulations with saltwater tidal inputs, sulfate reduction led to accumulation of sulfide, higher dissolved inorganic carbon concentrations, lower dissolved organic carbon concentrations, and lower methane emissions than simulations with freshwater tidal inputs. Model simulations compared well with measured porewater concentrations and surface gas emissions from coastal wetlands in the Northeastern United States. These results demonstrate how simulating geochemical reaction networks can improve land surface model simulations of subsurface biogeochemistry and carbon cycling.

Estimation of Potassium Bromate- an Alarming Carcinogen in Commercial Bread Samples Around Dhaka City

The primary goal of this study was to determine the presence of potassium bromate in bread samples both qualitatively and quantitatively, as well as to investigate the composition of the bread (moisture, ash, and sugar contents). Thirty different commercial bread samples from different areas of Dhaka city were collected for analysis. The ultraviolet-visible spectrophotometric technique was employed in this study to estimate potassium bromate in bread samples. It was based on the redox interaction of bromate and promethazine hydrocloride in an acidic medium which generate a red-pink coloration with maximum absorbance at 515nm. The amount of potassium bromate was found in the range of 1.24 to 24.91µg/g. Moisture and ash content were found to be 15.37 to 29.8% and 1.75 to 2.94%, respectively. The total sugar content was determined by the ultraviolet-visible spectrophotometric method by the modified phenol-sulfuric acid test and the maximum absorbance was obtained at 489 nm. Total sugar content was found in different types of white bread samples ranging from 3.33 to 11.31g per 100g. The average recovery (n=5) of potassium bromate was 91.58 ± 5.61% at a dosage of 10 μg/mL. Dhaka Univ. J. Sci. 72(1): 1-6, 2024 (January)