Ferrous Oxidation Research Articles

Enhanced removal of nanoplastics from freshwater using in-situ synthesized and anchored nano-Fe3O4 via two-step ferrous oxidation

Magnetic separation is a promising strategy for removing nanoplastics (NPs) from water; however, it often requires complex processeses, such as synthesizing nano-Fe3O4 magnets and attaching them to specific carriers. This study presents an innovative and efficient strategy to in-situ synthesize and anchor nano-Fe3O4 onto polystyrene (PS) NPs through a two-step oxidation of ferrous ions, which significantly enhances NPs removal via magnetic separation. The two-step process involves initial alkalization of a ferrous aqueous solution under anoxic conditions, followed by oxidation in air. In the presence of PS spheres, nano-Fe3O4 forms in-situ on the PS surfaces, promoting sedimentation under a magnetic field. Results demonstrate that two-step ferrous oxidation achieves superior removal rates, with 99.32 % for 500 nm PS spheres (PS-500) and 93.16 % for 100 nm PS spheres (PS-100) using a low Fe2+ dosage of 0.1 mM. In contrast, the conventional one-step method, which simultaneously alkalizes and oxidizes ferrous sulfate in aerobic conditions, fails to form nano-Fe3O4 and results in low removal rates of only 56.49 % for PS-500 and 8.89 % for PS-100, respectively. Furthermore, the turbidity and residual Fe can be reduced to below 1 NTU and 0.1 mg/L by using two-step process, respectively, meeting drinking water safety and hygiene standards. This approach not only simplifies the magnetic nanomaterial preparation process but also substantially improves the NP removal efficiency, offering a promising solution for enhanced water treatment technologies and safer drinking water.

Monoamine Oxidase Contributes to Valvular Oxidative Stress: A Prospective Observational Pilot Study in Patients with Severe Mitral Regurgitation.

Monoamine oxidases (MAOs), mitochondrial enzymes that constantly produce hydrogen peroxide (H2O2) as a byproduct of their activity, have been recently acknowledged as contributors to oxidative stress in cardiometabolic pathologies. The present study aimed to assess whether MAOs are mediators of valvular oxidative stress and interact in vitro with angiotensin 2 (ANG2) to mimic the activation of the renin-angiotensin system. To this aim, valvular tissue samples were harvested from 30 patients diagnosed with severe primary mitral regurgitation and indication for surgical repair. Their reactive oxygen species (ROS) levels were assessed by means of a ferrous oxidation xylenol orange (FOX) assay, while MAO expression was assessed by immune fluorescence (protein) and qRT-PCR (mRNA). The experiments were performed using native valvular tissue acutely incubated or not with angiotensin 2 (ANG2), MAO inhibitors (MAOI) and the angiotensin receptor blocker, irbesartan (Irb). Correlations between oxidative stress and echocardiographic parameters were also analyzed. Ex vivo incubation with ANG2 increased MAO-A and -B expression and ROS generation. The level of valvular oxidative stress was negatively correlated with the left ventricular ejection fraction. MAOI and Irb reduced valvular H2O2. production. In conclusion, both MAO isoforms are expressed in pathological human mitral valves and contribute to local oxidative stress and ventricular functional impairment and can be modulated by the local renin-angiotensin system.

Two targets, one strike: Efficient recovery of lithium and simultaneous removal of impurities from spent LFP batteries via ferric ions assisted air oxidation method

Recycling of spent lithium-ion batteries (LIBs) has become urgently imperative to address global environmental issues and achieve sustainable development of new energy industries. Prioritizing lithium and aluminum leaching is an ideal path for recovering lithium efficiently from spent LFP and preparing high-purity battery-grade FePO4. Here, a novel ferric ions-assisted air oxidation method was proposed for the simultaneous leaching of Li and Al. Fe3+ was ingeniously introduced playing two roles: acting as a catalyst for air oxidation and leaching aluminum. 98.8% Li and 95.2% Al are selectively leached under optimal conditions. The thermodynamic analysis indicated that the displacement reaction between Al and Fe3+ dominates the leaching of Al. Furthermore, Cl− can promote the leaching of Al by forming a stable complex [AlCl4]− with Al3+. The reaction course and mechanism were clarified by various characterizations, which indicate that the successful selective leaching of lithium does not destroy the original structure of LFP and the presence of carbon coatings. A cycling process was proposed for enriching the Li+ concentration and reusing Fe3+, and then Li2CO3 with a purity of 99wt.% was successfully prepared. This method demonstrates excellent economic efficiency and environmental friendliness, thus providing a sustainable and low-carbon recycling route for the spent LFP industry.

Metagenomic analysis reveals enhanced sludge dewaterability through acidified sludge inoculation: Regulation of Fe (II) oxidation electron transport pathway

The bioleaching utilizing indigenous microbial inoculation can continuously improve the dewaterability of sludge. In this study, metagenomic analysis was innovative employed to identify the key microorganisms and functional genes that affect the dewatering performance of sludge in the bioleaching conditioning process. The results demonstrated that long-term repeated inoculation of acidified sludge resulted in increased abundance of many functional genes associated with the transport of carbohydrate and amino acid. Additionally, genes encoding key iron transport proteins (such as afuA, fhuC, and fhuD) and genes related to electron transfer carriers in ferrous iron oxidation process (such as rus and cyc2) were significantly enriched, thereby promoting the improvement of sludge dewatering performance through enhanced iron oxidation. Notably, Acidithiobacillus, Betaproteobacteria, and Hyphomicrobium were the major sources of functional genes. This study reveals the microscopic mechanisms underlying the improvement of sludge dewaterability through bioleaching based on mixed culture from a novel perspective of gene metabolism.

Fe(II)-mediated Fe–N–P metabolism in an anammox-dominated system for enhanced nitrogen removal and Fe–P crystals (FePs) production

Low-carbon and high-efficiency processes for achieving simultaneous nitrogen removal and phosphorus recovery from wastewater are gaining increasing attention from researchers. This study investigated the performance and mechanism of a novel Fe(II)-mediated anaerobic ammonia oxidation (anammox) process characterized by stable nitrogen removal and production of high-value Fe–P crystals (FePs) as byproducts. Fe(II) promotes the synthesis of heme C and enhances the activity of nitrate reduction metabolic genes, which induce nitrate-dependent ferrous oxidation to form a complex Fe–N cycle. In addition, Fe(II) significantly enhanced the phosphorus removal efficiency up to 79.2 ± 6.9% by inducing Fe–P biomineralization. Biomolecular analysis has shown that most iron absorption and transport genes, as well as phosphate transport and regulation genes, are promoted by Fe(II). The composition and microstructure analyses of the anammox granules revealed the formation of FePs that consisted of phosphosiderite (FePO4·2H2O), ludlamite (Fe3(PO4)2·4H2O), and vivianite (Fe3(PO4)2∙8H2O). This study also provides an in-depth illustration of the structural characteristics and formation processes of anammox-FePs granules. Thus, an Fe(II)-induced Fe–N–P metabolic network in an anammox-dominated system was uncovered, offering a feasible approach for simultaneous nitrogen removal and phosphorus recovery.

New insights and enhancement mechanisms of activated carbon in autotrophic denitrification system utilizing zero-valent iron as indirect electron donors

Zero-valent iron acts as an indirect electron donor, supplying ferrous iron for the nitrate-dependent ferrous oxidation (NDFO) process. The addition of activated carbon (AC) increased the specific NDFO activity in situ and ex situ by 0.4 mg-N/(d·g VSS) and 2.2 mg-N/(d·g VSS), respectively, due to the enrichment of NDFO bacteria. Furthermore, AC reduced the nitrous oxide emission potential of the sludge, a mechanism that metagenomic analysis suggests may act as a cellular energy storage strategy. During a 196-day experiment, a total nitrogen removal efficiency of 53.7 % was achieved, which may be attributed to the upregulation of key genes involved in iron oxidation and denitrification. Based on these findings, a model involving pilin, ’nanowires,’ and a cyc2/?→/(FoxE→FoxY)/?→cymA/Complex III/?-mediated pathway for extracellular electron uptake was proposed. Overall, this work provides a feasible strategy for enhancing the nitrogen removal performance of the ZVI-NDFO process.

Ferrous iron oxidation efficiency and kinetics by indigenous iron-oxidizing bacteria in acid mine drainage

Biological Fe(II) oxidation by iron-oxidising bacteria (FeOBs) at low pH is a cost-effective treatment for acid mine drainage (AMD). However, treatments based on this process are limited because of uncertainties regarding the ability and rate of oxidation of Fe(II) from AMD. In the present study, an indigenous FeOBs consortium was enriched in AMD, and its ability to oxidise Fe(II) is described. The bio-oxidation rate of Fe(II) was 39.1 mg/(L·h) under optimal culture conditions [35 ℃, pH 2.0, 500 mg/L Fe(II)]. In addition, the oxidation rate equation of Fe(II) could be fitted to a zero-order kinetic model, indicating that Fe(II) was oxidised at a constant rate. Furthermore, a continuous-flow bioreactor was developed to simulate the Fe(II) oxidation efficiency of indigenous FeOBs for in situ AMD biological treatment. The maximum Fe(II) oxidation rate was 22.8 mg/(L·h) when the influent Fe(II) load was 32.3 mg/(L·h). Acidithiobacillus and Acidiphilium were the dominant species contributing to Fe(II) oxidation in the bioreactor, accounting for 67.7 % and 32.8 %, respectively. The results will help promote the application of FeOBs in AMD treatment.

Performances and mechanisms of anaerobic nitrogen removal through Fe (III)/Fe (II) cycle with sponge iron biofilm without external iron addition

Anaerobic ammonia oxidation coupled to Fe (III) reduction (Feammox) plays an important role in the natural nitrogen cycle. However, for its application in wastewater treatment process, the source of iron is a major limitation. In this study, Feammox process was successfully achieved without external iron addition using sponge iron biofilm. The products of Feammox process, nitrate and Fe (II), provided substrates for nitrate dependent ferrous oxidation (NDFO). Therefore, nitrogen removal and Fe (II)/Fe (III) cycle were achieved in reactor and nitrogen removal efficiency by Feammox and NDFO pathways was up to 58.4 %. The X-ray diffraction indicated the sludge contained magnetite and lepidocrocite, which provided Fe (III) for the occurrence of Feammox. Microorganisms related to Feammox process were dominated by Geothrix. It was found Feammox activity was similar at pH of 8 and 7, while inhibited at pH of 6, which was caused by the decrease of Feammox bacteria. And Feammox activity decreased with the decrease of temperature, in which the ammonia removal rate was 2 times faster at 30 °C than at 10 °C. Under micro‑oxygen aeration, the ammonia removal rate improved and Feammox and NDFO processes still played roles in system, nevertheless, under high dissolved oxygen condition, Feammox bacteria-Geothrix and NDFO bacteria Thiobacillus would be gradually eliminated from the system.

Synergistic effect of Ca(NO3)2 - CaO2 on the improvement of sediment microecology: Transformation of sulfur and ferrous iron, and improvement mechanism

The synergy of Ca(NO3)2 and CaO2 can effectively reduce the risks of secondary pollution caused by nitrate escape and release. However, the timing and suitable dosage of Ca(NO3)2 and CaO2 during the synergistic interaction have not been fully investigated. In this work, we separated acid volatile sulfides (AVS) oxidation and ferrous iron oxidation by controlling the dosage of Ca(NO3)2. Results indicated that at a low RN/1.6S2−ratio, there was an obvious competitive relationship between AVS oxidation and ferrous iron oxidation, and sulfide was oxidized prior to ferrous iron. More efficient AVS and ferrous iron oxidation was achieved using Ca(NO3)2 to oxidize AVS and CaO2 to oxidize ferrous iron. After the treatment with Ca(NO3)2 and CaO2, the anaerobic reduction environment of the sediment was modified, and the metabolic pathways dominated by sulfate respiration and methanogenic metabolism in the sediment were gradually converted to nitrate-reduction and dissimilatory iron reduction. The synergy of Ca(NO3)2 and CaO2 could reduce 99.61 % CH4 compared with control check and could reduce 81.66 % N2O compared with adding Ca(NO3)2 only. Furthermore, the biodegradability of organic matter was improved due to the transformation of stubborn organic matter. These results provide valuable guidance for applying Ca(NO3)2 and CaO2 in sediment remediation.

Improving the transfer of dissolved oxygen in a biological Fe2+ oxidation process using a venturi jet as an intensive aeration system

The low bio-production of Fe3+ as a leaching agent is one of the main limitations to implementing industrial bio-processes at feasibility conditions. The main limitation of the bio-oxidation process of Fe2+ is the low oxygen transfer to the aqueous phase because of the low oxygen solubility. This study assesses the effectiveness of the venturi jet as an innovative and intensive aeration device for overcoming the oxygen limitation in a continuous ferrous oxidation process in a fixed-bed reactor with immobilized acidithiobacillus ferrooxidans, in contrast to the conventional diffuser aeration device. Firstly, the influence of the airflow and the influence of the medium concentration were determined for the following parameters for both aeration devices; Volumetric mass transfer coefficient (kLa), Standard Oxygen Transfer Rate (SOTR), Standard Aeration Efficiency (SAE), and Standard Oxygen Transfer Efficiency (SOTE). Then, both aeration devices were compared in a continuous bio-oxidation process in an up-flow packed bio-reactor (UFPB). The system performance was assessed by monitoring temperature, pH, oxidation-reduction potential, and dissolved oxygen concentration for 69 days. Findings displayed that when aerating with the diffuser, the ferrous oxidation rate was restricted by the low dissolved oxygen availability, being about 1 ppm (1 mg L−1). Under these oxygen-limiting conditions, the maximum ferrous (Fe2+) oxidation rate was 9.09 g L−1 h−1. However, when aerating with the venturi jet, the dissolved oxygen concentration increased up to 2.70 mg L−1, achieving a maximum of 29.11 g L−1 h−1. So, this study has demonstrated that the change in the aeration device has resulted in an improvement in the process, achieving a 3.5-fold increase in the oxidation rate. Furthermore, the venturi jet offered additional advantages over the diffuser, such as requiring less power to deliver the same amount of air, being unaffected by jarosite precipitates, and not requiring a supply of compressed air.

Critical roles of low-molecular-weight organic acid in enhancing hydroxyl radical production by ferrous oxidation on γ-Al2O3 mineral surface

Recognizing the pervasive presence of alumina minerals and low-molecular-weight organic acids (LMWOAs) in the environment, this study addressed the gap in the interaction mechanisms within the ternary system involving these two components and Fe(II). Specifically, the impacts of LMWOAs on hydroxyl radicals (•OH) production and iron species transformation during Fe(II) oxidation on γ-Al2O3 mineral surface were examined. Results demonstrated that adding 0.5 mM oxalate (OA) or citrate (CA) to the γ-Al2O3/Fe(II) system (28.1 μM) significantly enhanced •OH production by 1.9-fold (51.9 μM) and 1.3-fold (36.2 μM), respectively, whereas succinate (SA) exhibited limited effect (30.7 μM). Raising OA concentration to 5 mM further promoted •OH yield to 125.0 μM after 24 h. Deeper analysis revealed that CA facilitated the dissolution of adsorbed Fe(II) and its subsequent oxygenation by O2 through both one- and two-electron transfer mechanisms, whereas OA enhanced the adsorption of dissolved Fe(II) and more efficient two-electron transfer for H2O2 production. Additionally, LMWOAs presence favored the formation of iron minerals with poor crystallinity like ferrihydrite and lepidocrocite rather than well-crystallized forms such as goethite. The distinct impacts of various LMWOAs on Fe(II) oxidation and •OH generation underscore their unique roles in the redox processes at mineral surface, consequently modulating the environmental fate of prototypical pollutants like phenol.

Enhanced Arsenate Immobilization by Kaolinite via Heterogeneous Pathways during Ferrous Iron Oxidation.

Clay minerals are ubiquitous in subsurface environments and have long been recognized as having a limited or negligible impact on the fate of arsenic (As) due to their negatively charged surfaces. Here, we demonstrate the significant role of kaolinite (Kln), a pervasive clay mineral, in enhancing As(V) immobilization during ferrous iron (Fe(II)) oxidation at near-neutral pH. Our results showed that Fe(II) oxidation alone was not capable of immobilizing As(V) at relatively low Fe/As molar ratios (≤2) due to the generation of Fe(III)-As(V) nanocolloids that could still migrate easily as truly dissolved As did. In the presence of kaolinite, dissolved As(V) was significantly immobilized on the kaolinite surfaces via forming Kln-Fe(III)-As(V) ternary precipitates, which had large sizes (at micrometer levels) to reduce the As mobility. The kaolinite-induced heterogeneous pathways for As(V) immobilization involved Fe(II) adsorption, heterogeneous oxidation of adsorbed Fe(II), and finally heterogeneous nucleation/precipitation of Fe(III)-As(V) phases on the edge surfaces of kaolinite. The surface precipitates were mixtures of amorphous basic Fe(III)-arsenate and As-rich hydrous ferric oxide. Our findings provide new insights into the role of clay minerals in As transformation, which is significant for the fate of As in natural and engineered systems.

Development of Technology for the Bioleaching of Uranium in a Solution of Bacterial Immobilization

This study presents findings regarding the kinetics of ferrous iron oxidation in solution mediated by Acidithiobacillus ferrooxidans bacteria within a continuous-flow bioreactor employing diverse types of immobilizers. The objective is to augment the rate of ferrous iron oxidation in solutions utilizing an immobilizer for Acidithiobacillus ferrooxidans strains. Immobilization represents a promising avenue for enhancing the efficiency of Fe2⁺ oxidation via acidophilic ferrooxidizing bacteria, leading to a several-fold increase in oxidation rate. A comparative analysis was conducted to evaluate the efficacy of different types of immobilizer in facilitating iron oxidation within a continuous-flow bioreactor, including the application of wood chips coated with Fe(OH)3. The results indicate that wood chips coated with iron hydroxide serve as effective type of immobilizer, facilitating the robust attachment of Acidithiobacillus ferrooxidans via electrostatic interactions between negatively charged bacteria and positively charged surfaces. Experimental investigations were conducted using novel immobilization matrices in pilot-scale tests simulating the underground borehole leaching (UBL) of uranium. The bioactivation of leaching solutions enhances the efficiency and environmental compatibility of UBL compared to conventional chemical oxidation methods. The relationships between redox potential and ferric iron content in bioactivated solutions during the UBL of uranium were delineated. The significance of this study lies in its elucidating the pivotal role of Fe2⁺ oxidation in uranium extraction processes, particularly in the context of UBL. By employing bioactivation mediated by Acidithiobacillus ferrooxidans, the study demonstrates not only enhanced uranium extraction efficiency, but also markedly improved environmental sustainability compared to traditional chemical oxidation methods. The findings reveal crucial correlations between redox potential and ferric iron concentration in bioactivated solutions.

#289 Lipocalin-2 promotes cardiovascular calcification in chronic kidney disease by upregulating STAT3/NCOA4-mediated ferritinophagy and ferroptosis

Abstract Background and Aims Cardiovascular calcification (CVC) is a common complication of chronic kidney disease (CKD) and contributes to cardiovascular morbidity and mortality without any effective therapies. To date, the underlying mechanism of CKD-CVC has not been elucidated. Recent studies suggest that ferroptosis is a novel programmed cell death that may play a role in the process of CKD-CVC, but the mechanism is largely unclear. Ferritinophagy is an important inducer of ferroptosis that is regulated by nuclear receptor coactivator 4 (NCOA4). However, the relationship between ferritinophagy and CKD-CVC has not been explored. Lipocalin-2 (LCN2) is an iron-trafficking protein that has been associated with both osteogenesis and ferroptosis, but the exact role and molecular mechanism of LCN2 in CKD-CVC needs to be explored. Method A cross-sectional clinical study was utilized to examine the association between LCN2 expression and CKD-CVC in serum and calcified radial arteries of CKD patients. LCN2 knockout mice, their wild type littermates and mice infected with VSMCs-targeted adeno-associated virus encoding LCN2 gene or negative control gene were all fed by the high adenine and phosphate diet to induce CKD-CVC.VSMCs transfected with LCN2-overexpressing lentivirus, LCN2-shRNA lentivirus or LCN2 siRNA and recombinant LCN2 stimulated VSMCs were treated under the condition of calcifying medium to investigate the role of LCN2 in CKD-CVC in vitro. Cardiovascular calcification was evaluated by Von-kossa staining and tissue calcium content assay. VSMCs calcification were checked by the Alizarin Red Staining and cellular calcium content assay. Cellular reactive oxygen species (ROS) were measured by the DCFDA assay. Lipid peroxidation was measured by the fluorescence of the fatty acid analog C11-BODIPY581/591 probe. Intracellular labile ferrous iron levels were measured by fluorescence of Phen Green SK probe and ferro-orange probe. Transmission electron microscopy was also used to examine mitochondrial change of ferroptosis. Results The cross-sectional study identified that LCN2 levels in serum and radial arteries were significantly increased as the severity of CKD-CVC increased. High adenine and phosphate diet intake provokes renal fibrosis and cardiovascular calcification in vivo. In vitro, five-days high phosphate sodium stimulation induced calcium deposition and osteoblastic trans differentiation of VSMCs. Meanwhile, high phosphate also increased the levels of ferroptosis in VSMCs as evidenced by decreased cell viability, iron and ROS accumulation, upregulated PTGS2 and MDA levels, reduced glutathione peroxidase 4 (GPX4) levels and significantly mitochondrial damage in VSMCs. Intriguingly, calcium deposition in VSMCs could be reversed by the ferroptosis inhibitor ferrostatin-1. LCN2 expression was significantly upregulated both in the aorta of mice and calcified VSMCs. Compared with WT mice, deletion of LCN2 inhibited cardiovascular calcification whereas VSMC-targeted LCN2 overexpression aggravated CKD-CVC. Consistently, LCN2 knockdown also alleviated calcium deposition of VSMCs. Meanwhile, inhibition of ferroptosis were observed after LCN2 silencing as evidenced by decreased ferrous and lipid oxidation while increased levels of GPX4. Mechanically, we demonstrated high phosphate increased the protein level of NCOA4 and downregulated FTH1, which was reversed by depletion of LCN2. Knockdown of NCOA4 partly alleviated the ferritin reduction, ferroptosis, and calcification in VSMCs, indicating that NCOA4-mediated ferritinophagy was required for VSMCs calcification. Furthermore, we found that the recombinant LCN2 treatment significantly upregulated phosphorylated STAT3. STAT3 signaling inhibitor abolished the recombinant LCN2 induced NCOA4 upregulation and calcification in VSMCs. Conclusion Our findings indicate that the pro-calcific effect of high phosphate is due to VSMCs ferroptosis mediated by LCN2 upregulation. LCN2 silencing alleviates CKD-CVC by suppressing the STAT3/ NCOA4/FTH1 signaling mediated ferritinophagy. LCN2 could serve as a candidate therapeutic strategy for CKD-CVC.

Advanced remediation in the presence of ferrous iron and carbonate-containing water by oxygen-induced oxidation of organic contaminants

Mechanistic investigations of an environmentally friendly and easy-to-implement oxidation method in the remediation of contaminated anoxic waters, i.e. groundwater, through the sole use of oxygen for the oxygen-induced oxidation of pollutants were the focus of this work. This was achieved by the addition of O2 under anoxic conditions in the presence of ferrous iron which initiated the ferrous oxidation and the simultaneous formation of reactive •OH radicals. The involvement of inorganic ligands such as carbonates in the activation of oxygen as part of the oxidation of Fe2+ in water was investigated, too. The formation of •OH radicals, was confirmed in two different, indirect approaches by a fluorescence-based method involving coumarin as •OH scavenger and by the determination of the oxidation products of different aromatic VOCs. In the latter case, the oxidation products of several typical aromatic groundwater contaminants such as BTEX (benzene, toluene, ethylbenzene, xylenes), indane and ibuprofen, were determined. The influence of other ligands in the absence of bicarbonate and the effect of pH were also addressed.The possibility of activation of O2 in carbonate-rich water i.e. groundwater, may also potentially contribute to oxidation of groundwater contaminants and support other primary remediation techniques.

Catalytic nanoreactors promote GLUT1-mediated BBB permeation by generating nitric oxide for potentiating glioblastoma ferroptosis

Glioblastoma, the most common malignant brain tumor with a poor prognosis, still needs to develop effective therapeutic strategies to prolong the patient’s survival. Inducing GBM tumor cell ferroptosis could be the specific assay to improve GBM therapeutic efficiency. In comparison, ferroptosis in GBM cells is limited by the low intracellular ferrous ion concentration and oxidation resistance. Herein, an MNP-based ferroptosis catalytic nanoreactor loading cisplatin (CMNP-Cis-Arg) was designed to evaluate their targeted delivery and therapeutic efficiency in GBM treatment. The ferroptosis catalytic nanoreactors achieved an effective GBM targeted transportation via chitosan oligosaccharide driven GLUT1-mediated BBB permeabilization and arginine-based tumor chemotactic. CMNP-Cis-Arg improves synergistically lipid oxidation in GBM cells by inducing ROS generation and depleting intracellular GSH. The MNPs elevate ROS levels in tumor cells by enhancing Fe2+-based Fenton reaction and the encapsulated cisplatin as a chemotherapy agent depleting GSH via inducing the DNA strand broken. Moreover, the CMNP-Cis-Arg further induces NO biosynthesis and generates ONOO– with high oxidability to increase lipid oxidation. The anti-GBM ability of the CMNP-Cis-Arg was evaluated both in vitro and in vivo, significantly inducing the GBM tumor cells’ apoptosis and reducing the tumor burden in an orthotopic mouse model. The investigation provided a novel ferroptosis catalytic nanoreactor and confirmed their anti-GBM efficiency in boosting tumor intracellular ferroptosis, suggesting a potential therapeutic strategy worth further investigating preclinically.

Assessing the Relationship between Indexed Epicardial Adipose Tissue Thickness, Oxidative Stress in Adipocytes, and Coronary Artery Disease Complexity in Open-Heart Surgery Patients.

Background and Objectives: This cross-sectional study conducted at the Timișoara Institute of Cardiovascular Diseases, Romania, and the Centre for Translational Research and Systems Medicine from "Victor Babeș" University of Medicine and Pharmacy of Timișoara, Romania, investigated the relationship between indexed epicardial adipose tissue thickness (EATTi) and oxidative stress in epicardial adipose tissue (EAT) adipocytes in the context of coronary artery disease (CAD) among open-heart surgery patients. The objective was to elucidate the contribution of EATTi as an additional marker for complexity prediction in patients with CAD, potentially influencing clinical decision-making in surgical settings. Materials and Methods: The study included 25 patients undergoing cardiac surgery, with a mean age of 65.16 years and a body mass index of 27.61 kg/m2. Oxidative stress in EAT was assessed using the ferrous iron xylenol orange oxidation spectrophotometric assay. The patients were divided into three groups: those with valvular heart disease without CAD, patients with CAD without diabetes mellitus (DM), and patients with both CAD and DM. The CAD complexity was evaluated using the SYNTAX score. Results: The EATTi showed statistically significant elevations in the patients with both CAD and DM (mean 5.27 ± 0.67 mm/m2) compared to the CAD without DM group (mean 3.78 ± 1.05 mm/m2, p = 0.024) and the valvular disease without CAD group (mean 2.67 ± 0.83 mm/m2, p = 0.001). Patients with SYNTAX scores over 32 had significantly higher EATTi (5.27 ± 0.66 mm/m2) compared to those with lower scores. An EATTi greater than 4.15 mm/m2 predicted more complex CAD (SYNTAX score >22) with 80% sensitivity and 86% specificity. The intra- and interobserver reproducibility for the EATTi measurement were excellent (intra-class correlation coefficient 0.911, inter-class correlation coefficient 0.895). Conclusions: EATTi is significantly associated with CAD complexity in patients undergoing open-heart surgery. It serves as a reliable indicator of more intricate CAD forms, as reflected by higher SYNTAX scores. These findings highlight the clinical relevance of EATTi in pre-operative assessment, suggesting its potential utility as a prognostic marker in cardiac surgical patients.

Exploring microbial adaptation of immobilised acidophilic cultures to improve microbial oxidation rates and copper tolerance in e-waste bioleaching

The rate of ferric iron regeneration by microbial oxidation is the rate determining step in the bioleaching of printed circuit boards (PCBs). Therefore, improvement of the volumetric rate of ferric iron formation is key for the overall bioleaching efficiency. The volumetric rate is impacted by both the specific rate and the biomass concentration. Limiting the exposure of the bioleaching microorganisms to accumulated toxic metal ions in solution, as well as the presence of inhibiting material components in PCBs through biofilm formation and immobilisation, as well as their adaptation to these inhibitors, is proposed to mitigate against decrease in specific rate while biomass retention by immobilisation is expected to positively impact volumetric rate. In this study, a mixed mesophilic culture, consisting of Leptospirillum (L.) ferriphilum, Acidithiobacillus (At.) caldus, Acidiplasma (Ap.) cupricumulans as dominant species was immobilised on polyurethane foam (PUF) and adapted to 6.0 g/L Cu2+. The rate of microbial ferrous iron oxidation by the immobilised culture was compared to that of planktonic cultures. Further, the performance of both the planktonic and immobilised Cu-adapted cultures (6.0 g/L of Cu2+) were compared with non-adapted planktonic and immobilised cells in the presence of increasing Cu2+ concentrations (0–50 g/L Cu2+).Both the Cu-adapted planktonic cells and the non-adapted immobilised cells demonstrated improved tolerance to Cu2+ stress relative to non-adapted planktonic cells. The Cu-adapted planktonic cells showed higher volumetric ferrous iron oxidation rates (0.0359 ± 0.0023 g Fe2+.L−1.h−1 at 22 g/L Cu2+) than the non-adapted immobilised cells (0.0331 ± 0.0021 g Fe2+.L−1.h−1) in the presence of Cu2+ concentrations exceeding 6 g/L. The Cu-adapted immobilised cells exhibited higher tolerance to Cu2+ stress and higher oxidation kinetics (0.0622 ± 0.0064 g Fe2+.L−1.h−1) than the Cu-adapted planktonic and non-adapted immobilised cells. This study provides a novel approach for improving culture performance and minimising the inhibitory effect of Cu2+ ion on L. ferriphilum dominated cultures. High microbial activity and metal tolerance of Cu-adapted immobilised cells presents an opportunity for immobilised microbial systems to be used both in bioleaching of e-waste streams, such as PCBs, and in bioleaching of mineral concentrates, ores and wastes with Cu2+-rich leachates.

Reactive oxygen species on indoor surfaces.

Reactive oxygen species (ROS) are relatively unstable oxygen-containing radicals or non-radicals, some of which may react with tissues and biomolecules after entering the body. ROS is present in indoor aerosols, but it is unclear how much of that ROS is of indoor origin. Indoor surface films have been hypothesized to be a major source of the ROS observed on indoor aerosols. In this study, the ROS concentration on residential indoor surfaces was measured using a xylenol orange ferrous oxidation assay after wiping and extraction. On genuine surfaces frequently touched by apartment occupants, the concentration was >0.2 nmol cm-2; infrequently touched surfaces were at or below detection limits. On clean glass plates that had been deployed in apartments for 6 weeks, horizontal plates had higher concentrations than vertically oriented plates. The highest concentration, 1.3 nmol cm-2, was observed on a horizontally oriented plate close to an electric stove. To simulate the dynamic oxidation of unsaturated hydrocarbons on indoor surfaces, a surface lipid mixture (SLM) was dosed on 19 glass plates which were then exposed to untreated laboratory air for periods ranging from 1 to 56 days. During the first 5-6 days, the ROS concentration increased roughly linearly to a maximum of 5-6 nmol cm-2. Then the concentration ceased to increase, perhaps because reactive sites had become depleted. After 2 weeks, ROS decreased slowly, possibly due to a combination of volatilization, decomposition and continued formation by autoxidation. These field and laboratory results support the hypothesis that indoor surfaces can be a source of ROS.

The significance of ferrous ion oxidation during corrosion of carbon steel in aerated near-neutral aqueous solutions

Numerical models were developed to investigate the significance of ferrous ion oxidation in carbon steel corrosion in near-neutral aerated aqueous solutions. The results demonstrated that the inclusion of ferrous ion oxidation improved the accuracy of pH predictions in deep crevices under cathodic protection and Evan's drop exposure conditions, closely matching experimental observations. The reaction rate for ferrous ion oxidation was found to be between 1 × 1014 and 2 × 1014 (mol/L)-2 atm−1 min−1. These findings highlight the importance of considering ferrous ion oxidation when modelling carbon steel corrosion in near-neutral aerated aqueous solutions.