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Background and Objective: This review aims to investigate the ferroptosis mechanism of fumarate hydratase (FH)-related tumors for the purpose of possible treatment of tumors. Ferroptosis is an iron (Fe)-dependent form of regulated cell death caused by lipid peroxidation on the cell membrane. Studies have implicated FH in tumorigenesis. As mutations in the FH gene alter cellular metabolism and increase tumorigenesis risk, particularly in the kidneys. As most tumor cells require higher amounts of ferrous ions (Fe2+) than normal cells, they are more susceptible to ferroptosis. Recent studies have indicated that ferroptosis is inhibited the pathogenesis and progression of FH-deficient tumors by regulating lipid and iron metabolism, glutathione-glutathione peroxidase 4 (GSH-GPX4), nuclear factor-erythroid 2-related factor 2 (NRF2)/heme oxygenase-1 (HO-1) pathways. While the Fe2+ content is significantly lower in FH-deficient tumor cells, than that in normal cells. It is promising to promote ferroptosis by increasing the concentration of Fe2+ in cells to achieve the purpose of tumor treatment. Methods: In this study, we searched for relevant articles on ferroptosis and FH-deficient tumors using PubMed database. Key Content and Findings: FH is a tumor suppressor. A number of basic studies have shown that the loss of FH plays an important role in hereditary leiomyomas and tumors such as renal cell carcinoma, ovarian cancer, and other tumors. This type of tumor cells can through induce ferroptosis, inhibit proliferation, migration and invasion of tumor cells, increase the sensitivity of tumor cells to chemotherapy, and reverse the drug resistance through various molecular mechanisms. At present, the research on ferroptosis in FH-related tumors is still in the basic experimental stage. Conclusions: This article reviews the anti-tumor effects and mechanisms of FH and ferroptosis, in order to further explore the medical value of ferroptosis in FH-related tumor therapy.

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Anaerobic ammonium oxidation (anammox) bacteria have a high requirement for iron for their growth and metabolism. However, it remains unclear whether iron supplementation can sustain the stability of mainstream anammox systems at varying temperatures. Here, we investigated the long-term effects of Fe2+ on the mainstream anammox systems. Our findings revealed that the nitrogen removal efficiency (NRE) of the anammox system supplemented with 5 mg/L Fe2+ decreased from 76.5 ± 0.76% at 35 °C to 39.0 ± 9.9% at 25 °C. Notably, higher dosages of Fe2+ (15 mg/L and 30 mg/L) inhibited the anammox system, resulting in NREs of 15.9 ± 8.1% and 2.5 ± 1.1% at 25 °C, respectively. The results of microbial communities and function profiles suggested that the high Fe2+ dosage seriously affected the iron assimilation and utilization in the mainstream anammox system. This was evident from the decreased abundance of genes associated with Fe(II) transport and uptake, which in turn hindered the biosynthesis of intracellular iron-cofactors, resulting in decrease in the absolute abundance of Candidatus Brocadia, a key anammox bacterium, as well as a decline in NRE. Furthermore, our results showed that the anammox process was more susceptible to iron supplementation at 25 °C compared to 35 °C, which may be due to the oxidative stress reactions induced by combined lowered temperature and a high Fe2+ dosage. Overall, these findings offer a deeper understanding of the effect of iron in mainstream anammox systems, which can contribute to improved stability maintenance and effectiveness of anammox processes.

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The application of one kind of metal-organic framework (MOF) material used in multiple fields is one of the most interesting research topics. In this work, four new tetra-nuclear cluster-based lanthanide metal-organic frameworks (LnMOFs) [Ln2(BTDB)3(DMA)(phen)]n (Ln = Tb TbMOF, Eu EuMOF, Gd GdMOF, Tb1.830Eu0.170 Tb,EuMOF, 3,5-bis(trifluoromethyl)-4',4″-dicarboxytriphenylamine = H2BTDB, 1,10-phenanthroline = phen) are obtained based on the ligand of H2BTDB that is synthesized in our laboratory, and the precise single-crystal structure of H2BTDB is obtained for the first time. The white phosphor was obtained by facilely hybridizing two components of the orange-yellow emission phosphor of Tb,EuMOF and the blue luminescence material of triphenylamine according to the trichromatic theory. At the same time, TbMOF, EuMOF, Tb,EuMOF, and the white phosphor can be used for information encryption, demonstrating their potential application in the field of anti-counterfeiting. Tb,EuMOF is also a multi-mode and self-calibrating thermometer within a broad temperature range of 110-300 K. Further studies show that EuMOF is a rapid response sensor for Fe2+, with a very low limit of detection of 2.0 nM, which is much lower than the national standards for Fe2+ (GB 5749-2005, 5.357 µM). It can achieve strong anti-interference detection of Fe2+ in actual samples of tap water and lake water. In addition, EuMOF can also be made into an easy-to-use sensing device of test paper for real-time and visual sensing of Fe2+.

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Metallomodulation cell death strategies are extensively investigated for antitumor therapy, such as cuproptosis, ferroptosis, and chemodynamic therapy (CDT). Undoubtedly, the accurate and specific elevation of metal ions levels in cancer cells is key to boosting their therapeutic index. Herein, a programmably controllable delivery system based on croconium dye (Croc)-ferrous ion (Fe2+ ) nanoprobes (CFNPs) is developed for multiscale dynamic imaging guided photothermal primed CDT. The Croc, with kinds of electron-rich iron-chelating groups, can form the Croc-Fe2+ complex with a precise stoichiometry of 1:1 to steadily maintain the valence state of Fe2+ . The CFNPs can achieve pH-responsive visualization and accurate Fe2+ release in cancerous tissues under the coactivation of "dual-key" stimulation of "acidity and near-infrared (NIR) light". The acidic tumor microenvironment actuates NIR fluorescence/photoacoustic imaging and photothermal properties of CFNPs. Sequentially, under exogenous NIR light, the CFNPs enable in vivo accurate visualization of Croc-Fe2+ complex delivery for photothermal primed Fe2+ release, thus achieving CDT of tumors. By leveraging multiscale dynamic imaging technologies, the complicated spatiotemporal release of Fe2+ is sketched in a programmably controllable manner, and the domino effect of tumor pH level, photothermal effect, and CDT is also revealed, endowing customized feedback of the therapeutic panorama within the disease microenvironment.

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The electrolysis of nitrate reduction to ammonia (NRA) is promising for obtaining value-added chemicals and mitigating environmental concerns. Recently, catalysts with high-performance ammonia synthesis from nitrate has been achieved under alkaline or acidic conditions. However, NRA in neutral solution still suffers from the low yield rate and selectivity of ammonia due to the low binding affinity and nucleophilicity of NO3-. Here, we confirmed that the in-situ-generated Fe(II) ions existed as specifically adsorbed cations in the inner Helmholtz plane (IHP) with a low redox potential. Inspired by this, a strategy (Fe-IHP strategy) was proposed to enhance NRA activity by tuning the affinity of the electrode-electrolyte interface. The specifically adsorbed Fe(II) ions [SA-Fe(II)] greatly alleviated the electrostatic repulsion around the interfaceresulting in a 10-fold lower in the adsorption-free energy of NO3- when compared to the case without SA-Fe(II). Meanwhile, the modulated interface accelerated the kinetic mass transfer process by 25 folds compared to the control. Under neutral conditions, a Faraday efficiency of 99.6%, a selectivity of 99%, and an extremely high NH3 yield rate of 485.8 mmol h-1 g-1 FeOOH were achieved. Theoretical calculations and in-situ Raman spectroscopy confirmed the electron-rich state of the SA-Fe(II) donated to p orbitals of N atom and favored the hydrogenation of *NO to *NOH for promoting the formation of high-selectivity ammonia. In sum, these findings complement the textbook on the specific adsorption of cations and provide insights into the design of low-cost NRA catalysts with efficient ammonia synthesis.

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Calcium and iron play crucial roles in human health, deficiencies of which have globally generated public health risks. The poor solubility, low bioavailability and gastrointestinal irritation of existing commercial mineral supplements limit their further application. As an emerging type of mineral supplement, mineral chelating peptides have drawn plenty of attention due to their advantages in stability, absorptivity and safety. A majority of calcium and ferrous ions chelating peptides have been isolated from food processing by-products. Enzymatic hydrolysis combined with affinity chromatography, gel filtration and other efficient separation techniques is the predominant method to obtain peptides with high calcium and ferrous affinity. Peptides with small molecular weight are more likely to chelate metals, and carboxyl, amino groups and nitrogen, oxygen, sulfur atoms in the side chain, which can provide lone-pair electrons to combine with metallic ions. Unidentate, bidentate, tridentate, bridging and α mode are regarded as common chelating modes. Moreover, the stability of peptide-mineral complexes in the gastrointestinal tract and possible transport pathways were summarized. This review is to present an overview of the latest research progress, existing problems and research prospects in the field of peptide-mineral complexes and to provide a more comprehensive theoretical basis for their exploitation in food industry.

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Wood-based products manufactured from fast-growing wood species such as eucalyptus have gained increasing attraction with the demand of using wood in architecture, furniture, and decoration. In this paper, a new type of wood scrimber based on eucalyptus veneers complexed with ferrous ions was prepared and its properties were characterized. The results showed that the presence of complexes did not affect the mechanical properties of eucalyptus wood scrimber, but made its surface more hydrophobic (contact angle increased by 38.48% and dimensional stability improved (thickness swelling rate decreased by 32.26%). Most importantly, the color of eucalyptus wood scrimber changed significantly, from the original brown to dark blue, and its anti-photoaging property also greatly improved. These advantages would make this type of wood scrimber based on the eucalyptus veneer complexes with ferrous ions more widely applicable in decorations and buildings.

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Haloperidol is a widely used antipsychotic agent that exerts antipsychotic effects through a strong antagonism of dopamine D2 receptors. In addition, haloperidol is classified as a sigma-1 receptor (S1R) antagonist that prevents endogenous oxidative stress in cultured cells. However, pharmacological activities of haloperidol against oxidative stress remain unclear. Oxytosis/ferroptosis are iron-dependent nonapoptotic oxidative cell deaths that are regarded as two names for the same cell death pathway and the potential physiological relevance of oxytosis/ferroptosis in multiple diseases is suggested. In the present study, the effects of haloperidol on oxytosis/ferroptosis were investigated in S1R-knockdown mouse hippocampal HT22 cells. The results indicate that haloperidol is a strong inhibitor of oxytosis/ferroptosis independent of S1R. Imaging of HT22 cells with a newly developed fluorescent probe showed that haloperidol was localized to late endosomes and lysosomes and reduced the accumulation of lysosomal ferrous ions, resulting in reduced production of intracellular reactive oxygen species and inhibition of cell death. These results indicate that haloperidol is useful not only as an antipsychotic agent but also as a neuroprotective agent against endogenous oxidative stress via distinct mechanisms. Furthermore, lysosome-targeting ferroptosis inhibitors could be useful for the treatment of various diseases, including cancers, ischemia-reperfusion injury, and neurodegenerative disorders, which have been associated with ferroptosis.

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Implantation of cardiovascular stents is an important therapeutic method to treat coronary artery diseases. Bare-metal and drug-eluting stents show promising clinical outcomes, however, their permanent presence may create complications. In recent years, numerous preclinical and clinical trials have evaluated the properties of bioresorbable stents, including polymer and magnesium-based stents. Three-dimensional (3D) printed-shape-memory polymeric materials enable the self-deployment of stents and provide a novel approach for individualized treatment. Novel bioresorbable metallic stents such as iron- and zinc-based stents have also been investigated and refined. However, the development of novel bioresorbable stents accompanied by clinical translation remains time-consuming and challenging. This review comprehensively summarizes the development of bioresorbable stents based on their preclinical/clinical trials and highlights translational research as well as novel technologies for stents (e.g., bioresorbable electronic stents integrated with biosensors). These findings are expected to inspire the design of novel stents and optimization approaches to improve the efficacy of treatments for cardiovascular diseases.

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In this work, a method of enhanced packed-bed microbial oxidation-neutralization has been employed to treat Fe2+-rich acid mine drainage. The method features the use of a large number of immobile Acidithiobacillus ferrooxidans (A. ferrooxidans) in a bioreactor to promote the oxidation of Fe2+ to Fe3+. Results show that when the influent Fe2+ concentration is about 900 mg/L and the Fe2+ oxidation efficiency tends to 100%, the maximum oxidation rate of Fe2+ in the bio-ceramsite, bio-volcanic stone, and bio-activated carbon packed columns are 301 mg/(L·h), 234 mg/(L·h), and 139 mg/(L·h), respectively. Compared with the direct neutralization method, the enhanced microbial oxidation-neutralization method has several advantages. Firstly, it oxidizes Fe2+ to Fe3+, directly neutralizing the acid mine drainage at low pH and reducing the consumption of neutralizer. Secondly, more economical CaCO3 can be used as neutralizer. Thirdly, it produces precipitates with high solid content (5.50%), good settling performance (SV30 = 4%), and small volume, and the capillary suction time (CST) is 8.9 s, which is easy to dehydrate.

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Marine euphotic zone is the pivotal region for interplay of light-mineral-microorganism and elements cycle, in which semiconducting minerals exist widely and iron-bearing goethite is a typical and widespread one. In this work, we have conducted in-depth researches on the effect of ferrous [Fe(II)] ions dissolved by photoreduction of goethite on microbial community structure and diversity. The mineral phase, structure and morphology of synthesized goethite were characterized by Raman, X-ray diffraction (XRD), energy disperse spectroscopy (EDS), environmental scanning electron microscope (ESEM), and atomic force microscope (AFM). Photoelectrochemical measurements tested photoelectric response and redox activity of goethite, having proved its significant property of photoelectric response with 44.11% increment of the average photocurrent density relative to the dark current density. The photoreduction experiments of goethite were conducted under light condition in simulated seawater. It has suggested the photoreduction of goethite could occur and Fe(III) was reduced to Fe(II). The dissolved Fe(II) from the photoreduction of goethite under light condition was nearly 11 times than that group without light after a 10-day reaction. Furthermore, results of microbial community sequencing analysis indicated that dissolved Fe(II) could affect the structure and regulate the decrease of microbial community diversity. The emergence of dominant bacteria associated with iron oxidation and transport protein has suggested their obvious selectivity and adaptability in the environment with adding dissolved Fe(II). This work revealed the photoreduction process of semiconducting goethite was remarkable, giving rise to a non-negligible dissolved Fe(II) and its selective effect on the structure, diversity, as well as the function of microbial community. This light-induced interaction between minerals and microorganisms may also further regulate correlative metabolic pathways of carbon cycle in the marine euphotic zone.

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Therapeutic monoclonal antibodies have exerted a transformative impact on clinical practice in last two decades. However, development of a therapeutic antibody remains a complex process. Various physiochemical and functional liabilities can compromise the production or the therapeutic efficacy of antibodies. One of these liabilities is the susceptibility to oxidation. In the present study, we portrayed an oxidation-dependent vulnerability of immunoglobulins that can be of concern for therapeutic antibodies. By using a library of 119 monoclonal IgG1 molecules, containing variable domain matching clinical-stage antibodies, we demonstrated that a substantial number of these molecules acquired antigen-binding polyreactivity upon exposure to ferrous ions. Statistical analyses revealed that the potential for induction of polyreactivity by the redox-active metal ions correlated with a higher number of somatic mutations in V genes encoding variable domains of heavy and light immunoglobulin chains. Moreover, the sensitive antibodies used with biased frequencies particular V gene families encoding variable domains of their light chains. Besides the exposure to ferrous ions the induction of polyreactivity of therapeutic antibodies occurred after contact with an unrelated pro-oxidative substance-hypochlorite ions. Our data also revealed that induction of polyreactivity by pro-oxidative agents did not impact the binding of antibodies to their cognate antigens. The results from this study may contribute for better selection of antibody therapeutics with suitable developability profiles.

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A turn on upconversion fluorescence probe based on the combination of ~32 nm NaYF4: Yb/Tm nanoparticles and MnO2 nanosheets has been established for rapid, sensitive detection of Fe2+ ions levels in aqueous solutions and serum. X-ray diffraction (XRD), transmission electron microscopy (TEM), absorption and emission spectra have been used to characterize the crystal structure, morphology and optical properties of the samples. MnO2 nanosheets on the surface of UCNPs act as a fluorescence quencher, resulting in the quenching of the blue fluorescence (with excitation/emission maximum of 980/476 nm) via fluorescence resonance energy transfer from upconversion nanoparticles to MnO2 nanosheets. With the adding of Fe2+, upconversion fluorescence of the nanocomposites recovers due to the reduction of MnO2 to Mn2+. Because of the low background of the probe offered by upconversion fluorescence, this probe can be used for detecting Fe2+ in aqueous solutions in the range of 0.1-22 µM with detection limit of 0.113 µM. The developed method has also been applied to detect 10 µM Fe2+ ions in serum with recoveries ranging from 97.6 to 105.3% for the five serum samples. Significantly, the probe shows fast response and stable signal, which is beneficial for long-time dynamic sensing. Thus, the proposed strategy holds great potential for disease diagnosis and treatment.

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Recent progress in nanotechnology and the ancient use of sulfur in treating dermatological disorders have promoted the development of nano-sulfides for antimicrobial applications. However, the variable valences and abundant forms of nano-sulfides have complicated investigations on their antibacterial activity. Here, carbon nanospheres (CNSs) with decoration of ultrasmall FeS2 nanoparticles (CNSs@FeS2 ) is synthesized, and their antibacterial ability and mechanism are explored. The CNSs@FeS2 released Fe2+ and sulfur ions simultaneously through dissolution and disproportionation. In vitro study indicated that the released Fe2+ killed bacteria by increasing the oxidative state of bacterial surfaces and intracellular molecules. Importantly, the released sulfur exhibited a protective effect on Fe2+ , ensuring the stable existence of Fe2+ to continuously combat bacteria. Moreover, the carbon shells of CNSs@FeS2 not only prevented the aggregation of FeS2 but also accelerated the release of Fe2+ through photothermal effects to achieve synergistic hyperthermia/Fe2+ therapy. In vivo experiments indicated that treatment with CNSs@FeS2 resulted in a marked reduction in bacterial number and improvement in survival in an acute peritonitis mouse model, and antibacterial wound experiments demonstrated high efficacy of CNSs@FeS2 -enabled synergistic hyperthermia/Fe2+ therapy. Thus, this study clarifies the antibacterial mechanism of FeS2 and offers a synergetic therapeutic platform with laser-mediated Fe2+ release for antibacterial applications.

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In reverse osmosis desalination, the concentrate is a saline solution that may become supersaturated. Heterogeneous nucleation of salts occurs at the membrane surface, resulting in the buildup of inorganic deposits on the membrane. The inorganic nucleation process, however, is complex in natural waters. Most studies focused primarily on single salt fouling of membranes, and related treatment for single solute systems. However, scale formation, especially gypsum, is affected by the presence of different salts and metals. In this wok, for the first time, we investigate the mixed precipitation of iron oxides and gypsum. The role of citric acid in the inhibition of precipitation was studied for different concentrations in both the absence and the presence of Fe2+. Conductivity and ion concentration measurements were used to estimate the formation time of gypsum. Scanning electron microscopy, X-Ray Diffraction (XDR) analysis, and Infra-Red spectroscopy analysis were used to provide structural information. Collected data showed that the presence of Fe2+ accelerates gypsum precipitation and shortens its induction time. Analytic results showed that gypsum crystals are greatly affected by the presence of Fe2+ ions, which generated needle shaped crystals. Citric acid can delay the induction time of gypsum precipitation. It also affects the morphology of gypsum crystals through adsorption mechanism. XDR diagrams revealed that the presence of citric acid (20 mg/L) can stabilize the bassanite phase (CaSO4·½H2O) for much longer periods. In the presence of Fe2+ ions, citric acid extends the induction time of calcium sulfate and minimizes the acceleration effect of Fe2+ ions. SEM images showed that the presence of ferrous ions during the chemical inhibition generates the ß-hemihydrate form of calcium sulfate.

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Herein, we have synthesized Gd2O3:Yb,Er@UiO-66-NH2 (UiO-66-NH2 represent a zirconium-based metal organic framework [Zr6O4(OH)4(ata)12], ata: 2-aminoterephthalate) core-shell composites to develop an upconversion fluorescent nanoprobe for efficient detection of trace methylene blue (MB) and ferrous ions (Fe2+). Due to the fluorescence of the nanoprobe can be quenched by MB based on inner filter effect, but gradually recover when contact with ·OH, which is generated from the reaction between H2O2 and Fe2+, we have achieved the detection of Fe2+. The detection linear range is from 1.78 to 15.8 µM, and the limit of detection (LOD) is 0.071 µM. Besides, in this process, we also simultaneously realize the detection of MB. The linear range of MB turn-off detection is 0-42.6 µM, and the LOD is 0.41 µM. To our knowledge, no example of using upconversion fluorescence probe for continuous detection of trace MB and Fe2+ has been reported for now, and test results are superior compared with most reported Fe2+ probes. Moreover, the combinations of upconversion nanoparticles (UCNPs) and the metal-organic frameworks (MOFs) have enhanced the selectivity and sensitivity of the probe towards MB and Fe2+. Therefore, we believe the designed upconversion fluorescent nanoprobe is a promising efficient tool in detecting MB and diagnose Fe2+ related diseases in the future.

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In previous studies, we interestingly found that several ligands (e.g., nitrilotriacetate and humic acid) could significantly accelerate the oxidation of NaClO by ferrous ion, via complexing with Fe(II). This inspired us to hypothesis that organic acids (OA) chelated Fe(II) might enhance the NaClO oxidation for improving sludge dewaterability. In this work, the OA chelated ferrous ions activated NaClO (OA-Fe(II)-NaClO) process was utilized for sludge conditioning, which exhibited significantly improved dewatering performance, as evidenced by capillary suction time (CST), specific resistance to filtration (SRF) and cake moisture of sludge. The normalized CST (CSTn) and SRF decreased to 1.22 s × L/g and 3.24 × 108 m/kg, when ratio dosage of [ClO-]/[Fe2+] (NaClO: 0.75%(v/v)) was 1 at pH of 2. During the NaClO activation by Fe(II), tightly bound extracellular polymeric substances (TB-EPS) was cracked into soluble EPS (S-EPS), followed by oxidizing into smaller molecular organic matters due to the production of hydroxyl radicals. Meanwhile, OA complexed to ferrous ion inhibited hydrolysis of ferric ions, leading to better catalytic performance of NaClO under neutral pH conditions. In addition, the molecular structure of OA determined the low complexing ability and steric hindrance for OA-Fe(II). When molar ratio of [Oxalic acid]/[Fe2+] was 1, oxalic acid-Fe(II)-NaClO improved sludge dewaterability significantly due to the coagulation and skeleton builder properties of formed iron oxalate precipitates. This work provides an eco-friendly and cost-effective method for improving sludge dewaterability.

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The magnetite nanoparticles (MNPs) are increasingly produced and studied for various environmental applications, yet the information on their ecotoxicity is scarce. We evaluated the ecotoxicity of MNPs (~7 nm) before and after the addition of humic acids (HAs). White mustard Sinapis alba and unicellular ciliates Paramecium caudatum were used as test species. The MNPs were modified by HAs and oxidized/aged under mild and harsh conditions. Bare MNPs proved not toxic to plants (96 h EC50 > 3300 mg/L) but the addition of HAs and mild oxidation increased their inhibitory effect, especially after harsh oxidation (96 h EC50 = 330 mg/L). Nevertheless, all these formulations could be ranked as 'not harmful' to S. alba (i.e., 96 h EC50 > 100 mg/L). The same tendency was observed for ciliates, but the respective EC50 values ranged from 'harmful' (24 h EC50 = 10-100 mg/L) to 'very toxic' (24h EC50 < 1 mg/L). The ecotoxicity of Fe-ions with and without the addition of HAs was evaluated in parallel: Fe (II) and Fe (III) ions were toxic to S. alba (96 h EC50 = 35 and 60 mg/L, respectively) and even more toxic to ciliates (24 h EC50 = 1 and 3 mg/L, respectively). Addition of the HAs to Fe-ions yielded the respective complexes not harmful to plants (96h EC50 > 100 mg/L) but toxic to ciliates (24h EC50 = 10-100 mg/L). These findings will be helpful for the understanding of the environmental fate and toxicity of iron-based NPs.

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Various pathological processes in humans are associated with biogenic iron accumulation and the mineralization of iron oxide nanoparticles, especially magnetite. Ferritin has been proposed as a precursor to pathological magnetite mineralization. This study quantifies spectroscopically the release of ferrous ions from native ferritin and magnetoferritin as a model system for pathological ferritin in the presence of potent natural reducing agents (vitamins C and B2) over time. Ferrous cations are required for the transformation of ferrihydrite (physiological) into a magnetite (pathological) mineral core and are considered toxic at elevated levels. The study shows a significant difference in the reduction and iron release from native ferritin compared to magnetoferritin for both vitamins. The amount of reduced iron formed from a magnetoferritin mineral core is two to five times higher than from native ferritin. Surprisingly, increasing the concentration of the reducing agent affects only iron release from native ferritin. Magnetoferritin cores with different loading factors seem to be insensitive to different concentrations of vitamins. An alternative hypothesis of human tissue magnetite mineralization and the process of iron-induced pathology is proposed. The results could contribute to evidence of the molecular mechanisms of various iron-related pathologies, including neurodegeneration.

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The influence of pH (pH 3, 5 and 7), ferrous ions (0 or 100 µM Fe2+), and tannic acid (0 to 0.1% TA) on the rate of lipid oxidation in plant-based emulsions containing quillaja saponin-coated flaxseed oil droplets was studied. Tannic acid formed complexes with Fe2+ whose properties depended on TA:Fe2+ ratio and pH. Emulsions were incubated at 37 °C in the dark, and changes in their particle size, surface potential, appearance, microstructure, and lipid oxidation status were monitored over time. The initial ζ-potential and mean particle diameter of the emulsions were -68 mV and 0.18 µm, respectively. In the absence of TA, the particle size increased appreciably during storage due to droplet coalescence, as rapid oxidation occurred. In the presence of TA, the emulsions were more resistant to both droplet aggregation and lipid oxidation, as a result of its strong ferrous ion-binding properties. The lipid oxidation rate increased with decreasing pH, which was attributed to an increase in ferrous ion's water-solubility and activity in acidic solutions. The addition of Fe2+ greatly accelerated lipid oxidation, but the oxidation rate was decreased by also adding TA. These results suggest that tannic acid is an effective antioxidant in emulsions, which can be attributed to its ferrous ion-chelation properties.

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