Amorphous Iron Oxide Research Articles

The rhizosphere soil properties and bacteria community of poplar are affected by magnetic field under salt condition

Magnetic fields (MFs) are konwn to affect plant growth, but their effects on soil conditions remain obscure. In this study, poplar seedlings (Populus×euramericana 'Neva') were subjected to a MF under saline conditions, and the rhizosphere soil properties and bacterial communities were then examined. Salt stress detrimentally influenced rhizosphere soil nutrients availability and bacterial community structure. However, MF treatments showed several positive effects, such as increasing the ammonium nitrogen (NH4+-N), amorphous iron oxide (Feo) and available phosphorus (AP) contents in the soil. Moreover,. soil urease and acid phosphatase activity increased by 59% and 63%, respectively. Meanwhile, MF treatments significantly improved the contents of extracellular polymeric substances (EPS) in rhizosphere soils and increased the relative abundance of dominant bacteria phyla (e.g., Actinobacteria, Gemmatimonadetes, and Proteobacteria). Furthermore, a co-occurrence network analysis revealed greater modular clustering in the MF treatments, however, the network stability did not improve. In conclusion, MFs increased rhizobacterial community modularity and promoted the production of bacterial EPS, these effects that then enhanced soil nutirent availability and poplar salt tolerance.

Fractionations of heavy metals and their correlations with magnetic susceptibility in soil from a typical alluvial island in the lower yangtze river, China

The use of magnetic susceptibility (χ) as a means of assessing heavy metal pollution in soils has been explored by researchers, yielding varying results in terms of the correlations between χ with heavy metals. The efficacy of χ as an indicator of soil heavy metal pollution remains a topic of debate. This study aims to elucidate the inter-relationships between χ, iron oxides, and heavy metals in soil through the application of a modified 5-step sequential extraction procedure (SEP), and to identify an effective approach for assessing metal concentrations in soil using magnetic susceptibility measurements. The soil samples were collected from a typical alluvial island in the lower Yangtze River, China, and a total of 6 forms (exchangeable and acid soluble fraction, easily reducible fraction, oxidizable fraction, amorphous iron oxide, crystallized iron oxyhydroxides and residual fraction) were partitioned and their heavy metal concentrations and χ were analyzed. The results show that crystalline Fe oxyhydroxides and residual fractions are the two uppermost fractions of heavy metals. By combining the fractionation of elements with the variation of χ of the soil during the processing of SEP, it was inferred that the external input of Fe, Pb, Cr and Cd in the soil likely originated from the vicinal steel production. The correlation analysis revealed a significant correlation between heavy metal concentrations and χ in the residual fraction, whereas no significant correlations were observed between the concentrations of heavy metals and χ in the bulk soil samples. It is recommended that the evaluation of heavy metal contamination in the soil neighboring industrial sites can be conducted via magnetic susceptibility measurements subsequent to the elimination of crystalline iron oxyhydroxides.

Responses of Soil Labile Organic Carbon on Aggregate Stability across Different Collapsing-Gully Erosion Positions from Acric Ferralsols of South China

Soil labile organic carbon (LOC) is a valuable and sensitive parameter of the changes in soil carbon (C) pools and further affects soil structural stability. However, the influences of soil-aggregate stability on LOC fractions under erosion conditions are still unclear, especially under the collapsing gully area of south China. Soils of five positions of collapsing gully erosion, including the upper catchment (UC), collapsing wall (CW), colluvial deposit (CD), scour channel (SC) and alluvial fan (AF) from Acric Ferralsols were investigated and sampled. Soil aggregate stability and LOC fractions were measured and analyzed. Soil water-stable aggregate and passive C (passive-C) contents significantly increased by 67–76% and 8.7–13.0% at the UC, CW, CD and SC positions, respectively, while soil labile C (labile-C) content was lower at these positions as compared to the AF position (p < 0.05). Moreover, the UC position’s soil C pool management index (CPMI) significantly increased by 37–40% compared to CW, CD, SC and AF soils, indicating that the soil of the UC position had a more stable C pool due to its stronger structural stability. SOC, silt, and amorphous iron oxide (Fea) contents significantly contributed to aggregate stability. We demonstrated that the depletion of soil aggregate stability could result in the decreases in soil LOC fractions, while soil properties of the OC but not the LOC pool regulated aggregate stability and thus affected soil structure across different collapsing gully erosion positions in the subtropical Acric Ferralsols region of south China. This study contributes to developing strategies to prevent soil erosion and improve global C cycle and soil quality, which could be beneficial to strengthen soil and water conservation, and improve soil fertility (e.g., SOC) and vegetation recovery, such as tea and tobacco.

Electrical, optical, and magnetic properties of amorphous yttrium iron oxide thin films and consequences for non-local resistance measurements

We present magnetic characterization, charge resistivity, and optical photoluminescence measurements on amorphous yttrium iron oxide thin films (a-Y–Fe–O), with supporting comparisons to amorphous germanium (a-Ge) films. We measured magnetic properties with both SQUID magnetometry and polarized neutron reflectometry. These results not only confirm that a-Y–Fe–O is a disordered magnetic material with strong predominantly antiferromagnetic exchange interactions and a high degree of frustration, but also that it is best understood electrically as a disordered semiconductor. As with amorphous germanium, a-Y–Fe–O obeys expectations for variable-range hopping through localized electron states over a wide range of temperature. We also clarify the consequences of charge transport through such a semiconducting medium for non-local voltage measurements intended to probe spin transport in nominally insulating magnetic materials. We further compare non-local resistance measurements made with “quasi-dc” automated current reversal to ac measurements made with a lock-in amplifier. These show that the “quasi-dc” measurement has an effective ac current excitation with frequency up to approximately 22 Hz, and that this effective ac excitation can cause artifacts in these measurements including incorrect sign of the non-local resistance. This comprehensive investigation of non-local resistance measurements in a-Y–Fe–O shows no evidence of spin transport on micrometer length scales, which is contrary to our original work, and in line with more recent investigations by other groups.

Comparing Indicators of Carbon Cycling Under Different Climatic Regions of Iran

ABSTRACT Dissolved organic carbon (DOC) and soil respiration (SR) are essential in carbon cycling and storage. Consequently, proper soil management requires knowledge of factors influencing DOC and SR in soil. The main objective is to identify the most critical indicators that control DOC and SR in the major climatic regions of Iran. The carbon cycling of sixteen pedons from six study sites with different soil moisture and temperature regimes was measured. Soil samples were collected from various genetic horizons to assess their physicochemical properties. Stepwise multiple linear regression (MLR) models were conducted on all horizons and B horizon properties (representing the subsoil) to identify the strongest correlation with DOC and SR. The MLR model revealed that organic carbon (OC) was negatively affected by pH, electrical conductivity (EC), amorphous and crystalline iron oxide contents in all horizons (R2 = 0.69), EC, and cation exchange capacity (CEC) in B horizons (R2 = 0.62). On the other hand, SR was negatively affected by pH, EC, soil water content, and clay contents in all horizons (R2 = 0.67), and calcium carbonate equivalent (CCE), pH, and sodium adsorption ratio in B horizons (R2 = 0.67). The most important indicators associated with carbon cycling included EC and pH in the different soil types of Iran. This study contributes to improving crop yield and mitigating soil degradation, mainly by controlling and managing salinity and pH threats for soil fertility to increase carbon storage in such climatic regions.

Removal of Pb(II) by Adsorption of HCO–(Fe3O4)x Composite Adsorbent: Efficacy and Mechanism

With the development of industry, the concentration of lead (Pb) in water bodies is gradually increasing, the forms of Pb pollution in water are becoming increasingly diversified, and the environmental and human health hazards caused by Pb pollution are receiving increasing attention. A HCO–(Fe3O4)x composite adsorbent prepared by the coprecipitation method of Fe3O4 mixed in cerium-rich grinding and polishing sludge was used to remove Pb from water. The effects of Ce/Fe molar ratio, pH, dosing amount, and time on the adsorption of HCO–(Fe3O4)x for Pb removal were investigated and the adsorption isotherm model, adsorption kinetics, and adsorption mechanism were studied. The results showed that the maximum adsorption capacity of HCO–(Fe3O4)x on Pb(II) was 35.93 mg·g−1 at a Ce/Fe molar ratio of 1.5:1, pH 4–5, and temperature of 25 °C, and the removal rate could reach 96.05%; the process of Pb(II) adsorption by HCO–(Fe3O4)x was in accordance with the Langmuir isothermal adsorption model and the pseudo-second-order reaction kinetic model; chemisorption was dominant. Characterization results, such as EDS, XRD, and XPS, showed that the composite preparation of HCO with Fe3O4 increased the specific surface area of HCO–(Fe3O4)x and generated amorphous iron oxides, such as FeCe2O4, FeOOH, Fe3O4, and Fe2O3, which provided conditions for the formation of Fe-O-Pb and Ce-O-Pb complexes during the adsorption process, thus facilitating the adsorption removal of Pb(II).

Amorphous cobalt iron oxide nanoparticles with high magnetization intensity for spin conversion of hydrogen at 77K

Conversion of ortho-hydrogen (o-H2) to para-hydrogen (p-H2) is a necessary process in hydrogen liquefaction, and investigating the catalysts that accelerate conversion is significant. Herein we report the effect of Co/Fe ratio in cobalt iron oxide catalysts on conversion of o-H2 to p-H2 at 77 K, and use XRD, BET, and VSM to explore the influence of different Co/Fe ratios on internal crystal structure, pore size, and magnetization strength. It is concluded that the synergistic effect of crystal structure disorder (increase in active sites), small pores (decrease in distance between o-H2 and active sites), and high magnetization strength (larger torque upon) resulted in the optimal catalytic performance for CFO-3 [n(Co):n(Fe) = 3:10]. When the hydrogen flow is 100 mL min−1, the content of p-H2 in the converted hydrogen is 47.61%.

Molecular characteristics of natural organic matter in the groundwater system with geogenic iodine contamination in the Datong Basin, Northern China

Natural organic matter (NOM) plays an important role in the iodine mobilization in the groundwater system. In this study, the groundwater and sediments from iodine affected aquifers in the Datong Basin were collected to perform chemistry analysis and molecular characteristics of NOM by Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS). Total iodine concentrations in groundwater and sediments ranged from 1.97 to 926.1 μg/L and 0.001–2.86 μg/g, respectively. A positive correlation was observed between DOC/NOM and groundwater/sediment iodine. FT-ICR-MS results showed that the DOM in the high-iodine groundwater system is characterized by less aliphatic and more aromatic compounds with higher NOSC, indicating the features of more unsaturated larger molecule structures and more bioavailability. Aromatic compounds could be the main carriers of sediment iodine and were easily absorbed on amorphous iron oxides to form the NOM-Fe-I complex. More aliphatic compounds, especially those containing N/S, experienced a higher degree of biodegradation, which further mediated the reductive dissolution of amorphous iron oxides and the transformation of iodine species, thereby causing the release of iodine into groundwater. The findings of this study provide some new insights into the mechanisms of high-iodine groundwater.

Diversity of Iron Oxides: Mechanisms of Formation, Physical Properties and Applications

Iron oxide compounds have naturally formed during the whole of Earth’s history. Synthetic compositions with iron oxides are produced with the use of various techniques and widely used for scientific and applied purposes. This review considers an attempt to classify all the information on different iron oxide compound formation mechanisms and intended applications in biomedicine, catalysis, waste remediation, geochemistry, etc. All the literature references analyzed were divided into several groups by their number of included iron oxide compounds: compositions containing only one compound (e.g., magnetite or wüstite), including various polymorphs of iron(III) oxide (α-, β-, γ-, ε-, ζ-, δ-Fe2O3); compositions with two different distinguishable iron oxide phases (e.g., maghemite and hematite); compositions containing non-crystalline phases (amorphous iron oxide or atomic clusters); and compositions with mixed iron oxide phases (indistinguishable separate iron oxide phases). Diagrams on the distribution of the literature references between various iron oxide compounds and between various applications were built. Finally, the outlook on the perspectives of further iron oxide studies is provided.

Formation of ferrihydrite induced by low pe+pH in paddy soil reduces Cd uptake by rice: Evidence from Cd isotope fractionation

Ferrihydrite (Fh) is an important iron mineral in paddy soil and is prone to phase transition during dynamic redox condition, which affects Cd distribution and induces Cd isotope fractionation across soil to rice. Here, we conducted rice culture experiments with or not Fh application under different irrigation regimes to study the relationship between Fe species and Cd availability, as well as the isotope ratio of Cd in different Cd pools in paddy soil-rice system. Fh addition under continuous flooding (FL) with the decrease of pe + pH from 9.36 to 3.44 promoted the formation of amorphous Fe oxides as increased by 120.1% and facilitated Cd immobilization along with the increase of Fe/Mn oxides bound Cd by 25.3%, compared with continuous drying (DY) treatment. The isotopically heavy Cd were preferentially enriched from soil to extractable Cd (Δ114/110Cdextractable Cd-soil = 0.39–0.62‰) and from soil to grain (Δ114/110Cdgrain-soil = 0.40–0.66‰) particularly at low pe + pH and with Fh addition, while light Cd were enriched in Fe/Mn oxides (Δ114/110CdFe/Mn oxides bound Cd-extractable Cd = −0.65 ∼ −0.14‰). Besides, the expression of transporters involved in Cd transport in rice like OsNRAMP1, OsNRAMP1, OsHMA3, OsHMA2 and OsLCT1 were suppressed under low pe + pH condition. These findings indicated that low pe + pH facilitated Cd stabilization by the existence of more amorphous iron oxides, which induced the enrichment of heavy Cd isotope in liquid phase and light in Fe/Mn (oxy)hydroxides, respectively.

Coupled effects of sedimentary iron oxides and organic matter on geogenic phosphorus mobilization in alluvial-lacustrine aquifers

The organic matter (OM) biodegradation and reductive dissolution of iron oxides have been acknowledged as key factors in the release of geogenic phosphorus (P) to groundwater. However, the coupled effects of natural OM with iron oxides on the mobilization of geogenic P remain unclear. Groundwater with high and low P concentrations has been observed in two boreholes in the alluvial-lacustrine aquifer system of the Central Yangtze River Basin. Sediment samples from these boreholes were examined for their P and Fe species as well as their OM properties. The results show that sediments from borehole S1 with high P levels contain more bioavailable P, particularly iron oxide bound P (Fe-P) and organic P (OP) than those from borehole S2 with low P levels. Regarding borehole S2, Fe-P and OP show positive correlations with total organic carbon as well as amorphous iron oxides (FeOX1), which indicate the presence of Fe-OM-P ternary complexes, further evidenced by FTIR results. In a reducing environment, the protein-like component (C3) and terrestrial humic-like component (C2) will biodegrade. In the process of C3 biodegradation, FeOX1 will act as electron acceptors and then undergo reductive dissolution. In the process of C2 biodegradation, FeOX1 and crystalline iron oxides (FeOX2) will act as electron acceptors. FeOX2 will also act as conduits in the microbial utilization pathway. However, the formation of stable P-Fe-OM ternary complexes will inhibit the reductive dissolution of iron oxides and OM biodegradation, thus inhibiting the mobilization of P. This study provides new insights into the enrichment and mobilization of P in alluvial-lacustrine aquifer systems.

Synergistic Apoptosis-Ferroptosis: Oxaliplatin loaded amorphous iron oxide nanoparticles for High-efficiency therapy of orthotopic pancreatic cancer and CA19-9 levels decrease

Pancreatic cancer is a highly malignant tumor with early metastasis, poor prognosis, and resistant to existing chemotherapy drugs such as oxaliplatin (Oxp). Therefore, a nanodrug of amorphous iron oxide packaged Oxp (AIOoxp) was proposed to achieve a more efficient treatment of orthotopic pancreatic cancer than that of free Oxp. The obtained AIOoxp increased the accumulation of Pt at tumor sites and effectively reduced Oxp-induced systemic toxicity. In addition, the Fe2+/Fe3+ ions released by AIOoxp react with H2O2 through Fenton’s reaction and produce a large amount of reactive oxygen species (ROS), which further induce ferroptosis, thus promoting Oxp-induced apoptosis and achieve synergistic tumor therapy. Furthermore, AIOoxp nanoplatforms can significantly reduce the levels of carbohydrate antigen 19–9 (CA19-9), which is the most important biomarker and promoter of pancreatic cancer, suggesting favorable therapeutic effects and prognosis. Overall, this study provides new insights and solutions for the clinical treatment of pancreatic cancer.

Cooperative effect of slow-release ferrous and phosphate for simultaneous stabilization of As, Cd and Pb in soil

The different chemical behavior of anionic As and cationic Cd and Pb makes the simultaneous stabilization of soils contaminated with arsenic (As), cadmium (Cd), and lead (Pb) challenging. The use of soluble, insoluble phosphate materials and iron compounds cannot simultaneously stabilize As, Cd, and Pb in soil effectively due to the easy re-activation of heavy metals and poor migration. Herein, we propose a new strategy of “cooperatively stabilizing Cd, Pb, and As with slow-release ferrous and phosphate”. To very this theory, we developed ferrous and phosphate slow-release materials to simultaneously stabilize As, Cd, and Pb in soil. The stabilization efficiency of water-soluble As, Cd and Pb reached 99% within 7d, and the stabilization efficiencies of NaHCO3-extractable As, DTPA-extractable Cd and Pb reached 92.60%, 57.79% and 62.81%, respectively. The chemical speciation analysis revealed that soil As, Cd and Pb were transformed into more stable states with the reaction time. The proportion of residual fraction of As, Cd, and Pb increased from 58.01% to 93.82%, 25.69 to 47.86%, 5.58 to 48.54% after 56 d, respectively. Using ferrihydrite as a representative soil component, the beneficial interactions of phosphate and slow-release ferrous material in stabilizing Pb, Cd, and As were demonstrated. The slow-release ferrous and phosphate material reacted with As and Cd/Pb to form stable ferrous arsenic and Cd/Pb phosphate. Furthermore, the slow-release phosphate converted the adsorbed As into dissolved As, then the dissolved As reacted with released ferrous to form a more stable form. Concurrently, As, Cd and Pb were structurally incorporated into the crystalline iron oxides during the ferrous ions-catalyzed transformation of amorphous iron (hydrogen) oxides. The results demonstrates that the use of slow-release ferrous and phosphate materials can aid in the simultaneous stabilization of As, Cd, and Pb in soil.

Crystalline Magnetic Gels and Aerogels Combining Large Surface Areas and Magnetic Moments.

The production of materials that simultaneously combine large surface areas and high crystallinities is a major challenge. Conventional sol-gel chemistry strategies to produce high-surface-area gels and aerogels generally result in amorphous or poorly crystalline materials. To attain proper crystallinities, materials are exposed to relatively high annealing temperatures that result in significant surface losses. This is a particularly limiting issue in the production of high-surface-area magnetic aerogels owing to the strong relationship between crystallinity and magnetic moment. To overcome this limitation, we demonstrate here the gelation of preformed magnetic crystalline nanodomains to produce magnetic aerogels with high surface area, crystallinity, and magnetic moment. To exemplify this strategy, we use colloidal maghemite nanocrystals as gel building blocks and an epoxide group as the gelation agent. After drying from supercritical CO2, aerogels show surface areas close to 200 m2 g-1 and a well-defined maghemite crystal structure that provides saturation magnetizations close to 60 emu g-1. For comparison, the gelation of hydrated iron chloride with propylene oxide provides amorphous iron oxide gels with slightly larger surface areas, 225 m2 g-1, but very low magnetization, below 2 emu g-1. Thermal treatment at 400 °C is necessary to crystallize the material, which results in a surface area loss down to 87 m2 g-1, well below the values obtained from the nanocrystal building blocks.

Characterization of Serpentine Soils from Eastern and Southern Rhodope Mountains (Bulgaria)

This work aims to characterize serpentine soils in Bulgaria and examine the biogeochemistry of pedogenic Ni and its relation to Ni available forms. Soils were collected from serpentine soils of the Eastern and Southern Rhodopes (Bulgaria). The chemical composition of serpentine soils is similar to serpentine soils from the Balkan Peninsula and is characterized by high contents of Ni (919.9–2397.2 mg.kg–1). The soils had a neutral to slightly alkaline reaction (pH 6.4 to 7.6) and a medium to high organic matter content. Of the primary minerals, those of the serpentine group (antigorite and lizardite), the talc group (willemseite), the amphibole group (riebeckite), the feldspar group (albite) and quartz are mainly present in the soil samples. The secondary minerals present in the samples include calcite and dolomite, and also representatives of the clay minerals, clinochlore and montmorillonite. The contents of free iron oxides (Fed), amorphous iron oxides (Feo), well-crystallized iron oxides (Fecr) (Fed-Feo) and activity index (Feo/Fed) showed significant differences (p<0.05) among soils from different locations. In the soils from Dobromirtsi, Parvenets, and Golyamo Kamenyane Ni bound to Fe oxides were evenly distributed between the well-crystallized and amorphous phases. In the soils from Kardzhali, Chernichevo and Dyulitsa more than half of the Ni bound to Fe oxides were bound to or occluded in amorphous Fe oxides, while in the soils from Kazak were bound to well-crystallized Fe oxides. Pedogenesis, weathering intensity, and Fe geochemistry influence Ni availability in serpentine soils.

Ambient Electrosynthesis of Urea with Nitrate and Carbon Dioxide over Iron‐Based Dual‐Sites

AbstractThe development of efficient electrocatalysts to generate key *NH2 and *CO intermediates is crucial for ambient urea electrosynthesis with nitrate (NO3−) and carbon dioxide (CO2). Here we report a liquid‐phase laser irradiation method to fabricate symbiotic graphitic carbon encapsulated amorphous iron and iron oxide nanoparticles on carbon nanotubes (Fe(a)@C‐Fe3O4/CNTs). Fe(a)@C‐Fe3O4/CNTs exhibits superior electrocatalytic activity toward urea synthesis using NO3− and CO2, affording a urea yield of 1341.3±112.6 μg h−1 mgcat−1 and a faradic efficiency of 16.5±6.1 % at ambient conditions. Both experimental and theoretical results indicate that the formed Fe(a)@C and Fe3O4 on CNTs provide dual active sites for the adsorption and activation of NO3− and CO2, thus generating key *NH2 and *CO intermediates with lower energy barriers for urea formation. This work would be helpful for design and development of high‐efficiency dual‐site electrocatalysts for ambient urea synthesis.

Ambient Electrosynthesis of Urea with Nitrate and Carbon Dioxide over Iron-Based Dual-Sites.

The development of efficient electrocatalysts to generate key *NH2 and *CO intermediates is crucial for ambient urea electrosynthesis with nitrate (NO3 - ) and carbon dioxide (CO2 ). Here we report a liquid-phase laser irradiation method to fabricate symbiotic graphitic carbon encapsulated amorphous iron and iron oxide nanoparticles on carbon nanotubes (Fe(a)@C-Fe3 O4 /CNTs). Fe(a)@C-Fe3 O4 /CNTs exhibits superior electrocatalytic activity toward urea synthesis using NO3 - and CO2 , affording a urea yield of 1341.3±112.6 μg h-1 mgcat -1 and a faradic efficiency of 16.5±6.1 % at ambient conditions. Both experimental and theoretical results indicate that the formed Fe(a)@C and Fe3 O4 on CNTs provide dual active sites for the adsorption and activation of NO3 - and CO2 , thus generating key *NH2 and *CO intermediates with lower energy barriers for urea formation. This work would be helpful for design and development of high-efficiency dual-site electrocatalysts for ambient urea synthesis.

Relating Soil Available Zinc With Physicochemical Properties In New Alluvial Zone Of West Bengal, India

An experiment was conducted to assess the dependency of available zinc on the physicochemical properties of soils. The soil samples were collected from 15 NBSS & LUP identified soil series of New Alluvial Zone of West Bengal, India. The soil samples were processed and analyzed for different standard physicochemical properties i.e. pH, EC, clay, organic carbon content, available nitrogen, phosphorus and potassium, zinc, copper, iron, manganese, amorphous iron, aluminium and manganese oxide content. Among the studied parameters, pH, clay, organic carbon, amorphous iron and amorphous aluminium oxide showed significant correlations (-0.591*, 0.601**, 0.784**, 0.563*, 0.509* respectively) with available zinc. Multilayer Perceptron Network (MPN) in Artificial Neural Network (ANN) yielded organic carbon, clay, pH and amorphous iron content as the most important parameters to affect the availability of soil zinc. Further, using multiple linear regression modeling, it was found that changes in organic carbon and clay content together contribute 70.7% change in available zinc in soil wherein, organic carbon alone contributed to 62.4% change. Identification of crops based on their zinc requirement in appropriate textural conditions of soil as well as proper maintenance of soil organic carbon can be a promising option for judicious management of zinc in soil.

Iron oxide-EDTA nanoparticles for chelation-enhanced chemodynamic therapy and ion interference therapy.

As an emerging anti-tumor strategy, chemodynamic therapy (CDT) utilizes a Fenton/Fenton-like reaction to generate highly toxic hydroxyl radicals to kill tumor cells. However, the efficiency of CDT is still hindered by the low Fenton/Fenton-like reaction rate. Herein, we report the combination of ion interference therapy (IIT) and chemodynamic therapy (CDT) via an amorphous iron oxide (AIO) nanomedicine with encapsulated EDTA-2Na (EDTA). Iron ions and EDTA are released from the nanomedicine in acidic tumors and chelate to form iron ion-EDTA, which improves the efficiency of CDT and promotes the generation of reactive oxygen species (ROS). In addition, EDTA can disrupt the homeostasis of Ca2+ in tumor cells by chelating with Ca2+ ions, which induces the separation of tumor cells and affects normal physiological activities. Both in vitro and in vivo experiments show that the nano chelating drugs exhibit significant improvement in Fenton reaction performance and excellent anti-tumor activity. This study based on chelation provides a new idea for designing efficient catalysts to enhance the Fenton reaction and provides more revelations on future research on CDT.

Impacts of coexisting mineral on crystallinity and stability of Fe(II) oxidation products: Implications for neutralization treatment of acid mine drainage.

The neutralization treatment of acid mine drainage involves the oxidation of Fe(II), but little is known about the effects of co-existing minerals on the oxidation and hydrolysis of Fe(II) to iron oxides. Here we investigated the transformation of fresh and heated Fe(II) oxidation coprecipitates, which were synthesized in the presence and the absence of five co-existing minerals (montmorillonite, kaolin, quartz (SiO2), aluminium oxide (Al2O3) and calcium carbonate (CaCO3)). In the FeSO4 system with montmorillonite or kaolin, the formation of lepidocrocite was inhibited with the increase of clay mineral contents. In the same system, heated coprecipitates of montmorillonite were mainly comprised of amorphous ferrihydrite and its transformation was retarded by the excess montmorillonite. In the FeCl2 system with SiO2, Al2O3 or CaCO3, akaganeite formation was inhibited with the increase in the corresponding mineral contents. In the same system, goethite formation was blocked by either CaCO3 or Al2O3 and the growth of lepidocrocite was inhibited by CaCO3 or SiO2. However, magnetite formation was enhanced by addition of CaCO3. These findings are important for predicting products of abiotic Fe(II) oxidation during the neutralization of acid mine drainage and for better understanding the transformation of amorphous iron oxides in the complicated environmental matrix.