Search Results (1,560)

Background/Objectives: Triple-negative breast cancer (TNBC) exhibits pronounced biological heterogeneity, aggressive behavior, and a high risk of recurrence and metastasis. The conventional treatments for TNBC have notable limitations: surgical resection may leave residual tumor cells; chemotherapy (CT) frequently induces systemic toxicity and drug resistance; and radiotherapy damages surrounding organs and compromises the patients’ immune function. Methods: Herein, we designed a carrier-free nanodrug delivery system composed of self-assembled Curcumin nanoparticles (NPs) coated with a tannic acid (TA)/Fe(III) network (denoted as CUR@TA-Fe(III) NPs). We systematically evaluated the in vitro cytotoxicity and photothermal–ferroptosis synergistic therapeutic efficacy of CUR@TA-Fe(III) NPs in 4T1 breast cancer cells, as well as the in vivo antitumor activity using 4T1 tumor-bearing mouse models. Results: CUR@TA-Fe(III) NPs had high drug loading efficiency (LE) of 27.99%, good dispersion stability, and photothermal properties. Curcumin could inhibit the growth of 4T1 cancer cells, while TA-Fe(III) efficiently converted light energy into heat upon exposure to near-infrared (NIR) light, leading to direct thermal ablation of 4T1 cells. Additionally, TA-Fe(III) could supply Fe(II) via TA, increase intracellular Fe(II) content, and generate reactive oxygen species (ROS) through the Fenton reaction, in turn inducing lipid peroxidation (LPO), a decrease in mitochondrial membrane potential (MMP), and glutathione depletion, eventually triggering ferroptosis. Conclusions: This treatment strategy, which integrates CT, PTT, and ferroptosis, is expected to overcome the limitations of traditional single-treatment methods and provide a more effective method for the treatment of TNBC. Full article

The coordination chemistry of benzimidazole ligands combines σ donation and π backbonding. Owing to this electronic flexibility, benzimidazole ligands stabilize both electron deficient and electron-rich transition states in the catalytic cycle of Ziegler-Natta polymerizations. In this study, Fe(III) and Ni(II) complexes of 2-substituted-benzimidazoles were tested as catalysts for ethylene and 1-butene oligomerization. The tests realized in toluene yielded mainly butenes and minor amounts of hexenes. When dichloromethane was used as solvent, a tandem reaction took place and 1-butene produced by ethylene dimerization was further oligomerized, yielding octenes and dodecenes as main products. All tested catalysts exhibited moderate selectivity for 1-octene, indicating 1-ω enchainment in 1-butene dimerization. Beyond catalytic tests, a theoretical study of the ligand 2,2′-(furan-2,5-diyl)bis(1H-benzimidazole) confirmed the planar structure of this compound as evidenced by NMR spectroscopy. Full article

The combination of electrochemical, surface, and spectroscopic techniques revealed that Pseudomonas aeruginosa biofilm accelerated corrosion of 304 stainless steel (SS), leading to localized pitting with depths up to 3.75 μm. Such damage did not occur on 304 SS treated with P. aeruginosa in the presence of Artemisia annua L. extract, or in sterile seawater. Introducing A. annua into biotic seawater hindered biofilm development and prevented the formation of porous Fe(III) corrosion products. Instead, a compact Fe₃O₄ layer formed, indicating a shift in corrosion product morphology and stability. ATR-FTIR analysis confirmed phenolic groups from the extract were adsorbed onto the steel interface, supporting the dual inhibitory role of A. annua through both surface modification and antimicrobial action. A. annua extract demonstrated a 74.4 ± 4.4% reduction in MIC-induced corrosion of 304 SS in marine conditions. Full article

This study examined the leaching behavior of copper and iron from a sphalerite concentrate in sulfuric acid utilizing an ensemble MnO₂–KI oxidizing system. The temperature was shown to significantly influence the leaching kinetics, with the efficiency notably improving between 40 °C and 80 °C. The introduction of KI affected the balance between sulfur passivation and oxidant availability, facilitating increased leaching efficiencies. At 3 wt% KI, maximum recoveries of 82.1% Cu and 85.3% Fe were achieved, which indicates a notable decrease in surface passivation. Kinetic study analysis revealed low activation energies of 28.90 kJ mol⁻¹ for copper and 18.94 kJ mol⁻¹ for iron, indicating that both processes proceed readily at moderate temperature regimes. Despite being diffusion-controlled, the mechanisms of dissolution are different: iron leaching is more complicated, involving pyrite oxidation, sulfur layer formation, transformation to marcasite, and ultimately iron (III) release, whereas copper leaching involves direct interaction of chalcopyrite with the oxidants, similar to the behavior of sphalerite. Full article

Ore mining and smelting are often related to environmental pollution. This study provides information about the geochemical features of Technosols at historical mining and metallurgical sites in the Tatra Mountains, southern Poland, evaluating the contents of potentially toxic trace elements (PTTE) and their behaviours in soils, as well as the influence of soil properties on PTTE mobility. Thirteen soil profiles were studied in eight abandoned mining and smelting sites. PTTE concentrations, including rare earth elements (REE), were measured using ICP-MS and ICP-OES. Selected elements (Cu, Zn, Pb, Cd, As, Sb, Ba, Sr, Co, Ni, Mn and Cr) were fractionated using the modified European Community Bureau of Reference (BCR) four-step sequential extraction. Contamination of soils with PTTE was compared against Polish regulatory limits, which were exceeded for Cu, Zn, Pb, Mo, Hg, As, Co, Ni and Ba, with concentrations exceeding limits by 16, 18, 34 and 160 times for Cu, Hg, As and Ba, respectively, in some profiles. Based on geochemical features depending on parent material properties, the soils examined were divided into three groups. Group I Technosols (near-neutral soils developed from Fe/Mn-ore and carbonate-bearing mining waste) were particularly enriched in Co, Ni, Mn and REE. Group II Technosols (acidic soils developed from polymetallic ore-bearing aluminosilicate mining waste) contained elevated concentrations of Cu, Zn, Hg, As, Sb, Bi, Co, Ag, Ba, Sr, U and Th; they contained lower contents of REE than Group I Technosols. Group III Technosols (soils developed in smelting-affected areas and containing metallurgical waste) were rich in Cu, As, Sb, Ba, Hg, Co and Ag and contained the lowest REE contents among the studied soils. Sequential BCR extraction revealed that PTTE mobility varied strongly according to soil group, with higher mobility of Mn, Cu and Zn in acidic polymetallic ore-derived soils (Group II), while carbonate-rich soils (Group I) showed mainly immobile forms. Metallurgical slag-derived soils (Group III) exhibited complex PTTE behaviour controlled by organic matter and Fe/Mn oxides. Soil properties (pH, carbonates and TOC) seem to control PTTE mobility. Full article

The coordination chemistry of a hydrazinylpyrazine-derived Schiff base ligand (L1), formed in situ from salicylaldehyde and 2-hydrazinopyrazine, with Fe(III) salts has been systematically investigated under varied synthetic conditions. Six discrete Fe(III) complexes (1a–1e and 2) were isolated and structurally characterised via single-crystal X-ray diffraction, revealing diverse coordination geometries ranging from five-coordinate pseudo-trigonal bipyramidal to six-coordinate pseudo-octahedral environments. The supramolecular architectures are governed by a rich interplay of non-covalent interactions, including hydrogen bonding, halogen bonding, and π–π stacking, which significantly influence the crystallisation pathways and final solid-state structures. Continuous shape measure (CShM) analysis highlights substantial geometric distortion in the bis-tridentate complexes, attributed to the steric and electronic constraints imposed by the ligand. Powder X-ray diffraction and infrared spectroscopy confirm the presence of multiple phases in bulk samples, underscoring the kinetic competition between crystallisation and coordination. The results demonstrate that supramolecular stabilisation of monoligated species can kinetically inhibit bis-ligation, with ligand excess and solvent polarity serving as key parameters to direct complex speciation. These findings provide insight into the delicate balance between coordination geometry, ligand strain, and supramolecular assembly in Fe(III) Schiff base complexes. Full article

Iron deficiency anemia (IDA) remains a global health challenge. This study pioneers the use of humic substances (HS) as natural, biocompatible macroligands to develop safer and more effective nanoferrotherapeutics. We synthesized a series of nanoscale Fe(III) oxyhydroxide complexes stabilized by different HS, employing various solvents (ethanol, isopropanol, and acetone) and precipitation methods to isolate fractions with optimized properties. The nanocomposites were comprehensively characterized using inductively coupled plasma atomic emission spectrometry, total organic carbon analysis, X-ray diffraction, transmission electron microscopy, and Mössbauer spectroscopy. Cytotoxicity and iron bioavailability of all HS-Fe(III) formulations were assessed in Caco-2 intestinal epithelial cells. The type of HS and precipitation conditions significantly influenced the nanocomposites’ properties, yielding spherical nanoparticles (1–2 nm) of ferrihydrite or goethite. Physicochemical analysis confirmed that solvent-driven fractionation effectively tailored the nanocomposites’ size, crystallinity, and elemental composition. All HS-Fe(III) formulations demonstrated exceptional cytocompatibility, starkly contrasting the significant cytotoxicity of the reference drug Ferrum Lek^®. Several complexes, particularly CHSFe-Et67, surpassed Ferrum Lek^® in cellular iron uptake efficiency. We conclude that HS are a highly promising platform for developing effective and safe iron-delivery nanoferrotherapeutics, leveraging their natural polyfunctionality to enhance bioavailability and mitigate toxicity. Full article

Molecular geometry, infrared (IR) vibrational frequencies, and ultraviolet–visible (UV-Vis) electronic absorption spectra of the trivalent iron tris(acetylacetonate) complex, Fe(III)(acac)₃, were computed using hybrid meta-generalized gradient approximation (meta-GGA) density functional theory (DFT). Calculations employed the Jorge double-$\zeta$ valence plus polarization basis sets (standard DZP and relativistic DZP + DKH). Solvent effects were modeled using the SMD continuum solvation framework with acetonitrile as the dielectric medium. This charge-neutral complex exhibits predominantly ionic metal–ligand bonding character, which simplifies the computational treatment. Despite extensive DFT applications to coordination compounds, systematic benchmarks for this bidentate ligand system remain limited. The computed harmonic frequencies ($\nu$) and electronic excitation energies (${\lambda }_{\max }$) demonstrate excellent agreement with available experimental measurements. These results enable comparative analysis of IR and UV-Vis spectral features, both with and without all-electron scalar relativistic effects with the second-order Douglas–Kroll–Hess approach. Full article

This study evaluates the sorption behavior of natural zeolite (NZ) and Fe(III)-modified natural zeolite (FeZ) for Ni(II) ions, with the objective of assessing their potential for application in the remediation of nickel-contaminated environments. Optimization of sorption parameters, including pH_o, solid/liquid ratio (S/L), contact time, and initial Ni(II) concentration was performed to maximize both the sorption capacity of the zeolites and the removal efficiency of Ni(II) from suspension. The results demonstrated that both pH_o and S/L ratio exert a significant influence on Ni(II) sorption onto both zeolites, with a particularly pronounced effect observed for FeZ. Experimental results confirmed that FeZ exhibits a four-to-five times higher sorption capacity for Ni(II) than NZ, which was additionally verified by elemental analysis, SEM-EDS, and elemental mapping of Ni(II)-saturated zeolites. Intraparticle diffusion was identified as the rate-limiting step in the transfer of Ni(II) ions to the active sorption sites. Ion exchange was identified as the main sorption mechanism accompanied by outer-sphere complexation and electrostatic attraction. Leaching tests of Ni(II)-saturated zeolites, conducted in accordance with the standard DIN 38414 S4 method, demonstrated that both zeolites effectively retained Ni(II) within their structures over a wide pH range, 4.11 ≤ pH_o ≤ 12.02. These findings indicate the potential applicability of zeolites for remediation of nickel-contaminated environments, with FeZ being particularly promising due to its enhanced sorption capacity for Ni(II) ions. Full article

In this article, the binding interactions of lysozyme with hexacyanoferrate(III)/(II), i.e., [Fe(CN)₆]³⁻ and [Fe(CN)₆]⁴⁻ ions, have been characterised using steady-state fluorescence spectroscopy (SF), isothermal titration calorimetry (ITC), circular dichroism spectroscopy (CD), cyclic voltammetry (CV), and molecular-dynamics-based computational approaches. Studies have shown that under experimental conditions (10 mM cacodylate buffer, pH 7, 298.15 K), complexes with a 1:1 stoichiometry are formed. Four distinct regions on the lysozyme surface patches with the potential to bind hexacyanoferrate(III)/(II) were identified and described. Thermodynamic parameters revealed that the interactions are predominantly governed by electrostatic and van der Waals forces. These interactions enhance the electron transfer kinetics of the [Fe(CN)₆]^3−/4− system. The secondary structure of the protein is not affected by these interactions. Enzyme activity studies demonstrated that the affinity of lysozyme for the substrate remained unchanged regardless of whether free lysozyme or the lysozyme-[Fe(CN)₆]^3−/4− complex was present in the test sample. Finally, biological tests performed on both Gram-positive (B. subtilis, S. aureus) and Gram-negative (E. coli, P. aeruginosa) bacteria confirmed the results of the biochemical analysis, indicating that [Fe(CN)₆]^3−/4− ions do not block the active site of the enzyme and do not interfere with its activity. Full article

The NAD⁺-dependent alcohol dehydrogenase AdhB from Aromatoleum aromaticum EbN1 belongs to family III of Fe-dependent alcohol dehydrogenases. It was recombinantly produced in Escherichia coli and biochemically characterized, showing activity only with ethanol or n-propanol. The enzyme contained substoichiometric amounts of Fe, Zn, and Ni and a yet unidentified nucleotide-like cofactor, as indicated by mass spectrometric data. As suggested by its narrow substrate spectrum and complementation of a related species to growth on ethanol, the most probable physiological function of AdhB is the oxidation of short aliphatic alcohols such as ethanol or n-propanol. The enzyme also exhibits a very high tolerance to ethanol and n-propanol, showing moderately substrate-inhibited Michaelis–Menten kinetics up to concentrations of 20% (v/v). AdhB can also be applied biotechnologically to convert acetate to ethanol in coupled enzyme assays with the tungsten enzyme aldehyde oxidoreductase, showing activity with either another aldehyde or pre-reduced benzyl viologen as electron donors. Full article

As an important agricultural ecosystem, greenhouse gas (GHG) emissions and arsenic (As) mobilization in rice paddy fields have gained significant attention on climate change and food safety. There is a certain correlation between the GHG and As migration in rice paddy fields. The oxidation of methane in paddy fields can provide electrons for the reduction and release of arsenate. Nitrate in rice paddy soil can promote the fixation of As by oxidizing Fe (II) to form iron oxide–As complexes or directly oxidize As (III) to As (V) to reduce the toxicity of As. However, incomplete denitrification of nitrate can lead to the emission of N₂O. This review systematically expounds the research advances, influencing factors and simultaneous mitigation measures of GHG emissions and As mobilization in rice paddy fields. It focuses on discussing the influence mechanisms of soil physical and chemical properties, water management measures, fertilization methods, and the addition of soil conditioner on As migration and GHG emission, and it looks forward to future research directions. It aims to provide a theoretical basis and practical guidance for reducing the risk of As contamination in rice fields, reducing GHG emission, and achieving sustainable development of rice production. Full article

Iron(III) (Fe(III)) complexes have recently emerged as safer alternatives to magnetic resonance imaging (MRI) contrast agents (CAs), reigniting interest in biomedical research. Although gadolinium Gd(III)-based contrast agents (CAs) have been widely used in MRI over the past four decades, their use in the current clinical routine is severely constrained due to concerns about high toxicity and environmental impact. Research is now focusing on synthesizing safer contrast agents with alternative paramagnetic ions like Fe(III) or Mn(II). MRI CAs with integrated potent therapeutic moieties may offer synergistic advantages over traditional contrast agents in clinical use. The study explored the use of salinomycin-ferrihydrite composites as possible effective ensembles of imaging and therapeutic units in the same molecule, evaluating their anticancer activity and influence on the signal in MRI. The composites were characterized using Mössbauer spectroscopy and ICP-MS for iron content determination. The in vitro relaxivity measurements in a high-field MR scanner demonstrated the potency of the composites as T₂ enhancers. The antitumor activity of one selected Sal-ferrihydrite composite was tested in three human cancer cell lines: A549 (non-small cell lung cancer); SW480 (colon cancer); and CH1/PA1 (ovarian teratocarcinoma) by the MTT cell viability assay. The new Sal-ferrihydrite composite showed a pronounced cytotoxicity in all three human cancers in line with enhanced signal in MRI, which makes it a promising candidate for future biomedical applications. The superior cytotoxic effect, together with the strong signal enhancement, makes these compounds promising candidates for further detailed investigations as future theranostic agents. Full article

This study explores the visible-light-driven photolysis of Ferrioxalate complexes for the degradation of Toluidine Blue (TB), a persistent phenothiazine dye, using a 1 L recirculating batch-loop photoreactor. The reactor system incorporated two tubular photochemical units (35 cm × 3 cm each) in series: the first equipped with an immersed blue fluorescent lamp (12 W, 30 cm-tube), and the second with dual external blue LED lamps (18 W total, 30 cm) encasing a double-walled glass cell. Continuous flow between the units was maintained via a peristaltic pump. Experimental investigations were used to evaluate the effects of key parameters such as Fe(III) and oxalate concentrations, initial TB load, pH, light source, flow rate, ligand type, dissolved gas type, external H₂O₂ addition, and the presence of various inorganic ions. The results demonstrate efficient dye degradation, with ~75% TB removal within 1 h under combined fluorescent and LED irradiation, where each reactor contributing comparably. The optimal performance was achieved at pH 4, with a 10 oxalate-to-Fe(III) molar ratio (1 mM:0.1 mM) and a flow rate of 25 mL s⁻¹. Among various ligands tested (oxalate, acetate, citrate, EDTA), oxalate proved to be the most effective. The presence and type of anions significantly influenced degradation efficiency due to their potential scavenging effects. Although the process achieved high dye removal, TOC analysis indicated only moderate mineralization, suggesting the accumulation of non-colored intermediates. External H₂O₂ addition moderately improved TOC removal, likely due to enhanced hydroxyl radical generation via the Fenton mechanism. These findings highlight the promise of Ferrioxalate-based photochemical systems under visible light for dye removal, while also emphasizing the need for further research into by-product identification, mineralization enhancement, and toxicity reduction to ensure safe effluent discharge. Full article

We investigated the effects of chemical and physical changes on the interplay between the Néel and Brown superspin relaxation mechanisms in ferrofluids containing 18 nm-diameter Co_0.2Fe_2.8O₄ magnetic nanoparticles. We attempted to tune the ferrofluid’s magnetization dynamics via three methods: (i) changing the carrier fluid from Isopar M to kerosene (ii) doubling the Co-doping level from x = 0.2 to x = 0.4, and (iii) diluting the Co_0.2Fe_2.8O₄/Isopar M nanomagnetic fluid from δ = 1 mg/mL to δ = 0.1 mg/mL. We used temperature-resolved ac-susceptibility measurements at different frequencies, χ″ vs. T|_f, to gain insight into the thermally driven superspin dynamics of the nanoparticles within the ferrofluid. Our data demonstrates that both increasing x and using a different carrier fluid quantitatively alter the temperature dependence of the Néel and Brown relaxation frequency (f_N vs. T and f_B vs. T) by changing the nanoparticles’ magnetic moments and the fluid’s viscosity. Yet, the two mechanisms remain decoupled, as indicated by the presence of two magnetic events (peaks in the χ″ vs. T|_f datasets) one corresponding to the Néel and the other to Brown relaxation. On the other hand, diluting the ferrofluid leads to a qualitative change in the collective superspin dynamics behavior. Indeed, there is just one χ″-peak in the data from the δ = 0.1 mg/mL nanofluid, and its f vs. T dependence is well-described by a model that includes coupled contributions from both the Néel and Brown relaxation: $\mathrm{f}\left(\mathrm{T}\right)=\mathrm{p}·{\displaystyle \frac{T}{{\gamma }_0}}·\mathrm{e}\mathrm{x}\mathrm{p}\left[-{\displaystyle \frac{{\mathrm{E}}^{\prime }}{{\mathrm{k}}_{\mathrm{B}}\left(\mathrm{T}-{\mathrm{T}}_0^{\prime }\right)}}\right]+$ (1 − p) ${\mathrm{f}}_0\mathrm{e}\mathrm{x}\mathrm{p}\left[-{\displaystyle \frac{{\mathrm{E}}_{\mathrm{B}}}{{\mathrm{k}}_{\mathrm{B}}\left(\mathrm{T}-{\mathrm{T}}_0\right)}}\right]$. This is a remarkable behavior that demonstrates the ability to control a ferrofluids magnetization dynamics through simple chemical and physical changes. Full article