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In porous water filters, the transport and entrapment of contaminants can be modeled as a classic mass transport problem, which employs the conventional convection–dispersion equation to predict the transport of species existing in trace amounts. Using the volume-averaging method (VAM), the upscaling has revealed two possible macroscopic equations for predicting contaminant concentrations in the filters. The first equation is the classical convection–dispersion equation, which incorporates a total dispersion tensor. The second equation involves an additional transport coefficient, identified as the adsorption-induced vector. In this study, the aforementioned equations were solved in 1D for column tests using 3D unit cells. The simulated breakthrough curves (BTCs), using the proposed micro–macro-coupling-based VAM model, are compared with the direct numerical simulation (DNS) results based on BCC-type unit cells arranged one-after-another in a daisy chain manner, as well as with three previously reported experimental works, in which the functionalized zeolite and zero-valent iron fillings were used as an adsorbent to remove phosphorous and arsenic from water, respectively. The disagreement of VAM BTC predictions with DNS and experimental results reveals the need for an alternative closure formulation in VAM. Detailed investigations reveal time constraint violations in all the three cases, suggesting this as the main cause of VAM's failure. [ABSTRACT FROM AUTHOR]

The absence of adequate methods for hydrogen storage has prevented the implementation of hydrogen as a major source of energy. Graphene-based materials have been considered for use as solid hydrogen storage, because of graphene's high specific surface area. However, these materials alone do not meet the hydrogen storage standard of 6.5 wt.% set by the United States Department of Energy (DOE). They can, however, be easily modified through either decoration or doping to alter their chemical properties and increase their hydrogen storage capacity. This review is a compilation of various published reports on this topic and summarizes results from theoretical and experimental studies that explore the hydrogen storage properties of metal-modified graphene materials. The efficacy of alkali, alkaline earth metal, and transition metal decoration is examined. In addition, metal doping to further increase storage capacity is considered. Methods for hydrogen storage capacity measurements are later explained and the properties of an effective hydrogen storage material are summarized. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) is growing into a major public health crisis worldwide. The reducing alternatives to conventional agents starve for novel antimicrobial agents. Due to their unique magnetic properties and excellent biocompatibility, iron oxide nanoparticles (IONPs) are the most preferable nanomaterials in biomedicine, including antibacterial therapy, primarily through reactive oxygen species (ROS) production. IONP characteristics, including their size, shape, surface charge, and superparamagnetism, influence their biodistribution and antibacterial activity. External magnetic fields, foreign metal doping, and surface, size, and shape modification improve the antibacterial effect of IONPs. Despite a few disadvantages, IONPs are expected to be promising antibacterial agents of a new generation. [ABSTRACT FROM AUTHOR]

An increase in the number of small electronics is anticipated, requiring the preparation of an adequate powering method. A triboelectric nanogenerator, capable of scavenging ambient mechanical energy, is proposed as an efficient means to reduce power consumption for self-sustainable sensors, although its electrical output needs enhancement to broaden its technological applicability. In this work, a magnetic composite comprising iron oxide and polyaniline was synthesized to augment triboelectricity through the modulation of magnetic field intensity using physical chemistry. The crystallinity of the composite, chemical bonding, and structure of the surface are analyzed. The surface potential of the composite, embedded into polydimethylsiloxane, is quantitatively evaluated by using Kelvin probe force microscopy. By amalgamating magnetic flux density and triboelectric outputs, the optimization of the triboelectric layer is achieved, yielding output values of 93.86 V, 6.9 µA, and 127.5 µW. Following a reduction in surface adhesion after the powder coating process, a wind-based triboelectric nanogenerator is fabricated. Its excellent sensitivity to wind and exceptional long-term endurance are assessed, confirming its suitability as a sensor. The practicality of employing this device in intrusion detection, leveraging a wireless door-opening sensor, is demonstrated using synthesized composite materials. [ABSTRACT FROM AUTHOR]

Photothermal therapy (PTT) can overcome cancer treatment resistance by enhancing the cell membrane permeability, facilitating drug accumulation, and promoting drug release within the tumor tissue. Iron oxide nanoparticles (IONPs) have emerged as effective agents for PTT due to their unique properties and biocompatibility. Approved for the treatment of anemia, as MRI contrast agents, and as magnetic hyperthermia mediators, IONPs also offer excellent light-to-heat conversion and can be manipulated using external magnetic fields for targeted accumulation in specific tissue. Optimizing parameters such as the laser wavelength, power density, shape, size, iron oxidation state, functionalization, and concentration is crucial for IONPs' effectiveness. In addition to PTT, IONPs enhance other cancer treatment modalities. They improve tumor oxygenation, enhancing the efficacy of radiotherapy and photodynamic therapy. IONPs can also trigger ferroptosis, a programmed cell death pathway mediated by iron-dependent lipid peroxidation. Their magneto-mechanical effect allows them to exert a mechanical force on cancer cells to destroy tumors, minimizing the damage to healthy tissue. This review outlines strategies for the management of the photothermal performance and PTT efficiency with iron oxide nanoparticles, as well as synergies with other cancer therapies. [ABSTRACT FROM AUTHOR]

Iron oxide nanoparticles were synthesized by co-precipitation using three different iron salt stoichiometric mole ratios. Powder X-ray diffraction patterns revealed the inverse cubic spinel structure of magnetite iron oxide. Transmission electron microscopic images showed Fe3O4 nanoparticles with different shapes and average particle sizes of 5.48 nm for Fe3O4-1:2, 6.02 nm for Fe3O4-1.5:2, and 6.98 nm for Fe3O4-2:3 with an energy bandgap of 3.27 to 3.53 eV. The as-prepared Fe3O4 nanoparticles were used as photocatalysts to degrade brilliant green (BG), rhodamine B (RhB), indigo carmine (IC), and methyl red (MR) under visible light irradiation. The photocatalytic degradation efficiency of 80.4% was obtained from Fe3O4-1:2 for brilliant green, 61.5% from Fe3O4-1.5:2 for rhodamine B, and 77.9% and 73.9% from Fe3O4-2:3 for both indigo carmine and methyl red. This indicates that Fe3O4-2:3 is more efficient in the degradation of more than one dye. This study shows that brilliant green degrades most effectively at pH 9, rhodamine B degrades best at pH 6.5, and indigo carmine and methyl red degrade most efficiently at pH 3. Recyclability experiments showed that the Fe3O4 photocatalysts can be recycled four times and are photostable. [ABSTRACT FROM AUTHOR]

This work presents a new and facile route for the preparation of iron oxide-based catalysts supported on alumina, which enables the targeted synthesis of catalysts with an increased amount of isolated tetrahedrally coordinated iron centers compared to a conventional impregnation procedure, and therefore leads to an increase in activity for CO oxidation reaction. By a multi-step impregnation–calcination protocol, the catalysts were synthesized with iron loadings of between 1 and 10 wt%, and their catalytic activity was then compared with a 10 wt% loaded catalyst prepared by conventional single impregnation. With a loading of 8 wt%, the presented catalysts showed an improved catalytic activity regarding light-off and full conversion temperatures compared to this reference. Through the application of several analytical methods (PXRD, PDF, DRUVS, SEM, XAFS), the improved catalytic activity can be correlated with an increased amount of isolated iron centers and a significantly reduced fraction of agglomerates or particles. [ABSTRACT FROM AUTHOR]

Rapid advancements in nanotechnology have expanded its applications and synergistic impact on modern nanosystems. The comprehensive assessment of nanomaterials' safety for human exposure has become crucial and heightened. In addition to the characterization of cell proliferation and apoptosis, probing the implication of autophagy is vital for understanding the ramification of nanomaterials. Hence, HEK-293 kidney cells were employed to understand the changes in induction and perturbation of autophagy in cells by iron oxide (Fe3O4) and silica (SiO2) nanoparticles. Interestingly, Fe3O4 worked as a potent modulator of the autophagy process through its catalytic performance, which can develop better than that of SiO2 nanoparticles mechanism, stressing their therapeutic implication in the understanding of cell behaviors. The quantification of reactive oxygen species (ROS) was measured along with the process of autophagy during cell growth. This modulated autophagy will help in cell fate determination in complementary therapy for disease treatment, provide a clinical strategy for future study. [ABSTRACT FROM AUTHOR]

Cancer is one of the leading causes of global mortality, and its incidence is increasing annually. Neutron capture therapy (NCT) is a unique anticancer modality capable of selectively eliminating tumor cells within normal tissues. The development of accelerator-based, clinically mountable neutron sources has stimulated a worldwide search for new, more effective compounds for NCT. We synthesized magnetic iron oxide nanoparticles (NPs) that concurrently incorporate boron and gadolinium, potentially enhancing the effectiveness of NCT. These magnetic nanoparticles underwent sequential modifications through silane polycondensation and allylamine graft polymerization, enabling the creation of functional amino groups on their surface. Characterization was performed using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive X-ray (EDX), dynamic light scattering (DLS), thermal gravimetric analysis (TGA), and transmission electron microscopy (TEM). ICP-AES measurements indicated that boron (B) content in the NPs reached 3.56 ppm/mg, while gadolinium (Gd) averaged 0.26 ppm/mg. Gadolinium desorption was observed within 4 h, with a peak rate of 61.74%. The biocompatibility of the NPs was confirmed through their relatively low cytotoxicity and sufficient cellular tolerability. Using NPs at non-toxic concentrations, we obtained B accumulation of up to 5.724 × 1010 atoms per cell, sufficient for successful NCT. Although limited by its content in the NP composition, the Gd amount may also contribute to NCT along with its diagnostic properties. Further development of the NPs is ongoing, focusing on increasing the boron and gadolinium content and creating active tumor targeting. [ABSTRACT FROM AUTHOR]

This work presents the green synthesis of iron oxide nanoparticles (IONPs) using Baccharis salicifolia extract and their incorporation in mesoporous silica MCM-41, obtaining an MCM-41@IONP composite. The MCM-41@IONP composite was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), nitrogen adsorption and desorption, scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The use of the natural reducing agent Baccharis salicifolia resulted in nanoparticles with an average size of 31 nm. Furthermore, we showcase the application of the MCM-41@IONP nanocomposite in a metal–insulator–semiconductor (MIS) diode, which was fabricated at room temperature. The current–voltage and capacitance–voltage curves of the MIS diode were carefully measured and subjected to detailed analysis. The results demonstrate the potential utility of MCM-41@IONP nanocomposite-based MIS diodes, suggesting their applicability in the design of biosensors or as discrete components in electronic devices. [ABSTRACT FROM AUTHOR]

The investigation and clarification of the properties of surface-functionalized superparamagnetic nanoparticles in a biological environment are key challenges prior to their medical applications. In the present work, electron paramagnetic resonance spectroscopy (EPR) combined with the spin labeling technique was utilized to better understand the behavior of nitroxides attached to magnetite nanoparticles dispersed in body fluid. EPR spectra of spin-labeled, silane-coated Fe3O4 nanoparticles in human serum and whole blood were recorded and analyzed for both room- and low-temperature values. In all cases, the obtained EPR signal consisted of a broad line from magnetite cores and a characteristic signal from the attached 4-Amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO). Even for liquid samples, the anisotropic components of magnetic tensors did not fully average out, which was reflected in the differences in the intensity of three narrow hyperfine lines from nitroxide. At 230 K the irregular slow-motion signal from the attached radical was also simulated using the EasySpin toolbox, which allowed to determine the parameters related to magnetic tensors and the dynamics of the spin label. The study showed that the anisotropy of the motion of the spin label 4-amino-TEMPO reflects its interactions with the surrounding medium and the manner of the attachment of the nitroxide to the surface of nanoparticles. [ABSTRACT FROM AUTHOR]

In this study, Fe3O4/Ag magnetite-silver (MSx) nanocomposites were investigated as catalysts for advanced oxidation processes by coupling the plasmonic effect of silver nanoparticles and the ferromagnetism of iron oxide species. A surfactant-free co-precipitation synthesis method yielded pure Fe3O4 magnetite and four types of MSx nanocomposites. Their characterisation included structural, compositional, morphological and optical analyses, revealing Fe3O4 magnetite and Ag silver phases with particle sizes ranging from 15 to 40 nm, increasing with the silver content. The heterostructures with silver reduced magnetite particle aggregation, as confirmed by dynamic light scattering. The UV–Vis spectra showed that the Fe:Ag ratio strongly influenced the absorbance, with a strong absorption band around 400 nm due to the silver phase. The oxidation kinetics of organic pollutants, monitored by in situ luminescence measurements using rhodamine B as a model system, demonstrated the higher performance of the developed catalysts with increasing Ag content. The specific surface area measurements highlighted the importance of active sites in the synergistic catalytic activity of Fe3O4/Ag nanocomposites in the photo-Fenton reaction. Finally, the straightforward fabrication of diverse Fe3O4/Ag heterostructures combining magnetism and plasmonic effects opens up promising possibilities for heterogeneous catalysis and environmental remediation. [ABSTRACT FROM AUTHOR]

This article presents the findings of a study on oxide reduction utilizing a novel reducing plasma torch, employing greenhouse gases such as CO2 and CH4 as plasma gases. The primary aim of this investigation is to establish the viability of this approach. The innovative plasma torch was employed to reduce various oxides, including aluminum oxide, iron oxide, and titanium oxide, as well as a mixed oxide composition, employing a CO2/CH4 molar ratio of 1:1 within a spouted bed reactor. Following plasma treatment, X-ray diffraction (XRD) analysis was conducted to examine the metallic phases, notably titanium, iron, and aluminum. SEM–EDS observations were carried out to assess microstructural changes and identify elemental compositions pre- and post-plasma treatment. The results demonstrate that within the conical section of the reactor, titanium oxide experiences partial reduction, resulting in limited titanium production, while aluminum oxide and iron oxides (magnetite and hematite) undergo reduction to yield aluminum and iron, respectively. Thermodynamic calculations, performed using Factsage software version 8.3, were utilized to predict stable-phase formations following plasma treatment for each material. [ABSTRACT FROM AUTHOR]

A commercial activated carbon (AC) was modified through iron oxide incorporation to obtain microwave absorbers (MWAs) for microwave-assisted pyrolysis. The influence of iron oxide content (5 and 20 wt% Fe3O4) and the modification methods were tested as follows: (1) in situ co-precipitation + washing step with Milli-Q; (2) in situ co-precipitation + washing step with Milli-Q/ethanol; and (3) physical iron oxide blending. The resulting MWAs were evaluated on the microwave-assisted pyrolysis of hardwood in a Milestone Flexiwave microwave reactor. The biochar yield varied from 24 wt% to 89 wt% and was influenced by the modification method rather than the iron oxide addition. The MWAs with physically blended iron oxide resulted in biochar yields comparable to conventional biochar (450 °C). Furthermore, the addition of iron oxide-activated carbon composites during the microwave-assisted pyrolysis caused a significant decrease in the biochar's 16 EPA polycyclic aromatic hydrocarbons, mainly by reducing the amount of pyrene in the biochar. [ABSTRACT FROM AUTHOR]

The iron industry is the largest energy-consuming manufacturing sector in the world, emitting 4–5% of the total carbon dioxide (CO2). The development of iron-based systems for CO2 capture and storage could effectively contribute to reducing CO2 emissions. A wide set of different iron oxides, such as hematite (Fe2O3), magnetite (Fe3O4), and wüstite (Fe(1−y)O) could in fact be employed for CO2 capture at room temperature and pressure upon an investigation of their capturing properties. In order to achieve the most functional iron oxide form for CO2 capture, starting from Fe2O3, a reducing agent such as hydrogen (H2) or carbon monoxide (CO) can be employed. In this review, we present the state-of-the-art and recent advances on the different iron oxide materials employed, as well as on their reduction reactions with H2 and CO. [ABSTRACT FROM AUTHOR]

The synthesis of novel catalysts for the oxygen reduction reaction, by means of a fast one-pot microwave-assisted procedure, is reported herein and deeply explained. In particular, the important role of doping atoms, like sulfur and nitrogen, in Fe2O3-reduced graphene oxide nanocomposites is described to address the modification of catalytic performance. The presence of dopants is confirmed by X-ray Photoelectron Spectroscopy analysis, while the integration of iron oxide nanoparticles, by means of decoration of the graphene structure, is corroborated by electron microscopy, which also confirms that there is no damage to the graphene sheets induced by the synthesis procedure. The electrochemical characterizations put in evidence the synergistic catalysis effects of dopant atoms with Fe2O3 and, in particular, the importance of sulfur introduction into the graphene lattice. Catalytic performance of as-prepared materials toward oxygen reduction shows values close to the Pt/C reference material, commonly used for fuel cell and metal–air battery applications. [ABSTRACT FROM AUTHOR]

Hyaluronic acid (HA) has attracted much attention in tumor-targeted drug delivery due to its ability to specifically bind to the CD44 cellular receptor, which is widely expressed on cancer cells. We present HA-capped magnetic nanoparticles (HA-MNPs) obtained via the co-precipitation method, followed by the electrostatic adsorption of HA onto the nanoparticles' surfaces. A theoretical study carried out with the PM3 method evidenced a dipole moment of 3.34 D and negatively charged atom groups able to participate in interactions with nanoparticle surface cations and surrounding water molecules. The ATR-FTIR spectrum evidenced the hyaluronic acid binding to the surface of the ferrophase, ensuring colloidal stability in the water dispersion. To verify the success of the synthesis and stabilization, HA-MNPs were also characterized using other investigation techniques: TEM, EDS, XRD, DSC, TG, NTA, and VSM. The results showed that the HA-MNPs had a mean physical size of 9.05 nm (TEM investigation), a crystallite dimension of about 8.35 nm (XRD investigation), and a magnetic core diameter of about 8.31 nm (VSM investigation). The HA-MNPs exhibited superparamagnetic behavior, with the magnetization curve showing saturation at a high magnetic field and a very small coercive field, corresponding to the net dominance of single-domain magnetic nanoparticles that were not aggregated with reversible magnetizability. These features satisfy the requirement for magnetic nanoparticles with a small size and good dispersibility for long-term stability. We performed some preliminary tests regarding the nanotoxicity in the environment, and some chromosomal aberrations were found to be induced in corn root meristems, especially in the anaphase and metaphase of mitotic cells. Due to their properties, HA-MNPs also seem to be suitable for use in the biomedical field. [ABSTRACT FROM AUTHOR]

Nanocrystalline cellulose (NCC) can be converted into carbon materials for the fabrication of lithium-ion batteries (LIBs) as well as serve as a substrate for the incorporation of transition metal oxides (TMOs) to restrain the volume expansion, one of the most significant challenges of TMO-based LIBs. To improve the electrochemical performance and enhance the longer cycling stability of LIBs, a nanocrystalline cellulose-supported iron oxide (Fe2O3) composite (denoted as NCC–Fe2O3) is synthesized and utilized as electrodes in LIBs. The obtained NCC–Fe2O3 electrode exhibited stable cycling performance, better capacity, and high-rate capacity, and delivered a specific discharge capacity of 576.70 mAh g−1 at 100 mA g−1 after 1000 cycles. Moreover, the NCC–Fe2O3 electrode was restored and showed an upward trend of capacity after working at high current densities, indicating the fabricated composite is a promising approach to designing next-generation high-energy density lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Iron oxide nanoparticles (IONPs) have many practical applications, ranging from environmental protection to biomedicine. IONPs are being investigated due to their high potential for antimicrobial activity and lack of toxicity to humans. However, the biological activity of IONPs is not uniform and depends on the synthesis conditions, which affect the shape, size and surface modification. The aim of this work is to synthesise IONPs using a mixed method, i.e., chemical co-precipitation combined with biogenic surface modification, using extracts from spent hops (Humulus lupulus L.) obtained as waste product from supercritical carbon dioxide hop extraction. Different extracts (water, dimethyl sulfoxide (DMSO), 80% ethanol, acetone, water) were further evaluated for antioxidant activity based on the silver nanoparticle antioxidant capacity (SNPAC), total phenolic content (TPC) and total flavonoid content (TFC). The IONPs were characterised via UV-vis spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and Fourier-transform infrared (FT-IR) spectroscopy. Spent hop extracts showed a high number of flavonoid compounds. The efficiency of the solvents used for the extraction can be classified as follows: DMSO > 80% ethanol > acetone > water. FT-IR/ATR spectra revealed the involvement of flavonoids such as xanthohumol and/or isoxanthohumol, bitter acids (i.e., humulones, lupulones) and proteins in the surface modification of the IONPs. SEM images showed a granular, spherical structure of the IONPs with diameters ranging from 81.16 to 142.5 nm. Surface modification with extracts generally weakened the activity of the IONPs against the tested Gram-positive and Gram-negative bacteria and yeasts by half. Only the modification of IONPs with DMSO extract improved their antibacterial properties against Gram-positive bacteria (Staphylococcus epidermidis, Staphylococcus aureus, Micrococcus luteus, Enterococcus faecalis, Bacillus cereus) from a MIC value of 2.5–10 mg/mL to 0.313–1.25 mg/mL. [ABSTRACT FROM AUTHOR]

Featured Application: Development of a method to characterize size distributions of magnetic nanoparticles and their magnetic behavior in polymeric matrices. Magnetic nanoparticles (MNPs) are interesting for their potential employment in biomedical and environmental technologies. Although they have been characterized by many techniques, there are some issues that need to be solved. For instance, it is not yet possible to finely characterize their size distribution or to detect their local magnetic properties. In this work, commercial MNPs were employed, which were made of iron oxide cores with a mean diameter of 8 nm embedded in a matrix of dextran to form skeins with a mean diameter of 20 nm. These MNPs have been dispersed in keratin, a natural protein extracted from wool. Thin films have been realized by spin coating water solutions with various MNP concentrations. Analysis was conducted using a set of techniques, namely Atomic Force Microscopy, Environmental Scanning Electron Microscopy, a Physical Property Measurement System–Vibrating Sample Magnetometer, and the spatially resolved Magneto-Optic Kerr Effect (NanoMOKE). These MNPs show superparamagnetic properties, although a wide distribution of blocking temperature values indicates that the cores are not isolated and interact with others. NanoMOKE not only allows us to map the magnetic behavior of MNP clusters, but also to detect the presence of isolated MNPs dispersed in the keratin matrix. [ABSTRACT FROM AUTHOR]

Antibacterial textiles can help prevent infections from antimicrobial-resistant pathogens without using antibiotics. This work aimed to enhance the cotton fabric's antimicrobial properties by depositing Fe2O3 nanoparticles on both sides of its surface. The nanoparticles were deposited using low-temperature plasma technology in a pure oxygen atmosphere, which is environmentally friendly. The Fe2O3 nanoparticles formed clusters on the fabric surface, rather than thin films that could reduce the airflow of the textile. The optimal conditions for the nanoparticle deposition were 200 W of plasma power, 120 min of immersion time, and 5 cm of Fe cathode–textile sample distance. The received antimicrobial textile was tested and the high efficiency of developed materials were successfully demonstrated against 16 microbial strains (Gram-positive and Gram-negative bacteria and fungi). [ABSTRACT FROM AUTHOR]

This study delves into the atmospheric corrosion behavior of chromium-free complex-phase (CP) steel, specifically investigating the influence of wet/dry frequency and ratio in cyclic corrosion tests (CCT). The study employs a modified ISO 14993 standard CCT method, which involves salt spray, dry, and wet stages. After 15 and 30 CCT cycles, mass loss, maximum corrosion depth, and corrosion products were analyzed to gain insights into corrosion mechanisms. In general, increasing the frequency and wet/dry stage ratio in CCT extends the time for autocatalytic reactions to occur, leading to accelerated localized CP steel corrosion and increased pitting factors. However, as the rust layer thickens, uniform corrosion may also intensify, so careful considerations are necessary. This study underscores the importance of controlling the frequency and ratio of wet/dry stages in CCT for effectively analyzing localized corrosion behavior in specimens. [ABSTRACT FROM AUTHOR]

Natural limonite, which contains mainly nano-sized iron and manganese oxides, is widely distributed worldwide. This study investigated the kinetics, thermodynamics, and the effects of pH, ion strength, and anions on the adsorption of Sb(III) via limonites sampled from Xinqiao and Yeshan (Tongling, China). Results show that adsorption equilibrium is achieved after 24 h for all experiments. Under initial Sb(III) = 200 mg/L, pH = 3.0, and temperature = 25 °C, Sb adsorption quantities for X1 (Mn-free limonite from Xinqiao), X2 (Mn-containing limonite from Xinqiao), Y1 (Mn-free limonite from Yeshan), and Y2 (Mn-containing limonite from Yeshan) are 10.92, 12.97, 27.12, and 89.34 mg/g, respectively. Manganese oxides in limonites promote Sb removal through oxidizing Sb(III) to Sb(V). The adsorption processes for all four limonites are fitted with a pseudo-second-order model. All adsorptions except for X1 fit with the Freundlich model; for X1, the Langmuir adsorption model is better. All adsorptions are spontaneous reactions (ΔG < 0). All adsorptions except for Y1 (ΔH < 0, exothermic reaction) are endothermic reactions (ΔH > 0). Antimony adsorption is independent of solution pH for Mn-free limonites but is negatively related to solution pH for Mn-containing limonites. Generally, ion strength has a weak positive effect on Sb adsorption. The effects of anions on Sb adsorption are grouped into three types: weak negative (NO3− and SO42−), negative (CO32−, SiO44−, and PO43−), and equivocal (humic acid). This study indicates that due to a much higher surface area, Yeshan (124.8 m2/g for X1 and 171.7 m2/g for X2) rather than Xinqiao (13.7 m2/g for Y1 and 12.8 m2/g for Y2) limonites are better materials for Sb(III) removal in an aqueous solution. The key factors for the better use of limonite as an Sb(III) treatment material include temperature, pH, ion strength, and Mn content. [ABSTRACT FROM AUTHOR]

Sulfur dioxide (SO2) is a known pollutant that must be captured from gas streams. Dry desulfurization processes are investigated due to their lower energy requirement and potentially high capture efficiency. Carbon materials and metal oxides have been shown to have an affinity with SO2. The aim of this study was to combine iron oxide and graphene oxide (GO) as a composite material for SO2 capture for low-concentration streams. Iron oxide particles were prepared using a polyol method in which the precursor was dispersed in ethylene glycol, heated under reflux and then deposited on GO, a two-dimensional, single-layer material with a surface area of 400 m2/g. The synthesized material was tested for continuous desulfurization in a flow-through capture system with a stream of gas containing 25 ppm SO2 entering at 20 °C and 100 °C. Under all conditions tested, the breakthrough times, evaluated when the SO2 started to be detected at the outlet with a concentration of 1 ppm, as well as the capture capacities, were significantly higher for the iron oxide GO composite than for the pristine GO alone. The presence of sulfur compounds as well as the composite composition were confirmed by energy-dispersive X-ray spectroscopy (EDXS) and X-ray photoelectron spectroscopy (XPS). The breakthrough experiment results at various temperatures also suggest that the capture was not governed only by pure physical adsorption with the presence of iron oxide. Addition of iron oxide particles positively influences SO2 affinity with the synthesized material as shown by the increase in breakthrough time and capture capacity. [ABSTRACT FROM AUTHOR]

Bimetallic nanoparticles (BMNPs) combine unique and synergistic properties of two metals, allowing new specific applications. In this study, bimetallic AuFe nanoparticles and their conjugates with methotrexate (MTX) were obtained with an environmentally safe method of metal-vapor synthesis. The composition and electronic structure of the particles were investigated with X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX) spectrum and X-ray absorption spectroscopy (XANES and EXAFS). The effects of BMNP-MTX conjugates on human primary cells and tumor cell lines were evaluated with neutral red uptake and MTT in vitro cytotoxicity assays. Bright-field microscopy analyses of tumor spheroid size and evaluations of tumor spheroid vitality based on SFDA AM staining were carried out. In vitro assays for an antibacterial activity evaluation of the generated samples were performed. The influence of BMNP-MTX on cytokine production with normal leukocytes was assessed using ELISA. X-ray analyses of the samples demonstrated that gold was in the ground state Au0 as well as Au+ and Au3+ states are present in small quantities, whereas iron existed as a mixture of non-histometric oxides with states close to Fe2+ and Fe3+. The modification of the AuFe system with MTX is accompanied by a threefold increase in the relative proportion of the Au+ state. BMNP-MTX conjugates demonstrated significant antitumor activity compared to the drug alone, which proves the ability of the generated nanoconjugates to improve the effectiveness of MTX therapy. This was confirmed by a marked reduction in the size and vitality of AuFe-MTX-treated 3D tumor spheroids. In addition to their selective antitumor activity, AuFe-MTX exhibited moderate antibacterial activity and induced sample-specific cytokine production with normal human leukocytes—which points to an immunostimulatory potential. The present findings indicate important and diverse biological properties of BMNP-MTX conjugates and thus highlight perspectives for their biomedical applications and new immune-specific abilities. [ABSTRACT FROM AUTHOR]

A lot of nanomaterials have been applied to various nano-biotechnological fields, such as contrast agents, drug or gene delivery systems, cosmetics, and so on. Despite the expanding usage of nanomaterials, concerns persist regarding their potential toxicity. To address this issue, many scientists have tried to develop biocompatible nanomaterials containing phytochemicals as a promising solution. In this study, we synthesized biocompatible nanomaterials by using gallic acid (GA), which is a phytochemical, and coating it onto the surface of iron oxide nanoparticles (IONPs). Importantly, the GA-modified iron oxide nanoparticles (GA-IONPs) were successfully prepared through environmentally friendly methods, avoiding the use of harmful reagents and extreme conditions. The presence of GA on the surface of IONPs improved their stability and bioactive properties. In addition, cell viability assays proved that GA-IONPs possessed excellent biocompatibility in human dermal papilla cells (HDPCs). Additionally, GA-IONPs showed antioxidant activity, which reduced intracellular reactive oxygen species (ROS) levels in an oxidative stress model induced by hydrogen peroxide (H2O2). To investigate the impact of GA-IONPs on exosome secretions from oxidative stress-induced cells, we analyzed the number and characteristics of exosomes in the culture media of HDPCs after H2O2 stimulation or GA-IONP treatment. Our analysis revealed that both the number and proportions of tetraspanins (CD9, CD81, and CD63) in exosomes were similar in the control group and the GA-IONP-treated groups. In contrast, exosome secretion was increased, and the proportion of tetraspanin was changed in the H2O2-treated group compared to the control group. It demonstrated that treatment with GA-IONPs effectively attenuated exosome secretion induced by H2O2-induced oxidative stress. Therefore, this GA-IONP exhibited outstanding promise for applications in the field of nanobiotechnology. [ABSTRACT FROM AUTHOR]

In order to realize the high value-added reuse of coal fly ash, a reusable Fe-modified fly ash catalyst was synthesized for ozone catalysis degradation of chemical oxygen demand (COD) in wastewater. Through enhancement of the pretreatment procedure and FeOx modification, the resulting fly ash with Fe modification demonstrated increased specific surface area and porosity. The presence of Fe loading significantly enhances the reactivity of surface oxidizing reactive species, particularly oxygen vacancy, leading to improved adsorption and activation properties towards ozone molecules. Sodium acetate is chosen as a probe for contaminants due to its status as a small organic substance that remains resistant to further direct oxidation by ozone. This makes it suitable for evaluating the catalyst's effectiveness in degrading chemical oxygen demand (COD). The quantitative detection of free radicals revealed the generation of •O2− was nearly 10 times that of •OH and dominated the reaction. This study showcases the potential of fly ash, an industrial byproduct, to be utilized as a cost-effective and easily prepared catalyst with consistent physical and chemical characteristics. [ABSTRACT FROM AUTHOR]

With the urgent demand for clean energy, rechargeable zinc–air batteries (ZABs) are attracting increasing attention. Precious-metal-based electrocatalysts (e.g., commercial Pt/C and IrO2) are reported to be highly active towards the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Nevertheless, the limited catalytic kinetics, along with the scarcity of noble metals, still hinder the practical applications of ZABs. Consequently, it is of great importance to explore efficient bifunctional ORR/OER electrocatalysts with abundant reserves. Although iron oxides are considered to have some of the greatest potential as catalysts among the metal oxides, owing to their excellent redox properties, lower toxicity, simple preparation, and natural abundance, their poor electrical conductivity and high agglomeration still limit their development. In this work, we report a special Se quantum dots@ CoFeOx (Se-FeOx-Co) composite material, which exhibits outstanding bifunctional catalytic properties. And the potential gap between ORR and OER is low at 0.87 V. In addition, the ZAB based on Se-FeOx-Co achieves a satisfactory open-circuit voltage (1.46 V) along with an operation durability over 800 min. This research explores an effective strategy to fabricate iron oxide-based bifunctional catalysts, which contributes to the future design of related materials. [ABSTRACT FROM AUTHOR]

Addressing the growing need for methods for ecofriendly dye removal from aqueous media, this study explores the potential of rice husks coated with iron oxide (Fe2O3@RH composites) for efficient Acid Blue 25 decontamination. The adsorption potential of Acid Blue 25 is analyzed using raw rice husks and Fe2O3 nanoparticles in the literature, but their enhanced removal capacity by means of Fe2O3@RH composites is reported for the first time in this study. Fe2O3@RH composites were analyzed by using analytical techniques such as TGA, SEM, FTIR, BET, and the point of zero charge (pH(PZC)). The Acid Blue 25 adsorption experiment using Fe2O3@RH composites showed maximum adsorption at an initial concentration of Acid Blue 25 of 80 ppm, a contact time of 50 min, a temperature of 313 K, 0.25 g of Fe2O3@RH composites, and a pH of 2. The maximum percentage removal of Acid Blue 25 was found to be 91%. Various linear and nonlinear kinetic and isothermal models were used in this study to emphasize the importance and necessity of the adsorption process. Adsorption isotherms such as the Freundlich, Temkin, Langmuir, and Dubinin–Radushkevich (D–R) models were applied. The results showed that all the isotherms were best fitted on the data, except the linear form of the D–R isotherm. Adsorption kinetics such as the intraparticle kinetic model, the Elovich kinetic model, and the pseudo-first-order and pseudo-second-order models were applied. All the kinetic models were found to be best fitted on the data, except the PSO model (types II, III, and IV). Thermodynamic parameters such as ΔG° (KJ/mol), ΔH° (KJ/mol), and ΔS° (J/K*mol) were studied, and the reaction was found to be exothermic in nature with an increase in the entropy of the system, which supported the adsorption phenomenon. The current study contributes to a comprehensive understanding of the adsorption process and its underlying mechanisms through characterization, the optimization of the conditions, and the application of various models. The findings of the present study suggest practical applications of this method in wastewater treatment and environmental remediation. [ABSTRACT FROM AUTHOR]

This review article describes a historical perspective of elucidation of the nature of the chemical bonds of the high-valent transition metal oxo (M=O) and peroxo (M-O-O) compounds in chemistry and biology. The basic concepts and theoretical backgrounds of the broken-symmetry (BS) method are revisited to explain orbital symmetry conservation and orbital symmetry breaking for the theoretical characterization of four different mechanisms of chemical reactions. Beyond BS methods using the natural orbitals (UNO) of the BS solutions, such as UNO CI (CC), are also revisited for the elucidation of the scope and applicability of the BS methods. Several chemical indices have been derived as the conceptual bridges between the BS and beyond BS methods. The BS molecular orbital models have been employed to explain the metal oxyl-radical character of the M=O and M-O-O bonds, which respond to their radical reactivity. The isolobal and isospin analogy between carbonyl oxide R2C-O-O and metal peroxide LFe-O-O has been applied to understand and explain the chameleonic chemical reactivity of these compounds. The isolobal and isospin analogy among Fe=O, O=O, and O have also provided the triplet atomic oxygen (3O) model for non-heme Fe(IV)=O species with strong radical reactivity. The chameleonic reactivity of the compounds I (Cpd I) and II (Cpd II) is also explained by this analogy. The early proposals obtained by these theoretical models have been examined based on recent computational results by hybrid DFT (UHDFT), DLPNO CCSD(T0), CASPT2, and UNO CI (CC) methods and quantum computing (QC). [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative diseases and a major contributor to dementia. Although the cause of this condition has been identified long ago as aberrant aggregations of amyloid and tau proteins, effective therapies for it remain elusive. The complexities of drug development for AD treatment are often compounded by the impermeable blood–brain barrier and low-yield brain delivery. In addition, the use of high drug concentrations to overcome this challenge may entail side effects. To address these challenges and enhance the precision of delivery into brain regions affected by amyloid aggregation, we proposed a transferrin-conjugated nanoparticle-based drug delivery system. The transferrin-conjugated melittin-loaded L-arginine-coated iron oxide nanoparticles (Tf-MeLioNs) developed in this study successfully mitigated melittin-induced cytotoxicity and hemolysis in the cell culture system. In the 5XFAD mouse brain, Tf-MeLioNs remarkably reduced amyloid plaque accumulation, particularly in the hippocampus. This study suggested Tf-LioNs as a potential drug delivery platform and Tf-MeLioNs as a candidate for therapeutic drug targeting of amyloid plaques in AD. These findings provide a foundation for further exploration and advancement in AD therapeutics. [ABSTRACT FROM AUTHOR]

Methylene blue (MB) is a hazardous chemical that is widely found in wastewater, and its removal is critical. One of the most common methods to remove MB is adsorption. To enhance the adsorption process, magnetic adsorbents, particularly those based on superparamagnetic iron oxide nanoparticles (SPION), play a vital role. This study focuses on comparing recent novel SPION-based MB adsorbents and how to acquire the critical parameters needed to evaluate the adsorption and desorption mechanisms, including isotherms, kinetics, and thermodynamic properties. Moreover, the review article also discusses the future aspects of these adsorbents. [ABSTRACT FROM AUTHOR]

The role of precipitates from acid mine drainage (AMD) in arsenic removal in water is a process to be investigated in more detail. The present study is focused on the potential use of two AMD precipitates using oxidation and Ca(OH)2 (OxPFe1) or CaCO3 (OxPFe2) as As(V) adsorbents and the comparison of their performance with two commercial adsorbents (nanohematite and Bayoxide®). The AMD's supernatants and precipitates were characterized using several techniques and assessed with theoretical speciation and mass balance methods. Gypsum was identified by XRD and assessed as the main component of the precipitates. Amorphous iron hydroxide was assessed as the second component (22% in mass), and jurbanite or aluminum hydroxide were present in the third likely phase. The equilibrium adsorption of As(V) in water at a pH between 4 and 6 was tested with the four adsorbents, and the Langmuir model correlated well. The maximum adsorption capacity (qmax) had the highest value for OxPFe1 and the lowest value for nanohematite (that could be explained in terms of the adsorbent surface speciation). The two precipitates have limited application to the adsorption of very low concentrations of arsenic because they have a binding constant (b) lower than the commercial adsorbents and could release a small amount of the arsenic contained in the precipitate. [ABSTRACT FROM AUTHOR]

In this study, a novel electrochemical assay for determining 17-β-estradiol (E2) was proposed. The approach involves modifying a glassy carbon electrode (GCE) with a nanocomposite consisting of α-Fe2O3 nanoparticles supported on carbon nanotubes (CNTs)—denoted as α-Fe2O3-CNT/GCE. The synthesis of the α-Fe2O3-CNT nanocomposite was achieved through a simple and cost-effective hydrothermal process. Morphological and chemical characterization were conducted using scanning electron microscopy (SEM), Raman spectroscopy, and energy-dispersive X-ray spectroscopy (EDX). The presence of the α-Fe2O3-CNT film on the GCE surface resulted in an enhanced electrochemical response to E2, preventing electrode surface fouling and mitigating the decrease in peak current intensity during E2 oxidation. These outcomes substantiate the rationale behind the GCE modification. After the optimization of experimental conditions, E2 was determined by the square wave voltammetry technique using 0.1 mol L−1 KCl solution (pH = 7.0) with 20% ethanol as a supporting electrolyte. A linear concentration range of 5.0–100.0 nmol L−1 and a low limit of detection of 4.4 nmol L−1 were obtained. The electroanalytical method using α-Fe2O3-CNT/GCE was applied for E2 determination in pharmaceutical, lake water, and synthetic urine samples. The obtained results were attested by recovery tests and by high-performance liquid chromatography as a comparative technique at a 95% confidence level. Thus, the developed electrochemical sensor is simple and fast to obtain, presents high accuracy, and is viable for determining E2 in routine analysis. [ABSTRACT FROM AUTHOR]

A dire need for real-time detection of toxic chemical compounds exists in both civilian and military spheres. In this paper, we demonstrate that inexpensive, commercially available Fe2O3 nanoparticles are capable of selective sensing of chemical warfare agents (CWAs) using frequency-dependent impedance spectroscopy, with additional potential as an orthogonal magnetic sensor. X-ray magnetic circular dichroism analysis shows that Fe2O3 nanoparticles possess moderately lowered moment upon exposure to 2-chloroethyl ethyl sulfide (2-CEES) and diisopropyl methylphosphonate (DIMP) and significantly lowered moment upon exposure to dimethyl methylphosphonate (DMMP) and dimethyl chlorophosphate (DMCP). Associated X-ray absorption spectra confirm a redox reaction in the Fe2O3 nanoparticles due to CWA structural analog exposure, with differentiable energy-dependent features that suggest selective sensing is possible, given the correct method. Impedance spectroscopy performed on samples dosed with DMMP, DMCP, and tabun (GA, chemical warfare nerve agent) showed strong, differentiable, frequency-dependent responses. The frequency profiles provide unique "shift fingerprints" with which high specificity can be determined, even amongst similar analytes. The results suggest that frequency-dependent impedance fingerprinting using commercially available Fe2O3 nanoparticles as a sensor material is a feasible route to selective detection. [ABSTRACT FROM AUTHOR]

We demonstrate the utilization of iron oxide (Fe2O3) as light-absorbing material in an erbium-doped fiber laser (EDFL) for the generation of Q-switched pulses. A sandwich-type saturable absorber (SA) with Fe2O3 nanoparticles between fiber ferrules is proposed. A fiber ferrule tip is tapped onto a cap of index-matching gel, which is then dipped into Fe2O3 nanoparticle powder to allow its deposition through the adhesion effect. By incorporating Fe2O3–SA in an EDFL, self-started and stable Q-switched pulses are attained at a threshold power of 50.1 mW. The pulse repetition rate is tunable from 9.92 kHz to 22.47 kHz, whereas the pulse duration reduces from 38.4 µs to 13.8 µs with the pump power increment. The maximum pulse energy achieved is 36.9 nJ. This work offers a simple integration method of Fe2O3 nanoparticles as potential SAs for the generation of Q-switched pulses. [ABSTRACT FROM AUTHOR]

Nanoparticle-based drugs offer attractive advantages like targeted delivery to the diseased site and size and shape-controlled properties. Therefore, understanding the particulate flow of the nanodrugs is important for effective delivery, accurate prediction of required dosage, and developing efficient drug delivery platforms for nanodrugs. In this study, the transport of nanodrugs including flow velocity and deposition is investigated using three model metal oxide nanodrugs of different sizes including iron oxide, zinc oxide, and combined Cu-Zn-Fe oxide synthesized via a modified polyol approach. The hydrodynamic size, size, morphology, chemical composition, crystal phase, and surface functional groups of the water-soluble nanodrugs were characterized via dynamic light scattering, transmission electron microscopy, scanning electron microscopy-energy dispersive X-ray, X-ray diffraction, and fourier transform infrared spectroscopy, respectively. Two different biomimetic flow channels with customized surfaces are developed via 3D printing to experimentally monitor the velocity and deposition of the different nanodrugs. A diffusion dominated mechanism of flow is seen in size ranges 92 nm to 110 nm of the nanodrugs, from the experimental velocity and mass loss profiles. The flow velocity analysis also shows that the transport of nanodrugs is controlled by sedimentation processes in the larger size ranges of 110–302 nm. However, the combined overview from experimental mass loss and velocity trends indicates presence of both diffusive and sedimentation forces in the 110–302 nm size ranges. It is also discovered that the nanodrugs with higher positive surface charges are transported faster through the two test channels, which also leads to lower deposition of these nanodrugs on the walls of the flow channels. The results from this study will be valuable in realizing reliable and cost-effective in vitro experimental approaches that can support in vivo methods to predict the flow of new nanodrugs. [ABSTRACT FROM AUTHOR]

This comprehensive study investigates the properties of chemical nanomagnetic iron oxide particles (CNMIOPs) synthesized through a chemical method. The primary objective is to examine how pH levels and washing solvents affect the magnetism properties of these nanoparticles. Three different pH levels (1.2, 7.5, and 12.5) using NaOH and two washing solvents (ethanol and water) are employed. The characterization techniques include FTIR, SEM, TEM, XRD, ZSP, and VSM. Furthermore, the study incorporates two specific pH- and solvent-dependent CNMIOPs into PCL electrospun materials to analyze their performance in a targeted application. The results show that pH and the washing process significantly affect the CNMIOPs' properties. Higher pH levels result in smaller particles with higher crystallinity and reduce crystalline anisotropy. SEM and TEM analysis confirm different morphologies, including cubic, spherical, and elongated shapes. Ethanol-washed CNMIOPs exhibit superior magnetic behavior, with the highest magnetization saturation at pH 12.5 (Ms = 58.3 emu/g). The stability of the CNMIOPs ranges from −14.7 to −23.8 mV, and higher pH levels exhibit promising antioxidant activity. Furthermore, the study explores the effects of pH and washing solvents on CNMIOP-infused nanofiber membranes, with better dispersion observed with ethanol washing. Overall, this research provides valuable insights into the properties and behavior of CNMIOPs under varying pH and washing conditions. [ABSTRACT FROM AUTHOR]

The ubiquitous presence of pharmaceutical pollution in the environment and its adverse impacts on public health and aquatic ecosystems have recently attracted increasing attention. Graphene oxide coated with magnetite (GO-Fe3O4) is effective at removing pharmaceuticals in water by adsorption. However, the myriad compositions in real water are known to adversely impact the adsorption performance. One objective of this study was to investigate the influence of pore blockage by natural organic matter (NOM) with different sizes on pharmaceutical adsorption onto GO-Fe3O4. Meanwhile, the feasibility of pore dimension tuning of GO-Fe3O4 for selective adsorption of pharmaceuticals with different structural characteristics was explored. It was shown in the batch experiments that the adsorbed pharmaceutical concentrations onto GO-Fe3O4 were significantly affected (dropped by 2–86%) by NOM that had size ranges similar to the pore dimensions of GO-Fe3O4, as the impact was enhanced when the adsorption occurred at acidic pHs (e.g., pH 3). Specific surface areas, zeta potentials, pore volumes, and pore-size distributions of GO-Fe3O4 were influenced by the Fe content forming different-sized Fe3O4 between GO layers. Low Fe contents in GO-Fe3O4 increased the formation of nano-sized pores (2.0–12.5 nm) that were efficient in the adsorption of pharmaceuticals with low molecular weights (e.g., 129 kDa) or planar structures via size discrimination or inter-planar π-π interaction, respectively. As excess larger-sized pores (e.g., >50 nm) were formed on the surface of GO-Fe3O4 due to higher Fe contents, pharmaceuticals with larger molecular weights (e.g., 296 kDa) or those removed by electrostatic attraction between the adsorbate and adsorbent dominated on the GO-Fe3O4 surface. Given these observations, the surface characteristics of GO-Fe3O4 were alterable to selectively remove different pharmaceuticals in water by adsorption, and the critical factors determining the adsorption performance were discussed. These findings provide useful views on the feasibility of treating pharmaceutical wastewater, recycling valuable pharmaceuticals, or removing those with risks to public health and ecosystems. [ABSTRACT FROM AUTHOR]

Octylamine (OTA), 1-dodecanethiol (DDT), and tri-n-octylphosphine (TOP) capped magnetite nanoparticles were prepared by co-precipitation method. Powder X-ray diffraction patterns confirmed inverse spinel crystalline phases for the as-prepared iron oxide nanoparticles. Transmission electron microscopic micrographs showed iron oxide nanoparticles with mean particle sizes of 2.1 nm for Fe3O4-OTA, 5.0 nm for Fe3O4-DDT, and 4.4 nm for Fe3O4-TOP. The energy bandgap of the iron oxide nanoparticles ranges from 2.25 eV to 2.76 eV. The iron oxide nanoparticles were used as photocatalysts for the degradation of methylene blue with an efficiency of 55.5%, 58.3%, and 66.7% for Fe3O4-OTA, Fe3O4-DDT, and Fe3O4-TOP, respectively, while for methyl orange the degradation efficiencies were 63.8%, 47.7%, and 74.1%, respectively. The results showed that tri-n-octylphosphine capped iron oxide nanoparticles are the most efficient iron oxide nano-photocatalysts for the degradation of both dyes. Scavenger studies show that electrons (e−) and hydroxy radicals (•OH) contribute significantly to the photocatalytic degradation reaction of both methylene blue and methyl orange using Fe3O4-TOP nanoparticles. The influence of the dye solution's pH on the photocatalytic reaction reveals that a pH of 10 is the optimum for methylene blue degradation, whereas a pH of 2 is best for methyl orange photocatalytic degradation using the as-prepared iron oxide nano-photocatalyst. Recyclability studies revealed that the iron oxide photocatalysts can be recycled three times without losing their photocatalytic activity. [ABSTRACT FROM AUTHOR]

The hierarchical structure is an ideal nanostructure for conversion-type anodes with drastic volume expansion. Here, we demonstrate a tin-doping strategy for constructing Fe2O3 brushes, in which nanowires with exposed (001) facets are stacked into the hierarchical structure. Thanks to the tin-doping, the conductivity of the Sn-doped Fe2O3 has been improved greatly. Moreover, the volume changes of the Sn-doped Fe2O3 anodes can be limited to ~4% vertical expansion and ~13% horizontal expansion, thus resulting in high-rate performance and long-life stability due to the exposed (001) facet and the unique hierarchical structure. As a result, it delivers a high reversible lithium storage capacity of 580 mAh/g at a current density of 0.2C (0.2 A/g), and excellent rate performance of above 400 mAh/g even at a high current density of 2C (2 A/g) over 500 cycles, which is much higher than most of the reported transition metal oxide anodes. This doping strategy and the unique hierarchical structures bring inspiration for nanostructure design of functional materials in energy storage. [ABSTRACT FROM AUTHOR]

Core–shell nanoparticles are functional materials with tailored properties, able to improve the requirements of various applications. Both core and shell components can be inorganic or organic, and there are numerous studies in this field regarding their synthesis methods, properties, and applications. This review aims to study core–shell nanostructures with Fe3O4 cores and different shell types, observing their antibacterial and anticancer properties. By the type of coating, Fe3O4 core–shell nanoparticles (NPs) are classified into four categories: metal-coated NPs, metal-organic framework (MOF) coated NPs, metal oxide coated NPs, and polymer-coated NPs. Each category is briefly presented, emphasizing anticancer or antibacterial properties and specific applications (cancer diagnosis or therapy, drug carrier). Moreover, synthesis methods and particle size for both core and shell nanostructures, as well as the magnetic properties of the final core–shell material, are summarized in this review. Most of the consulted papers discussed sphere-like core–shell nanoparticles obtained by chemical methods such as coprecipitation, hydrothermal, and green synthesis methods using plant extract. These types of core–shell nanoparticles could be used as drug nanocarriers for tumor-targeted drug delivery, hyperthermia treatment, or contrast agents. Further work needs to be conducted to understand nanoparticles' interaction with living cells and their traceability in the human body. [ABSTRACT FROM AUTHOR]

In this work, F e 2 O 3 was investigated as a doping agent for poly(methyl methacrylate) (PMMA) in order to enhance the plasmonic effect in sensors based on D-shaped plastic optical fibers (POFs). The doping procedure consists of immerging a premanufactured POF sensor chip in an iron (III) solution, avoiding repolymerization and its related disadvantages. After treatment, a sputtering process was used to deposit a gold nanofilm on the doped PMMA in order to obtain the surface plasmon resonance (SPR). More specifically, the doping procedure increases the refractive index of the POF's PMMA in contact with the gold nanofilm, improving the SPR phenomena. The doping of the PMMA was characterized by different analyses in order to determine the effectiveness of the doping procedure. Moreover, experimental results obtained by exploiting different water–glycerin solutions have been used to test the different SPR responses. The achieved bulk sensitivities confirmed the improvement of the plasmonic phenomenon with respect to a similar sensor configuration based on a not-doped PMMA SPR-POF chip. Finally, doped and non-doped SPR-POF platforms were functionalized with a molecularly imprinted polymer (MIP), specific for the bovine serum albumin (BSA) detection, to obtain dose-response curves. These experimental results confirmed an increase in binding sensitivity for the doped PMMA sensor. Therefore, a lower limit of detection (LOD), equal to 0.04 μM, has been obtained in the case of the doped PMMA sensor when compared to the one calculated for the not-doped sensor configuration equal to about 0.09 μM. [ABSTRACT FROM AUTHOR]

The goal of this work is to investigate the effectiveness of amorphous SiO2−FexOy loaded by functionalization with Ce(SO4)2, Li2SO4, and 3-aminopropyltriethoxysilane (APTES) for CO2 adsorption. Silica and iron-based materials are gaining popularity due to their wide range of applications, such as catalysis, photocatalysis, imaging, etc.; however, there are very few studies regarding the adsorption of CO2 with the aforementioned materials. In our study, we proposed to test their ability in this direction by adding cerium sulfate and lithium sulfate. Three base materials were obtained and characterized using XRD, FTIR, RAMAN, TG, SEM, and BET followed by their functionalization with amino groups by using of the APTES precursor. The SEM images indicate an increase in size, forming clusters from 100 nm for base materials to 500 nm for functionalized materials. The results indicate a maximum CO2 adsorption of 1.58 mmol/g material for the SiO2−FexOy−Li−APTES sample. [ABSTRACT FROM AUTHOR]

In recent years, during industrial development, the expanding discharge of harmful metallic ions from different industrial wastes (such as arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, or zinc) into different water bodies has caused serious concern, with one of the problematic elements being represented by selenium (Se) ions. Selenium represents an essential microelement for human life and plays a vital role in human metabolism. In the human body, this element acts as a powerful antioxidant, being able to reduce the risk of the development of some cancers. Selenium is distributed in the environment in the form of selenate (SeO42–) and selenite (SeO32–), which are the result of natural/anthropogenic activities. Experimental data proved that both forms present some toxicity. In this context, in the last decade, only several studies regarding selenium's removal from aqueous solutions have been conducted. Therefore, in the present study, we aim to use the sol–gel synthesis method to prepare a nanocomposite adsorbent material starting from sodium fluoride, silica, and iron oxide matrices (SiO2/Fe(acac)3/NaF), and to further test it for selenite adsorption. After preparation, the adsorbent material was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The mechanism associated with the selenium adsorption process has been established based on kinetic, thermodynamic, and equilibrium studies. Pseudo second order is the kinetic model that best describes the obtained experimental data. Also, from the intraparticle diffusion study, it was observed that with increasing temperature the value of the diffusion constant, Kdiff, also increases. Sips isotherm was found to best describe the experimental data obtained, the maximum adsorption capacity being ~6.00 mg Se(IV) per g of adsorbent material. From a thermodynamic point of view, parameters such as ΔG0, ΔH0, and ΔS0 were evaluated, proving that the process studied is a physical one. [ABSTRACT FROM AUTHOR]

Ti3C2Tx–Fe3O4–carbon nanotube composites were prepared for electrochemical energy storage in the negative electrodes of supercapacitors. The electrodes show a remarkably high areal capacitance of 6.59 F cm−2 in a neutral Na2SO4 electrolyte, which was obtained by the development of advanced nanofabrication strategies and due to the synergistic effect of the individual components. Enhanced capacitance was achieved using the in-situ synthesis method for the Fe3O4 nanoparticles. The superparamagnetic behavior of the Fe3O4 nanoparticles facilitated the fabrication of electrodes with a reduced binder content. Good mixing of the components was achieved using a celestine blue co-dispersant, which adsorbed on the inorganic components and carbon nanotubes and facilitated their co-dispersion and mixing. The capacitive behavior was optimized by the variation of the electrode composition and mass loading in a range of 30–45 mg cm−2. An asymmetric device was proposed and fabricated, which contained a Ti3C2Tx–Fe3O4–carbon nanotube negative electrode and a polypyrrole–carbon nanotube positive electrode for operation in an Na2SO4 electrolyte. The asymmetric supercapacitor device demonstrated high areal capacitance and excellent power-density characteristics in an enlarged voltage window of 1.6 V. This investigation opens a new avenue for the synthesis and design of MXene-based asymmetric supercapacitors for future energy storage devices. [ABSTRACT FROM AUTHOR]

Herein, unique three-dimensional (3D) hierarchically structured carbon nanofiber (CNF)/metal oxide/conducting polymer composite materials were successfully synthesized by combinations of various experimental methods. Firstly, base CNFs were synthesized by carbonization of electrospun PAN/PVP fibers to attain electric double-layer capacitor (EDLC) characteristics. To further enhance the capacitance, tin oxide (SnO2) and iron oxide (Fe2O3) were coated onto the CNFs via facile hydrothermal treatment. Finally, polypyrrole (PPy) was introduced as the outermost layer by a dispersion polymerization method under static condition to obtain 3D-structured CNF/SnO2/PPy and CNF/Fe2O3/PPy materials. With each synthesis step, the morphology and dimension of materials were transformed, which also added the benign characteristic for supercapacitor application. For the practical application, as-synthesized CNF/SnO2/PPy and CNF/Fe2O3/PPy were applied as active materials for supercapacitor electrodes, and superb specific capacitances of 508.1 and 426.8 F g−1 (at 1 A g−1) were obtained (three-electrode system). Furthermore, an asymmetric supercapacitor (ASC) device was assembled using CNF/SnO2/PPy as the positive electrode and CNF/Fe2O3/PPy as the negative electrode. The resulting CNF/SnO2/PPy//CNF/Fe2O3/PPy device exhibited excellent specific capacitance of 101.2 F g−1 (at 1 A g−1). Notably, the ASC device displayed a long-term cyclability (at 2000 cycles) with a retention rate of 81.1%, compared to a CNF/SnO2//CNF/Fe2O3 device of 70.3% without an outermost PPy layer. By introducing the outermost PPy layer, metal oxide detachment from CNFs were prevented to facilitate long-term cyclability of electrodes. Accordingly, this study provides an effective method for manufacturing a high-performance and stable supercapacitor by utilizing unique 3D hierarchical materials, comprised of CNF, metal oxide, and conducting polymer. [ABSTRACT FROM AUTHOR]

Nanomaterials design, synthesis, and characterization are ever-expanding approaches toward developing biodevices or neural interfaces to treat neurological diseases. The ability of nanomaterials features to tune neuronal networks' morphology or functionality is still under study. In this work, we unveil how interfacing mammalian brain cultured neurons and iron oxide nanowires' (NWs) orientation affect neuronal and glial densities and network activity. Iron oxide NWs were synthesized by electrodeposition, fixing the diameter to 100 nm and the length to 1 µm. Scanning electron microscopy, Raman, and contact angle measurements were performed to characterize the NWs' morphology, chemical composition, and hydrophilicity. Hippocampal cultures were seeded on NWs devices, and after 14 days, the cell morphology was studied by immunocytochemistry and confocal microscopy. Live calcium imaging was performed to study neuronal activity. Using random nanowires (R-NWs), higher neuronal and glial cell densities were obtained compared with the control and vertical nanowires (V-NWs), while using V-NWs, more stellate glial cells were found. R-NWs produced a reduction in neuronal activity, while V-NWs increased the neuronal network activity, possibly due to a higher neuronal maturity and a lower number of GABAergic neurons, respectively. These results highlight the potential of NWs manipulations to design ad hoc regenerative interfaces. [ABSTRACT FROM AUTHOR]

In environmental and agronomic settings, even minor imbalances can trigger a range of unpredicted responses. Despite the widespread use of metal-based nanoparticles (NPs) and new bio-nanofertilizers, their impact on crop production is absent in the literature. Therefore, our research is focused on the agronomic effect of spray application of gold nanoparticles anchored to SiO2 mesoporous silica (AuSi-NPs), zinc oxide nanoparticles (ZnO-NPs), and iron oxide nanoparticles (Fe3O4-NPs) on sunflowers under real-world environments. Our findings revealed that the biosynthetically prepared AuSi-NPs and ZnO-NPs were highly effective in enhancing sunflower seasonal physiology, e.g., the value of the NDVI index increased from 0.012 to 0.025 after AuSi-NPs application. The distribution of leaf trichomes improved and the grain yield increased from 2.47 t ha−1 to 3.29 t ha−1 after ZnO-NPs application. AuSi-NPs treatment resulted in a higher content of essential linoleic acid (54.37%) when compared to the NPs-free control (51.57%), which had a higher determined oleic acid. No NPs or residual translocated metals were detected in the fully ripe sunflower seeds, except for slightly higher silica content after the AuSi-NPs treatment. Additionally, AuSi-NPs and NPs-free control showed wide insect biodiversity while ZnO-NPs treatment had the lowest value of phosphorus as anti-nutrient. Contradictory but insignificant effect on physiology, yield, and insect biodiversity was observed in Fe3O4-NPs treatment. Therefore, further studies are needed to fully understand the long-term environmental and agricultural sustainability of NPs applications. [ABSTRACT FROM AUTHOR]

Heavy metal pollution is a global problem affecting the environment and human health. Sediment is the source sink of heavy metals in water. Under certain circumstances, the migration of heavy metals will cause water pollution. Therefore, it is of great significance to study sediment composition and composite complexes in the migration and transformation of heavy metals. To understand the adsorption mechanisms of composite complexes and improve the theoretical understanding of adsorption in multi-component complex systems, this study explored the characteristics and rules of Cu adsorption to organic–inorganic, inorganic minerals, and iron-oxide–clay complexes in the estuary sediments of the Dianchi Lake. The Langmuir and Freundlich isotherm models were used for Cu adsorption experiments on three complexes to study their adsorption kinetics. X-ray diffraction and Fourier transform infrared spectroscopy characterized the samples before and after adsorption. The relationship between adsorption capacity and sediment composition was analyzed through redundant analyses. The results showed that the Freundlich isothermal model was better than the Langmuir model in describing the adsorption behavior of the adsorbents. The contribution of iron and aluminum oxides to Cu adsorption was more than that of organic matter. The organic–inorganic complexes functional groups involved in copper adsorption are the most, which resulting in a higher adsorption capacity. The organic matter removal (organic degradation in sediment) will reduce the polar functional groups and reduce silicide activity, leading to heavy metal desorption and re-entry into the water body. [ABSTRACT FROM AUTHOR]