Ultrafine Iron Oxide Research Articles

Pb/As simultaneous removal from soil leachate of Pb/Zn smelting sites by magnetic biochar

Lead (Pb) and arsenic (As) contaminated soils, caused by Pb and zinc (Zn) smelting activities, pose an urgent environmental issue. Magnetic biochar (MB) has been regarded as an increasingly appealing candidate for the remediation of multi-metals in contaminated soils or their leachate. Finding economically feasible preparation methods for MB and demonstrating its remediation potential is desperately required for the remediation of such complex smelting sites. In this study, a modified MB was prepared using an optimized co-precipitation method, and its application potential for Pb/As simultaneous removal based on the basic properties of a typical Pb/Zn smelting site was evaluated. The surface modifications of MB facilitated the encapsulation of various ultrafine iron oxide particles, predominantly γ-Fe2O3 and Fe3O4, whilst notably enhancing the presence of oxygen-containing surface functional groups. The adsorption of Pb(II) and As(III) by MB was well-described using the pseudo-second-order adsorption and Langmuir models. The existence of SO42− and Ca2+ in the soil leachate competed with the adsorption sites for Pb(II) and As(III). Notably, within the pH range of 5–9, the adsorption efficiency of Pb(II) by MB increased with the rising solution pH, whereas alterations in pH minimally affected the removal rate of As(III), maintaining a consistent removal rate exceeding 95%. Furthermore, dissolved organic matter (DOM) abundant in organic functional groups, particularly CO and CC groups, significantly augmented the adsorption affinity for both Pb(II) and As(III). An application rate of 2 g/L could effectively reduce the concentration of Pb(II) and As(III) in soil leachate to <0.05 mg/L. The findings demonstrated the potential of the prepared MB for simultaneous removal of As(III) and Pb(II) in soil leachate, which should be beneficial to multi-metals polluted soil remediation in Pb/Zn smelting sites.

EFFECT OF CATALYZER ON PRIMARY COMBUSTION AND MECHANICAL PROPERTIES OF HIGHLY METALIZED FUEL-RICH PROPELLANTS

Highly metalized fuel-rich propellants containing 40-50&amp;#37; nano-micro aluminum and the catalyzed compositions comprise ultra-fine iron oxide (UFIO) content of 0.3-2.0&amp;#37; were considered. Primary combustion features and mechanical properties of these propellants were investigated for water ramjet propulsion applications. These propellants exhibit almost 70&amp;#37; burning rate enhancement at all the tested pressures with UFIO catalyzed ones as compared with uncatalyzed compositions. Simultaneously, the burning rate pressure exponent of these UFIO catalyzed propellants was considerably reduced. The quenched agglomerates from the primary combustion exhibit over wider size ranges from few microns to few millimeters, which are of several times larger as compared with parent Al particles. The number density effect of Al particles causing the agglomeration at the burning surface outweighs the particle size and catalyzer effect in these highly aluminized propellant compositions. The crack free propellant grain structure was achieved by optimizing the molding pressure range and the rate of compaction. Addition of UFIO increased the compressive strength marginally whereas it reduced the elastic properties of the propellant grain marginally.

Targeted Ultrafine Iron Oxide Nanoparticles for Delivery of the Topoisomerase Inhibitor SN38 and Ovarian Cancer Treatment

Ovarian cancer remains a challenge to decrease mortality and improve diagnostic efficiency in gynecological cancers. To develop a delivery system capable of efficient cancer cell targeting and delivering novel efficacious therapeutics, we assembled folic acid (FA) conjugated ultrafine iron oxide nanoparticles (uIONP) with encapsulation of DNA topoisomerase inhibitor SN38, which target ovarian cancer cells with over-expression of folate receptor alpha (FRα) and deliver SN38 to induce apoptosis. The assembled FA-uIONP-SN38 exhibited higher drug loading efficiency than the larger counterparts with core diameters more than 10 nm. The targeting specificity of FA-uIONP-SN38 for SKOV-3 cancer cells was validated, with HEK293 kidney cells and Raw264.7 macrophages as non-targeted cell line control. It was found that more SKOV-3 cancer cells were killed due to apoptosis by FA-uIONP-SN38 at the same SN38 dosages compared with uIONP-SN38 and free SN38, respectively. The delivery of this inhibitor to SKOV-3 cancer cells by FRα-targeted FA-uIONP carrier was enhanced by about 10-folds with less cytotoxicity comparing to the free drug SN38. The developed FA-uIONP-SN38 holds a great potential as a theranostic approach in treating ovarian cancer.

Targeted Delivery of DNA Topoisomerase Inhibitor SN38 to Intracranial Tumors of Glioblastoma Using Sub‐5 Ultrafine Iron Oxide Nanoparticles (Adv. Healthcare Mater. 14/2022)

Targeted Delivery of DNA Topoisomerase Inhibitor SN38 to Intracranial Tumors of Glioblastoma Using Sub‐5 Ultrafine Iron Oxide Nanoparticles (Adv. Healthcare Mater. 14/2022)

Targeted Delivery of DNA Topoisomerase Inhibitor SN38 to Intracranial Tumors of Glioblastoma Using Sub-5 Ultrafine Iron Oxide Nanoparticles.

Effectively delivering therapeutics for treating brain tumors is hindered by the physical and biological barriers in the brain. Even with the compromised blood-brain barrier and highly angiogenic blood-tumor barrier seen in glioblastoma (GBM), most drugs, including nanomaterial-based formulations, hardly reach intracranial tumors. This work investigates sub-5nm ultrafine iron oxide nanoparticles (uIONP) with 3.5nm core diameter as a carrier for delivering DNA topoisomerase inhibitor 7-ethyl-10-hydroxyl camptothecin (SN38) to treat GBM. Given a higher surface-to-volume ratio, uIONP shows one- or three-folds higher SN38 loading efficiency (48.3± 6.1%, mg/mg Fe) than those with core sizes of 10 or 20nm. SN38 encapsulated in the coating polymer exhibits pH sensitive release with <10%over 48 h at pH 7.4, but 86% at pH 5, thus being protected from converting to inactive glucuronide by UDP-glucuronosyltransferase 1A1. Conjugating αv β3 -integrin-targeted cyclo(Arg-Gly-Asp-D-Phe-Cys) (RGD) as ligands, RGD-uIONP/SN38 demonstrates targeted cytotoxicity to αv β3 -integrin-overexpressed U87MG GBM cells with a half-maximal inhibitory concentration (IC50 ) of 30.9± 2.2nm. The efficacy study using an orthotopic mouse model of GBM reveals tumor-specific delivery of 11.5% injected RGD-uIONP/SN38 (10mg Fe kg-1 ), significantly prolonging the survival in mice by 41%, comparing to those treated with SN38 alone (p <0.001).

Actively targeted delivery of SN38 by ultrafine iron oxide nanoparticle for treating pancreatic cancer.

Pancreatic cancer remains one of the most lethal cancers largely due to the inefficient delivery of therapeutics. Nanomaterials have been extensively investigated as drug delivery platforms, showing improved drug pharmacodynamics and pharmacokinetics. However, their applications in pancreatic cancer have not yet been successful due to limited tumor delivery caused by dense tumor stroma and distorted tumor vasculatures. Meanwhile, smaller-sized nanomaterials have shown improved tumor delivery and retention in various tumors, including pancreatic tumors, suggesting their potential in enhancing drug delivery. An ultrafine iron oxide nanoparticle (uIONP) was used to encapsulate 7-ethyl-10-hydroxyl camptothecin (SN38), the water-insoluble active metabolite of pancreatic cancer chemotherapy drug irinotecan. Insulin-like growth factor 1 (IGF-1) was conjugated to uIONP as a ligand for targeting pancreatic cancer cells overexpressing IGF-1 receptor (IGF1R). The SN38 loading and release profile were characterized. The pancreatic cancer cell targeting using IGF1-uIONP/SN38 and subsequently induced cell apoptosis were also investigated. IGF1-uIONP/SN38 demonstrated a stable drug loading in physiological pH with the loading efficiency of 68.2 ± 3.5% (SN38/Fe, wt%) and < 7% release for 24h. In tumor-interstitial- and lysosomal-mimicking pH (6.5 and 5.5), 52.2 and 91.3% of encapsulated SN38 were released over 24h. The IGF1-uIONP/SN38 exhibited specific receptor-mediated cell targeting and cytotoxicity Ato MiaPaCa-2 and Panc02 pancreatic cancer cells with IC50 of 11.8 ± 2.3 and 20.8 ± 3.5nM, respectively, but not to HEK293 human embryonic kidney cells. IGF1-uIONP significantly improved the targeted SN38 delivery to pancreatic cancer cells, holding the potential for in vivo theranostic applications.

Synchronously improved mechanical strength and electrical conductivity of Carbon/Copper composites by forming Fe3C interlayer at C/Cu interface

Carbon/Copper (C/Cu) composites have been widely used in aerospace, transportation and military products because of their excellent properties of mechanical strength, self-lubrication and electrical conductivities. One of the challenges in preparing C/Cu composites materials is how to overcome the poor wettability between Cu and carbon. In this study, ultrafine iron oxide (Fe2O3), as a precursor, was introduced into the carbon matrix to improve the C/Cu interfacial bonding of C/Cu composites prepared by pressure infiltration. The effect of Fe on the phase composition, microstructure and properties of C/Cu composites were systematically evaluated. The results revealed that the interfacial bonding between Cu and carbon was enhanced by the “bridge architecture” of iron carbide (Fe3C). The wettability between Cu and carbon improved for the contact angle decreased from 124° to 38°. Compared with the unmodified composites, the composites doping 5 wt% Fe2O3 exhibited best performance. The compression and flexural strength increased by 37.4% and 120.4% respectively. Meanwhile, the electrical conductivity improved by 283.7%. It was concluded that the Fe3C layer had an important effect on the electron transport and crack propagation of the C/Cu composites.

Experimental Study of Ultrafine Superparamagnetic Iron Oxide-Enhanced MRI in an Atherosclerotic Plaque Model.

Unstable atherosclerotic (AS) plaques contain numerous macrophages that can phagocytose a specific contrast agent, namely ultrafine superparamagnetic iron oxide (USPIO). This study prepared USPIO nanoparticles, defined their physical and magnetic properties and transmission characteristics, explored the feasibility of their use as a magnetic resonance negative contrast agent, and used them to detect unstable AS plaque as a specific marker of macrophages. We randomly divided 20 healthy male New Zealand white rabbits into two groups, experimental and control (n = 10 each). The experimental group was fed pure high-fat feed. The magnetic resonance imaging (MRI) performance of arterial plaque before and after USPIO enhancement compare with pathological results. The experimental group successfully established a rabbit AS plaque model, and 8 of 10 rabbits developed AS plaque. USPIO-enhanced T2W1 sequence showed that the central signal of the plaque was reduced, and the signal-to-noise ratio of the vascular wall was the lowest at 96 h. The control group showed no change in the wall signal before and after enhancement. The USPIO-enhanced PJN2D-TOF sequence showed dotted filling defects on the tube wall. Pathological examination showed that USPIO nanoparticles were mainly deposited under the arterial intima. A simple high-fat diet can establish a rabbit AS plaque model, and USPIO-enhanced MRI reflects the condition of rabbit AS plaque, which is helpful in evaluating AS lesion diagnosis.

Agglomeration of Return Fines of Sinter for Blast Furnace Raw Materials

Return fines of sinter were agglomerated with a binder material such as cement and fine powder of blast furnace slag in order to use the agglomerates as raw materials in the blast furnace. Reduction tests of the agglomerates were carried out to investigate the high temperature properties of the agglomerates. The following findings were obtained. The agglomerates have lower RDI (RDI<20%) than sinter because sinter, which consists of brittle glassy silicate, was arranged discretely in the agglomerates and bonded by the soft materials of the binder, and as a result, size degradation during reduction was prevented. The agglomerates have higher RI (DI>70%) than sinter due to the high abundance ratio of fine pores in the agglomerates. Moreover, in comparison with sinter, the agglomerates also have equal or greater strength after reduction at 700°C and 900°C because solid phase sintering was promoted by adding ultrafine iron oxide powder. Therefore, as a blast furnace raw material, the permeability and reducibility of the agglomerates of return fines of sinter are superior to those of conventional sinter. This concept is considered to be effective for utilizing sinter fines as blast furnace raw materials in a high pulverized coal rate and low coke rate operation.

Probing and Enhancing Ligand-Mediated Active Targeting of Tumors Using Sub-5 nm Ultrafine Iron Oxide Nanoparticles.

Rationale: “Active targeting” based on the ligand-target affinity is a common strategy to precisely deliver nanoparticle (NP) imaging probes or drug carriers to the diseased tissue. However, such ligand-mediated active targeting inevitably takes place with prerequisite “passive targeting”, driven by the enhanced permeability and retention (EPR) effect. Thus, the efficiency of active targeting in relation to off-targeted unbound NPs is of great importance in quantitative imaging of tumor biomarkers and delivery. With the notion that easy clearance of off-targeted uIONPs may lead to enhanced active targeting and tumor accumulation, we examined the NP size effect on “active targeting” of the transferrin receptor (TfR) using transferrin (Tf)-conjugated sub-5 nm (3 nm core) ultrafine iron oxide NPs (uIONPs) and larger IONPs (30 nm core).Methods: Green fluorescent dye (FITC)-labeled active targeting uIONPs (FITC-Tf-uIONPs) and red fluorescent dye (TRITC)-labeled passive targeting uIONPs (TRITC-uIONPs) were prepared. FITC-Tf-IONPs and TRITC-IONPs were used as comparison for the NP size effect. Multiphoton imaging, confocal fluorescence imaging, histological staining and computational analysis were applied to track different types of NPs in tumors at 1, 3 and 24 hours after co-injection of equal amounts of paired NPs, e.g., active targeting FITC-Tf-uIONPs and non-targeting TRITC-uIONPs, or FITC-Tf-IONPs and TRITC-IONPs into the same mice bearing 4T1 mouse mammary tumors.Results: Active targeting uIONPs exhibited an almost 6-fold higher level of tumor retention with deeper penetration comparing to non-targeting uIONPs at 24 hours after co-injection. However, accumulation of active targeting IONPs with a 30-nm core is only about 1.15-fold higher than non-targeting IONPs. The enhanced active targeting by uIONPs can be attributed to the size dependent clearance of unbound off-targeted NPs, as majority off-targeted uIONPs were readily cleared from the tumor by intravasation back into tumor blood vessels likely due to high interstitial pressure, even though they are not favorable for macrophage uptake.Conclusion: Ligand-mediated active targeting improves the delivery and accumulation of the sub-5 nm NPs. The improvement on active targeting is size-dependent and facilitated by NPs with sub-5 nm core sizes. Thus, sub-5 nm NPs may serve as favorable platforms for development of NP-based molecular imaging probes and targeted drug carriers.

Electrochemical evaluation of the performance of cathodically grown ultra-fine magnetite nanoparticles as electrode material for supercapacitor applications

Ultra-fine nanoparticles of magnetite iron oxide (Fe3O4) were prepared through a poly(vinyl alcohol) (PVA) assisted cathodic electrosynthesis. According to this method, Fe3O4 was deposited on a stainless steel cathode form an aqueous electrolyte containing 0.005 M Fe(NO3)3/FeCl2 and 0.1 g/L PVA. The structural characterization of the electro-synthesized deposit through X-ray diffraction (XRD), field emission and transmission electron microscopies (FE-SEM and TEM) confirmed that the product was composed of pure magnetite spherical particles with average size of 5 nm. The surface area of the resulting Fe3O4 nanoparticles was determined to be 171.5 m2/g through Brunauer–Emmett–Teller (BET) gas-sorption measurements. The electrochemical performance of the prepared ultra-fine nanoparticles was evaluated using cyclic voltammetry(CV), continuous charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques. The obtained electrochemical data showed that the prepared Fe3O4 nanoparticles had suitable charge storage ability with a specific capacitance of as high as 195.8 F g−1, and they maintain about 94% of their initial capacity after 3000 cycles at a current load of 0.5 A g−1. These data proved the suitability of the prepared nanoparticles for use in supercapacitors. Furthermore, this work provides a facile electrochemical route for the synthesis of ultra-fine iron oxide nanoparticles for application in the next generations of energy storage materials.

Exerting Enhanced Permeability and Retention Effect Driven Delivery by Ultrafine Iron Oxide Nanoparticles with T1-T2 Switchable Magnetic Resonance Imaging Contrast.

Poor delivery efficiency remains a major challenge in nanomaterial-based tumor-targeted imaging and drug delivery. This work demonstrates a strategy to improve nanoparticle delivery and intratumoral distribution using sub-5 nm (3.5 nm core size) ultrafine iron oxide nanoparticles (uIONP) that can easily extravasate from the tumor vasculature and readily diffuse into the tumor tissue compared to the iron oxide nanoparticle (IONP) with larger sizes, followed by self-assembling in the acidic tumor interstitial space to limit their re-entering into circulation. By combining enhanced extravasation and reduced intravasation, we achieved improved delivery and tumor retention of nanoparticles. Multiphoton imaging of mice bearing orthotopic tumors co-injected with fluorescent dye-labeled nanoparticles with different sizes showed that uIONPs exhibited more efficient extravasation out of tumor vessels and penetrated deeper into the tumor than larger sized IONP counterparts. Moreover, in vivo magnetic resonance imaging revealed that uIONPs exhibited "bright" T1 contrast when dispersed in the tumor vasculature and peripheral area at 1 h after intravenous administration, followed by emerging "dark" T2 contrast in the tumor after 24 h. Observed T1-T2 contrast switch indicated that uIONPs single-dispersed in blood with T1 contrast may self-assemble into larger clusters with T2 contrast after entering the tumor interstitial space. Improved passive targeting and intratumoral delivery along with increased tumor retention of uIONPs are due to both easy extravasation into the tumor when single-dispersed and restricting intravasation back into circulation after forming clusters, thus exerting the enhanced permeability and retention effect for nanoparticle delivery to tumors.

The synthesis of doxorubicin-conjugated magnetite nanoparticles and their magnetic resonance and cytotoxic properties

The possibility of increasing the effectiveness of antitumor drugs such as doxorubicin by preparing its complex with ultrafine magnetic iron oxide nanoparticles is considered. A method for binding doxorubicin molecules to magnetic nanoparticles via citric acid is proposed. The main magnetic properties of the obtained conjugates were studied by proton relaxometry and Mossbauer spectroscopy, while their cytotoxic activity was evaluated via spectrophotometric MTT assay in HeLa cells. It was shown that the conjugates of magnetite nanoparticles with doxorubicin are characterized by a high level of contrast in magnetic resonance imaging. The magnetic properties of doxorubicin-free and bound magnetite nanoparticles are mainly determined by the average size of nanoobjects and the phase composition and slightly depend on the composition of the stabilizing shell. The cytotoxic effect of the synthesized conjugates of magnetite nanoparticles with doxorubicin is higher than that of unbound doxorubicin. This makes it possible to increase the antitumor effect of doxorubicin and control the dynamics of its delivery in the form of a conjugate into the disease focus due to the magnetic contrast properties of nanoparticles.

Ultrafine superparamagnetic iron oxide decorated polymer vesicles for enhanced T2 MRI and drug delivery

Ultrafine superparamagnetic iron oxide decorated polymer vesicles for enhanced T2 MRI and drug delivery

Plasma dynamic synthesis and obtaining ultrafine powders of iron oxides with high content of ε-Fe2O3

The ultrafine iron oxide powders were successfully synthesized using the plasma dynamic synthesis method, based on the use of a coaxial magnetoplasma accelerator with the iron electrode system. The synthesis was implemented in the high-speed iron-containing plasma jet, flowing into the space of the sealed chamber, filled with the gaseous mixture of oxygen and argon at different ratios. The XRD investigations showed that the synthesized products were heterophase and consisted of three main phases such as magnetite Fe3O4, hematite α-Fe2O3 and ε-Fe2O3. The SEM data confirmed the presence of three particle types: the hollow spheroids with sizes about hundreds of micrometers (magnetite), the particles with sizes up to 100μm from the porous material of sintered submicron particles (hematite), and nanoscale particles (ε-phase). We found that at the higher oxygen concentration the content of ε-Fe2O3 is increased up to ~50% at the same time with decreasing the Fe3O4 phase. The magnetic properties of the products are mainly determined by magnetite characteristics and are significantly reduced with decreasing its content in the powder. In order to investigate the synthesized ε-Fe2O3 on the ability to absorb the electromagnetic radiation in the millimeter wavelength range, we separated the product with the higher ε-phase concentration. The fraction mainly, consisting of ε-Fe2O3, showed the occurrence of the natural resonance at frequencies of 8.3GHz and 130GHz.

Rational design of carbon support to prepare ultrafine iron oxide catalysts for air oxidation of alcohols

The efficient carbon supports change not only the physical but also the chemical properties of iron oxide and create new active sites for the enhancement of catalytic activity in the oxidation of alcohols with air as an oxygen source.

Ultrafine iron oxide nanoparticles supported on N-doped carbon black as an oxygen reduction reaction catalyst

An oxygen reduction reaction (ORR) catalyst comprising ultrafine iron oxide nanoparticles supported on N-doped Vulcan carbon (FeO1.4/N-C) was prepared via a two-step method. X-ray photoelectron spectroscopy revealed the iron oxide nanoparticles comprised Fe2O3 and FeO phases with a combined average oxidation state of 2.8. The FeO1.4/N-C catalyst produced an ORR onset potential of −0.056 V and a half-wave potential of −0.190 V in alkaline media, which was comparable to that of commercial Pt/C catalyst. Moreover, FeO1.4/N-C had higher methanol tolerance than Pt/C catalyst and thus affords a promising non-precious metal ORR catalyst for fuel cells.

Superparamagnetic nanocomposites obtained by dispersion of ultrafine magnetic iron oxide nanoparticles in poly(3-hydroxybutyrate)

Superparamagnetic nanocomposites were obtained by dispersion of oleic acid-coated magnetic ultrafine iron oxide nanoparticles (NPs) in poly(hydroxybutyrate) (PHB), a semicrystalline, biodegradable and biocompatible polymer. Film nanocomposites displayed an optically homogeneous structure formed by sub-micrometric clusters created by a strong NPs segregation that occurred during solvent evaporation and polymer crystallization. Number and size of clusters increased with the concentration of NPs producing a controlled shift in the blocking temperature but hardly affecting PHB crystallinity and melting temperature. The presence of NPs decreased the elastic modulus of PHB and slightly reduced its hardness, leading to materials with improved resistance to permanent damage. This softening effect was attributed to the oleic acid shell covering the iron oxide core of the NPs. The present results shed some light on the mechanisms controlling morphology of semicrystalline-based nanocomposites modified with ultrafine NPs, opening interesting possibilities for the design of materials with controlled functional properties.

Between Quantum and Classical: Evolution of Electron Magnetic Resonance with Growth of a Spin System Size

ABSTRACTSystems with a single or several coupled electron spins are commonly described with the quantum approach while ferromagnetic domains with millions of coupled spins are classical systems. Large spin clusters and superparamagnetic nanoparticles contain hundreds of coupled electron spins, and are on the boundary between classical and quantum behavior. Electron magnetic resonance observed in ultra-fine iron oxide nanoparticles (∼ 5 nm size) reveals several features which are typical for paramagnetic spins and absent in macroscopic systems, including multiple quantum transitions observed at H0/n, where n = 2, 3, 4 and H0 is the field of the main resonance. In order to better understand the transition from quantum to classical behavior and magnetization dynamics at the nanoscale, we study the evolution of the EMR signal with increase of the particle size in suspensions of magnetite nanoparticles. The experimental data are compared with numerical simulations.

Development of fluxed micropellets for sintering utilising iron oxide waste fines

Ultrafine iron oxide wastes such as slime, blue dust and Linz–Donawitz (LD) converter sludge have very limited use in sintering of iron ore due to their excessive fineness (−50 μm). Pelletisation of these ultrafine materials for use in blast furnace involves high temperature curing, which is a highly energy intensive process. Briquetting of LD sludge requires costly binders and contains high moisture, which creates problem at high temperature of the downstream process. In order to alleviate these problems, the current study has developed a process for preparing micropellets of waste iron oxide fines (2–6 mm size) without using any binder. The strength of the micropellet has been increased by a novel CO2 treatment process at room temperature. Developed micropellets exhibit very suitable drop strength (125 Nos), tumbler properties and cold compressive strength (∼9 kg/pellet) to withstand cold handling. Low lime containing micropellets have the possibility of being used as a mixed material in usual sinter making, and high lime containing micropellets may be exploited for making super fluxed sinter that can be used as synthetic flux in the basic oxygen furnace process towards the formation of low melting oxidising slag at the early stage of blow.