Uncoated Iron Research Articles

Uptake and clearance analysis of Technetium99m labelled iron oxide nanoparticles in a rabbit brain.

Nanoparticles as solid colloidal particles are extensively studied and used as anticancer drug delivery agents because of their physical properties. This current research aims to prepare water base suspension of uncoated iron oxide nanoparticles and their biodistribution study to different organs, especially the brain, by using a single photon emission computed tomography gamma camera. The water-based suspension of iron oxide nanoparticles was synthesised by a reformed version of the co-precipitation method and labelled with Tc99m for intravenous injection. The nanoparticles were injected without surface modification. X-ray diffraction (XRD), energy dispersive spectrometry (EDS) and transmission electron microscope (TEM) techniques were used for characterisation. Peaks of XRD and EDS indicate that the particles are magnetite and exist in aqueous suspension. The average diameter of iron oxide nanoparticles without any surface coating determined by TEM is 10 nm. These particles are capable of evading the reticuloendothelial system and can cross the blood-brain barrier in the rabbit. The labelling efficiency of iron oxide nanoparticles labelled with Tc99m is 85%, which is good for the biodistribution study. The sufficient amount of iron oxide nanoparticles concentration in the brain as compared with the surrounding soft tissues and their long blood retention time indicates that the water-based suspension of iron oxide nanoparticles may be an option for drug delivery into the brain.

Study of AC Magnetic Properties and Core Losses of Fe/Fe3O4-epoxy Resin Soft Magnetic Composite

Soft Magnetic Composites (SMC) were prepared by coating of nanocrystalline Fe3O4 particles, synthesized by co-precipitation method, on atomized iron powder of particle size less than 53μm in size using epoxy resin as a binder between iron and Fe3O4. Fe3O4 was chosen, for its high electric resistivity and suitable magnetic properties, to keep the coating layer magnetic and seek improvement to the magnetic properties of SMC. SEM images and XRD patterns were recorded in order to investigate the coatings on the surface of iron powder. A toroid was prepared by cold compaction of coated iron powder at 1050MPa and subsequently cured at 150˚C for 1 hr in argon atmosphere. For comparison of properties, a toroid of uncoated iron powder was also compacted at 1050MPa and annealed at 600˚C for 2 hr in argon atmosphere. The coated iron powder composite has a resistivity of greater than 200μΩm, measured by four probe method. A comparison of Magnetic Hysteresis loops and core losses using B-H Loop tracer in the frequency range 0 to 1500Hz on the coated and uncoated iron powder is reported.

Guanidine-functionalized Fe3O4 magnetic nanoparticles as basic recyclable catalysts for biodiesel production

Two organic superbases, 1,5,7-triazabicyclo[4,4,0]dec-5-ene (TBD) and 1,1,3,3-tetramethylguanidine (TMG), were anchored onto silica-coated and uncoated iron oxide nanoparticles, resulting in three recoverable basic nanocatalysts.

Review of Archie's equation through theoretical derivation and experimental study on uncoated and hematite coated soils

Abstract This theoretical and experimental study investigated the applicability of Archie's equation to iron oxide coated soils as a function of pore water chemistry, with the ultimate goal of developing a relationship to estimate electrical conductivity based on the physical properties of soils. The study performed an experimental investigation to quantify the electrical properties of uncoated and lab-prepared iron oxide coated sands and clay, in order to evaluate the role of sorbed hematite on the measured electrical conductivity/resistivity of the soils. It was demonstrated that the observed conductivity/resistivity of hematite coated and uncoated clean sands showed good agreement under the tested salinities and iron contents, and both coated and uncoated sands could be represented by Archie's equation. In contrast, the electrical conductivity of iron oxide coated clay indicated a slightly higher value than that of clean kaolinite at low salinity due to the higher relevance of surface conduction; however, with further increase in salinity, the electrical properties of both coated and uncoated kaolinites were comparable and governed by pore water conduction, which agreed with the prediction from Archie's equation.

Influence of iron oxide nanoparticles on bending elasticity and bilayer fluidity of phosphotidylcholine liposomal membranes

Iron oxide nanoparticles with improved surface characteristics have tremendous applications in various biomedical fields such as magnetic resonance imaging, hyperthermia, immunoassay and targeted drug delivery. The aim of this work was to study the influence of iron oxide (γ-Fe2O3) nanoparticles on the bilayer fluidity and bending elasticity of zwitterionic phosphatidylcholine liposomal membranes. Small unilamellar vesicles prepared with l-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine lipids were encapsulated with uncoated iron oxide nanoparticles and silica coated iron oxide nanoparticles to study their effect on bilayer fluidity. Anisotropy measurements using the fluorescent probes 1,6-diphenyl-1,3,5-hexatriene and N,N,N-trimethyl-4-(6-phenyl-1,3,5-hexatrien-1-yl) phenylammonium p-toluensufonate did not show a significant difference in the lipid ordering and bilayer fluidity. Thermally induced shape fluctuations of the giant quasi-spherical lipid vesicles were used to study the influence of both types of iron oxide nanoparticles on the bending elasticity modulus kc of the lipid membrane. The results showed that in the case of uncoated iron oxide (in the studies concentration) the obtained value for the bending elasticity modulus does not differ in the frames of the experimental error from that of pure phospholipid membrane. In the case of silica coated iron oxide nanoparticles the bending elasticity modulus of the membrane decreased by 25%.

Oxidized Silicon Nanoparticles and Iron Oxide Nanoparticles for Radiation Therapy

Oxidized Silicon Nanoparticles and Iron Oxide Nanoparticles for Radiation Therapy Our research objective is to develop superparamagnetic iron oxide nanoparticles and silicon nanoparticles as radiosensitizers for cancer therapy. After internalization by breast tumor cells and irradiation with X-rays, the nanoparticles were observed to enhance the oxidative stress in tumor cells. While silicon nanoparticles increase the reactive oxygen species production under X-ray treatment due to their incompletely oxidized surface, positively charged amino-functionalized silicon nanoparticles enhance the formation of mitochondrial reactive oxygen species formation because of their direct interaction with the mitochondrial membrane. On the other hand, uncoated and citrate-coated superparamagnetic iron oxide nanoparticles were found to increase the reactive oxygen species formation in X-ray treated tumor cells via two particular surface features, being, first, the leakage of iron ions and second, the catalytic activity of nanoparticle surfaces. Both may initiate the Haber-Weiss and Fenton reaction.

Microstructure and wear resistance of Fe based TiB2 composite coating

Fe based TiB2 composite coating was in situ synthesised by plasma transferred arc cladding. The microstructure and microhardness of the composite coating were investigated by optical microscopy, SEM and microhardness tester. Sliding wear behaviour of the composite coating was investigated on a block on ring wear tester rubbing against GCr15 steel ring. Wear resistance of TiB2/Fe composite coating was 16–25 times than that of the uncoated iron matrix. The good interfacial bonding between TiB2 particles and iron matrix led to no transition from mild wear to severe wear over the applied load range. The sliding wear resistance of the composite coating decreased with increasing sliding speed and applied load. The wear mechanism of the composite coating was a comprehensive action of microcutting wear, surface flaking, adhesive wear, slight abrasive wear and fatigue wear. High applied loads resulted in particle detachment and accelerated the abrasive wear and the fatigue wear.

Coating-dependent induction of cytotoxicity and genotoxicity of iron oxide nanoparticles

Surface coatings of nanoparticles (NPs) are known to influence advantageous features of NPs as well as potential toxicity. Iron oxide (Fe3O4) NPs are applied for both medical diagnostics and targeted drug delivery. We investigated the potential cytotoxicity and genotoxicity of uncoated iron oxide (U-Fe3O4) NPs in comparison with oleate-coated iron oxide (OC-Fe3O4) NPs. Testing was performed in vitro in human lymphoblastoid TK6 cells and in primary human blood cells. For cytotoxicity testing, relative growth activity, trypan blue exclusion, 3H-thymidine incorporation and cytokinesis-block proliferation index were assessed. Genotoxicity was evaluated by the alkaline comet assay for detection of strand breaks and oxidized purines. Particle characterization was performed in the culture medium. Cellular uptake, morphology and pathology were evaluated by electron microscopy. U-Fe3O4 NPs were found not to be cytotoxic (considering interference of NPs with proliferation test) or genotoxic under our experimental conditions. In contrast, OC-Fe3O4 NPs were cytotoxic in a dose-dependent manner, and also induced DNA damage, indicating genotoxic potential. Intrinsic properties of sodium oleate were excluded as a cause of the toxic effect. Electron microscopy data were consistent with the cytotoxicity results. Coating clearly changed the behaviour and cellular uptake of the NPs, inducing pathological morphological changes in the cells.

Drug Embedded PVP Coated Magnetic Nanoparticles for Targeted Killing of Breast Cancer Cells

Magnetic drug targeting is a drug delivery system that can be used in loco-regional cancer treatment. Coated magnetic particles, called carriers, are very useful for delivering chemotherapeutic drugs. Magnetic carriers were synthesized by co-precipitation of iron oxide followed by coating with polyvinyl pyrrolidone (PVP). Characterization was performed using X-ray diffraction, TEM, TGA, FTIR and UV-Vis Spectroscopy. Magnetite (Fe3O4) remained as the core of the carrier. The amount of PVP bound to the iron oxide nanoparticles was estimated by thermogravimetric analysis (TGA) and the attachment of PVP to the iron oxide nanoparticles confirmed by FTIR analysis. The loading efficiency of Epirubicin hydrochloride onto the PVP coated and uncoated iron oxide nanoparticles was measured at intervals such as 1 hr and 24 hrs by UV-Vis Spectroscopy. The binding of Epirubicin hydrochloride to the PVP coated and uncoated iron oxide nanoparticles were confirmed by FTIR analysis. The present findings showed that Epirubicin hydrochloride loaded PVP coated iron oxide nanoparticles are promising for magnetically targeted drug delivery. The drug displayed increased cell cytotoxicity at lower concentrations when conjugated with the nanoparticles than being administered conventionally as individual drugs.

Development and Characterization of Thermosensitive Polymer- CoatedIron Oxide Nanoparticles as a Novel Ferrofluid

In this work, we aim to study the development and characterization of thermosensitive polymer-coated iron oxide nanoparticles as a novel ferroFluid (fF) with thermosensitive properties. For this purpose, polymerization was conducted in the presence of various ratios of N-isopropylacrylamide (NIPAAm), acrylamide (AAm) and N-vinylpyrrolidone (NVP) as monomers, and N,N´-azobisisobutyronitrile (AIBN) as an initiator. Particles having average sizes of 8 nm and 8–10 nm were respectively observed for Fe3O4/fF and Fe3O4/polymers. As visualized by transmission electron microscopy (TEM) images, both the coated and uncoated iron oxide nanoparticles were uniform in shape and seem to have been monodispersed. Vibrating sample magnetometry (VSM) measurements of Fe3O4/VTES-fF and Fe3O4/Poly (NIPAAm- AAm NVP) at room temperature showed that they had a superparamagnetic nature with saturation magnetization values of 23.14 emu/g and 4.33 emu/g, respectively. In the thermosensitivity analysis, the lower critical solution temperature (LCST) was around 36-40°C, as determined by UV-Vis absorption spectroscopy. Furthermore, the polymerization of (NIPAAm-AAm-NVP) with the surface modified magnetic ferroFluid was confirmed by Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). These aqueous, stable, magnetic nanoparticles coated with temperature-sensitive polymers have attracted great attention because of their various applications in the fields of biotechnology and medicine.

Forces of interactions between iron and aluminum silicates: Effect of water chemistry and polymer coatings

Atomic force microscopy-based force spectroscopy (AFM) was employed to investigate the forces of interaction between aluminum silicates (mica and a synthetic aluminum–silicate) and iron particles, both bare and coated with carboxymethyl cellulose (CMC) polymer. Experiments were conducted in water and salt solutions (100mM NaCl and 100mM CaCl2) at pH 5.5, in water at pH 4 and 8, and in 10mg/l humic acid solutions. In addition, humic acid sorption onto the synthetic aluminum–silicate was probed with a quartz crystal microbalance with dissipation monitoring (QCM-D). Interactions between bare iron particles and aluminum silicate were attractive except at pH 8 and in the presence of humic acids in which case forces upon approach were repulsive. Interactions between bare iron and mica were similar, except that repulsive forces upon approach were measured in 100mM NaCl solutions, possibly due to increased hydration of mica compared to aluminum silicate. Interactions between CMC coated iron particles and aluminum–silicates were either repulsive or at most weakly attractive, likely due to repulsive electro-steric forces associated with the CMC. QCM-D results indicated that humic acids adsorbed to aluminum silicate, producing electro-steric repulsion to coated and uncoated iron. AFM data were successfully modeled using extended DLVO theory and a modified Ohshima’s model. This modeling provided insights into the contributions of various processes to the measured interaction forces, highlighting the importance of van der Waals and hydration forces.

Iron oxide nanoparticle toxicity testing using high-throughput analysis and high-content imaging

Applying validated in vitro assays to the study of nanoparticle toxicity is a growing trend in nanomaterial risk assessment. Precise characterisation of reference nanomaterials and a well-regulated in vitro testing system are required to determine the physicochemical descriptors which dictate the toxic potential of nanoparticles. The use of automated, high-throughput technologies to facilitate the identification and prioritisation of nanomaterials which could pose a risk is desirable and developments are underway. In this study, two mammalian fibroblast lines (Balb/c 3T3 and COS-1 cells) were treated with a range of concentrations of iron oxide nanomaterials manufactured for use in medical diagnostics, using an automated platform and high-content-imaging endpoints for cell viability, oxidative stress and DNA damage (double-strand breaks). At the same time, the high-throughput comet assay was employed to measure DNA strand breaks and oxidised bases. Our results show that these methods provide a fast way to determine the toxicity of coated and uncoated iron oxide nanoparticles and, furthermore, to predict the mechanism of toxicity in vitro.

Forces of interaction between fresh iron particles and iron oxide (magnetite): Effect of water chemistry and polymer coatings

Atomic force microscopy-based force spectroscopy (AFM) was employed to probe the forces of interaction between iron oxide (magnetite) surfaces and fresh zero-valent iron particles, either bare or coated with carboxymethyl cellulose polymer. Experiments were conducted at different pH values (4, 5.5 and 8), ionic strengths (water, 100mM NaCl and 100mM CaCl2), and in 10mg/l humic acid solutions (pH 6.75). pH values of 4 and 5.5 produced attraction between magnetite and iron particles (either bare or polymer coated), promoting attachment. Attractive forces between uncoated particles and magnetite were also measured in 100mM NaCl and CaCl2 at pH 8. Attachment of uncoated and CMC-coated iron particles was unfavorable in water at pH 8 and in humic acid solutions, as the forces upon approach were repulsive and, in addition, adhesive forces were on average weaker than in the other chemistries. A quartz-crystal microbalance with dissipation monitoring was used to probe humic acid sorption onto magnetite, and assess its impact on the forces of interaction.

Ultrafast electron and energy transfer in dye-sensitized iron oxide and oxyhydroxide nanoparticles

An emerging area in chemical science is the study of solid-phase redox reactions using ultrafast time-resolved spectroscopy. We have used molecules of the photoactive dye 2',7'-dichlorofluorescein (DCF) anchored to the surface of iron(III) oxide nanoparticles to create iron(II) surface atoms via photo-initiated interfacial electron transfer. This approach enables time-resolved study of the fate and mobility of electrons within the solid phase. However, complete analysis of the ultrafast processes following dye photoexcitation of the sensitized iron(III) oxide nanoparticles has not been reported. We addressed this topic by performing femtosecond transient absorption (TA) measurements of aqueous suspensions of uncoated and DCF-sensitized iron oxide and oxyhydroxide nanoparticles, and an aqueous iron(III)-dye complex. Following light absorption, excited state relaxation times of the dye of 115-310 fs were found for all samples. Comparison between TA dynamics on uncoated and dye-sensitized hematite nanoparticles revealed the dye de-excitation pathway to consist of a competition between electron and energy transfer to the nanoparticles. We analyzed the TA data for hematite nanoparticles using a four-state model of the dye-sensitized system, finding electron and energy transfer to occur on the same ultrafast timescale. The interfacial electron transfer rates for iron oxides are very close to those previously reported for DCF-sensitized titanium dioxide (for which dye-oxide energy transfer is energetically forbidden) even though the acceptor states are different. Comparison of the alignment of the excited states of the dye and the unoccupied states of these oxides showed that the dye injects into acceptor states of different symmetry (Ti t2gvs. Fe eg).

Stress reaction of kidney epithelial cells to inorganic solid-core nanoparticles

A route of accumulation and elimination of therapeutic engineered nanoparticles (NPs) may be the kidney. Therefore, the interactions of different solid-core inorganic NPs (titanium-, silica-, and iron oxide-based NPs) were studied in vitro with the MDCK and LLC-PK epithelial cells as representative cells of the renal epithelia. Following cell exposure to the NPs, observations include cytotoxicity for oleic acid-coated iron oxide NPs, the production of reactive oxygen species for titanium dioxide NPs, and cell depletion of thiols for uncoated iron oxide NPs, whereas for silica NPs an apparent rapid and short-lived increase of thiol levels in both cell lines was observed. Following cell exposure to metallic NPs, the expression of the tranferrin receptor/CD71 was decreased in both cells by iron oxide NPs, but only in MDCK cells by titanium dioxide NPs. The tight association, then subsequent release of NPs by MDCK and LLC-PK kidney epithelial cells, showed that following exposure to the NPs, only MDCK cells could release iron oxide NPs, whereas both cells released titanium dioxide NPs. No transfer of any solid-core NPs across the cell layers was observed.

Preparation and corrosion resistance of nanostructured PVC/ZnO–polyaniline hybrid coating

ZnO–polyaniline nanocomposite with core–shell nanostructure was prepared by in situ polymerization of aniline monomer in the presence of ZnO nanoparticles. Fourier transform infrared spectroscopy, X-ray diffraction patterns, field emission scanning electron microscopy and transmission electron microscopy techniques were used to characterize the composition and structure of ZnO–polyaniline nanocomposite. d.c. electrical conductivity measurement showed that the electrical conductivity of ZnO–polyaniline nanocomposite pellets is higher than that of pristine polyaniline and ZnO nanoparticles pellets. The addition of ZnO nanoparticles causes to the increasing of polyaniline electrical conductivity. ZnO–polyaniline nanocomposite was mixed with polyvinyl chloride (PVC) through a solution mixing method and the three components PVC/ZnO–polyaniline hybrid material was applied as coating on iron coupon by the solution casting method. Corrosion protection efficiency of PVC/ZnO–polyaniline hybrid coating on iron coupons was studied by open circuit potential and Tafel techniques in 3.5% NaCl solution as corrosive environment. According to the results, PVC/ZnO–polyaniline hybrid nanocomposite coating showed dramatically increased corrosion protection effect on iron samples compared to that of uncoated iron coupon and pure polyaniline anticorrosive coating. It was found that ZnO nanoparticles improve the barrier and electrochemical anticorrosive properties of polyaniline and the addition of polyvinyl chloride increases the barrier effect of polyaniline coating.

Superparamagnetic iron oxide nanoparticles as radiosensitizer via enhanced reactive oxygen species formation

Internalization of citrate-coated and uncoated superparamagnetic iron oxide nanoparticles by human breast cancer (MCF-7) cells was verified by transmission electron microscopy imaging. Cytotoxicity studies employing metabolic and trypan blue assays manifested their excellent biocompatibility. The production of reactive oxygen species in iron oxide nanoparticle loaded MCF-7 cells was explained to originate from both, the release of iron ions and their catalytically active surfaces. Both initiate the Fenton and Haber–Weiss reaction. Additional oxidative stress caused by X-ray irradiation of MCF-7 cells was attributed to the increase of catalytically active iron oxide nanoparticle surfaces.

Induction of oxidative stress, lysosome activation and autophagy by nanoparticles in human brain-derived endothelial cells

Different types of NPs (nanoparticles) are currently under development for diagnostic and therapeutic applications in the biomedical field, yet our knowledge about their possible effects and fate in living cells is still limited. In the present study, we examined the cellular response of human brain-derived endothelial cells to NPs of different size and structure: uncoated and oleic acid-coated iron oxide NPs (8-9 nm core), fluorescent 25 and 50 nm silica NPs, TiO2 NPs (21 nm mean core diameter) and PLGA [poly(lactic-co-glycolic acid)]-PEO [poly(ethylene oxide)] polymeric NPs (150 nm). We evaluated their uptake by the cells, and their localization, generation of oxidative stress and DNA-damaging effects in exposed cells. We show that NPs are internalized by human brain-derived endothelial cells; however, the extent of their intracellular uptake is dependent on the characteristics of the NPs. After their uptake by human brain-derived endothelial cells NPs are transported into the lysosomes of these cells, where they enhance the activation of lysosomal proteases. In brain-derived endothelial cells, NPs induce the production of an oxidative stress after exposure to iron oxide and TiO2 NPs, which is correlated with an increase in DNA strand breaks and defensive mechanisms that ultimately induce an autophagy process in the cells.

Biocompatibility of chitosan-coated iron oxide nanoparticles with osteoblast cells

Background:Bone disorders (including osteoporosis, loosening of a prosthesis, and bone infections) are of great concern to the medical community and are difficult to cure. Therapies are available to treat such diseases, but all have drawbacks and are not specifically targeted to the site of disease. Chitosan is widely used in the biomedical community, including for orthopedic applications. The aim of the present study was to coat chitosan onto iron oxide nanoparticles and to determine its effect on the proliferation and differentiation of osteoblasts.Methods:Nanoparticles were characterized using transmission electron microscopy, dynamic light scattering, x-ray diffraction, zeta potential, and vibrating sample magnetometry. Uptake of nanoparticles by osteoblasts was studied by transmission electron microscopy and Prussian blue staining. Viability and proliferation of osteoblasts were measured in the presence of uncoated iron oxide magnetic nanoparticles or those coated with chitosan. Lactate dehydrogenase, alkaline phosphatase, total protein synthesis, and extracellular calcium deposition was studied in the presence of the nanoparticles.Results:Chitosan-coated iron oxide nanoparticles enhanced osteoblast proliferation, decreased cell membrane damage, and promoted cell differentiation, as indicated by an increase in alkaline phosphatase and extracellular calcium deposition. Chitosan-coated iron oxide nanoparticles showed good compatibility with osteoblasts.Conclusion:Further research is necessary to optimize magnetic nanoparticles for the treatment of bone disease.

Elucidating the morphological and structural evolution of iron oxide nanoparticles formed by sodium carbonate in aqueous medium

Ferrimagnetic iron oxides are the common choice for many current technologies, especially those with application in biology and medicine. Despite the comprehensive knowledge accumulated about their chemistry in the bulk state, the sequence of changes taking place during the precipitation of iron oxide nanoparticles in aqueous media is much less extensive. We show that using sodium carbonate as a co-precipitating agent for the synthesis of uncoated iron oxide nanoparticles, the reaction proceeds sufficiently slowly to enable a detailed study of both the reaction pathway and products. The effect of pH, temperature and reaction time on particle size, morphology, crystalline phase and its magnetic properties was investigated. The obtained nanoparticles showed an increase in average particle size of about 10 nm per pH unit for the magnetite phase leading to 6.9 ± 0.4 nm, 18 ± 3 nm and 28 ± 5 nm for pH 8, 9 and 10 respectively. Goethite was initially formed by an olation mechanism at room temperature, followed by a slow transformation into magnetite over a 24 h period, as tracked by X-ray diffraction. In another set of experiments where the reaction temperatures were varied, magnetite was obtained directly by the oxolation mechanism at temperatures above 45 °C. The optimization of the experimental parameters led to superparamagnetic nanoparticles with a high saturation magnetization of 82 A m2 kg−1 at 300 K when synthesized at pH 9.