The cytotoxicity evaluation of magnetic iron oxide nanoparticles on human aortic endothelial cells

One major obstacle for successful application of nanoparticles in medicine is its potential nanotoxicity on the environment and human health. In this study, we evaluated the cytotoxicity effect of dimercaptosuccinic acid-coated iron oxide (DMSA-Fe₂O₃) using cultured human aortic endothelial cells (HAECs). Our results showed that DMSA-Fe₂O₃ in the culture medium could be absorbed into HAECs, and dispersed in the cytoplasm. The cytotoxicity effect of DMSA-Fe₂O₃ on HAECs was dose-dependent, and the concentrations no more than 0.02 mg/ml had little toxic effect which were revealed by tetrazolium dye assay. Meanwhile, the cell injury biomarker, lactate dehydrogenase, was not significantly higher than that from control cells (without DMSA-Fe₂O₃). However, the endocrine function for endothelin-1 and prostacyclin I-2, as well as the urea transporter function, was altered even without obvious evidence of cell injury in this context. We also showed by real-time PCR analysis that DMSA-Fe₂O₃ exposure resulted in differential effects on the expressions of pro- and anti-apoptosis genes of HAECs. Meanwhile, it was noted that DMSA-Fe₂O₃ exposure could activate the expression of genes related to oxidative stress and adhesion molecules, which suggested that inflammatory response might be evoked. Moreover, we demonstrated by in vitro endothelial tube formation that even a small amount of DMSA-Fe₂O₃ (0.01 and 0.02 mg/ml) could inhibit angiogenesis by the HAECs. Altogether, these results indicate that DMSA-Fe₂O₃ have some cytotoxicity that may cause side effects on normal endothelial cells.     

Structural and magnetic characterization of norbornene-deuterated norbornene dicarboxylic acid diblock copolymers doped with iron oxide nanoparticles

A series of iron oxide doped norbornene (NOR)/deuterated norbornene dicarboxylic acid (NORCOOH) diblock copolymers were synthesized and characterized by X-ray photoelectron spectroscopy (XPS), small angle neutron scattering (SANS) and superconducting quantum interference device (SQUID) experiments. γ-Fe₂O₃ nanoparticles were synthesized within the microdomains of diblock copolymers with volume fractions of NOR/NORCOOH 0.64/0.36, 0.50/0.50 and 0.40/0.60. A spherical nanoparticle morphology was displayed in the polymer with 0.64/0.36 volume fraction. Polymers with 0.50/0.50 and 0.40/0.60 volume fractions exhibited interconnected metal oxide nanostructures. The observed changes in the shape and peak positions of the small-angle neutron scattering profiles of polymers after metal doping were related to the scattering from the metal oxide particles and to the possible deformed morphologies due to the strong interparticle interactions between metal particles, which may influence the polymer microphase separation. The combined scattering from both polymer domains and magnetic particles was depicted in SANS profiles of metal oxide doped polymers. γ-Fe₂O₃ containing block copolymers were superparamagnetic at room temperature. An increase in the blocking temperature (T_b) of interconnected nanoparticles was observed and was related to the interparticle interactions, which depends on the average distance (d) between particles and individual particle diameter (2R). The sample with volume fraction of 0.4/0.6 have the lowest d/(2R) ratio and exhibit the highest T_b at 115 K.     

Magnetic resonance imaging of glioma with novel APTS-coated superparamagnetic iron oxide nanoparticles

We report in vitro and in vivo magnetic resonance (MR) imaging of C6 glioma cells with a novel acetylated 3-aminopropyltrimethoxysilane (APTS)-coated iron oxide nanoparticles (Fe₃O₄ NPs). In the present study, APTS-coated Fe₃O₄ NPs were formed via a one-step hydrothermal approach and then chemically modified with acetic anhydride to generate surface charge-neutralized NPs. Prussian blue staining and transmission electron microscopy (TEM) data showed that acetylated APTS-coated Fe₃O₄ NPs can be taken up by cells. Combined morphological observation, cell viability, and flow cytometric analysis of the cell cycle indicated that the acetylated APTS-coated Fe₃O₄ NPs did not significantly affect cell morphology, viability, or cell cycle, indicating their good biocompatibility. Finally, the acetylated APTS-coated Fe₃O₄ nanoparticles were used in magnetic resonance imaging of C6 glioma. Our results showed that the developed acetylated APTS-coated Fe₃O₄ NPs can be used as an effective labeling agent to detect C6 glioma cells in vitro and in vivo for MR imaging. The results from the present study indicate that the developed acetylated APTS-coated Fe₃O₄ NPs have a potential application in MR imaging.     

Surfactant-assisted combustion synthesis of agglomerated-free,size- and shape-controlled magnetic iron oxide nanoparticles for biomedical applications

An advanced version of the solution combustion synthesis (SCS) method was developed to prepare iron oxide (IO) nanoparticles, through controlling the agglomeration, size and shape of nanoparticles by assisting a cationic surfactant, “cetyltrimethylammonium bromide (CTAB)” and ethanol. Various IO nanoparticles were prepared in the presence of different CTAB:ethanol molar compositions of 0:0, 0.27:0, 0.55:0, 0.27:17.1, 0.55:17.1 and 0.82:17.1. The morphological evolution from agglomerated-shape particles to the well-dispersed as well as the size- and shape-controlled particles depended directly on the CTAB:ethanol molar composition. A shift from ferromagnetic behavior to superparamagnetic was observed by the application of CTAB along with ethanol, where the lowest blocking temperature (T_b, 60 K), highest saturation magnetization (M_s, 83.5 emu g⁻¹), zero coercivity and remanance magnetization were revealed for the particles prepared by CTAB:ethanol molar compositions of 0.55:17.1. These particles showed an acceptable specific absorption rate (SAR) value (320 W g⁻¹) as well as no obvious hemolytic and cytotoxic effects. This work provides new insights into advancing the SCS method and thus controlling the morphology, size and shape of metal oxide nanoparticles.     

Fabrication and characterization of zinc oxide nanoparticle coated magnetic iron oxide: Effect of S-layers adsorption on surface of oxide

Mixed zinc oxide nanoparticle coated magnetic iron oxide has been prepared by a sol–gel and co-precipitation routes. Magnetic iron oxide nanoparticles were synthesized by co-precipitation of ferric and ferrous ions with ammonia, and then zinc oxide was coated onto the surface of magnetic iron oxide by hydrolysis of zinc precursors. As a result, zinc oxide coated magnetic iron oxide nanoparticles with an average size of 68 nm were obtained. The crystalline bacterial cell surface layer)S-layer (used in this study was isolated from Lactobacillus helveticus ATCC 12046. The S-layer was adsorbed onto the surface of zinc oxide nanoparticle coated magnetic iron oxide. The nanoparticles were analyzed by X-ray powder diffractometry (XRD), infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM) were used to characterize the structural and the chemical features of the nanocomposites. The infrared spectra indicate that the S-layer-nanoparticle interaction occurs. This novel nanoparticle showed admirable potential in adsorption of S-layers on the surface of oxides for drug delivery.     

Low-temperature synthesis of redispersible iron oxide nanoparticles under atmospheric pressure and ultradense reagent concentration

Highly dispersed α-Fe₂O₃ nanoparticles ca. 3 to 8 nm in diameter were prepared at atmospheric pressure, low temperature, and at an ultradense reagent concentration by titrating an aqueous ammonia solution into a dense iron oleate/toluene mixture. A transparent suspension was obtained by redispersing the prepared particles in nonpolar solvents since they were redispersible to primary particles without aggregate formations. The prepared particles were characterized by TEM, XRD, and FT-IR, and their dispersion stability in organic solvents was determined by dynamic light scattering (DLS) and viscosity measurements. In order to analyze the formation process of the highly dispersed α-Fe₂O₃ nanoparticles, time-course measurements of DLS and viscosity during the nanoparticle synthesis in toluene were carried out. A significant increase in the suspension viscosity and the formation of an aggregated structure were observed as soon as the titration of the aqueous ammonia solution. The suspension viscosity and aggregated particle size gradually reduced with continuous vigorous stirring; finally, α-Fe₂O₃ nanoparticles that were completely redispersible in nonpolar solvents were obtained after ca. 24 h. The particle size could be controlled by the synthesis temperature, and such redispersible α-Fe₂O₃ nanoparticles were obtained even when the reagent concentration was increased to 2.8 mol/L.     

Composite magnetic particles: 2. Encapsulation of iron oxide by surfactant-free emulsion polymerization

This is a second paper in the series concerning the synthesis and characterization of composite polymeric particles with encapsulated magnetic iron oxide and bearing reactive β-diketone groups on the surface. Composite particles have been prepared by two-step method in which first step requires preparation of the iron oxide nano-particles and during second step iron oxide was encapsulated into formed poly(styrene/acetoacetoxyethyl methacrylate) (PS-AAEM) particles directly during polymerization process. It has been found that the modification of the iron oxide nano-particle surface with sodium oleate improves significantly the encapsulation during polymerization process. This procedure gives a possibility to obtain composite particles with raspberry morphology and both the particle size and iron oxide content can be varied. Change of monomer to iron oxide ratio gives a possibility to change effectively the morphology of hybrid particles, however, polydispersity of composite particles increases at higher content of magnetic particles in the system. Variation of AAEM concentration in reaction mixture at constant iron oxide particles concentration gives a possibility to control the particle size of formed hybrid microspheres. Composite particles were characterized by dynamic light scattering and electron microscopy (SEM) with respect to their particle size and morphology of the surface layer. X-ray diffraction (XRD) and magnetization measurements indicate presence of maghemite (γ-Fe₂O₃) in composite particles.     

Formation and characterization of iron oxide nanoparticles loaded on self-organized TiO2 nanotubes

The iron oxide nanoparticles were loaded onto self-organized TiO₂ nanotube layers grown by anodization of Ti in fluoride containing electrolytes. The nanoparticles were obtained by electrodepositing method in glycerol/water/FeCl₃·6H₂O electrolytes at room temperature. The X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) measurements showed that the nanoparticles consisted of iron nanocrystalline (Fe) and magnetite (Fe₃O₄). The hematite (α-Fe₂O₃) structure was obtained by annealing in air at 450 °C. The growth mechanism of the nanoparticles and their morphology were also described. Furthermore, the nanoparticles exhibited good ferromagnetic properties at room temperature.     

Efficient visible light magnetic modified iron oxide photocatalysts

Magnetite iron oxide (Fe₃O₄) nanoparticles were synthesized via simple co-precipitation method using ferrous and ferric ions salts. Fe₃O₄ nanoparticles were modified by silica and titania. Pure and modified nanoparticles were employed for dye degradation under visible light. X-ray diffraction analysis indicated inverse spinel structure of Fe₃O₄ nanoparticles. The particle size of magnetite nanoparticles is decreased due to coating of silica and titania. Scanning and transmission electron microscopy indicated the spherical morphology for all samples. The synthesized Fe₃O₄ nanoparticles were ferromagnetic in nature with highest saturation magnetization value of 1.1034 emu as compared to silica and titania coated samples. Fourier transform infra-red spectra confirmed the incorporation of magnetite nanoparticles with silica and titania. Titania modified magnetite sample showed the highest photocatalytic activity as compared to silica modified magnetite nanoparticles and bare iron oxide under visible light irradiations.     

Crystallization and unusual rheological behavior in poly(ethylene oxide)-clay nanocomposites

We report a systematic study of the crystallization and rheological behavior of poly(ethylene oxide) (PEO)-clay nanocomposites. To that end a series of nanocomposites based on PEOs of different molecular weight (10³ < MW < 10⁵ g/mol) and clay surface modifier was synthesized and characterized. Incorporation of organoclays with polar (MMT-OH) or aromatic groups (MMT-Ar) suppresses the crystallization of polymer chains in low MW PEO, but does not significantly affect the crystallization of high MW matrices. In addition, the relative complex viscosity of the nanocomposites based on low MW PEO increases significantly, but the effect is less pronounced at higher MWs. The viscosity increases in the series MMT-Alk < MMT-OH < MMT-Ar. In contrast to the neat PEO which exhibits a monotonic decrease of viscosity with temperature, all nanocomposites show an increase after a certain temperature. This is the first report of such dramatic enhancements in the viscoelasticity of nanocomposites, which are reversible, are based on a simple polymer matrix and are true in a wide temperature range.     

Influence of iron oxide pigments on the properties of concrete interlocking blocks

Concrete interlocking blocks (CIBs) are utilized in a variety of commercial, municipal, and industrial applications. Superior engineering properties, low maintenance, ease of placement and removal, reuse of original blocks, aesthetic appeal, and immediate availability are the primary reasons for choosing concrete block pavement over other paving surfaces. It is a common practice to pigment building materials, such as mortar, concrete pavers, concrete roof tiles, and prefabricated concrete products; CIBs are colored using iron oxide pigments. This article presents experimental results detailing the properties of CIBs dyed with pigments. The results of these experiments are as follows: Because the particles of iron oxide pigments are finer than those of brown iron oxide, interlocking blocks mixed with the former acquired higher color strength than with the latter. Additional analysis determined a definite relationship between the flexural strength and the absorption ratio of pigment-dyed blocks; the correlation coefficient (R²) of interlocking blocks at 91 days was .90. It is suggested that if iron oxide pigments are to be used to color CIBs, the pigment-to-cement ratio should be below 4%.     

TEM characterization of diblock copolymer templated iron oxide nanoparticles: Bulk solution and thin film surface doping approach

The morphology of a novel diblock copolymer, poly(norbornene methanol)-b-poly(norbornene dicarboxylic acid), was investigated before and after metal oxide doping by transmission electron microscopy (TEM) using a novel iodine vapor staining method to image the undoped polymer. A lamellar morphology was observed by TEM after staining the undoped diblock copolymer with iodine vapor. Thin film surface doping resulted in a confinement of the iron oxide nanoparticles within the lamellar domains. Spherical nanoparticle aggregates were observed through a bulk solution doping method. It was observed that the particles were templated by the underlying lamellar structure of the copolymer when the thin film surface doping method was used.     

Effects of irradiation energy and nanoparticle concentrations on the structure and morphology of laser sintered magnesia with alumina and iron oxide nanoparticles

The laser sintering mechanism of composites based on magnesia and oxide nanoparticles was studied in terms of nanoparticle concentration and laser energy fluence. Iron oxide and aluminum oxide nanoparticles were mechanically mixed with magnesia (MgO) powder (5, 7 and 10 wt%) and the compacted pellets were irradiated with the fundamental output (1064 nm) of a pulsed Nd:YAG laser at 2.5 and 3.0 J/cm². Crystal structure, elemental composition and morphology were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. X-ray diffraction results confirmed the crystalline phases and spinel formation by addition of oxide nanoparticles and laser sintering. X-ray photoelectron spectroscopy analysis confirmed their surface composition and chemical states of the corresponding elements. Morphological changes were observed due to the laser fluence and the oxide nanoparticle concentrations. Results show that a coarsening mechanism was predominant with a high energy fluence and concentration of oxide nanoparticles.     

Nanocomposites based on chalcogenide glass semiconductor and metal phtalocyanine

A novel technique for the fabrication of chalcogenide nanocomposites based on chalcogenide glass (ChGs) and manganese phtalocyanine (MnPc) is presented. The structural and optical characterization of obtained composites in comparison to chalcogenide glass was carried out. Two-component nanocomposite films were obtained by simultaneous vacuum co-condensation of the ChGs components and organic dye on the substrate surface. The spatial arrangement of the two evaporators and substrates in a vacuum chamber allowed obtain samples with varied composite ratio. ChGs films optical band gap values were not sufficiently changed with growth rate and films thickness. It was shown that in case of dye concentration reduction for more than three orders specific absorption per dye molecule will be decreased by two orders. At greater concentrations solid solution of dye is clusterized, dye is distinctly aggregated and the absorbance is nearly the same as of the pure dye in the form of thin film. Therefore composite properties changes from cluster solution into molecular solution and thus dye molecule absorbance decrease. Relation of specific dye absorption on composite concentration was explained as electrons exchange with donor and acceptor subsystems and corresponding electron levels population. Sketch of electron density diagrams and corresponding bonds schema for composites are presented.     

Application of magnetic iron oxide nanoparticles prepared from microemulsions for protein purification

BACKGROUND: Magnetic nanoparticles are of immense interest for their applications in biotechnology. This paper reports the synthesis of magnetic iron oxide nanoparticles from two different water‐in‐oil microemulsion systems (ME‐MIONs), their characterization and also their use in purification of coagulant protein. RESULTS: ME‐MIONs have demonstrated to be an efficient binder in the purification of Moringa oleifera protein when compared with the superparamagnetic iron oxide nanoparticles prepared from coprecipitation in aqueous media. The size and morphology of the ME‐MIONs were studied by transmission electron microscopy (TEM) while the structural characteristics were studied by X‐ray diffraction (XRD). The microemulsion magnetic iron oxide nanoparticles (ME 1‐MION and ME 2‐MION) obtained have a size range 7–10 nm. The protein and ME‐MIONs interaction was investigated by Fourier transform infrared spectroscopy (FT‐IR); the presence of three peaks at 2970, 2910 and 2870 cm^?1 respectively, confirms the binding of the protein. The purification and molecular weight of the coagulant protein was 6.5 kDa as analyzed by SDS‐PAGE. CONCLUSION: The ME‐MIONs have the advantage of being easily tailored in size, are highly efficient as well as magnetic, cost effective and versatile; they are, thus, very suitable for use in a novel purification technique for protein or biomolecules that possess similar characteristics to the Moringa oleifera coagulant protein. Copyright © 2011 Society of Chemical Industry     

Synthesis of in situ functionalized iron oxide nanoparticles presenting alkyne groups via a continuous process using near-critical and supercritical water

The preparation of iron oxide nanoparticle dispersions of varying properties (e.g. color, crystal structure, particle size distribution) in a continuous hydrothermal pilot plant operating under near-critical and supercritical conditions with the aim of producing in situ functionalized nanoparticles suitable for secondary functionalization via click chemistry is reported. The effect of varying the mixing setup, reaction temperature and the starting material (iron salt) in the presence of different carboxylic acids on the resulting nanoparticle dispersions was investigated. The stability of the clickable ligands in the harsh hydrothermal environment was also tested and the clickability of the functionalized particles was demonstrated by means of XPS and fluorescence measurements after model click reactions.     

BSA修饰Fe_3O_4纳米颗粒用于苦瓜提取液中活性成分的筛选

用一步法直接合成了表面氨基化修饰的Fe3O4纳米颗粒(NH2-MION),通过双功能团试剂戊二醛将牛血清白蛋白(BSA)固定在NH2-MION表面,将BSA-MION用于苦瓜提取液中活性成分的筛选,利用气相色谱-质谱联用技术鉴定出了3种与BSA作用较强的活性成分。     

Kinetic behaviour of iron oxide sorbent in hot gas desulfurization

Although a number of reports on sorbents containing ZnO for H₂S removal from coal-derived gases can be found in the literature, it is shown in our study that a special sorbent containing Fe₂O₃·FeO (SFO) with minor promoters (Al₂O₃, K₂O, and CaO) as the main active species is more attractive for both sulfidation and regeneration stages, also under economic considerations. This paper presents the kinetic behaviour of SFO in a hot gas desulfurization process using a thermogravimetric analysis under isothermal condition in the operating range between 500 and 800 °C. The gas stream was N₂ with a 2% wt of H₂S. Experiences carried out on sorbent sulfidation with SFO (particle sizes in the range of 0.042-0.12 mm) indicate that the sorbent sulfidation capacity sharply increases with temperature in the range of 500-600 °C. It is also shown that the sample weight reaches its maximum absorption capacity, near saturation, at 600 °C so that it makes no sense to increase the sulfidation temperature from this point. To make a comparison between SFO and a zinc titanate based sorbent, a set of sulfidation tests was carried out at 600 °C during 7200 s using the same sieve range for both sorbents between 42 and 90 μm. Results show that the sulfidation capacity of SFO is 1.9 times higher than that of zinc titanate.     

CVD synthesis of coal-gas-derived carbon nanotubes and nanocapsules containing magnetic iron carbide and oxide

Iron carbide-oxide filled carbon nanotubes and nanocapsules (CNCs) are separately synthesized by catalytic chemical vapor deposition of coal gas at 950 °C with ferrocene as catalyst. The products are examined using transmission electron microscopy and XRD techniques, showing that nanosized iron carbide-oxide particles are encapsulated by well ordered carbon layers. Magnetic moment measurement reveals that these carbon encapsulated iron carbide-oxides exhibit large magnetic coercivity at room temperature. It has been found that the filled CNCs are corrosion-proof and stable in hydrochloric acid. The effect and interaction between different gaseous components in the coal-gas during the formation of magnetic iron carbide-oxide filled carbon nanostructures are discussed.