Ultrasmall superparamagnetic iron oxides enhanced MR imaging in rats with experimentally induced endometriosis

Purpose

The purpose of our study was to evaluate the feasibility of magnetic resonance imaging (MRI) using ultrasmall superparamagnetic iron oxides (USPIO) in the detection of experimentally induced endometriosis.

Materials and methods

Endometriosis was surgically induced in rats by transplanting an autologous fragment of uterine tissue onto the inner surface of the abdominal wall, the posterior surface of the uterine body and the arterial cascades of the small intestines adjacent to mesenteric blood vessels. Six weeks later, MRI using Gd-DTPA and USPIO was performed for the evaluation of the ectopic uterine tissue (EUT). A scoring system was developed for image interpretation (0=absence, 1=probably absence, 2=probably presence and 3=presence). We defined MR index (MRIx) as the sum of T1-weighted and enhanced T1-weighted and T2-weighted image scores, and USPIO MRIx (MRIx^+USPIO) as the MRIx score plus the score of USPIO-enhanced T2-weighted image.

Results

The MRIx^+USPIO was also higher in the successfully autotransplanted group than in the failed group (6.19±1.72 versus 3.94±1.20, P<.001). There was also a significant linear relationship between MRIx^+USPIO and pathologic status (R²=0.494, P<.001). Thirty-one (64.6%) of the 48 implanted uterine tissues were histologically confirmed on pathologic review. The area of MRIx and MRIx^+USPIO in the detection of EUT more than 3 mm in size was 0.739 and 0.913, respectively.

Conclusion

Our results suggest that USPIO-enhanced MRI could be a novel diagnostic tool for diagnosis in experimentally induced peritoneal endometriosis.     

Magnetic composites based on hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides

Materials containing hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides were obtained from a chemical precursor prepared by admixing chitosan and iron and aluminum hydroxides. The oxides were first characterized with scanning electron microscopy, X-ray diffraction, and Mössbauer spectroscopy. Scanning electron microscopy micrographs showed the size distribution of the resulting spheres to be highly homogeneous. The occurrence of nano-composites containing aluminum oxides and iron oxides was confirmed from powder X-ray diffraction patterns; except for the sample with no aluminum, the superparamagnetic relaxation due to iron oxide particles were observed from Mössbauer spectra obtained at 298 and 110 K; the onset six line-spectrum collected at 20 K indicates a magnetic ordering related to the blocking relaxation effect for significant portion of small spheres in the sample with a molar ratio Al:Fe of 2:1.     

One-dimensional iron oxides nanostructures

Iron oxides,including α-Fe2O3,γ-Fe2O3,Fe3O4,etc.are one of the most widely investigated materials for their fundamental properties and potential applications.One-dimensional(1-D) iron oxides nanostructures are the focus of recent research activities because of their wide applications in magnetic refrigeration,information storage,electronics,catalysts,Li-ion battery,pigment,gas sensors,etc.This review covers the recent progress in the synthesis,properties and applications of 1-D iron oxides nanostructures.Th...     

Inflammatory imaging with ultrasmall superparamagnetic iron oxide

The purpose of this study was to investigate the usefulness and feasibility of magnetic resonance imaging (MRI) with ultrasmall superparamagnetic iron oxide (USPIO) (USPIO-enhanced MRI) for imaging inflammatory tissues. First, we investigated the relationship between the apparent transverse relaxation rate (R2*) and the concentration of USPIO by phantom studies and measured the apparent transverse relaxivity (r2*) of USPIO. Second, we performed animal experiments using a total of 30 mice. The mice were divided into five groups [A (n=6), B (n=6), C (n=6), sham control (n=6), and control (n=6)]. The mice in Groups A, B, C and control were subcutaneously injected with 0.1 ml of turpentine oil on Day 0, while those in the sham control group were subcutaneously injected with 0.1 ml of saline. The mice in Groups A, B, C and sham control were intraperitoneally injected with 200 μmol Fe per kilogram body weight of USPIO (28 nm in diameter) immediately after the first MRI study on Days 3, 5, 7 and 7, respectively, and those in the control group were not injected with USPIO. The second and third MRI studies were performed at 24 and 48 h after USPIO administration, respectively. The maps of R2* were generated from the apparent transverse relaxation time (T2*)-weighted images with six different echo times. The phantom studies showed that there was a linear relationship between R2* and the concentration of USPIO (r=0.99) and the r2* value of USPIO was 105.7 mM⁻¹ s⁻¹. There was a significant increase of R2* in inflammatory tissues in Group C at 24 h after USPIO administration compared with the precontrast R2* value. Our results suggest that USPIO-enhanced MRI combined with R2* measurement is useful for detecting inflammatory tissues.     

PEGylation of superparamagnetic iron oxide nanoparticle for drug delivery applications with decreased toxicity: an in vivo study

Journal of Nanoparticle Research - Superparamagnetic iron oxide nanoparticles (SPIONs) are evolving as a mainstay across various applications in the field of Science and Technology. SPIONs have...     

Temperature dependence of superparamagnetic resonance of iron oxide nanoparticles

Nanoparticles of maghemite (γ-Fe₂O₃) are formed in a sol–gel silicate glass with a molar ratio Fe/Si of 2% by a treatment at 1000°C for 6 h. Electron paramagnetic resonance spectrum at 300 K shows a relatively narrow sharp line at g_eff≈2. As the temperature lowers to 5 K, the apparent resonance field decreases and the linewidth considerably increases. We develop a theoretical formalism based on a distribution of diameters or volumes of the nanoparticles following a lognormal. The nanoparticles are considered as single magnetic domains with random orientations of magnetic moments and thermal fluctuations of anisotropic axes. The individual line shape function is derived from the damped precession equation of Landau–Lifshitz. An appropriate linewidth expression is put forward, which account for the averaging of the fluctuations of orientations of the magnetic moments with respect to the magnetic field and to the magnetic anisotropy axes. A single set of parameters provides good fits to the spectra recorded at the different temperatures. The low-temperature blocking of the nanoparticle magnetic moments has been clearly evidenced in the resonance absorption intensity and the blocking temperature of the assembly of nanoparticles (averaged over the distribution in the nanoparticle volume) has been evaluated as 90 K.     

Cellular uptake of folate-conjugated lipophilic superparamagnetic iron oxide nanoparticles

We prepared five folate-conjugated lipophilic superparamagnetic iron oxide nanoparticles (F₅-Liposuperparamagnetic iron oxide nanoparticles(SPIONs), 5.5 and 11 nm) and investigated their cellular uptake with KB cells, which is one of the representative folate-receptor over-expressing human epidermoid carcinoma cells, using MRI. The cellular uptake tests with the respective 5.5 and 11 nm F₅-LipoSPIONs at a fixed particle concentration showed appreciable amount of receptor-mediated uptakes and the specificity was higher in 5.5 nm SPIONs, due to its higher folic acid (FA) density, without inhibition. However, the numbers of the particles taken up under FA inhibition were similar, irrespective of their sizes.     

Nitric acid-stabilized superparamagnetic iron oxide nanoparticles studied with X-rays

Using density functional theory, we systematically investigate the adsorption geometries and electrical properties of (3,3) carbon nanotube (CNT) integrated on hydrogen-terminated Si(001):1?×?1 surface. Prior to adsorption of the CNT, the surface is patterned in two different ways by desorbing selective hydrogen atoms from the surface. The (3,3) CNT which is metallic in nature becomes semiconducting with a band gap around the fermi level when it is supported on patterned hydrogen-terminated Si(001):1?×?1 surface. However, the band gap is reduced when a transverse electric field is applied, allowing the (3,3) CNT on the patterned hydrogen-terminated Si(001):1?×?1 to become metallic at a critical field strength. The tuning of electrical properties of the (3,3) CNT integrated with Si surface may have potential technological applications.     

Magnetic characterization of some nanometric iron oxides

Nanosized magnetite particles embedded in polypyrrole matrix have been studied by Mössbauer and electron magnetic resonance spectroscopy. Comparison with as grown magnetite is made. Hyperfine fields distribution is determined and line shape of resonance curves are discussed in terms of composite structure, sizes and treatments.     

Ion exchange properties of lithium iron oxides

The αLiFeO₂ rock salt material has been prepared from lithium carbonate and ferric oxide. It was found that the lithium can be exchanged for silver in silver nitrate and, initially, a substituted rock salt is produced, Ag_xLi_1−xFeO₂. The ultimate phase in the ion-exchange process is αAgFeO₂. The diffusion coefficient of Ag in Ag_xLiFeO₂, determined by transient electrochemical measurements, was found to be around 5 × 10⁻⁸ cm⁻² s⁻¹.     

Variation of superparamagnetic properties with iron loading in mammalian ferritin

The average blocking temperatures of ferritin molecules containing differing amounts of iron were determined by Mossbauer spectroscopy. The results imply that the magnetic anisotropy of the ferritin core particles is a function of particle volume. By addition of⁵⁷Fe to ferritin core particles it was determined that, at a given temperature within the superpara-magnetic temperature region, the “last-in” ferric ions have average relaxation times that are shorter than those of the bulk ferric ions.     

Synthesis and characterization of superparamagnetic iron oxide nanoparticles for biomedical applications

Monodisperse iron oxide nanoparticles (NPs) of 4 nm were obtained through high-temperature solution phase reaction of iron (III) acetylacetonate with 1, 2-hexadecanediol in the presence of oleic acid and oleylamine. The as-synthesized iron oxide nanoparticles have been characterized by X-ray diffraction, transmission electron microscopy, Mössbauer spectroscopy and magnetic measurements. The species obtained were Fe₃O₄ and/or $\upgamma$ -Fe₂O₃. These NPs are superparamagnetic at room temperature and even though the reduced particle size they show a high saturation magnetization (MS ≈ 90 emu/g).     

Covalent immobilization of invertase on PAMAM-dendrimer modified superparamagnetic iron oxide nanoparticles

In this study, polyamidoamine (PAMAM) dendrimer was synthesized on the surface of superparamagnetite nanoparticles to enhance invertase immobilization. The amount of immobilized enzyme on the surface-hyperbranched magnetite nanoparticle was up to 2.5 times (i.e., 250%) as much as that of magnetite nanoparticle modified with only amino silane. Maximum reaction rate (V _max) and Michaelis–Menten constant (K _m) were determined for the free and immobilized enzymes. Various characteristics of immobilized invertase such as; the temperature activity, thermal stability, operational stability, and storage stability were evaluated and results revealed that stability of the enzyme is improved upon immobilization.     

Cobalt-modified iron oxides with improved aging stability

Surface modification of cobalt-modified iron oxides with silicon- or aluminium-containing inorganic compounds suppresses the coercivity aging that otherwise occurs in these particles. At the same time, the inorganic surface coatings change the adsorption characteristics of the particles, allowing them to be matched with the components of the tape formulation.     

In vivo Mössbauer spectroscopy of iron uptake and ferrometabolism inEscherichia coli

Hyperfine Interactions - Iron limited growth of microbes results in derepression of siderophore receptor and transport-systems which can be utilized for controlled and specific siderophore...     

The effects of iron oxides on proton relaxivity

The magnetic properties and relaxivities of superparamagnetic, ferromagnetic and paramagnetic iron oxides are presented and compared. The iron in colloids of ferromagnetic iron oxide has a large spin-spin relaxivity and a small spin-lattice relaxivity. The iron in colloids of paramagnetic iron oxide has a low spin-spin and spin-lattice relaxivity. The iron in colloids of highly dispersed superparamagnetic iron oxides has a large spin-spin relaxivity and a large spin-lattice relaxivity. Superparamagnetic colloids with various particle sizes in solution have been made by varying the number of superparamagnetic iron oxide crystals per particles in solution. Superparamagnetic colloids of larger solution particle size have a lower spin-lattice relaxivity than colloids comprised of smaller solution particle sizes.