O. Silva

Magnetic Resonance of a Dextran-Coated Magnetic Fluid Intravenously Administered in Mice

Magnetic resonance was used to investigate the kinetic disposition of magnetite nanoparticles (9.4 nm core diameter) from the blood circulation after intravenous injection of magnetite-based dextran-coated magnetic fluid in female Swiss mice. In the first 60 min the time-decay of the nanoparticle concentration in the blood circulation follows the one-exponential (one-compartment) model with a half-life of (6.9 +/- 0.7) min. The X-band spectra show a broad single line at g approximately 2, typical of nanomagnetic particles suspended in a nonmagnetic matrix. The resonance field shifts toward higher values as the particle concentration reduces, following two distinct regimes. At the higher concentration regime (above 10(14) cm(-3)) the particle-particle interaction responds for the nonlinear behavior, while at the lower concentration regime (below 10(14) cm(-3)) the particle-particle interaction is ruled out and the system recovers the linearity due to the demagnetizing field effect alone.

Magneto-optical properties of a highly transparent cadmium ferrite-based magnetic fluid

The magneto-optical properties of a highly stable ionic magnetic fluid sample containing CdFe2O4 nanoparticles were investigated using static magnetic birefringence, zero-field optical transmissivity, and transmission electron microscopy. From our measurements we found that the transmittivity and the birefringence of the CdFe2O4-based sample is several times greater than a typical magnetic fluid sample (γ-Fe2O3 based), giving this magnetic material great potential for magneto-optics applications. We also found that the birefringence can be increased by several orders of magnitude, allowing full manipulation of the observed negative differential transmitted optical intensity feature.

Light microscopy and magnetic resonance characterization of a DMSA-coated magnetic fluid in mice

Light microscopy and magnetic resonance were used to investigate the biodistribution of magnetite nanoparticles coated with dimercaptosuccinic acid, after intravenous injection of a single dose in mice. Morphological analysis showed a huge amount of magnetic nanoparticles (MNPs) in the lung 30 min after injection. In contrast to the lung, morphological analysis revealed lower concentration of MNPs in the liver. A progressive decrease of MNPs in both lung and liver was observed from 30 min to 4 hours after intravenous injection. MNPs were not observed in any other organs using morphological analysis. In support of the LM observations MR signals were detected in both lung and liver as early as 5 min after injection. In addition, no MR signal was observed in the blood stream as early as 5 min after injection of the single dose.

Magnetic resonance and light microscopy investigation of a dextran coated magnetic fluid

A dextran-coated magnetite-based magnetic fluid (MF) sample (DexMF) was developed for cancer diagnostic and therapeutic purposes. In order to perform biological studies DexMF samples were endovenously injected into female Swiss mice. Magnetic resonance (MR) spectra showed a broad line around g=2, typical of magnetic nanoparticles (MNPs) suspended in a nonmagnetic matrix. The MR data showed that MNPs essentially spread in liver, spleen, and bone marrow. MNPs in blood stream were found up to 60 min after injection. Histological analysis also showed MNP agglomeration in liver, spleen, and bone marrow, from 1 h up to 28 days. No damaged cells or any other kind of alteration were observed in the investigated tissues. The data suggested that DexMF sample is biocompatible and adequate for biomedical applications.

In Vivo Effects of Cagaita (Eugenia dysenterica, DC.) Leaf Extracts on Diarrhea Treatment

Eugenia dysenterica is a plant typically found in the Cerrado biome and commonly used in popular medicine due to its pharmacological properties, which include antidiarrheal, skin healing, and antimicrobial activities. The effects of ethanolic extract, aqueous extract and infusion of E. dysenterica leaves on intestinal motility and antidiarrheal activity were evaluated using ricin oil-induced diarrhea in rats. At doses of 400 and 800 mg·Kg−1, the ethanolic extract decreased intestinal motility while the other extracts showed no significant effects. Moreover, serum levels of chloride, magnesium, and phosphorus were also measured in rats. Histopathologic and enzymatic analyses were also performed to investigate any toxic effect. Animals treated with infusion, ethanolic extract, ricin oil, and loperamide presented morphological alterations in the small intestine, such as mucosa lesion, epithelial layer damage, and partial loss and/or morphological change of villi. Furthermore, the liver showed congestion and hydropic degeneration. Serum levels of alanine aminotransferase increased significantly in all treatments, but none rose above reference values. In summary, our results suggest that compounds present in leaves of E. dysenterica may have therapeutic benefits on recovery from diarrhea despite their toxic effects.

Biodistribution and biocompatibility investigation in magnetoliposome treated mice

Magnetoliposomes (MLs) may be successfully applied for several purposes. A dimyristoylphosphatidyl-choline- based ML (ML-2) sample was developed as a precursor of more complex thermal cancer therapy systems. The present study reports on morphology and magnetic resonance (MR) investigations carried out with the magnetite-based ML-2 sample. For the experiments, adult female Swiss mice were endovenously treated with a bolus dose of 100 µl of ML-2. Morphology and room-temperature MR studies (X-band experiments) were performed in several organs collected from 1 hour to 28 days after ML administration. Histological data showed magnetic nanoparticle (MNP) clusters up to the 28th day in the liver and spleen tissues. In spite of the presence of MNP clusters, no morphological alterations were observed, supporting the biocompatibility of the ML-2. MR signal was detected only in the liver and spleen tissues and showed that the MNPs concentration was not altered from 48 hours to 28 days after ML injection. Using MR data, important pharmacokinetic parameters, such as the effective clearance (half-life) and peak concentration, were obtained for the liver and spleen.

Cadmium ferrite ionic magnetic fluid: Magnetic resonance investigation

In contrast to all magnetic resonance investigations previously performed using magnetic fluids (MFs) based on spinel ferrite nanoparticles, cadmium–ferrite-based MFs present an intense, relatively sharp resonance line near g=4, in addition to the typical, broad structure near g=2. The broad resonance structure is associated with larger cadmium–ferrite nanoparticles, whereas the sharp resonance line is associated with ultrasmall cadmium–ferrite nanoparticles. Transmission electron microscopy (TEM) data confirm the bimodal particle size distribution in the sample investigated. The temperature T dependence of the resonance field HR is almost linear, for both high-field (HF) and low-field (LF) resonance lines, in the range of 100–300 K. In support of the identification of the HF line (around g=2) and LF line (around g=4) with larger and smaller Cd–ferrite nanoparticles, respectively, the slope of the HR versus T curve is lower for the HF line (1.3 G/K) compared to the LF line (1.69 G/K), whereas the intercep...

Cadmium-ferrite-based magnetic fluid: birefringence and transmission electron microscopy investigation

In this paper, a new hydrocarbon based MF sample containing cadmium ferrite nanoparticles surface-coated with oleic acid is investigated using TEM and SMB. In contrast to all MF samples based on spinel ferrite nanoparticles this new MF sample is relatively transparent at particle concentration in the range of 10/sup 16/ to 10/sup 17/ particle/cm/sup 3/. Further, the saturation birefringence is one order of magnitude higher than any other MF sample ever reported. This two points are extremely interesting, making the cadmium ferrite based MF and exceptional candidate for applications in optical devices.

Investigation of magnetic nanoparticles in acrylonitrile-methyl methacrylate-divinylbenzene mesoporous template

Abstract Preparation and characterization of nanosized magnetic particles using alkaline oxidation of ferrous ion retained in acrylonitrile-methyl methacrylate-divinylbenzene (AN-MMA-DVB) spherical micron-sized polymer template is described. Atomic absorption, transmission electron microscopy and magnetic resonance were used to investigate chemically cycled nanoparticle-based composites. The resonance field shifts towards higher values as the nanoparticle concentration reduces in the polymeric template, following two very distinct regimes.

Magnetic Resonance and Light Microscopy Investigation of Raw Cells Treated With Dextran-Based Magnetic Fluid

In the present study, magnetic resonance (MR) and light microscopy (LM) were used to investigate in vitro effects of MNPs on mouse raw cells, specially their interactions and subsequent cytotoxicity.