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Nanoparticles of CoFe2O4 were prepared through coprecipitation method. The particle size from Scherrer equation is 49.84 nm. The particles approach the state of superparamagnetism although the study is conducted below the temperature when the state is achieved. Some unusual unanticipated peaks have been observed in FC (field cooled) and ZFC (zero field cooled) curves and we have tried to explain them on the basis of domain wall pinning. Another feature is the large coercivity and low saturation magnetization of CoFe2O4 particles at 5K in comparison to lower coercivity and larger saturation magnetization at 300K which is attributed to anisotropy. [ABSTRACT FROM AUTHOR]

Superparamagnetic properties of iron-oxide nanoparticles paved the way for various biomedical applications, such as magnetic resonance imaging (MRI), magnetic targeting of drug vectors or magnetically-induced therapeutic hyperthermia. Living cells interact with nanoparticles by internalizing them within intracellular compartments, called lysosomes. In the course of cellular uptake, the spatial distribution of magnetic nanoparticles changes from dilute isolated nanoparticles to a highly concentrated assembly of nanoparticles confined in micrometric lysosomes. This local organization of nanoparticles, which is induced by the intracellular environment, may have important consequences for their superparamagnetic behaviour. In particular, it may deeply affect their magnetic properties used for biomedical purposes and therefore must be considered when optimizing the properties of nanoparticles for a peculiar application. In this paper, we review the role of intracellular confinement of nanoparticles for their three main biomedical uses: MR cellular imaging, magnetic targeting of cells and magnetically induced hyperthermia. [ABSTRACT FROM AUTHOR]

The new magnetic reactor based solid phase synthesis strategy allows magnetic immobilization of nanoparticles in order to perform the derivatization step(s) with relevant biomolecules on the immobilized magnetic nanoparticles. Monoclonal Mouse anti-Human CD11b shows affinity toward monocyte/macrophage integrin MAC-1 (CD11b/CD18) which is involved in leukocyte adhesion and functions as a cell receptor and was coupled on superparamagnetic iron oxide nanoparticles (SPIONs) in this reactor. The resulting anti-CD11b derivatized SPIONs were analyzed and compared to conventionally derivatized SPIONs. The reactor-derivatized anti-CD11b-SPIONs show enhanced colloidal stability during and after the surface derivatization steps. The yield and quality of the resulting particles can also be significantly improved in terms of reaction time and yield, particle size distribution, and scalability by using this magnetic reactor. These highly specific particles were successfully used in imaging studies of monocytes. [ABSTRACT FROM AUTHOR]

Monodisperse nickel nanoparticles (Ni-NPs) were synthesized via a thermal decomposition process. The NPs were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). They were spherical with mean diameter of 4 nm. Zero field cooled (ZFC) and field cooled (FC) magnetization versus temperature data displayed interesting magnetic interactions. ZFC showed a peak at 4.49 K, indicating the super paramagnetic behavior. Magnetic anisotropic constant was estimated to be 4.62x105 erg/cm³ and coercive field was 168 Oe at 3 K. [ABSTRACT FROM AUTHOR]

In the present manuscript, MnxCo1-xFe2O4 (x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) nanoparticles have been synthesized with co-precipitation method by annealing at 900 °C and studied the structural and magnetic properties. X ray diffraction pattern reveals the formation of single phase cubic spinel structure with the space group Fd-3m. An impurity peak of a-Fe2O3 has been observed in the XRD patterns of samples with Mn composition, x ≥ 0.4. However, this impurity phase of a-Fe2O3 is not observed in the MnFe2O4 sample synthesized by annealing at 500 oC. FESEM results indicate the formation of nano-sized particles. Magnetic measurements show ferrimagnetic interaction in MnxCo1-xFe2O4 (x≥0) nanoparticles at room temperature. However, MnFe2O4 sample synthesized by annealing at 500 °C shows superparamagnetic behavior. We have fitted the M-H curve of MnFe2O4 synthesized by annealing at 500 °C with modified Langvenin function to confirm superparamagnetism .The correlation between the structural and observed magnetic properties of as synthesized samples nanoparticles will be described and discussed in this paper. [ABSTRACT FROM AUTHOR]

Nanosized Co0.3Zn0.7Fe2O4 having average particle size ~20 nm has been synthesized by mechanochemical method. The results of dc magnetic and Mössbaeur studies suggest that the sample is ferrimagnetic in nature and shows superparamagnetic behavior above 230K. Magnetic ordering in the sample evolves gradually upon cooling the system below blocking temperature. Moreover, the sample exhibits enhancement of magnetic order and ordering temperature with respect to its counterpart synthesized by chemical routes mainly due to increase of stress anisotropy induced by high energy ball milling. We have shown that maintaining suitable cation distribution helps in enhancement of magnetization by reducing the adverse effect of spin canting. [ABSTRACT FROM AUTHOR]

Nanoparticles of FePd and FePdPt with the average size of ∼3 nm have been prepared by modified polyol route. As-prepared nanoparticles are crystallized in fcc phase, whereas, 550-600° C annealed nanoparticles are crystallized in fct phase. As-prepared samples are superparamagnetic at 300 K, whereas, annealed samples are strongly ferromagnetic at 300 K. As compared to fct FePd nanoparticles (Hc = 1180 Oe), the fct FePdPt nanoparticles show significantly high coercivity (Hc = 4675 Oe) and squareness ratio (σr/σs = 0.71) and thus, the addition of Pt in FePd nanoalloy improves the magnetic anisotropy significantly. The Curie temperature of FePd nanoalloy increases with increasing annealing temperature because of increase of atomic ordering in fct phase. [ABSTRACT FROM AUTHOR]

Ni/NiO core-shell nanoparticles have been synthesized by a new simple chemical method. XRD patterns show that the volume fraction of core-shell particles can be controlled by the heat treatment process. The blocking temperature was found to increase with the increase of the volume fraction of Ni/NiO particles, indicating an enhancement in the blocking process. This enhancement can be attributed to the interparticle interaction and exchange bias. [ABSTRACT FROM AUTHOR]

NiFe2O4-SiO2 nanocomposites were prepared by sol–gel method. X-ray diffraction (XRD) method and transmission electron microscope (TEM) were used to identify the phase and sizes (3.5–19 nm) of the sample. AC and DC magnetic measurements showed bellow ∼7 nm the particles are superparamagnet at room temperature. Tln(t/τ0) scaling approach was considered to generate master curves in order to analyze the thermally activated dynamic relaxation phenomena in the nonometric ferrite samples. [ABSTRACT FROM AUTHOR]

Nanocrystalline Gd2O3 particles of average particle size 25 nm (p25) and 18 nm (p18) are prepared through sol-gel route. Magnetization measurements in both samples show a linear variation of χ-1 with T having two different slopes in the temperature range 30 K- 260 K. In the temperature range 135 K ≤ T ≤ 260 K (TR1) the effective moment (μeff) per Gd3+ is estimated to be 7.70 μB and 7.56 μB whereas, in the temperature range 30 K ≤ T ≤ 135 K (TR2) they are estimated as 7.92 μB and 7.79 μB for p25 and p18, respectively. The enhancement of μeff in the TR2 region may be related with the clustering of spins. Below 30 K, χ-1 deviates from the linearity. At 5K magnetization curve displays superparamagnetic like characteristic features. [ABSTRACT FROM AUTHOR]