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Journal ArticleDOI

Influence of Surfactant Variation on Effective Anisotropy and Magnetic Properties of Mechanically Milled Magnetite Nanoparticles and Their Biocompatibility

TL;DR: In this paper, magnetite nanoparticles were synthesized with different amounts of surfactant addition (8-12 wt%) and the variation in their effective anisotropy and magnetic properties were investigated.
Abstract: Magnetite nanoparticles were prepared with starch as surfactant by ball milling for 30 h a toluene medium. The nanoparticles were synthesized with different amounts of surfactant addition (8-12 wt%) and the variation in their effective anisotropy and magnetic properties with surfactant content is investigated. The samples were characterized by X-ray diffraction, FT-IR, and scanning electron microscopy. Magnetic measurements were carried out using a vibrating sample magnetometer. The cytotoxicity of the magnetite nanoparticles coated with 12% starch was evaluated on L929 cell lines using MTT assay. The analysis of FT-IR spectrum reveals a new bond at 810 cm-1 in the sample coated with 9 wt% starch, but this is not observed in other samples. The particle size of this sample is higher, whereas the lattice strain, coercivity (Hc) and saturation magnetization (Ms) are less compared with other samples. As the size decreases, the Ms, Hc and magnetic effective anisotropy Keff of these samples increase. The increase in Ms with particle size reduction may be attributed to magnetic anisotropy, grain boundary effects, and changes in surface anisotropy caused by surfactant variation.
Citations
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Journal ArticleDOI
TL;DR: In this paper, starch was used for the first time for coating such magnetic powders, and X-ray powder diffraction was performed to study the structural properties of all samples.

57 citations

Journal ArticleDOI
TL;DR: In this article, the effect of surface functionalization on Fe3O4 assembled nanoclusters with biopolymers, like chitosan and dextran using the solvo-thermal route was reported.

16 citations

Journal ArticleDOI
TL;DR: In this paper , the formation of the CoFe 2 O 4 spinel phase has been validated using XRD and Rietveld analyses, showing that surface modification influences the specific loss power (SLP) value of the magnetic nanoparticles.
Abstract: We report the study of CoFe 2 O 4 with biopolymers (chitosan and dextran), synthesized via a solvothermal method. The formation of the CoFe 2 O 4 spinel phase has been validated using XRD and Rietveld analyses. The pattern of polyhedral and spherical shapes was observed for uncoated and coated samples using TEM. Mössbauer's study revealed the mixed spinel nature of the nanoparticles, in which Fe 3+ and Co 2+ ions are distributed in both tetrahedral and octahedral sites. The M − H curves obtained at ambient temperature show the typical ferromagnetic behavior for all the magnetic nanoparticles. The surface modification influences the specific loss power (SLP) value of the magnetic nanoparticles. Furthermore, our study revealed that dipole-dipole interactions are responsible for the self-heating behavior. SLP values demonstrated non-monotonic behavior for all the nanoparticle samples, implying that both Néel and Brownian relaxation is the responsible for heat generation in a high viscosity medium.

1 citations

Journal ArticleDOI
11 May 2019
TL;DR: In this paper, the crystallographic and magnetic changes of PM upon SO42− and CO32− adsorption were investigated, and the authors attributed the magnetic changes to the electronegativity of anions and the size distribution of PM.
Abstract: Porous maghemite (PM) was prepared by two-step calcinations. The crystallographic and magnetic changes of PM upon SO42− and CO32− adsorption were investigated. The crystallite size (~ 27 nm) and PM texture remain unchanged after adsorption. Fourier transform infrared spectra showed that SO42− and CO32− are adsorbed on the PM mainly through outer- and inner-sphere surface complexations, respectively. X-ray photoelectron spectra showed the increase and decrease of binding energy for Fe 2p3/2 electrons after SO42− and CO32− adsorption, respectively. Sulfate adsorption increases the magnetic susceptibility (χ) of PM by ~ 4.5%, and decreases the saturation magnetization (Ms) of PM by 24.6%. By comparison, carbonate adsorption decreases χ by ~ 3.7% and increases Ms by 17.8%. The magnetic changes upon SO42− and CO32− adsorption are attributed both to the electronegativity of anions and the size distribution of PM.

1 citations

References
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Journal ArticleDOI
TL;DR: A tetrazolium salt has been used to develop a quantitative colorimetric assay for mammalian cell survival and proliferation and is used to measure proliferative lymphokines, mitogen stimulations and complement-mediated lysis.

50,114 citations


"Influence of Surfactant Variation o..." refers background in this paper

  • ...The production of formazan is directly proportional to the number of viable cells [10]....

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Journal ArticleDOI
TL;DR: This review discusses the synthetic chemistry, fluid stabilization and surface modification of superparamagnetic iron oxide nanoparticles, as well as their use for above biomedical applications.

6,207 citations


"Influence of Surfactant Variation o..." refers background in this paper

  • ...The magnetic interactions in the surface layer and interactions between the core particle and the surface layer could have notable effects on the magnetic properties of the nanoparticles [2]–[4]....

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  • ...Spin canting in ball milling mechanism reduces magnetic moment [5], [19] as the core of aligned spins is surrounded by canted spins on the shell formed because of spin pinning due to coated surfactants [2], [21]....

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Journal ArticleDOI

5,284 citations


"Influence of Surfactant Variation o..." refers background in this paper

  • ...RECENTLY, magnetic nanoparticles have been subjected to extensive research due to their potential biomedical applications [1]–[3]....

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Journal ArticleDOI
TL;DR: In this paper, a model of the magnetization within these particles consisting of ferrimagnetically aligned core spins and a spin-glass-like surface layer is proposed, and the qualitative features of this model are reproduced by a numerical calculation of the spin distribution.
Abstract: Nickel ferrite nanoparticles exhibit anomalous magnetic properties at low temperatures: low magnetization with a large differential susceptibility at high fields, hysteresis loops which are open up to 160 kOe, time-dependent magnetization in 70 kOe applied field, and shifted hysteresis loops after field cooling. We propose a model of the magnetization within these particles consisting of ferrimagnetically aligned core spins and a spin-glass-like surface layer. We find that qualitative features of this model are reproduced by a numerical calculation of the spin distribution. Implications of this model for possible macroscopic quantum tunneling in these materials are discussed.

1,407 citations


"Influence of Surfactant Variation o..." refers background in this paper

  • ...The third possible mechanism for reduction in Ms proposed includes spin canting; according to that, there are competing interactions between sublattices that yield magnetic disorder at the particle surface [5], [15], [16]....

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  • ...Such effects include changes in the average coordination number, the presence of uncompensated spins due to symmetry breaking at the boundaries and the increase in anisotropy due to surface anisotropy that results in surface spin misalignment with respect to the ordered core spins [5]–[8]....

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  • ...Spin canting in ball milling mechanism reduces magnetic moment [5], [19] as the core of aligned spins is surrounded by canted spins on the shell formed because of spin pinning due to coated surfactants [2], [21]....

    [...]