Surfactant effects in magnetite nanoparticles of controlled size

Guardia, Pablo; Batlle-Brugal, B.; Roca, Alejandro G.; Iglesias, Òscar; Morales, M.P.; Serna, Carlos J.; Labarta, A.; Batlle, Xavier

doi:10.1016/j.jmmm.2007.03.085

Cited by 293 publications

(281 citation statements)

References 17 publications

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“…The interaction effects are investigated by varying the packing fraction of the composite systems. We assume a temperature T = 310K, and values of K and the saturation magnetisation (M S ) of 5x10 6 erg/cc [14] and 1700 emu/cc for FePt and 5x10 5 erg/cc [15] and 400 emu/cc for magnetite, respectively. Figure 1: Magnetisation curves for various field cycle frequencies for an FePt nanoparticle composite with 5% packing density.…”

Section: Resultsmentioning

confidence: 99%

Energy losses in interacting fine-particle magnetic composites

Burrows¹,

Parker²,

Evans³

et al. 2010

J. Phys. D: Appl. Phys.

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Abstract. The coercivity and energy losses in superparamagnetic magnetite and FePt nanoparticle composites subjected to an external, alternating magnetic field have been calculated as a function of the mean particle-size and packing density. The effect of interactions has been investigated by fitting the Sharrock law to the coercivity results as a function of the field cycle frequency of the magnetic field. This fitting leads to effective parameters for the anisotropy field H ef f K and β ef f = KV /k B T , which are themselves dependent on the interaction strength. The increase or decrease of the coercivity with interactions depends upon the relative change of H ef f K and β ef f , thus demonstrating the complex effect that interactions have in these nanoparticle composites. The interparticle interactions have a non-trivial effect on the energy loss per cycle. The energy loss is reduced for systems with larger particles since the reduction in coercivity together with a corresponding reduction in the remanence dominates. For small particle sizes, the energy loss is increased. The primary mechanism here seems to be an enhancement of the energy barrier due to interactions, which changes the nature of the particles from superparamagnetic to being thermally stable.

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Section: Resultsmentioning

confidence: 99%

Energy losses in interacting fine-particle magnetic composites

Burrows¹,

Parker²,

Evans³

et al. 2010

J. Phys. D: Appl. Phys.

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“…90 emu g -1 , what points to a negligible spin-canting in the atomic surface and emphasizes the long range atomic order due to the surface functionalization with OA. 37 After the incorporation of Fe 3 O 4 @OA nanoparticles into the triglyceride-based formulations, MSLN1 and MSLN2, the superparamagnetic behavior was preserved, as it comes exclusively from the magnetite nanoparticles. However, the saturation magnetization normalized to the total mass decreased drastically, with values of 2.2 and 2.8 emu g -1 for MSLN1 and MSLN2, respectively ( Figure 5B).…”

Section: Magnetic Properties Of the Samplesmentioning

confidence: 96%

Preliminary Evaluation of Novel Triglyceride-Based Nanocomposites for Biomedical Applications

Almeida¹,

Gallo²,

Silva³

et al. 2017

J. Braz. Chem. Soc.

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This work describes the development and characterization of triglyceride-based magnetic nanocomposites for application in magnetic hyperthermia and controlled drug delivery. The magnetic solid lipid nanocomposites (MSLN) constituted by mixtures of trilaurin-tricaprylin and trilaurin-tricaprin have been successfully obtained by emulsification-solvent evaporation method. The developed MSLNs were subjected to an external oscillating magnetic field and showed significant hyperthermia. The samples were exposed to frequencies of 688 and 869 kHz causing, respectively, a temperature increase of 15.5 and 22.7 °C (trilaurin-tricaprylin) and 17.3 and 26.1 °C (trilaurin-tricaprin). Also, in vitro assays in the absence of magnetic field showed that the triglyceride-based formulations were able first to encapsulate and then to sustained release an antitumoural hydrophobic drug. After 72 h of assay trilaurin-tricaprylin and trilaurin-tricaprin released 73 and 55% of their cargo, respectively. In addition, MSLN exhibited low in vitro cytotoxic activity against human neutrophils.Keywords: lipid mixture, magnetic hyperthermia, drug delivery, oncocalyxone-A IntroductionNanotechnology is an expanding sector and the use of superparamagnetic iron oxide nanoparticles (SPIONs) is attracting increasing attention in several areas. SPIONs are widely employed for biotechnological applications through the development of magnetic systems for use in: cell separation, as contrast agents for magnetic resonance imaging (MRI), magnetic hyperthermia, targeted bioactive compounds delivery and biosensors. [1][2][3][4] Such applications explore the biggest advantages of using SPIONs: biocompatibility and satisfactory magnetic response at applied magnetic field (superparamagnetic character). 5,6 The surface of the magnetic nanoparticles should be modified, not only in order to prevent oxidation and aggregation, but also to provide colloidal stability, reduced magnetic susceptibility, as well as to expand the effectiveness of cellular uptake and biodistribution. The hydroxyl groups present on the surface of nanoparticles can function as an anchor point for various types of compounds such as oleic acid, which is commonly used in the synthesis of magnetic ferrofluids. The criteria adopted to select the appropriate coating of magnetic nanoparticles depends mainly on the intended application. In the case of this research, magnetic nanoparticles made of iron oxide were coated with oleic acid (Fe 3 O 4 @OA) for subsequent incorporation into lipid carriers. 7-9The lipid carriers have been widely used as they also possess excellent characteristics such as biocompatibility Preliminary Evaluation of Novel Triglyceride-Based Nanocomposites for Biomedical Applications J. Braz. Chem. Soc. 1548 and versatility, and they have been proposed for the delivery of bioactive compounds by oral, intravenous, topical and parenteral routes. 10,11The solid lipid nanoparticles (SLNs) emerged in the early 90's and currently are alternative encapsulation systems and carriers o...

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“…It should be noticed that the same type of increase of M S has been reported for the oleic acid coating and PPy coating of magnetite nanoparticles, respectively. [5][6][7][8][9][10][11][12] It seems that the attachment of organic molecules to the surface of magnetic nanoparticles could induce a reduction of the surface spin disorder resulting in an increase of the saturation magnetization values.…”

Section: Resultsmentioning

confidence: 99%

“…10. The line positions and integral intensities for A 1 , A 2 , and B components are summarized in Table III. The lowest peaks (6537À6542 eV), labeled A 1 and A 2 as indicated by Guardia et al, 5 are generally assumed to be caused by 1s to 3d transitions. Because 1s !…”

Section: Resultsmentioning

confidence: 99%

“…[1][2][3] Surface modification of magnetic nanoparticles by coating with surfactants or polymers may produce important changes of their magnetic properties. 4,5 By adjusting the coating layers, one can induce changes in the nanoparticles' surface spin disorder and interparticle interactions; this results in different values for the characteristic parameters like saturation magnetization, coercitivity, and magnetic anisotropy of the nanoparticles obtained by different procedures. [6][7][8][9][10][11][12] In this work, we report the synthesis and characterization of novel core-shell hybrid organic-inorganic nanostructures, consisting in the deposition of a conjugated polymer layer on the magnetic La 0.67 Sr 0.33 MnO 3 (LSMO) nanoparticle surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Interface charge transfer in polypyrrole coated perovskite manganite magnetic nanoparticles

Panâ

Soran

Leoștean

et al. 2012

Journal of Applied Physics

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Structure and magnetism of nanocrystalline and epitaxial (Mn,Zn,Fe)3O4 thin films J. Appl. Phys. 111, 07A337 (2012) Memory effects in superparamagnetic and nanocrystalline Fe50Ni50 alloy J. Appl. Phys. 111, 033919 (2012) Bulk nanocomposite using self-forming core/shell nanoparticles and its magnetic properties for high-frequency applications J. Appl. Phys. 111, 07A307 (2012) E-field tuning microwave frequency performance of Co2FeSi/lead zinc niobate-lead titanate magnetoelectric coupling composites J. Appl. Phys. 111, 07C705 (2012) Additional information on J. Appl. Phys. Different hybrid structures were obtained by coating magnetic nanoparticles of perovskite type manganite at optimal doping (La 0.67 Sr 0.33 MnO 3 ,LSMO) with different quantities of polypyrrole (PPy). The amorphous layer of polypyrrole surrounding the crystalline magnetic core was observed by high resolution transmission electron microscopy (HRTEM) and analyzed by using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) measurements in near edge structure (XANES) techniques. By analyzing the magnetic behavior of the samples one can observe that the surface modification of magnetic nanoparticles by PPy results in an increase in the saturation magnetization of the composites. The process is ascribed to paired electrons transferred from the delocalized p states of the PPy into the outer disordered layers of the manganite. The analysis of pre-edge peak of the Mn K-edge XANES spectra in the case of PPy coated LSMO nanoparticles indicates that the charge transfer between polymer and nanoparticles is (directed) going to missing or distorted oxygen positions, hence increasing the 3d electrons' mobility and orbital hybridization between the neighboring manganese ion. As a consequence, within the surface layers of LSMO nanoparticles, both energy bands disrupted the structure, and the double exchange process between Mn ions was reestablished determining the saturation magnetizations and pre-edge features increase, respectively.

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Surfactant effects in magnetite nanoparticles of controlled size

Cited by 293 publications

References 17 publications

Energy losses in interacting fine-particle magnetic composites

Energy losses in interacting fine-particle magnetic composites

Preliminary Evaluation of Novel Triglyceride-Based Nanocomposites for Biomedical Applications

Interface charge transfer in polypyrrole coated perovskite manganite magnetic nanoparticles

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