Enhancement of AC-losses of magnetic nanoparticles for heating applications

Hergt, R.; Hiergeist, R.; Zeisberger, Matthias; Glöckl, Gunnar; Weitschies, Werner; Ramírez, Luz Adriana Orozco; Hilger, Ingrid; Kaiser, Werner A.

doi:10.1016/j.jmmm.2004.03.034

Cited by 180 publications

(160 citation statements)

References 12 publications

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“…39 Among the studied samples, A22 displays at 44 mT a hysteresis area A = 1.83 mJ/g, which is a very good value for iron oxide magnetic nanoparticles. 40,41 and consequently this sample was selected for dextran coating and evaluating coating effect on magnetic and heating properties.…”

Section: Particles With Sizes Larger Than 35 Nm Showed Saturation Magmentioning

confidence: 99%

Large scale production of biocompatible magnetite nanocrystals with high saturation magnetization values through green aqueous synthesis

Marciello

Connord

Veintemillas-Verdaguer

et al. 2013

J. Mater. Chem. B

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In this work, a straightforward aqueous synthesis for mass production (up to 20 g) of uniform and crystalline magnetite nanoparticles with a core sizes between 20 and 30 nm, which are the optimum nanoparticle core sizes for hyperthermia application, is proposed. Magnetic and heating properties have been analyzed showing very high saturation magnetization and magnetic heating values. To stabilize the naked magnetite nanocrystals at physiological pH and increase their circulation time in blood, they have been covalently coated with carboxy-methyl-dextran, a biocompatible polymer.The influence of this superficial modification on magnetic and heating properties has been studied showing that these biocompatible magnetic nanocrystals maintain high magnetization saturation values, good colloidal stability and hyperthermia properties in the presence of the polymeric external layer. These particles, properly functionalized, could be used to selectively kill cancer cells under a moderate alternating magnetic field (44 mT and 70 kHz).

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Section: Particles With Sizes Larger Than 35 Nm Showed Saturation Magmentioning

confidence: 99%

Large scale production of biocompatible magnetite nanocrystals with high saturation magnetization values through green aqueous synthesis

Marciello

Connord

Veintemillas-Verdaguer

et al. 2013

J. Mater. Chem. B

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“…This difference is frequently encountered in the literature and may be due to the presence of a magnetic dead layer around the particle, resulting in a magnetic particle volume derived from magnetization data smaller than the crystalline core volume. 4 Also, some of the iron oxide species exist as a nonmagnetic amorphous phase, which does not contribute to the magnetic behavior, or as an iron phase that will have a smaller effect on magnetization than a magnetite only phase.…”

Section: ͑2͒mentioning

confidence: 99%

“…2 The prepared suspensions of coated magnetic nanoparticles have recently been the focus of intensive research not only for the study of the physics of magnetism in the nanometer scale, 3 but also for the use of ferrofluids in many technological and biomedical applications such as technical heating processes, media contrast agents in magnetic resonance imaging ͑MRI͒, and as therapeutic agents for RF-magnetic hyperthermia. [4][5][6][7][8][9][10][11][12][13] Specifically, MRI contrast agents are chemical substances introduced to the anatomical or functional region being imaged, in order to increase the differences between different tissues or between normal and abnormal tissue, by altering the relaxation times. MRI contrast agents are classified according to the different changes in relaxation times after their injection.…”

Section: Introductionmentioning

confidence: 99%

In vitro studies on ultrasmall superparamagnetic iron oxide nanoparticles coated with gummic acid for T2 MRI contrast agent

et al. 2007

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Ultrasmall superparamagnetic iron oxide nanoparticles coated with gummic acid have been investigated as possible constituents of aqueous ferrofluids for biomedical applications and especially for MRI contrast agent. The structural characteristics and the size of the nanoparticles have been analyzed as well as the magnetic properties. In order to evaluate any possible capabilities as a contrast agent, the relaxation time, T2, of hydrogen protons in the colloidal solutions of nanoparticles have been measured in order to gain information on the relaxation behavior compared to other MRI contrast agents. The in vitro cytotoxicity of the obtained magnetic nanoparticles of iron oxide coated with gummic acid was investigated by two separate methods ͑MTT and FACS analysis͒ and by using three different normal and transformed cell lines. Our results showed that the synthesized nanoparticles had no toxic effect on any of the cell lines used.

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“…Namely, there are two mechanisms to account for heat generation of magnetic of NPs less than about 30 nm in diameter: ͑a͒ Néel relaxation, that is, the fluctuation of a crystal's magnetic moment over an anisotropic energy barrier and ͑b͒ Brown relaxation to viscous losses due to particle reorientation in solution. 6 Given that, for clinical practice, 7 Brownian contributions to ac losses are eliminated in the case of immobilized particles, 8 larger particles ͑showing ferromagnetic hysteresis͒ seem a better choice for these applications using alternating magnetic fields below the megahertz range. 6 On the other hand, the losses due to magnetization reorientation in ferromagnetic particles depend on the type of remagnetizing process which, besides the intrinsic magnetic properties-like magnetocrystalline anisotropy-is determined in complicated ways by particle size, shape and microstructure.…”

Section: Introductionmentioning

confidence: 99%

Influence of dipolar interactions on hyperthermia properties of ferromagnetic particles

Serantes

Baldomir

Martínez-Boubeta

et al. 2010

Journal of Applied Physics

169

152

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Published by the American Institute of Physics. Related ArticlesFe3O4-citrate-curcumin: Promising conjugates for superoxide scavenging, tumor suppression and cancer hyperthermia J. Appl. Phys. 111, 064702 (2012) Integrated intravital microscopy and mathematical modeling to optimize nanotherapeutics delivery to tumors AIP Advances 2, 011208 (2012) In vitro cytotoxicity of Selol-loaded magnetic nanocapsules against neoplastic cell lines under AC magnetic field activation J. Appl. Phys. 111, 07B335 (2012) Magnetically driven spinning nanowires as effective materials for eradicating living cells J. Appl. Phys. 111, 07B329 (2012) Experimental characterization of electrochemical synthesized Fe nanowires for biomedical applications J. Appl. Phys. 111, 056103 (2012) Additional information on J. Appl. Phys. We show both experimental evidences and Monte Carlo modeling of the effects of interparticle dipolar interactions on the hysteresis losses. Results indicate that an increase in the intensity of dipolar interactions produce a decrease in the magnetic susceptibility and hysteresis losses, thus diminishing the hyperthermia output. These findings may have important clinical implications for cancer treatment.

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Enhancement of AC-losses of magnetic nanoparticles for heating applications

Cited by 180 publications

References 12 publications

Large scale production of biocompatible magnetite nanocrystals with high saturation magnetization values through green aqueous synthesis

Large scale production of biocompatible magnetite nanocrystals with high saturation magnetization values through green aqueous synthesis

In vitro studies on ultrasmall superparamagnetic iron oxide nanoparticles coated with gummic acid for T2 MRI contrast agent

Influence of dipolar interactions on hyperthermia properties of ferromagnetic particles

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