Nanoparticle Size Effect on Some Magnetic Properties

Caizer, Costică

doi:10.1007/978-3-319-15338-4_24

Cited by 31 publications

(17 citation statements)

References 116 publications

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“…In between Dth and Dc, the phenomenon of Neel relaxation, i.e., magnetic relaxation (D), takes shape. When D > Dth, but nearer to Dth, the single domain MNPs reveal more or less pronounced divergence from the Langevin function, depending on temperature condition, size, and nature of NPs [44]. For D < Dc, but nearer to Dc, the uni domain MNPs exhibits stable magnetization and magnetization of NPs done as reported by the Stoner-Wohlfarth model.…”

Section: Fig 3 Magnetization Behaviour Of Ferromagnetic Nps [47]mentioning

confidence: 55%

“…As discussed earlier ferromagnetic, ferrimagnetic are magnetically ordered materials. Meanwhile the size of bulk ferri or ferromagnetic materials is reduced to nanoscale, it was notice that the specific magnetic properties of bulk materials changes significantly, irrespective of kind of magnetic ordering [44]. Therefore, another special class acquired by Bean and Livingston in 1959 called superparamagnetism to distinguish magnetic nanomaterials (NMs) from bulk magnetic materials, i.e., ferro/ferromagnetic and paramagnetic ones [45].…”

Section: Magnetism Of Mnpsmentioning

confidence: 99%

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Magnetic Nanoparticles: Fabrications and Applications in Cancer Therapy and Diagnosis

Shrirame¹

2023

Magnetic Nanoparticles for Biomedical Applications

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Cancer is a global epidemic disease. Millions of people are affected by this disease every year. It affects humans including, children to old age. Nonetheless, there are several therapeutic treatments and drugs available to cure cancer. Recently, the use of smart nanoparticles (NPs) has been a promising technique to eradicate cancer. Among these NPs, magnetic NPs are efficient in treating cancer. Targeted drug-delivery based on 'smart' nanoparticles is the next step towards more efficient oncologic therapies, by delivering a minimal dose of drug only to the vicinity of the target. In the present chapter the methods used for fabrication and engineering of magnetic NPs is discussed. We have focused on current state of research on various applications of magnetic nanoparticles as well as recent breakthrough in the development of these NPs in cancer therapy, diagnosis, and targeted delivery.

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Section: Fig 3 Magnetization Behaviour Of Ferromagnetic Nps [47]mentioning

confidence: 55%

Section: Magnetism Of Mnpsmentioning

confidence: 99%

Magnetic Nanoparticles: Fabrications and Applications in Cancer Therapy and Diagnosis

Shrirame¹

2023

Magnetic Nanoparticles for Biomedical Applications

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“…At the same time, the Fe 3 O 4 nanoparticles, whose saturation magnetization was lower due to surface effects [32,33], were additionally covered with the PAA-(HP-γ-CDs) organic layer, which further reduced the saturation magnetization. The high value of the specific saturation magnetization in this case was due to the reduced thickness of the organic layer of PAA-(HP-γ-CDs) on the surface of the nanoparticles, which was only ~3.2 nm; this determined a volume packaging fraction [34] that was significantly higher than in the case of other larger biostructures (e.g., liposomes, which have much larger sizes of tens or hundreds of nm) [26].…”

Section: Magnetic Behavior Of Fe 3 O 4 -Paa-(hp-γ-cds) Nanobioconjugatesmentioning

confidence: 80%

High Efficacy on the Death of Breast Cancer Cells Using SPMHT with Magnetite Cyclodextrins Nanobioconjugates

et al. 2023

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In this study, we present the experimental results obtained in vitro on the human breast adenocarcinoma cell line (MCF-7) by applying superparamagnetic hyperthermia (SPMHT) using novel Fe3O4-PAA–(HP-γ-CDs) (PAA is polyacrylic acid and HP-γ-CDs is hydroxypropyl gamma-cyclodextrins) nanobioconjugates previously obtained by us. In the in vitro SPMHT experiments, we used concentrations of 1, 5 and 10 mg/mL of Fe3O4 ferrimagnetic nanoparticles from Fe3O4-PAA–(HP-γ-CDs) nanobioconjugates suspended in culture media containing 1 × 105 MCF-7 human breast adenocarcinoma cells. The harmonic alternating magnetic field used in the in vitro experiments that did not affect cell viability was found to be optimal in the range of 160–378 Gs and at a frequency of 312.2 kHz. The appropriate duration of the therapy was 30 min. After applying SPMHT with these nanobioconjugates under the above conditions, MCF-7 cancer cells died out in a very high percentage, of until 95.11%. Moreover, we studied the field up to which magnetic hyperthermia can be safely applied without cellular toxicity, and found a new upper biological limit H × f ~9.5 × 109 A/m⋅Hz (H is the amplitude and f is the frequency of the alternating magnetic field) to safely apply the magnetic field in vitro in the case of MCF-7 cells; the value was twice as high compared to the currently known value. This is a major advantage for magnetic hyperthermia in vitro and in vivo, because it allows one to achieve a therapy temperature of 43 °C safely in a much shorter time without affecting healthy cells. At the same time, using the new biological limit for a magnetic field, the concentration of magnetic nanoparticles in magnetic hyperthermia can be greatly reduced, obtaining the same hyperthermic effect, while at the same time, reducing cellular toxicity. This new limit of the magnetic field was tested by us in vitro with very good results, without the cell viability decreasing below ~90%.

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“…Magnetic nanoparticles (NPs) are complex systems where unique properties can emerge that differ greatly compared to bulk counterparts such as enhanced magnetocrystalline anisotropy or Curie temperature dependent on size and shape of NPs [1][2][3]. Such properties can be further tailored in core/shell NP structures by careful selection of the constituent materials where interfacial coupling plays a strong role in the exchange interaction between layers [4].…”

Section: Introductionmentioning

confidence: 99%

“…As such, the sensitivity of the magnetic system on surface contributions becomes crucial and surface effects become driving forces in determining the overall magnetic properties [14]. Surface spin disorder as a result of symmetry breaking in the crystal structure at the NP surface and altered exchange interactions lead to canted spins and a reduction in magnetic moment of the NP [2]. In general, surface spins are more susceptible to spin canting than interior moments and such canting has been observed experimentally in many ferrites and iron oxides NPs [15][16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Spin Canting in Exchange Coupled Bi-Magnetic Nanoparticles: Interfacial Effects and Hard / Soft Layer Ordering

Kons,

Krycka,

Robles

et al. 2021

Preprint

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We investigate the spatial distribution of spin orientation in magnetic nanoparticles consisting of hard and soft magnetic layers. The nanoparticles are synthesized in a core / shell spherical morphology where the magnetically hard, high anisotropy layer is CoFe 2 O 4 (CFO) while the lower anisotropy material is Fe 3 O 4 (FO). The nanoparticles have a mean diameter of ∼9.2 -9.6 nm and are synthesized as two variants: a conventional hard / soft core / shell structure with a CFO core / FO shell (CFO@FO) and the inverted structure FO core / CFO shell (FO@CFO). High resolution electron microscopy confirms the coherent spinel structure across the core / shell boundary in both variants while magnetometry indicates the nanoparticles are superparamagnetic at 300 K and develop a considerable anisotropy at reduced temperatures. Low temperature M vs. H loops suggest a multi-step reversal process. Temperature dependent small angle neutron scattering (SANS) with full polarization analysis reveals a strong perpendicular plane alignment of the spins near zero field, indicative of spin canting, but the perpendicular alignment quickly disappears upon application of a weak field and little spin ordering parallel to the field until the coercive field is reached. Above the coercive field of the sample, spins orient predominantly along the field direction. At both zero field and near saturation, the parallel magnetic SANS peak coincides with the structural peak, indicating the magnetization is uniform throughout the nanoparticle volume, while near the coercive field the parallel scattering peak shifts to higher momentum transfer (Q), suggesting that the coherent scattering volume is smaller and likely originates in the softer Fe 3 O 4 portion of the nanoparticle.

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Nanoparticle Size Effect on Some Magnetic Properties

Cited by 31 publications

References 116 publications

Magnetic Nanoparticles: Fabrications and Applications in Cancer Therapy and Diagnosis

Magnetic Nanoparticles: Fabrications and Applications in Cancer Therapy and Diagnosis

High Efficacy on the Death of Breast Cancer Cells Using SPMHT with Magnetite Cyclodextrins Nanobioconjugates

Spin Canting in Exchange Coupled Bi-Magnetic Nanoparticles: Interfacial Effects and Hard / Soft Layer Ordering

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