View source for Iron oxide nanoparticle

{{Nanomaterials}}
'''Iron oxide nanoparticles''' are [[iron oxide]] particles with diameters between about 1 and 100 [[nanometer]]s. The two main forms are composed of [[magnetite]] ({{chem2|auto=1|Fe3O4}}) and its oxidized form [[maghemite]] (γ-{{chem2|Fe2O3}}). They have attracted extensive interest due to their [[superparamagnetic]] properties and their potential applications in many fields (although [[cobalt]] and [[nickel]] are also highly magnetic materials, they are toxic and easily oxidized) including [[molecular imaging]].<ref name="pmid22481569">{{cite journal |vauthors=Colombo M, Carregal-Romero S, Casula MF, Gutiérrez L, Morales MP, Böhm IB, Heverhagen JT, Prosperi D, Parak WJ |title=Biological applications of magnetic nanoparticles |journal=Chem Soc Rev |volume=41 |issue=11 |pages=4306–4334 |year=2012 |pmid=22481569 |doi=10.1039/c2cs15337h}}</ref>

Applications of iron oxide nanoparticles include [[terabit]] [[magnetic storage]] devices, [[catalysis]], [[sensor]]s, [[superparamagnetic relaxometry]], high-sensitivity biomolecular [[magnetic resonance imaging]], [[magnetic particle imaging]], [[magnetic fluid hyperthermia]], separation of biomolecules, and targeted drug and gene delivery for medical diagnosis and therapeutics. These applications require coating of the nanoparticles by agents such as long-chain [[fatty acid]]s, [[amine#Alkylation|alkyl-substituted amines]], and [[diol]]s. {{Citation needed|date=February 2014}} They have been used in formulations for supplementation.<ref>{{cite book | vauthors = Pai AB | veditors = Sigel A, Freisinger E, Sigel RK, Carver PL | title = Essential Metals in Medicine: Therapeutic Use and Toxicity of Metal Ions in the Clinic | series= Metal Ions in Life Sciences | volume = 19 | date = 2019 | publisher = de Gruyter GmbH | location = Berlin | isbn = 978-3-11-052691-2 | doi = 10.1515/9783110527872-012 | pages = 157–180 | chapter = Chapter 6. Iron Oxide Nanoparticle Formulations for Supplementation | pmid = 30855107 | s2cid = 216683956 }}
</ref>

== Structure ==
Magnetite has an [[spinel group#The spinel structure|inverse spinel structure]] with oxygen forming a face-centered [[cubic crystal system]]. In magnetite, all tetrahedral sites are occupied by {{chem|Fe|3+}} and octahedral sites are occupied by both {{chem|Fe|3+}} and {{chem|Fe|2+}}. Maghemite differs from magnetite in that all or most of the iron is in the trivalent state ({{chem|Fe|3+}}) and by the presence of [[ion|cation]] [[vacancy defect|vacancies]] in the octahedral sites. Maghemite has a cubic [[unit cell#Unit cell|unit cell]] in which each cell contains 32 oxygen ions, 21{{frac|1|3}} {{chem|Fe|3+}} ions and 2{{frac|2|3}} vacancies. The cations are distributed randomly over the 8 tetrahedral and 16 octahedral sites.<ref name= laurent>{{cite journal | vauthors = Laurent S, Forge D, Port M, Roch A, Robic C, Vander Elst L, Muller RN | title = Magnetic iron oxide nanoparticles: synthesis, stabilization, vectorization, physicochemical characterizations, and biological applications | journal = Chemical Reviews | volume = 108 | issue = 6 | pages = 2064–2110 | date = June 2008 | pmid = 18543879 | doi = 10.1021/cr068445e }}</ref><ref name= buschow>{{cite book | veditors = Buschow KH |title= Hand Book of Magnetic Materials |publisher= Elsevier |year= 2006}}</ref>

==Magnetic properties==
Due to its 4 [[unpaired electron]]s in [[electron shell|3d shell]], an iron atom has a strong [[magnetic moment]]. Ions {{chem|Fe|2+}} have also 4 unpaired electrons in 3d shell and {{chem|Fe|3+}} have 5 unpaired electrons in 3d shell. Therefore, when crystals are formed from iron atoms or ions {{chem|Fe|2+}} and {{chem|Fe|3+}} they can be in [[ferromagnetism|ferromagnetic]], [[antiferromagnetism|antiferromagnetic]], or [[ferrimagnetism|ferrimagnetic]] states.

In the [[paramagnetic]] state, the individual atomic magnetic moments are randomly oriented, and the substance has a zero net magnetic moment if there is no [[magnetic field]]. These materials have a relative [[permeability (electromagnetism)|magnetic permeability]] greater than one and are attracted to magnetic fields. The magnetic moment drops to zero when the applied field is removed. But in a ferromagnetic material, all the atomic moments are aligned even without an external field. A ferrimagnetic material is similar to a ferromagnet but has two different types of atoms with opposing magnetic moments. The material has a magnetic moment because the opposing moments have different strengths. If they have the same magnitude, the crystal is antiferromagnetic and possesses no net magnetic moment.<ref name= teja>{{cite journal |doi= 10.1016/j.pcrysgrow.2008.08.003 |title= Synthesis, properties, and applications of magnetic iron oxide nanoparticles |year= 2009 | vauthors = Teja AS, Koh PY |journal= Progress in Crystal Growth and Characterization of Materials |volume= 55 |issue= 1–2 |pages= 22–45}}</ref>

When an external magnetic field is applied to a ferromagnetic material, the [[magnetization]] (''M'') increases with the strength of the magnetic field (''H'') until it approaches [[saturation (magnetic)|saturation]]. Over some range of fields the magnetization has [[hysteresis]] because there is more than one stable magnetic state for each field. Therefore, a [[remanence|remanent magnetization]] will be present even after removing the external magnetic field.<ref name= teja/>

A [[single domain (magnetic)|single domain]] magnetic material (e. g. magnetic nanoparticles) that has no hysteresis loop is said to be [[superparamagnetic]]. The ordering of magnetic moments in ferromagnetic, antiferromagnetic, and ferrimagnetic materials decreases with increasing temperature. Ferromagnetic and ferrimagnetic materials become disordered and lose their magnetization beyond the [[Curie temperature]] <math>T_C</math> and antiferromagnetic materials lose their magnetization beyond the [[Néel temperature]] <math>T_N</math>. [[Magnetite]] is ferrimagnetic at room temperature and has a Curie temperature of 850 [[Kelvin|K]]. [[Maghemite]] is ferrimagnetic at room temperature, unstable at high temperatures, and loses its [[magnetic susceptibility|susceptibility]] with time. (Its Curie temperature is hard to determine). Both magnetite and maghemite nanoparticles are superparamagnetic at room temperature.<ref name= teja/>
This superparamagnetic behavior of iron oxide nanoparticles can be attributed to their size. When the size gets small enough (<10&nbsp;nm), [[thermal fluctuations]] can change the direction of magnetization of the entire crystal. A material with many such crystals behaves like a [[paramagnetism|paramagnet]], except that the moments of entire crystals are fluctuating instead of individual atoms.<ref name= teja/>

Furthermore, the unique superparamagnetic behavior of iron oxide nanoparticles allows them to be manipulated magnetically from a distance. In the latter sections, external manipulation will be discussed in regards to biomedical applications of iron oxide nanoparticles. Forces are required to manipulate the path of iron oxide particles. A spatially uniform magnetic field can result in a torque on the magnetic particle, but cannot cause particle translation; therefore, the magnetic field must be a gradient to cause translational motion. The force on a point-like magnetic dipole moment {{math|'''m'''}} due to a magnetic field {{math|'''B'''}} is given by the equation:
:<math>\mathbf{F}_{m}= \mathbf{\nabla} \left(\mathbf{m}\cdot\mathbf{B}\right)</math>

In biological applications, iron oxide nanoparticles will be translate through some kind of fluid, possibly bodily fluid,<ref name= Benz>{{cite journal |title= Superparamagnetism:Theory and Applications |year= 2012 | vauthors = Benz M |journal= Discussion of Two Papers on Magnetic Nanoparticles |pages= 27}}</ref> in which case the aforementioned equation can be modified to:<ref>[[Magnetic tweezers]]</ref>
:<math> \mathbf{F}_{m}= \begin{cases} \frac{V \chi}{2 \mu_0} \mathbf{\nabla}\left| \mathbf{B}\right|^2 & \qquad \text{in a weak magnetic field} \\ \frac{1}{2} \mathbf{\nabla} \left( \mathbf{m}_{sat} \cdot \mathbf{B} \right) & \qquad \text{in a strong magnetic field} \end{cases} </math>

Based on these equations, there will be the greatest force in the direction of the largest positive slope of the energy density scalar field.

Another important consideration is the force acting against the magnetic force. As iron oxide nanoparticles translate toward the magnetic field source, they experience Stokes' drag force in the opposite direction. The drag force is expressed below.
:<math> \mathbf{F}_{d}= 6\pi\,\eta\,R\,v\,</math>

In this equation, η is the fluid viscosity, R is the hydrodynamic radius of the particle, and 𝑣 is the velocity of the particle.<ref>{{cite journal |title= Applications of magnetic nanoparticles in biomedicine |year= 2003 | vauthors = Pankhurst QA, Connolly J, Jones SK, Dobson J |journal= Journal of Physics D: Applied Physics |volume= 36 |issue= 13 |pages= R167–R181 |doi= 10.1088/0022-3727/36/13/201|s2cid= 250870659 }}</ref>

==Synthesis==
The preparation method has a large effect on shape, size distribution, and [[surface chemistry]] of the particles. It also determines to a great extent the distribution and type of structural defects or impurities in the particles. All these factors affect magnetic behavior. Recently, many attempts have been made to develop processes and techniques that would yield "[[monodisperse]] [[colloid]]s" consisting of nanoparticles uniform in size and shape.

===Coprecipitation===
By far the most employed method is [[coprecipitation]]. This method can be further divided into two types.
In the first, [[iron(II) hydroxide|ferrous hydroxide]] [[suspension (chemistry)|suspensions]] are partially oxidized with different oxidizing agents. For example, spherical magnetite particles of narrow size distribution with mean diameters between 30 and 100&nbsp;nm can be obtained from a {{chem|Fe(II)}} salt, a base and a mild oxidant ([[nitrate]] ions).<ref>{{cite journal |doi= 10.1016/0021-9797(80)90187-3 |title= Formation of uniform spherical magnetite particles by crystallization from ferrous hydroxide gels |year= 1980 | vauthors = Sugimoto T |journal= Journal of Colloid and Interface Science |volume= 74 |issue= 1 |pages= 227–243 |bibcode= 1980JCIS...74..227S}}</ref> The other method consists in ageing stoichiometric mixtures of ferrous and ferric hydroxides in aqueous media, yielding spherical magnetite particles homogeneous in size.<ref>{{cite journal | vauthors = Massart R, Cabuil V | title = Monodisperse magnetic nanoparticles: preparation and dispersion in water and oils. | journal = J. Chem. Phys. | date = 1987 | volume = 84 | pages = 967–973 }}</ref> In the second type, the following chemical reaction occurs:
:{{chem2|2 Fe(3+) + Fe(2+) + 8 [[hydroxide|OH-]] -> Fe3O4↓ + 4 H2O}}

Optimum conditions for this reaction are [[pH]] between 8 and 14, {{chem|Fe|3+}}/{{chem|Fe|2+}} ratio of 2:1 and a non-oxidizing environment. Being highly susceptibile to oxidation, magnetite ({{chem2|Fe3O4}}) is transformed to maghemite (γ{{chem2|Fe2O3}}) in the presence of oxygen:<ref name= laurent/>
:{{chem2|2 Fe3O4 + O2 → 2 γFe2O3}}

The size and shape of the nanoparticles can be controlled by adjusting pH, [[ionic strength]], temperature, nature of the [[salt (chemistry)|salts]] ([[perchlorate]]s, [[chloride]]s, [[sulfate]]s, and nitrates), or the {{chem|Fe(II)}}/{{chem|Fe(III)}} concentration ratio.<ref name= laurent/>

===Microemulsions===
A [[microemulsion]] is a stable [[isotropy|isotropic]] [[dispersion (chemistry)|dispersion]] of 2 [[immiscible]] liquids consisting of nanosized domains of one or both liquids in the other stabilized by an [[interface (chemistry)|interfacial]] film of surface-active molecules. Microemulsions may be categorized further as oil-in-water (o/w) or water-in-oil (w/o), depending on the dispersed and continuous phases.<ref name= buschow/>
Water-in-oil is more popular for synthesizing many kinds of nanoparticles. The water and oil are mixed with an amphiphillic [[surfactant]]. The surfactant lowers the surface tension between water and oil, making the solution transparent. The water nanodroplets act as nanoreactors for synthesizing nanoparticles. The shape of the water pool is spherical. The size of the nanoparticles will depend on size of the water pool to a great extent. Thus, the size of the spherical nanoparticles can be tailored and tuned by changing the size of the water pool.<ref>{{cite journal |doi= 10.1016/0021-9797(76)90030-8 |title= An expedient technique for determining solubility phase boundaries in surfactant–water systems |year= 1976 | vauthors = Laughlin R |journal= Journal of Colloid and Interface Science |volume= 55 |issue= 1 |pages= 239–241 |bibcode= 1976JCIS...55..239L}}</ref>

===High-temperature decomposition of organic precursors===
The decomposition of iron precursors in the presence of hot organic surfactants results in samples with good size control, narrow size distribution (5-12&nbsp;nm) and good [[crystallinity]]; and the nanoparticles are easily dispersed. For biomedical applications like magnetic resonance imaging, magnetic cell separation or magnetorelaxometry, where particle size plays a crucial role, magnetic nanoparticles produced by this method are very useful. Viable iron precursors include {{chem|Fe([[Cupferron|Cup]])|3}}, {{chem|Fe(CO)|5}}, or {{chem|Fe([[acetylacetone|acac]])|3}} in organic solvents with surfactant molecules. A combination of Xylenes and Sodium Dodecylbenezensulfonate as a surfactant are used to create nanoreactors for which well dispersed iron(II) and iron (III) salts can react.<ref name= laurent/>

==Biomedical applications==
Magnetite and maghemite are preferred in [[biomedicine]] because they are [[biocompatibility|biocompatible]] and potentially non-toxic to humans{{Citation needed|reason=please add reference for human cytotoxicity to support this claim|date=November 2010}}. Iron oxide is easily degradable and therefore useful for in vivo applications{{Citation needed|reason=the Brunner et al study consists entirely of in vitro evidence; please add references for in vivo cytotoxicity |date=November 2010}}. Results from exposure of a human [[mesothelium]] [[cell line]] and a [[murine]] [[fibroblast]] cell line to seven industrially important nanoparticles showed a nanoparticle specific [[cytotoxic]] mechanism for uncoated iron oxide.<ref>{{cite journal | vauthors = Brunner TJ, Wick P, Manser P, Spohn P, Grass RN, Limbach LK, Bruinink A, Stark WJ | display-authors = 6 | title = In vitro cytotoxicity of oxide nanoparticles: comparison to asbestos, silica, and the effect of particle solubility | journal = Environmental Science & Technology | volume = 40 | issue = 14 | pages = 4374–4381 | date = July 2006 | pmid = 16903273 | doi = 10.1021/es052069i | bibcode = 2006EnST...40.4374B }}</ref> Solubility was found to strongly influence the cytotoxic response.
Labelling cells (e.g. [[stem cell]]s, [[dendritic cell]]s) with iron oxide nanoparticles is an interesting new tool to monitor such labelled cells in real time by [[magnetic resonance tomography]].<ref>{{cite journal | vauthors = Bulte JW, Kraitchman DL | title = Iron oxide MR contrast agents for molecular and cellular imaging | journal = NMR in Biomedicine | volume = 17 | issue = 7 | pages = 484–499 | date = November 2004 | pmid = 15526347 | doi = 10.1002/nbm.924 | s2cid = 19434047 }}</ref><ref>{{cite book | vauthors = Geraldes CF, Delville MH | title = Metal Ions in Bio-Imaging Techniques | publisher = Springer | year = 2021 | pages = 271–297 | chapter = Chapter 9. Iron Oxide Nanoparticles for Bio-Imaging | doi = 10.1515/9783110685701-015 | s2cid = 233704325 }}</ref> Some forms of Iron oxide nanoparticle have been found to be toxic and cause transcriptional reprogramming.<ref>{{cite journal | vauthors = Kodali V, Littke MH, Tilton SC, Teeguarden JG, Shi L, Frevert CW, Wang W, Pounds JG, Thrall BD | display-authors = 6 | title = Dysregulation of macrophage activation profiles by engineered nanoparticles | journal = ACS Nano | volume = 7 | issue = 8 | pages = 6997–7010 | date = August 2013 | pmid = 23808590 | pmc = 3756554 | doi = 10.1021/nn402145t }}</ref><ref>{{cite journal | vauthors = Sharma G, Kodali V, Gaffrey M, Wang W, Minard KR, Karin NJ, Teeguarden JG, Thrall BD | display-authors = 6 | title = Iron oxide nanoparticle agglomeration influences dose rates and modulates oxidative stress-mediated dose-response profiles in vitro | journal = Nanotoxicology | volume = 8 | issue = 6 | pages = 663–675 | date = September 2014 | pmid = 23837572 | pmc = 5587777 | doi = 10.3109/17435390.2013.822115 }}</ref>

[[File:Algorithm_cancer_magnetic_nanotherapy.jpg|thumb|The magneto-mechano-chemical synthesis (1) is accompanied by splitting of electron energy levels (SEELs) and electron transfer in magnetic field (2) from nanoparticles Fe3O4 to doxorubicin. The concentration of paramagnetic centers (free radicals) is increased in the magneto-sensitive complex (MNC) (3). The local combined action of constant magnetic and electromagnetic fields and MNC in tumor (4) initiated SEELs, free radicals, leading to [[oxidative stress]], [[electron transport|electron-]] and [[proton transport|proton-transport]] deregulation in the mitochondrion and changes in mechanochemical tumor heterogeneity (5). Magnetic nanotherapy has more effectively inhibited the synthesis of ATP in mitochondria of tumor cell and induced the death of tumor cells compared to conventional doxorubicin.]]

Iron oxide nanoparticles are used in cancer magnetic nanotherapy that is based on the magneto-spin effects in [[free-radical reaction]]s and semiconductor material ability to generate [[reactive oxygen species|oxygen radicals]], furthermore, control [[oxidative stress]] in biological media under inhomogeneous [[electromagnetic radiation]]. The magnetic nanotherapy is remotely controlled by external [[electromagnetic field]] reactive oxygen species (ROS) and [[reactive nitrogen species|reactive nitrogen species (RNS)]]-mediated local [[toxicity]] in the [[neoplasm|tumor]] during [[chemotherapy]] with antitumor magnetic complex and lesser side effects in normal tissues. Magnetic complexes with magnetic memory that consist of iron oxide nanoparticles loaded with antitumor drug have additional advantages over conventional antitumor drugs due to their ability to be remotely controlled while [[targeted drug delivery|targeting]] with a constant magnetic field and further strengthening of their antitumor activity by moderate [[magnetic hyperthermia|inductive hyperthermia]] (below 40&nbsp;°C). The combined influence of inhomogeneous constant magnetic and electromagnetic fields during nanotherapy has initiated [[energy level splitting|splitting of electron energy levels]] in magnetic complex and unpaired [[electron transfer]] from iron oxide nanoparticles to anticancer drug and [[cancer cell|tumor cells]]. In particular, anthracycline antitumor antibiotic doxorubicin, the native state of which is [[diamagnetism|diamagnetic]], acquires the magnetic properties of paramagnetic substances. Electromagnetic radiation at the [[hyperfine structure|hyperfine splitting]] frequency can increase the time that radical pairs are in the [[triplet state]] and hence the probability of [[dissociation (chemistry)|dissociation]] and so the concentration of [[radical (chemistry)|free radicals]]. Free radicals in cancer cells induce changes in [[Mechanochemistry|mechanochemical]] [[Tumour heterogeneity|tumor heterogeneity]] by modifying bonds which influence the spatial arrangement of molecules in cell structures. The translation of the magnetic force exerted on the tumor and its microenvironment by magnetic nanoparticles into biochemical signaling pathways is known as the magneto-mechanochemical effect. This leads to the formation of regions with different biomechanical and biochemical properties within the tumor. [[Reactivity (chemistry)|The reactivity]] of magnetic particles depends on their [[Spin (physics)|spin state]]. The experimental data was received about correlation between the frequency of electromagnetic field radiation with magnetic properties and quantity paramagnetic centres of complex. It is possible to control the [[chemical kinetics|kinetics]] of malignant tumor. Cancer cells are then particularly vulnerable to an oxidative assault and induction of high levels of oxidative stress locally in tumor tissue, that has the potential to destroy or arrest the growth of cancer cells and can be thought as therapeutic strategy against cancer. Multifunctional magnetic complexes with magnetic memory can combine cancer magnetic nanotherapy, tumor targeting and [[medical imaging]] functionalities in theranostics approach for personalized cancer medicine.<ref>{{cite journal | vauthors = Orel VE, Tselepi M, Mitrelias T, Rykhalskyi A, Romanov A, Orel VB, Shevchenko A, Burlaka A, Lukin S, Barnes CH | display-authors = 6 | title = Nanomagnetic Modulation of Tumor Redox State | journal = Nanomedicine | volume = 14 | issue = 4 | pages = 1249–1256 | date = June 2018 | pmid = 29597047 | doi = 10.1016/j.nano.2018.03.002 | s2cid = 4931512 }}</ref><ref>{{cite book | vauthors = Orel VE, Tselepi M, Mitrelias T, Shevchenko AD, Rykhalskiy OY, Golovko TS, Ganich OV, Romanov AV, Orel VB, Burlaka AP, Lukin SN | display-authors = 6 | chapter = Magnetic resonance cancer nanotheranostics. | chapter-url = https://www.springerprofessional.de/en/magnetic-resonance-cancer-nanotheranostics/15802110 | title = World Congress on Medical Physics and Biomedical Engineering | date = 2018 | pages = 651–654 | publisher = Springer | location = Singapore }}</ref><ref>{{cite journal | vauthors = Orel V, Shevchenko A, Romanov A, Tselepi M, Mitrelias T, Barnes CH, Burlaka A, Lukin S, Shchepotin I | display-authors = 6 | title = Magnetic properties and antitumor effect of nanocomplexes of iron oxide and doxorubicin | journal = Nanomedicine | volume = 11 | issue = 1 | pages = 47–55 | date = January 2015 | pmid = 25101880 | doi = 10.1016/j.nano.2014.07.007 }}</ref><ref>{{cite journal | vauthors = Orel V, Mitrelias T, Tselepi M, Golovko T, Dynnyk O, Nikolov N, Romanov A, Rykhalskiy A, Barnes CC, Yaroshenko O, Orel I | display-authors = 6 |title=Imaging of Guerin Carcinoma During Magnetic Nanotherapy |journal=Journal of Nanopharmaceutics and Drug Delivery |volume=2 |date=2014 |pages= 58–68 |doi= 10.1166/jnd.2014.1044 |url=https://www.researchgate.net/publication/273402616}}</ref><ref>{{Cite journal |last=Orel |first=Valerii B. |last2=Galkin |first2=Olexander Yu. |last3=Orel |first3=Valerii E. |last4=Dasyukevich |first4=Olga Yo. |last5=Rykhalskyi |first5=Oleksandr Yu. |last6=Kurapov |first6=Yurii A. |last7=Litvin |first7=Stanislav A. |last8=Yukhymchuk |first8=Volodymyr O. |last9=Isayeva |first9=Oksana F. |last10=Syvak |first10=Liubov A. |last11=Dedkov |first11=Anatoliy G. |date=August 2023 |title=Mechanoluminescence of Walker-256 Carcinosarcoma Cells Induced by Magneto-Mechanochemical Effects of Fe3O4–Au Nanocomposite |url=https://www.worldscientific.com/doi/10.1142/S0219519423400274 |journal=Journal of Mechanics in Medicine and Biology |volume=23 |issue=06 |pages=2340027 |doi=10.1142/S0219519423400274 |issn=0219-5194|doi-access=free }}</ref>

Yet, the use of inhomogeneous stationary [[magnetic fields]] to target iron oxide magnetic nanoparticles can result in enhanced tumor growth. [[Magnetic force]] transmission through magnetic nanoparticles to the tumor due to the action of the inhomogeneous stationary magnetic field reflects [[Mechanochemistry|mechanical stimuli]] converting iron-induced reactive oxygen species generation to the modulation of biochemical signals.<ref>{{cite journal | vauthors = Orel VE, Dasyukevich O, Rykhalskyi O, Orel VB, Burlaka A, Virko S |title=Magneto-mechanical effects of magnetite nanoparticles on Walker-256 carcinosarcoma heterogeneity, redox state and growth modulated by an inhomogeneous stationary magnetic field |journal=Journal of Magnetism and Magnetic Materials |date=November 2021 |volume=538 |pages=168314 |doi=10.1016/j.jmmm.2021.168314 |bibcode=2021JMMM..53868314O }}</ref>

Iron oxide [[nanoparticle]]s may also be used in magnetic hyperthermia as a [[cancer]] treatment method. In this method, the [[ferrofluid]] which contains iron oxide is injected to the tumor and then heated up by an alternating high frequency magnetic field. The temperature distribution produced by this heat generation may help to destroy cancerous cells inside the tumor.<ref>{{cite journal | vauthors = Javidi M, Heydari M, Attar MM, Haghpanahi M, Karimi A, Navidbakhsh M, Amanpour S | title = Cylindrical agar gel with fluid flow subjected to an alternating magnetic field during hyperthermia | journal = International Journal of Hyperthermia | volume = 31 | issue = 1 | pages = 33–39 | date = February 2015 | pmid = 25523967 | doi = 10.3109/02656736.2014.988661 | s2cid = 881157 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Javidi M, Heydari M, Karimi A, Haghpanahi M, Navidbakhsh M, Razmkon A | title = Evaluation of the effects of injection velocity and different gel concentrations on nanoparticles in hyperthermia therapy | journal = Journal of Biomedical Physics & Engineering | volume = 4 | issue = 4 | pages = 151–162 | date = December 2014 | pmid = 25599061 | pmc = 4289522 }}</ref><ref>{{cite journal |doi=10.1142/S0219519415500888|title= Magnetic Fluid Hyperthermia in a Cylindrical Gel Contains Water Flow |journal=[[Journal of Mechanics in Medicine and Biology]] |volume=15 |issue=5 |pages=1550088|year= 2015| vauthors = Heydari M, Javidi M, Attar MM, Karimi A, Navidbakhsh M, Haghpanahi M, Amanpour S }}</ref>

The use of superparamagnetic iron oxide (SPIO) can also be used as a tracer in sentinel node biopsy instead of radioisotope.<ref>{{cite journal | vauthors = Karakatsanis A, Daskalakis K, Stålberg P, Olofsson H, Andersson Y, Eriksson S, Bergkvist L, Wärnberg F | display-authors = 6 | title = Superparamagnetic iron oxide nanoparticles as the sole method for sentinel node biopsy detection in patients with breast cancer | journal = The British Journal of Surgery | volume = 104 | issue = 12 | pages = 1675–1685 | date = November 2017 | pmid = 28877348 | doi = 10.1002/bjs.10606 | s2cid = 28479096 }}</ref>

== See also ==
* [[Neuroregeneration]]
* [[Regenerative medicine]]

== References ==
{{Reflist}}

== External links ==
{{Commons category-inline|Magnetite nanoparticles}}

[[Category:Iron compounds]]
[[Category:Nanoparticles by composition]]
[[Category:Experimental cancer treatments]]
[[Category:Transition metal oxides]]
[[Category:Biomagnetics]]