Biocompatible Magnetic Fluids of Co-Doped Iron Oxide Nanoparticles with Tunable Magnetic Properties
Magnetite (Fe<sub>3</sub>O<sub>4</sub>) particles with a diameter around 10 nm have a very low coercivity (H<sub>c</sub>) and relative remnant magnetization (M<sub>r</sub>/M<sub>s</sub>), which is unfavorable for magnetic fluid hyperthermia...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2020-05-01
|
| Series: | Nanomaterials |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2079-4991/10/6/1019 |
| _version_ | 1827716148490141696 |
|---|---|
| author | Silvio Dutz Norbert Buske Joachim Landers Christine Gräfe Heiko Wende Joachim H. Clement |
| author_facet | Silvio Dutz Norbert Buske Joachim Landers Christine Gräfe Heiko Wende Joachim H. Clement |
| author_sort | Silvio Dutz |
| collection | DOAJ |
| description | Magnetite (Fe<sub>3</sub>O<sub>4</sub>) particles with a diameter around 10 nm have a very low coercivity (H<sub>c</sub>) and relative remnant magnetization (M<sub>r</sub>/M<sub>s</sub>), which is unfavorable for magnetic fluid hyperthermia. In contrast, cobalt ferrite (CoFe<sub>2</sub>O<sub>4</sub>) particles of the same size have a very high H<sub>c</sub> and M<sub>r</sub>/M<sub>s</sub>, which is magnetically too hard to obtain suitable specific heating power (SHP) in hyperthermia. For the optimization of the magnetic properties, the Fe<sup>2+</sup> ions of magnetite were substituted by Co<sup>2+</sup> step by step, which results in a Co doped iron oxide inverse spinel with an adjustable Fe<sup>2+</sup> substitution degree in the full range of pure iron oxide up to pure cobalt ferrite. The obtained magnetic nanoparticles were characterized regarding their structural and magnetic properties as well as their cell toxicity. The pure iron oxide particles showed an average size of 8 nm, which increased up to 12 nm for the cobalt ferrite. For ferrofluids containing the prepared particles, only a limited dependence of H<sub>c</sub> and M<sub>r</sub>/M<sub>s</sub> on the Co content in the particles was found, which confirms a stable dispersion of the particles within the ferrofluid. For dry particles, a strong correlation between the Co content and the resulting H<sub>c</sub> and M<sub>r</sub>/M<sub>s</sub> was detected. For small substitution degrees, only a slight increase in H<sub>c</sub> was found for the increasing Co content, whereas for a substitution of more than 10% of the Fe atoms by Co, a strong linear increase in H<sub>c</sub> and M<sub>r</sub>/M<sub>s</sub> was obtained. Mössbauer spectroscopy revealed predominantly Fe<sup>3+</sup> in all samples, while also verifying an ordered magnetic structure with a low to moderate surface spin canting. Relative spectral areas of Mössbauer subspectra indicated a mainly random distribution of Co<sup>2+</sup> ions rather than the more pronounced octahedral site-preference of bulk CoFe<sub>2</sub>O<sub>4</sub>. Cell vitality studies confirmed no increased toxicity of the Co-doped iron oxide nanoparticles compared to the pure iron oxide ones. Magnetic heating performance was confirmed to be a function of coercivity as well. The here presented non-toxic magnetic nanoparticle system enables the tuning of the magnetic properties of the particles without a remarkable change in particles size. The found heating performance is suitable for magnetic hyperthermia application. |
| first_indexed | 2024-03-10T19:34:29Z |
| format | Article |
| id | doaj.art-33a7ae4b51c949e7a8728e181885d660 |
| institution | Directory Open Access Journal |
| issn | 2079-4991 |
| language | English |
| last_indexed | 2024-03-10T19:34:29Z |
| publishDate | 2020-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Nanomaterials |
| spelling | doaj.art-33a7ae4b51c949e7a8728e181885d6602023-11-20T01:50:42ZengMDPI AGNanomaterials2079-49912020-05-01106101910.3390/nano10061019Biocompatible Magnetic Fluids of Co-Doped Iron Oxide Nanoparticles with Tunable Magnetic PropertiesSilvio Dutz0Norbert Buske1Joachim Landers2Christine Gräfe3Heiko Wende4Joachim H. Clement5Institute of Biomedical Engineering and Informatics (BMTI), Technische Universität Ilmenau, D-98693 Ilmenau, GermanyMagneticFluids, Köpenicker Landstraße 203, D-12437 Berlin, GermanyFaculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, D-47057 Duisburg, GermanyDepartment Hematology and Oncology, Jena University Hospital, D-07747 Jena, GermanyFaculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, D-47057 Duisburg, GermanyDepartment Hematology and Oncology, Jena University Hospital, D-07747 Jena, GermanyMagnetite (Fe<sub>3</sub>O<sub>4</sub>) particles with a diameter around 10 nm have a very low coercivity (H<sub>c</sub>) and relative remnant magnetization (M<sub>r</sub>/M<sub>s</sub>), which is unfavorable for magnetic fluid hyperthermia. In contrast, cobalt ferrite (CoFe<sub>2</sub>O<sub>4</sub>) particles of the same size have a very high H<sub>c</sub> and M<sub>r</sub>/M<sub>s</sub>, which is magnetically too hard to obtain suitable specific heating power (SHP) in hyperthermia. For the optimization of the magnetic properties, the Fe<sup>2+</sup> ions of magnetite were substituted by Co<sup>2+</sup> step by step, which results in a Co doped iron oxide inverse spinel with an adjustable Fe<sup>2+</sup> substitution degree in the full range of pure iron oxide up to pure cobalt ferrite. The obtained magnetic nanoparticles were characterized regarding their structural and magnetic properties as well as their cell toxicity. The pure iron oxide particles showed an average size of 8 nm, which increased up to 12 nm for the cobalt ferrite. For ferrofluids containing the prepared particles, only a limited dependence of H<sub>c</sub> and M<sub>r</sub>/M<sub>s</sub> on the Co content in the particles was found, which confirms a stable dispersion of the particles within the ferrofluid. For dry particles, a strong correlation between the Co content and the resulting H<sub>c</sub> and M<sub>r</sub>/M<sub>s</sub> was detected. For small substitution degrees, only a slight increase in H<sub>c</sub> was found for the increasing Co content, whereas for a substitution of more than 10% of the Fe atoms by Co, a strong linear increase in H<sub>c</sub> and M<sub>r</sub>/M<sub>s</sub> was obtained. Mössbauer spectroscopy revealed predominantly Fe<sup>3+</sup> in all samples, while also verifying an ordered magnetic structure with a low to moderate surface spin canting. Relative spectral areas of Mössbauer subspectra indicated a mainly random distribution of Co<sup>2+</sup> ions rather than the more pronounced octahedral site-preference of bulk CoFe<sub>2</sub>O<sub>4</sub>. Cell vitality studies confirmed no increased toxicity of the Co-doped iron oxide nanoparticles compared to the pure iron oxide ones. Magnetic heating performance was confirmed to be a function of coercivity as well. The here presented non-toxic magnetic nanoparticle system enables the tuning of the magnetic properties of the particles without a remarkable change in particles size. The found heating performance is suitable for magnetic hyperthermia application.https://www.mdpi.com/2079-4991/10/6/1019cobalt ferritecoercivityferrimagnetismmagnetic fluid hyperthermiamagnetic nanoparticlesmagnetite |
| spellingShingle | Silvio Dutz Norbert Buske Joachim Landers Christine Gräfe Heiko Wende Joachim H. Clement Biocompatible Magnetic Fluids of Co-Doped Iron Oxide Nanoparticles with Tunable Magnetic Properties Nanomaterials cobalt ferrite coercivity ferrimagnetism magnetic fluid hyperthermia magnetic nanoparticles magnetite |
| title | Biocompatible Magnetic Fluids of Co-Doped Iron Oxide Nanoparticles with Tunable Magnetic Properties |
| title_full | Biocompatible Magnetic Fluids of Co-Doped Iron Oxide Nanoparticles with Tunable Magnetic Properties |
| title_fullStr | Biocompatible Magnetic Fluids of Co-Doped Iron Oxide Nanoparticles with Tunable Magnetic Properties |
| title_full_unstemmed | Biocompatible Magnetic Fluids of Co-Doped Iron Oxide Nanoparticles with Tunable Magnetic Properties |
| title_short | Biocompatible Magnetic Fluids of Co-Doped Iron Oxide Nanoparticles with Tunable Magnetic Properties |
| title_sort | biocompatible magnetic fluids of co doped iron oxide nanoparticles with tunable magnetic properties |
| topic | cobalt ferrite coercivity ferrimagnetism magnetic fluid hyperthermia magnetic nanoparticles magnetite |
| url | https://www.mdpi.com/2079-4991/10/6/1019 |
| work_keys_str_mv | AT silviodutz biocompatiblemagneticfluidsofcodopedironoxidenanoparticleswithtunablemagneticproperties AT norbertbuske biocompatiblemagneticfluidsofcodopedironoxidenanoparticleswithtunablemagneticproperties AT joachimlanders biocompatiblemagneticfluidsofcodopedironoxidenanoparticleswithtunablemagneticproperties AT christinegrafe biocompatiblemagneticfluidsofcodopedironoxidenanoparticleswithtunablemagneticproperties AT heikowende biocompatiblemagneticfluidsofcodopedironoxidenanoparticleswithtunablemagneticproperties AT joachimhclement biocompatiblemagneticfluidsofcodopedironoxidenanoparticleswithtunablemagneticproperties |