Resumen: Biocompatibility restrictions have limited the use of magnetic nanoparticles for magnetic hyperthermia therapy to iron oxides, namely magnetite (Fe3O4) and maghemite (ε-Fe2O3). However, there is yet another magnetic iron oxide phase that has not been considered so far, in spite of its unique magnetic properties: ε-Fe2O3. Indeed, whereas Fe3O4 and ε-Fe2O3 have a relatively low magnetic coercivity, ε-Fe2O3 exhibits a giant coercivity. In this report, the heating power of ε-Fe2O3 nanoparticles in comparison with ε-Fe2O3 nanoparticles of similar size (~20 nm) was measured in a wide range of field frequencies and amplitudes, in uncoated and polymer-coated samples. It was found that ε-Fe2O3 nanoparticles primarily heat in the low-frequency regime (20-100 kHz) in media whose viscosity is similar to that of cell cytoplasm. In contrast, ε-Fe2O3 nanoparticles heat more effectively in the high frequency range (400-900 kHz). Cell culture experiments exhibited no toxicity in a wide range of nanoparticle concentrations and a high internalization rate. In conclusion, the performance of ε-Fe2O3 nanoparticles is slightly inferior to that of ¿-Fe2O3 nanoparticles in human magnetic hyperthermia applications. However, these ε-Fe2O3 nanoparticles open the way for switchable magnetic heating owing to their distinct response to frequency. Idioma: Inglés DOI: 10.1039/d0ra04361c Año: 2020 Publicado en: RSC Advances 10, 48 (2020), 28786-28797 ISSN: 2046-2069 Factor impacto JCR: 3.361 (2020) Categ. JCR: CHEMISTRY, MULTIDISCIPLINARY rank: 81 / 178 = 0.455 (2020) - Q2 - T2 Factor impacto SCIMAGO: 0.746 - Chemistry (miscellaneous) (Q1) - Chemical Engineering (miscellaneous) (Q1)