Abstract
Conjugation of optical and magnetic responses in a unique system at the nanoscale emerges as a powerful tool for several applications. Here, we fabricated bifunctional CoFe2O4-core/ZnO-shell nanoparticles with simultaneous photoluminescence in the visible range and ac magnetic losses suitable for hyperthermia. The structural characterization confirms that the system is formed by a ≈7 nm CoFe2O4 core encapsulated in a ≈1.5-nm-thick semiconducting ZnO shell. As expected from its high anisotropy, the magnetic losses in an ac magnetic field are dominated by the Brown relaxation mechanism. The ac magnetic response of the core/shell system can be accurately predicted by the linear response theory and differs from that one of bare CoFe2O4 nanoparticles as a consequence of changes in the viscous relaxation process due to the effect of the magnetostatic interactions. Concerning the optical properties, by comparing core/shell CoFe2O4/ZnO and single-phase ZnO nanoparticles, we found that the former exhibits a broade...
Highlights
Research on magnetic nanoparticles (NPs) for biomedical applications has been continuously growing in fields such as magnetic fluid hyperthermia (MFH), drug delivery, magnetic separation of biomolecules and contrast agents for magnetic resonance imaging (MRI)[1].MFH consists in destroying tumor cells by the localized heat generation of a colloid of magnetic NPs exposed to a biologically relevant radiofrequency magnetic field and is currently one of the most promising strategies to supplement traditional oncological therapies[2,3,4,5]
CoFe2O4 and CoFe2O4/ZnO core/shell NPs were successfully synthesized by adapting the heat-up method that has demonstrated a remarkable versatility for the fabrication of multicomponent nanostructures
In this work we synthesized 7 nm CoFe2O4 and 10 nm CoFe2O4/ZnO core/shell nanoparticles and we evaluated the effects of the structure and morphology on the dc and ac magnetic behavior and on the optical response
Summary
Research on magnetic nanoparticles (NPs) for biomedical applications has been continuously growing in fields such as magnetic fluid hyperthermia (MFH), drug delivery, magnetic separation of biomolecules and contrast agents for magnetic resonance imaging (MRI)[1]. Besides the control of the NPs’ size and composition, their properties are governed by their shape, morphology, interactions and long-range order, which remain an important research goal to be addressed In this way, we expect distinct magnetic and optical properties for bifunctional core/shell structures when compared to the respective properties of isolated single-phase. The design of novel multifunctional NP-based systems to address specific biomedical issues usually requires the development of complex materials and incorporating imaging probes in a single compact bifunctional nanoparticle is a key aspect of multifunctional nanosystems[6] In this aim, here we fabricated and studied a core/shell nanoparticle system formed by a magnetic CoFe2O4 core and a photoluminescent ZnO shell. We analyzed the influence of the structure and morphology of CoFe2O4/ZnO core/shell NPs on the magnetic properties, on the hyperthermia output and on the optical response
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