Abstract
Magnetic ferrite nanoparticles (MFNs) with high heating efficiency are highly desirable for hyperthermia applications. As conventional MFNs usually show low heating efficiency with a lower specific loss power (SLP), extensive efforts to enhance the SLP of MFNs have been made by varying the particle compositions, sizes, and structures. In this study, we attempted to increase the SLP values by creating core-shell structures of MFNs. Accordingly, first we synthesized three different types of core ferrite nanoparticle of magnetite (mag), cobalt ferrite (cf) and zinc cobalt ferrite (zcf). Secondly, we synthesized eight bi-magnetic core-shell structured MFNs; Fe3O4@CoFe2O4 (mag@cf1, mag@cf2), CoFe2O4@Fe3O4 (cf@mag1, cf@mag2), Fe3O4@ZnCoFe2O4 (mag@zcf1, mag@zcf2), and ZnCoFe2O4@Fe3O4 (zcf@mag1, zcf@mag2), using a modified controlled co-precipitation process. SLP values of the prepared core-shell MFNs were investigated with respect to their compositions and core/shell dimensions while varying the applied magnetic field strength. Hyperthermia properties of the prepared core-shell MFNs were further compared to commercial magnetic nanoparticles under the safe limits of magnetic field parameters (<5 × 109 A/(m·s)). As a result, the highest SLP value (379.2 W/gmetal) was obtained for mag@zcf1, with a magnetic field strength of 50 kA/m and frequency of 97 kHz. On the other hand, the lowest SLP value (1.7 W/gmetal) was obtained for cf@mag1, with a magnetic field strength of 40 kA/m and frequency of 97 kHz. We also found that magnetic properties and thickness of the shell play critical roles in heating efficiency and hyperthermia performance. In conclusion, we successfully enhanced the SLP of MFNs by engineering their compositions and dimensions.
Highlights
Magnetic ferrite nanoparticles (MFNs) can act as nano-heaters by generating heat under an alternating magnetic field (AMF) and have shown great potential for applications in biomedical fields, such as hyperthermia cancer treatment [1]
This solution-based synthesis method is sensitive to the composition of precursor materials and the reaction temperature, allowing for the synthesis of the bi-magnetic core-shell structured MFNs with controlled size and degree of crystallinity. This method is appealing since it allows the synthesis of heterostructures with exquisite control of the sizes and morphologies. This method is based on a two-step synthesis process, where pre-made nanoparticles are used as seeds for the posterior deposition of the shell
Core-shell structured MFNs, i.e., Fe3O4@CoFe2O4, CoFe2O4@Fe3O4, Fe3O4@ZnCoFe2O4, and ZnCoFe2O4@Fe3O4, were prepared by a controlled co-precipitation method, which is a simple, environmentally friendly, low-temperature method [6,20]
Summary
Magnetic ferrite nanoparticles (MFNs) can act as nano-heaters by generating heat under an alternating magnetic field (AMF) and have shown great potential for applications in biomedical fields, such as hyperthermia cancer treatment [1]. Intensive efforts have been made to enhance the heating efficiency of MFNs by controlling their composition, size, and/or structures This solution-based synthesis method is sensitive to the composition of precursor materials and the reaction temperature, allowing for the synthesis of the bi-magnetic core-shell structured MFNs with controlled size and degree of crystallinity. The fine control over the IONCs’ effective anisotropy, which can be provided by the interface coupling between core and shell, could lead to SAR values up to ∼2400 W/gmetal for water colloids and ∼1000 W/gmetal for immobilized particles at 80 mT and 309 kHz [15] Such high SAR values were achieved at high field amplitude and frequency values that are unsuitable for clinical applications. We performed the systematic studies on synthesis and characterization of bi-magnetic core-shell MFNs by varying the ferrite material types, the core/shell locations, and the dimensions using the co-precipitation method for the production of high SLP
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