Saturation of Specific Absorption Rate for Soft and Hard Spinel Ferrite Nanoparticles Synthesized by Polyol Process

Cristian Iacovita,Roxana Dudric,Constantin Mihai Lucaciu,Rares Ionut Stiufiuc,Gabriela Fabiola Stiufiuc,Romulus Tetean,Nicoleta Vedeanu

doi:10.3390/magnetochemistry6020023

Abstract

Spinel ferrite nanoparticles represent a class of magnetic nanoparticles (MNPs) with enormous potential in magnetic hyperthermia. In this study, we investigated the magnetic and heating properties of spinel soft NiFe2O4, MnFe2O4, and hard CoFe2O4 MNPs of comparable sizes (12–14 nm) synthesized by the polyol method. Similar to the hard ferrite, which predominantly is ferromagnetic at room temperature, the soft ferrite MNPs display a non-negligible coercivity (9–11 kA/m) arising from the strong interparticle interactions. The heating capabilities of ferrite MNPs were evaluated in aqueous media at concentrations between 4 and 1 mg/mL under alternating magnetic fields (AMF) amplitude from 5 to 65 kA/m at a constant frequency of 355 kHz. The hyperthermia data revealed that the SAR values deviate from the quadratic dependence on the AMF amplitude in all three cases in disagreement with the Linear Response Theory. Instead, the SAR values display a sigmoidal dependence on the AMF amplitude, with a maximum heating performance measured for the cobalt ferrites (1780 W/gFe+Co), followed by the manganese ferrites (835 W/gFe+Mn), while the nickel ferrites (540 W/gFe+Ni) present the lowest values of SAR. The heating performances of the ferrites are in agreement with their values of coercivity and saturation magnetization.

Highlights

In recent decades, the potential applications of magnetic nanoparticles (MNPs) in various fields, have increased exponentially due to their specific characteristics [1,2,3,4]
The Specific Absorption Rate (SAR) values display a sigmoidal dependence on the alternating magnetic fields (AMF) amplitude, with a maximum heating performance measured for the cobalt ferrites (1780 W/gFe+Co), followed by the manganese ferrites (835 W/gFe+Mn), while the nickel ferrites (540 W/gFe+Ni) present the lowest values of SAR
Our results show that our MNPs have small sizes (12–14 nm), they present a nonzero coercitivity at room temperature and their SAR dependence on H cannot be described in the frame of the linear response theory (LRT); instead, a saturated dependence was recorded

Summary

Introduction

The potential applications of magnetic nanoparticles (MNPs) in various fields, have increased exponentially due to their specific characteristics [1,2,3,4]. While MNPs possess common features with other nanoparticulate systems owing to their size, such as a high surface to volume ratio, they have specific unparalleled advantages, like the possibility of remotely controlling their movement, temperature, and organization by using external magnetic fields. These characteristics have led to numerous biomedical applications of MNPs in fields like targeted drug delivery, neural stimulation, biological separation, bio-sensing, magnetic resonance/particle imaging, and as heat dissipation agents in cancer treatment [5,6,7,8,9,10].

Methods

Results

Conclusion