Synthesis and Characterization of Bi-Magnetic Core/Shell Nanoparticles for Hyperthermia Applications

Magnetic nanoparticles, which exhibit a high specific absorption rate (SAR), have drawn a great deal of interest for hyperthermia. Bi-magnetic CS-MNPs of Zn
_x
Co
_1-x
Fe
₂
O
₄
@MnFe
₂
O
₄
with x ranging between 0 and 0.8 have been synthesized by seed-mediated growth. Structural morphology and magnetic properties have been studied. This paper presents the effects of substitution of Zn
²⁺
on the structural and magnetic properties of Zn
_x
Co
_1-x
Fe
₂
O
₄
@MnFe
₂
O
₄
nanoparticles. The structure and morphology of the CS-MNPs was established by using X-ray diffraction (XRD), transmission electron microscopy (TEM), and dark field TEM (DF-TEM). XRD patterns confirm the existence of a single-phase cubic spinel crystal structure. The average particle size has been estimated from the statistical analysis of the TEM images. DF-TEM results confirmed the formation of CS-MNPs. Vibrating sample magnetometery demonstrated an increase in saturation magnetization with an increasing Zn concentration up to x = 0.4 and a decrease thereafter. High heating efficacy of CS-MNPs may extend hyperthermia therapy to deeper tumors. The experimental results showed that CS-MNPs have a higher SAR than the core ones. These nanoparticles are coupled-exchange between soft and hard magnetic phases.