Abstract
Exchange bias (EB) of magnetic nanoparticles (MNPs) in the nanoscale regime has been extensively studied by researchers, which have opened up a novel approach in tuning the magnetic anisotropy properties of magnetic nanoparticles (MNPs) in prospective application of biomedical research such as magnetic hyperthermia. In this work, we report a comparative study on the effect of magnetic EB of normal and inverted core@shell (CS) nanostructures and its influence on the heating efficiency by synthesizing Antiferromagnetic (AFM) NiO (N) and Ferrimagnetic (FiM) Fe3O4 (F). The formation of CS structures for both systems is clearly authenticated by XRD and HRTEM analyses. The magnetic properties were extensively studied by Vibrating Sample Magnetometer (VSM). We reported that the inverted CS NiO@Fe3O4 (NF) MNPs have shown a greater EB owing to higher uncompensated spins at the interface of the AFM, in comparison to the normal CS Fe3O4@NiO (FN) MNPs. Both the CS systems have shown higher SAR values in comparison to the single-phased F owing to the EB coupling at the interface. However, the higher surface anisotropy of F shell with more EB field for NF enhanced the SAR value as compared to FN system. The EB coupling is hindered at higher concentrations of NF MNPs because of the enhanced dipolar interactions (agglomeration of nanoparticles). Both the CS systems reach to the hyperthermia temperature within 10 min. The cyto-compatibility analysis resulted in the excellent cell viability (> 75%) for 3 days in the presence of the synthesized NPs upto 1 mg/ml. These observations endorsed the suitability of CS nanoassemblies for magnetic fluid hyperthermia applications.
Highlights
Exchange bias (EB) of magnetic nanoparticles (MNPs) in the nanoscale regime has been extensively studied by researchers, which have opened up a novel approach in tuning the magnetic anisotropy properties of magnetic nanoparticles (MNPs) in prospective application of biomedical research such as magnetic hyperthermia
We have shown that higher MNPs heating ability or maximum Specific absorption rate (SAR) value is obtained when the EB coupling at their interface is higher
The co-existence of both N and F in the normal CS and inverted CS−is clearly authenticated from the XRD pattern
Summary
The co-existence of both N and F in the normal CS and inverted CS−is clearly authenticated from the XRD pattern. The XRD−results endorse a face-centred cubic structure with Fm 3 m space group for N 78-0643) and Fd 3 m space group for F The average crystallite size analysis is put through the full-width at half-maxima (FWHM) of the most intense peaks for N, F, NF and FN NPs by using the Scherer’s formula[41]. Reduction in the lattice constant is encountered in the case of nanocomposite CS for FN and NF (Table 1). The decreasing notice in the lattice constant for the CS system may be attributed to the lattice dissimilarities between N and F respectively[44,45]
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