This work reports the fabrication of magnetite (Fe3O4) nanoparticles (NPs) coated with various biocompatible surfactants such as glutamic acid (GA), citric acid (CA), polyethylene glycol (PEG), polyvinylpyrrolidine (PVP), ethylene diamine (EDA) and cetyl-trimethyl ammonium bromide (CTAB) via co-precipitation method and their comparative inductive heating ability for hyperthermia (HT) applications. X-ray and electron diffraction analyses validated the formation of well crystallined inverse spinel structured Fe3O4 NPs (crystallite size of ~ 8–10 nm). Magnetic studies confirmed the superparamagnetic (SPM) behaviour for all the NPs with substantial magnetisation (63–68 emu/g) and enhanced magnetic susceptibility is attributed to the greater number of occupations of Fe2+ ions in the lattice as revealed by X-ray photoelectron spectroscopy (XPS). Moreover, distinctive heating response (specific absorption rate, SAR from 130 to 44 W/g) of NPs with similar size and magnetisation is observed. The present study was successful in establishing a direct correlation between relaxation time (~ 9.42–15.92 ns) and heating efficiency of each surface functionalised NPs. Moreover, heat dissipated in different surface grafted NPs is found to be dependent on magnetic susceptibility, magnetic anisotropy and magnetic relaxation time. These results open very promising avenues to design surface functionalised magnetite NPs for effective HT applications.

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Magnetically induced hyperthermia employing iron oxide nanoparticles is an effectual alternative to the conventional cancer therapeutic modalities. However, colloidal instability, heterogeneous heat distribution in polydispersed nanostructures, and nonspecific targeted delivery still pose major challenges hampering clinical translation. Due to a larger surface area, enhanced blood circulation time, and prolonged retention in tumors, one-dimensional nanostructured materials are of interest of research. Here, we report monodisperse oleate-coated magnetite nanorods (average length of ∼74 ± 13 nm) synthesized using an iron oleate precursor via thermal decomposition. The formation of rod-shape morphology is primarily ascribed to the selective growth along the (110) direction resulting from the preferential adsorption of oleate to (111) facets of Fe3O4. The nanorods are single domain particles with a saturation magnetization of 72 emu/g, which possess negligible coercivity and magnetic dipolar interactions. Hydrophobic-to-hydrophilic phase transition of oleate-coated magnetite nanorods was achieved using an amphiphilic surfactant tetramethylammonium 11-aminoundecanoate, suitable for hyperthermia and biological studies. Distinctive heating responses in various nonaqueous, aqueous, and physiological media evidenced the highest SAR of ∼376 W/g under an alternating current magnetic field of 500 Oe and 315 kHz, which is primarily attributed to effective relaxation losses. Hyperthermia studies conducted in simulated body fluid exhibited an improved heating efficiency (∼369 W/g) compared to water (∼252 W/g). Our results pinpoint the significance of the dispersion stability of magnetite nanorods on the heating performance in varying viscous fluids. In vitro assessment of hydrophilic magnetite nanorods against MCF-7 breast cancer cell lines demonstrated anticancer activity. Moreover, the nanorods induced minimal damage against erythrocytes, resulting in reduced hemolysis. These results indicate the potential use of magnetite nanorods as targeted nanoheating agents for hyperthermia applications.

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Synthesis of ultrafine Co1-(x+y)NixZnyFe2O4 magnetic nanoparticles with different chemical compositions is essential to study the magnetic fluid hyperthermia (MFH) as a treatment in which the superparamagnetic behaviour of materials is beneficial. In this paper, Co1-(x+y)NixZnyFe2O4 magnetic nanoparticles with different x and y amounts were synthesized to find out a tuning pattern for magnetic properties, especially anisotropy constant to gain the best heating efficiency. We proved that the co‐presence of ions will greatly affect the magnetic performance of our superparamagnetic nanoparticles in whichCo0.59Zn0.41Fe2O4 for values of x=0.00 and y=0.41 exhibits the highest magnetic anisotropy constant after CoFe2O4 CoFe2O4. This success in customizing magnetic properties to reach high magnetic properties by using less toxic materials might be another good starting point for researchers to focus more on their possible applications.

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