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The work reports, enhancement in colloidal stability and hyperthermia efficiency of nano-spinel magnesium ferrite (MgFe2O4) by hydrophobic-to-hydrophilic surface transformation via oleic acid (OA) coating. The nano-spinel structured MgFe2O4 was prepared by the auto-combustion assisted sol-gel route and consequently, its surface was coated by OA. The uncoated and coated MgFe2O4 were portrayed by various physicochemical characterizations. The XRD analysis assured the unchanged single phasic cubic spinel structure and nanocrystalline nature of both the samples. FT-IR spectral analysis indicated the spinel belonging two vibrational stretching modes and OA attachment over the MgFe2O4 core. FE-SEM images revealed the nano-metric spherical type grain-morphology and visualization of OA coating. The drastic diminishment in contact angle values signifies hydrophobic to hydrophilic surface transition. M − H plots revealed the superparamagnetic appearance of uncoated and coated samples. Physisorption analysis showed the elevated surface area and pore size values. Zeta potential and DLS study displayed the enhancement in fluidic dispersion and hydro-dynamic size. The nano-particle concentration (2–10 mg/mL) dependent hyperthermia analysis was carried out for both the samples. Cell viability studies confirmed the improvement in the bio-friendly nature of MgFe2O4 via OA coating. All the outcomes show the superiority of the surface transformed MgFe2O4 nanoparticles in nano-magnetic hyperthermia treatments.

Here, we report the influence of nonmagnetic Al3+ and magnetic Cr3+ co-substitution on the structural, morphological, magnetic and Mossbauer properties of nickel ferrite nanoparticles synthesized via sol-gel auto combustion route. Citric acid was used as a fuel and metal nitrate to fuel ratio was chosen to be 1:3. The resultant powder was sintered at 550 °C for 4 h and used for further characterizations. Single phase formation and nanocrystalline nature was confirmed through X-ray diffraction analysis. The crystallite size of all the samples calculated through Debye-Scherrer’s formula found to be in the range of 18–55 nm. The lattice constant calculated from XRD data show decreasing trend. Scanning electron microscopy technique was used to study the surface morphology of typical samples (x = 0.0 and 0.4). The average grain size determined through SEM images found to be 70 nm–35 nm respectively for x = 0.0 and 0.4 samples. The magnetic properties were investigated through magnetization and Mossbauer spectroscopy technique. The saturation magnetization measured from M-H hysteresis plot show decreasing trend with increase in Al–Cr content x. Using Mossbauer spectra the relative area of a sextet (T), Isomer shift (δ), Hyperfine Field (Hf), Quadrupole Splitting (Δ) and Line width (Γ) were calculated. Overall, the co-substitution of Al–Cr has significantly influenced the structural, morphological and magnetic properties of nickel ferrite nanoparticles.