Hydrophobic to hydrophilic surface transformation of nano-scale zinc ferrite via oleic acid coating: Magnetic hyperthermia study towards biomedical applications

Nanoscale spinel zinc ferrite (ZNF) was prepared by sol-gel auto-ignition route and subsequently its surface was modified by oleic-acid (OA) coating. The pristine and surface modified ZNF nanoparticles (UC-ZNF and OA-ZNF) were characterized by standard techniques. XRD patterns of both the samples ensured the nanocrystalline monophasic cubic-spinel lattice structure with 'Fd-3m space-group'. FT-IR spectra revealed the presence of vibrational frequency-modes of spinet structure and successful coating of OA over ZNF. The nano-size spherical grains with some agglomeration and OA coating over ZNF were visualized in FE-SEM images. The hydrophobic-to-hydrophilic surface-transition of ZNF was confirmed by water contact-angle measurements. The BET surface-area and distribution of pore-radius was evaluated by recording N-2-isotherms. The M - H plots confirmed the superparamagnetic nature of both the samples. Optical properties were studied by UV-Vis and PL spectroscopy techniques. The colloidal-stability and distribution of particle-sizes were estimated by zeta-potential and DLS measurements. Magnetic hyperthermia studies were carried out for different concentrations (2, 4, 6, 8 and 10 mg/mL) of both the samples. The biocompatible nature of both the samples was studied by cell-viability studies. All these results ensure the implementation of OA-ZNF nanoparticles with minimum dose rate (8 mg/mL) in magnetic hyperthermia therapies for cancer treatment.