Multifunctional Core-Shell NiFe₂O₄ Shield with TiO₂/rGO Nanostructures for Biomedical and Environmental Applications

Multifunctional core@shell nanoparticles have been synthesized in this paper through 3 stages: NiFe₂O₄ nanoparticles by microwave irradiation using Pedalium murex leaf extract as a fuel, core@shell NiFe₂O₄@TiO₂ nanoparticles by sol-gel, and NiFe₂O₄@TiO₂@rGO by sol-gel using preprepared reduced graphene oxide obtained by modified Hummer's method. XRD analysis confirmed the presence of both cubic NiFe₂O₄ spinel and tetragonal TiO₂ rutile phases, while Raman spectroscopy analysis displays both D and G bands (I /I  = 1.04) associated with rGO. Morphological observations by HRTEM reveal a core-shell nanostructure formed by NiFe₂O₄ core as confirmed by SAED with subsequent thin layers of TiO₂ and rGO. Magnetic measurements show a ferromagnetic behavior, where the saturation magnetization drops drastically from 45 emu/g for NiFe₂O₄ to 15 emu/g after TiO₂ and rGO nonmagnetic bilayers coating. The as-fabricated multifunctional core@shell nanostructures demonstrate tunable self-heating characteristics: rise of temperature and specific absorption rate in the range of ΔT = 3-10°C and SAR = 3-58 W/g, respectively. This effectiveness is much close to the threshold temperature of hyperthermia (45°C), and the zones of inhibition show the better effective antibacterial activity of NTG against various Gram-positive and Gram-negative bacterial strains besides simultaneous good efficient, stable, and removable sonophotocatalyst toward the TC degradation.