Surface-functionalized nanoscale nickel-ferrites (NiFe₂O₄) nanoparticles as heating agents for cancer theranostics

Recently, surface-functionalized magnetic nanoparticles have gained prominence as promising materials for nanotheranostics. Nickel ferrite nanoparticles (NiFe₂O₄) exhibit superparamagnetism, a phenomenon in which the material behaves as if it is a single magnetic domain without remanence. This study reports the synthesis of surface-functionalized nickel ferrite (NiFe₂O₄) nanoparticles via a simple co-precipitation route, followed by oleic acid coating to enhance stability and biocompatibility. Structural, morphological, vibrational, and magnetic analyses (XRD, FE-SEM, Raman, FTIR, and VSM) confirm the cubic spinel structure, superparamagnetic nature, and successful functionalization of the nanoparticles. Nanofluids of surface-modified nickel ferrite nanoparticles were heated by induction for 900 s to optimize nanoparticle concentration and magnetic field. As a result of induction heating experiments, nanoparticles were found to possess hyperthermic properties, with increasing concentrations leading to higher temperatures. An X-ray diffraction analysis identified cubic spinel structures in the Fd3m space group. FTIR spectra confirmed the presence of carboxylic acid groups post-functionalization, indicated by vibrational modes at 1660 cm⁻¹ and 1531 cm⁻¹ on NiFe₂O₄ nanoparticles. Induction heating studies reveal a rapid temperature rise up to 54.13 °C at relatively low field strength of 4.0 kA/m, with specific absorption rate (SAR) values reaching 177 W/g. Unlike previous studies requiring higher fields or lacking surface modification, this work demonstrates that oleic acid–coated NiFe₂O₄ nanoparticles can achieve efficient heating under clinically safer conditions, highlighting their unique potential for practical hyperthermia therapy.