Oleic Acid-Coated Zinc Ferrite Nanocubes: A Promising Nanocarrier for Neuroblastoma Therapy

This study focuses on the synthesis of OA@ZnFe₂O₄ NPs and the investigation of their structural, magnetic, and biological characteristics as well as their pH-responsive drug release behavior for potential biomedical use. The particles with an average particle size of ∼23 nm exhibited a single-phase spinel structure and superparamagnetic behavior. DOX was successfully loaded onto the NPs with a remarkably high efficiency (∼99%). In vitro release studies demonstrated that the OA@ZnFe₂O₄ NPs exhibited a pH-dependent release behavior in phosphate-buffered saline and citrate buffers. The release rate was highest at pH 4.5, followed by pH 6.5 and then pH 7.4 in both buffer media. The OA@ZnFe₂O₄ NPs (0.5 mg/mL) in citrate buffer at pH 4.5 demonstrated a markedly higher release efficiency, reaching approximately 77% cumulative release over ∼5 days. Cell imaging demonstrated efficient uptake of the DOX@OA@ZnFe₂O₄ NPs in SH-SY5Y neuroblastoma cells. Biocompatibility assays showed that the OA@ZnFe₂O₄ NPs were nontoxic to normal 3T3 fibroblasts, while the DOX@OA@ZnFe₂O₄ NPs exhibited strong anticancer activity comparable to free DOX. These findings support the potential of the OA@ZnFe₂O₄ NPs as a pH-sensitive nanocarrier for targeted neuroblastoma therapy with reduced systemic side effects.