Tehran University of Medical Sciences Nanomedicine Research Journal 2476-3489 11 1 2026 03 01 Optimized Gold-Coated CoFe₂O₄ Magnetic Nanoparticles: Advancing Theranostic Applications in MRI Enhancement and Magnetic Hyperthermia for Cancer Treatment 105 114 737698 10.22034/nmrj.2026.01.010 EN Zahra Mohammadi Radiological Technology Department, Faculty of Paramedical Sciences, Babol University of Medical Sciences, Babol, Iran Alireza Montazerabadi Medical Physics Research Center, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Bahareh Khalili Najafabad Department of Biomedical Engineering and Medical Physics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran Ameneh Sazgarnia Medical Physics Research Center, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Journal Article 2025 12 10 <strong>Objective(s): </strong>Magnetic nanoparticles (MNPs), including cobalt ferrite (CoFe₂O₄), have been investigated as promising tools in improvement of medical imaging and treatment methodologies. While CoFe₂O₄ exhibits superior magnetic properties, its biomedical applications require surface modifications to address biocompatibility concerns. This study is another step to explore the dual functionality of optimized gold-coated CoFe2O4 nanoparticles, aiming to enhance magnetic resonance imaging (MRI) contrast and improve the efficacy of magnetic hyperthermia (MH) within a cellular environment.<br><strong>Methods</strong>: Optimized CoFe2O4 @Au (cobalt ferrite core, gold shell) nanoparticles were utilized in this study. MR imaging parameters (r1, r2, and r2/r1) were then calculated in cellular environments. Subsequently, the effects of magnetic hyperthermia induction on cell survival were evaluated at temperatures of 41°C, 44°C, 47°C, and 52.5°C immediately after treatment using the MTT assay. <br><strong>Results:</strong> Among various incubation times, CoFe2O4 @Au exhibited the highest r2 value of 165.5 mM⁻¹s⁻¹ at 4 hours incubation time in a cell medium. A phantom prepared with the MDA-MB 231 cell line incubated with CoFe2O4@Au@dextran showed a magnetic susceptibility artifact. Inducing cellular hyperthermia at temperatures below 47°C did not significantly affect cell survival, while higher temperatures (47-52.5°C) caused substantial cell damage and death through protein denaturation and thermoablation. <br><strong>Conclusions: </strong>These findings highlight the potential of CoFe2O4@Au@dextran nanoparticles in theranostic applications, combining diagnostic imaging with targeted cancer therapy. Further research is essential to optimize these nanoparticles for clinical use, with a focus on achieving a balance between efficacy, safety, and biocompatibility. https://www.nanomedicine-rj.com/article_737698_1075a2fc25506d05557bd7dbe1c24fe4.pdf