Theranostic Iron@Gold Core–Shell Nanoparticles for Simultaneous Hyperthermia-Chemotherapy upon Photo-Stimulation

The challenges of nanoparticles, such as size-dependent toxicity, nonbiocompatibility, or inability to undergo functionalization for drug conjugation, limit their biomedical application in more than one domain. Oval-shaped iron@gold core–shell (oFe@Au) magnetic nanoparticles are engineered and their applications in magnetic resonance imaging (MRI), optical coherence tomography (OCT), and controlled drug release, are explored via photo stimulation-generated hyperthermia. The oFe@Au nanoparticles have a size of 42.57 ± 5.99 nm and consist of 10.76 and 89.24 atomic % of Fe and Au, respectively. Upon photo-stimulation for 10 and 15 minutes, the levels of cancer cell death induced by methotrexate-conjugated oFe@Au nanoparticles are sixfold and fourfold higher, respectively, than oFe@Au nanoparticles alone. MRI and OCT confirm the application of these nanoparticles as a contrast agent. Finally, results of in vivo experiments reveal that the temperature is elevated by 13.2 °C, when oFe@Au nanoparticles are irradiated with a 167 mW cm⁻² 808 nm laser, which results in a significant reduction in tumor volume and scab formation after 7 days, followed by complete disappearance after 14 days. The ability of these nanoparticles to generate heat upon photo-stimulation also opens new doors for studying hyperthermia-mediated controlled drug release for cancer therapy. Applications include biomedical engineering, cancer therapy, and theranostics fields.