Magnetic vortex iron oxide nanorings coated with mesoporous silica as smart diagnostic and therapeutic nanoagents: negative MRI-guided tumor magnetothermal-chemotherapy

Encapsulated magnetic vortex iron oxide nanorings (MVIONs) within mesoporous silica (MVIONs@SiO 2 ) have been developed to address key challenges in magnetic hyperthermia—specifically, controlled drug release and precise thermal management in tumor therapy. This study showcases the design of these nanoparticles for the targeted delivery of the chemotherapeutic agent doxorubicin (DOX), facilitated by alternating magnetic fields (AMF). The MVIONs@SiO 2 nanoparticles exhibit exceptional specific absorption rates (SAR) of approximately 1021   W∙g -1 , indicating high thermal efficiency that ensures effective tumor heating without harming surrounding tissues. Additionally, these nanoparticles achieve a DOX loading capacity of 23.4% and a release rate of 60% under magnetic heating conditions, optimizing drug delivery to the tumor site. The relaxation rate r 2 of MVIONs@SiO 2 is recorded at 53.32   mM -1 s -1 , demonstrating significant MRI contrast enhancement correlating with nanoparticle concentration within tumors. Experimental results from cell and animal studies confirm the biocompatibility and potent antitumor activity of MVIONs@SiO 2 , highlighting its dual function in improving chemotherapy and magnetic hyperthermia. This innovation in nanoparticle-based theranostics marks a significant advance in integrating diagnostic imaging and therapeutic heating, potentially revolutionizing cancer treatment and diagnostics.