Synthesis of Ferromagnetic Fe0.6Mn0.4O Nanoflowers as a New Class of Magnetic Theranostic Platform for In Vivo T1-T2 Dual-Mode Magnetic Resonance Imaging and Magnetic Hyperthermia Therapy

Uniform wustite Fe0.6Mn0.4O nanoflowers have been successfully developed as an innovative theranostic agent with T-1-T-2 dual-mode magnetic resonance imaging (MRI), for diagnostic applications and therapeutic interventions via magnetic hyperthermia. Unlike their antiferromagnetic bulk counterpart, the obtained Fe0.6Mn0.4O nanoflowers show unique room-temperature ferromagnetic behavior, probably due to the presence of an exchange coupling effect. Combined with the flower-like morphology, ferromagnetic Fe0.6Mn0.4O nanoflowers are demonstrated to possess dual-modal MRI sensitivity, with longitudinal relaxivity r(1) and transverse relaxivity r(2) as high as 4.9 and 61.2 mm(-1)s(-1) [Fe]+[Mn], respectively. Further in vivo MRI carried out on the mouse orthotopic glioma model revealed gliomas are clearly delineated in both T-1- and T-2-weighted MR images, after administration of the Fe0.6Mn0.4O nanoflowers. In addition, the Fe0.6Mn0.4O nanoflowers also exhibit excellent magnetic induction heating effects. Both in vitro and in vivo magnetic hyperthermia experimentation has demonstrated that magnetic hyperthermia by using the innovative Fe0.6Mn0.4O nanoflowers can induce MCF-7 breast cancer cell apoptosis and a complete tumor regression without appreciable side effects. The results have demonstrated that the innovative Fe0.6Mn0.4O nanoflowers can be a new magnetic theranostic platform for in vivo T-1-T-2 dual-mode MRI and magnetic thermotherapy, thereby achieving a one-stop diagnosis cum effective therapeutic modality in cancer management.