Multi-modal MR imaging and magnetic hyperthermia study of Gd doped Fe₃O₄ nanoparticles for integrative cancer therapy

Among different kinds of cancer theranostic mediators, gadolinium (Gd) doped iron oxide nanoparticles are one of the most promising candidates in combining diagnostics (imaging) and therapeutics (molecular therapy) functions in a single, multimodal platform. Due to its larger size, the doping of Gd into the Fe₃O₄ is difficult. We have overcome this difficulty by modifying a polyol based reflux method that has been previously used for, for example, cobalt-zinc (Co-Zn) doping of ferrites but not for doping with Gd. This modified approach allowed a facile synthesis of Gd-doped superparamagnetic iron oxide (Fe₃O₄) nanoparticles (GdSPIONPs) with a lower Curie temperature (T_c) for hyperthermia superparamagnetism with low coercivity, both T₁ and T₂ based MRI contrast enhancements, low cytotoxicity and optimal hemocompatibility. Such a combination of theranostics properties in a single nanosystem is unprecedented and highly desirable for heat controlled magnetic hyperthermia in minimizing treatment resistance, and maximizing treatment efficacy.