Pseudo single domain NiZn-γFe2O3 colloidal superparamagnetic nanoparticles for MRI-guided hyperthermia application

Magnetic resonance imaging (MRI)-guided magnetic nanofluid hyperthermia (MNFH) is highly desirable in cancer treatment because it can allow for diagnosis, therapeutics, and prognosis simultaneously. However, the application of currently developed iron-oxide based superparamagnetic nanoparticles (IOSPNPs) for an MRI-guided MNFH agent is technically limited by the low AC heat induction power at the physiologically tolerable range of AC magnetic field (H AC,safe), and the low transverse r 2-relaxivity responsible for the insufficient heating of cancers, and the low resolution of contrast imaging, respectively. Here, pseudo single domain colloidal Ni x Zn1−x –γFe2O3 (x = 0.6) superparamagnetic nanoparticle (NiZn-γFe2O3 PSD-SPNP) physically and theoretically designed at the H AC,safe, specifically by the applied frequency, is proposed for a highly enhanced MRI-guided MNFH agent application. The NiZn-γFe2O3 PSD-SPNP showed the superparamagnetic characteristics, significantly enhanced AC heat induction performance (ILP = 6.3 nHm2 kg−1), highly improved saturation magnetization (M s = 97 emu g−1 Fe, 3.55 × 105 A m−1) and r 2-relaxivity (r 2 = 396 mM−1 s−1) that are desirable for highly efficient MRI-guided MNFH agent applications. According to the analyzed results, the remarkably enhanced effective relaxation time constant and its dependent out-of-phase magnetic susceptibility, as well as the DC/AC magnetic softness optimized by the PSD-SPNP at the H AC,safe were revealed as the main physical reason for the significance. All the fundamental in vitro and in vivo experimental results demonstrated that the physically designed NiZn-γFe2O3 PSD-SPNP is bio-technically feasible for a highly efficient MRI-guided MNFH agent for future cancer nanomedicine.