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,H-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 NixZn1-x-gamma Fe2O3 (x = 0.6) superparamagnetic nanoparticle (NiZn-gamma Fe2O3 PSD-SPNP) physically and theoretically designed at the H-AC,H-safe, specifically by the applied frequency, is proposed for a highly enhanced MRI-guided MNFH agent application. The NiZn-gamma Fe2O3 PSD-SPNP showed the superparamagnetic characteristics, significantly enhanced AC heat induction performance (ILP = 6.3 nHm(2) kg(-1)), highly improved saturation magnetization (M-s = 97 emu g(-1) Fe, 3.55 x 10(5) 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 outof-phase magnetic susceptibility, as well as the DC/AC magnetic softness optimized by the PSDSPNP at the H-AC,H-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-gamma Fe2O3 PSD-SPNP is bio-technically feasible for a highly efficient MRI-guided MNFH agent for future cancer nanomedicine.
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