Pseudo-single domain colloidal superparamagnetic nanoparticles designed at a physiologically tolerable AC magnetic field for clinically safe hyperthermia

Magnetic nanofluid hyperthermia (MNFH) with pure superparamagnetic nanoparticles (P-SPNPs) has drawn a huge attraction for cancer treatment modality. However, the low intrinsic loss power (ILP) and attributable degraded-biocompatibility resulting from the use of a heavy dose of P-SPNP agents as well as low heat induction efficiency in biologically safe AC magnetic field (H_AC,safe) are challenging for clinical applications. Here, we report an innovatively designed pseudo-single domain-SPNP (PSD-SPNP), which has the same translational advantages as that of conventional P-SPNPs but generates significantly enhanced ILP at H_AC,safe. According to the analyzed results, the optimized effective relaxation time, τ_eff, and magnetic out-of-phase susceptibility, χ'', precisely determined by the particle size at the specific frequency of H_AC,safe are the main reasons for the significantly enhanced ILP. Additionally, in vivo MNFH studies with colloidal PSD-SPNPs strongly demonstrated that it can be a promising agent for clinically safe MNFH application with high efficacy.