Alternating magnetic field-driven superparamagnetic iron/carbon nanoparticles induce significant in vivo tumor...

In this study, superparamagnetic iron-carbon (Fe/C) nanoparticles (SPINs) engineered for alternating magnetic field (AMF)-based cancer therapy were synthesized using a co-precipitation approach with optimized precursor ratios. The resulting nanoparticles exhibited high magnetic performance, achieving saturation magnetizations of up to 149 emu/g, which are favorable for efficient AMF-mediated therapeutic activation. Consistent with this magnetic behavior, our previously published in vitro cytotoxicity studies demonstrated significant dose-dependent reductions in cell viability at relatively low nanoparticle concentrations, supporting their therapeutic potential. Based on these findings, in vivo AMF-mediated treatments were evaluated in DU145 prostate and MCF-7 breast cancer xenograft models using intratumoral SPIN injections at concentrations of 50 and 100 µg/mL. In the DU145 model, the 50 µg/mL dose produced gradual tumor regression, whereas the 100 µg/mL dose resulted in more rapid tumor reduction in responsive animals. Comparable dose-dependent therapeutic responses were observed in the MCF-7 model, with the higher SPIN concentration producing more pronounced tumor regression over the treatment period. Notably, thermal imaging revealed no detectable bulk heating during treatment, consistent with numerical modeling predictions, suggesting that the observed therapeutic efficacy occurred in the absence of conventional bulk hyperthermia. Collectively, these findings provide proof-of-concept evidence for achieving tumor regression without detectable bulk heating and support the potential of Fe/C SPINs as a promising platform for AMF-mediated cancer therapy. STATEMENT OF SIGNIFICANCE: • Alternating magnetic field (AMF)-driven superparamagnetic iron nanoparticles (SPINs) achieve significant tumor regression in two in vivo cancer models • Therapeutic effect arises from nanoscale magnetic dynamics, not bulk hyperthermia • Non-thermal mechanism challenges prevailing assumptions in magnetic hyperthermia • Findings establish a design paradigm for externally programmable nanotherapies.