The impact of graphene oxide on the magnetic and hyperthermia properties of CoFe2O4 and MnFe2O4 ferrites

Abstract

Abstract MnFe 2 O 4 and CoFe 2 O 4 nanoparticles, along with their graphene oxide (GO) composites, were synthesized and characterized for potential use in magnetic hyperthermia applications. MnFe 2 O 4 and CoFe 2 O 4 were synthesized through hydrothermal method and characterized using XRD, TEM, Raman, FTIR spectroscopy and VSM to determine their structural, morphological, and magnetic properties. Magnetic measurements revealed superparamagnetic behavior in MnFe 2 O 4 , while CoFe 2 O 4 exhibited ferromagnetic properties. MnFe 2 O 4 , with soft ferrite characteristics, demonstrated higher magnetization and heating efficiency compared to CoFe 2 O 4 , a hard ferrite with higher magnetic anisotropy. The incorporation of graphene oxide introduced competing effects: while it improved colloidal dispersion and offered a surface platform amenable to bioconjugation and functionalization for targeted drug delivery, it consistently reduced SAR values across both ferrite systems. This reduction is attributed to magnetic phase dilution by the nonmagnetic GO matrix, as well as domain pinning caused by interfacial strain and structural defects, reflecting perturbations to the magnetic microstructure. Enhancing the hyperthermia performance of ferrites may require optimizing more than just saturation magnetization; factors such as the anisotropy constant of the ferrite must be tuned to match the relaxation timescale with the applied field frequency. Hyperthermia experiment demonstrated enhanced heating efficiency (SAR values) for MnFe 2 O 4 , achieving 110 W/g, compared to its GO composite (60 W/g), highlighting the synergistic effects of both Néel and Brownian relaxation mechanisms whose effective relaxation time is better matched to the applied frequency. On the other hand, CoFe 2 O 4 system operates predominately through Brownian relaxation, as its Néel relaxation is thermally inaccessible under these conditions, resulting in a much lower SAR of 70 W/g. The composite, CoFe 2 O 4 -GO, exhibited lower but comparable SAR values, decreasing from 70 to 60 W/g, consistent with a Brownian-dominated mechanism relatively insensitive to GO-induced magnetic modifications. In this study, we identify some key parameters influencing hyperthermia performance (e.g., particle size, morphology, and magnetic anisotropy) in an effort to present optimized nanoparticles for effective hyperthermia-based cancer treatment.