Superparamagnetic heating and cytotoxicity properties of bimagnetic core-shell nanoparticles ligated with different dispersants

Heat generation by magnetic losses (hysteresis or relaxation) in magnetic nanoparticles under alternate magnetic field (AMF) have many applications in biomedical heat treatment domain. Hence localized magnetic hyperthermia was widely researched for adjunct or independent therapy and efficient drug release in cancer treatment. For this application, the main criterion is that magnetic nanoparticles should have good biocompatibility and high heating capacity for in vivo applications and use of small quantity of nanoparticles for heat generation. It is understood that magnetic heating capacity of nanoparticles depends on saturation mass magnetization (M_s), magnetic anisotropic constant (K_A), and magnetic hysteresis. Majority of researchers modified these parameters by chemical substitution, and magnetic nanoparticles volume (size) variation. Here both M_s and K_A were modified by magnetic exchange bias field in bimagnetic hard magnetic core-soft magnetic shell nanoparticles (CSNPs). Here ZnFe₂O₄ (soft magnetic) and CoFe₂O₄ (hard magnetic) based bimagnetic ZnFe₂O₄-CoFe₂O₄ (soft core-hard shell) and CoFe₂O₄-ZnFe₂O₄ (hard core-soft shell) CSNPs with average particle diameter of 11 nm were synthesized and evaluated their magnetic heating capacities and cytocompatibility at different CSNPs concentrations under AMFs. Superparamagnetic heating capacity and cytotoxicity studies on both oleic acid, and zwitterionic dopamine sulfonate (ZDS) dispersants ligated core-shell nanoparticles show good cytocompatibility and magnetic heating capacities. Among all the samples, ZnFe₂O₄-CoFe₂O₄ CSNPs at 0.5 mg/mL concentration exhibited high heating capacity of 427 W/g. All CSNPs exhibited high cytocompatibility with L929 cells in MTT assay, in 100–900 µg/mL concentration range. These CSNPs show promising candidacy for localized magnetic hyperthermia in cancer treatment.