Effect of ligand dispersant on superparamagnetic heating capacity and cytotoxicity properties of MnFe2O4 nanoparticles

Localized superparamagnetic hyperthermia (SPHT) is used in modern cancer treatments. SPHT results from both Neel and Brown magnetic spin relaxations in superparamagnetic nanoparticles (SPNPs). Brown relaxation depends on hydrodynamic diameter of SPNPs and viscosity of the medium. In real biological applications, live cells will adhere to SPNPs resulting in decrease of Brown relaxation. To understand the effect of ligand dispersants on magnetic relaxation, hyperthermia, and cytotoxicity properties, various dispersants ligated MnFe2O4(MFO) nanoparticles synthesized by solvothermal reflux were studied. Crystallinity, morphology, surface dispersants, colloidal stability, and magnetic properties of MFO nanoparticles were characterized. SPHT properties of: (a) long chain oleic acid (OA), (b) short chain zwitterionic dopamine sulfonate (ZDS) dispersants ligated MFO nanoparticles (NPs), and (c) MFO nanoparticles without dispersant were studied at 0.5, 1, and 3 mg/mL MNPs concentration under alternate mag-netic field (AMF) of 408 and 455 Oe at fixed 316 kHz frequency were reported. All 18 samples studied were shown increase of specific heat power emission (SPE) with NPs concentration and AMF strength (H). Among all the samples, ZDS ligated MFO nanoparticles at 3 mg/mL shows highest SPE of 426 kW/kg under 455 Oe. But the intrinsic loss power (ILP) indicates that ZDS ligated MFO sample shows saturation of SPE even at 408 Oe. Whereas OA ligated MFO NPs shows no saturation of SPE under same field. This is attributed to slower relaxation of OA ligated MFO nanoparticles. Both OA- and ZDS-ligated MnFe2O4 NPs show good cytocompatibility with CaCo-2 cells in 100-900 mu g/mL NPs Ps concentration.