Design of carboxylated Fe3O4/poly(styrene-co-acrylic acid) ferrofluids with highly efficient magnetic heating effect

Magnetic heating effect of Fe3O4 ferrofluids, surface-carboxylated and encapsulated by poly(styrene-acrylic acid) was studied. Magnetic Fe3O4 NPs were synthesized by coprecipitation method and characterized by X-ray diffraction (XRD), Field Emission Electron Microscope (FESEM) and Vibrating Sample Magnetometer (VSM). Spectroscopic data (Infra red (IR) and Proton Nuclear Magnetic Resonance (1H NMR) spectra) confirmed that Fe3O4 NP surface was carboxylated and capable for protein binding (e.g., Hepatitis B surface antibody (HBsAb)). Magnetic measurement by Physical Properties Measurement System (PPMS) and magnetic heating experiments revealed that the saturation temperature of the ferrofluids could be advantageously applied in hyperthermic treatment, namely it could achieve as high as 48.6°–57 °C, with as low as 0.3–0.5 mg/ml of Fe3O4 in the fluid, under magnetic field of 60 Oe and 236 kHz. Under those AC field parameters, the specific loss power (SLP) was measured as 0.84 kW/g and Sarcoma 180 cells were killed after 70–80 min-treatment in ex vivo heating experiment, meaning that the synthesized ferrofluid may be considered as promising in hyperthermic cancer treatments.