Tuning specifc loss power of CoFe_2O_4 nanoparticles by changing surfactant concentration in a combined co-precipitation and thermal decomposition method

摘要

New synthetic approaches of nanoparticles (NPs) can be used for magnetic hyperthermia, destroying malignant cells without damaging healthy tissues. Here, a combination of co-precipitation and thermal decomposition techniques was employed to synthesize monodisperse CoFe_2O_4 NPs. A mixture of oleylamine and oleic acid with different concentrations was utilized as a surfactant, signifcantly changing magnetic, morphological and structural properties of the NPs. Increasing the surfactant concentration from 1 to 7.5 mmol resulted in maximum and minimum coercivity and saturation magnetization of 420.0 Oe 73.6 emu/g, and 67.2 Oe and 48.3 emu/g, respectively, arising from the prevention of agglomeration and reduction in crystallite size. The frst-order reversal curve analysis was employed to clarify the role of the surfactant in magnetic distributions and detailed characteristics. The specifc loss power of the NPs was found to be tuned for the different surfactant concentrations, achieving a maximum of 268.5 W/g at 7.5 mmol for CoFe_2O_4 NPs with enhanced super-paramagnetic contribution in Neel and Brownian mechanisms. MTT assay of the NPs was also carried out, indicating their low cytotoxicity.