Preparation of magnetic fluids based on La0.80Ag0.15MnO3-δ nanoparticles

Abstract

Water-based magnetic fluids were prepared using La_0.80Ag_0.15MnO_3-δ magnetic carriers with the maximal Curie temperature T_C = 319.5 K (46.4 °C). The starting nanoparticles mainly consisted from agglomerates with average particle size between 43 and 47 nm. Separation of nanoparticles from aggregates using a stirred ball mill in combination with the use of anionic sodium dodecyl sulphate surfactant led to the preparation of electrostatically stabilised magnetic fluid with average hydrodynamic size of particles x_av less than 75 nm. A combination of mechanical grinding, sonication and etching in different acids was used to prepare Dextran 40 kDa sterically and carboxymethyl-dextran 15 kDa electrosterically stabilised magnetic fluid with average hydrodynamic size of particles ranging between 50 and 190 nm. Milling and etching results in reduction of T_C of about 3 K, etching causes a drastic decrease in saturation magnetization, but the magnetocaloric properties are unaffected by the preparation of the magnetic fluid, only the magnetic entropy change is reduced by three orders of magnitude. Magnetic carrier has the potential to reach the desired magnetic heating temperature T = 43.6 °C for applications in hyperthermia and magnetic fluids are capable to reach T = 38.1 °C by magnetic heating. The maximal specific absorption rate of magnetic carrier SAR = 134.7 W/g and in the case of magnetic fluid SAR = 41.9 W/g. The synthesized nanoparticles and the prepared magnetic fluids may represent materials with potential in cancer treatment, as the most pronounced effect was observed in the case of lung cancer cell line A549. Analysed nanoparticles induced a decrease in metabolic activity even at relatively low concentrations.