Synthesis and Magnetic Characterizations of La_1−x Sr _x MnO₃ Nanoparticles for Biomedical Applications

The La_1−x Sr _x MnO₃ (LSMO) nanoparticles have been synthesized by citric gel process followed by ball milling method. These nanoparticles demonstrated high crystalline quality. Nanoparticle size was further decreased by ball milling technique as observed by the field-emission scanning electron microscopic studies. The ball milled and silica coated LSMO nanoparticles show magnetic transition at about 370 K with a superparamagnetic properties. The ferromagnetic resonance (FMR) spectra analysis of LSMO nanoparticles shows large FMR linewidth due to the surface strain of the nanoparticles. Both magnetization and FMR studies demonstrate that the LSMO nanoparticles are highly anisotropic. The toxicity of the nanoparticles was studied for safe biomedical applications. Measurement of intracellular reactive oxygen species (ROS) and MTT assay results show that LSMO nanoparticles are relatively nontoxic and the toxicity is further reduced by SiO₂ coating. These results are very important for applications in the field of biotechnology.