Enhanced colloidal stability of polymer coated La_0.7Sr_0.3MnO₃ nanoparticles in physiological media for hyperthermia application

Surface of La_0.7Sr_0.3MnO₃ (LSMO) magnetic nanoparticles (MNPs) is functionalized with polymer (dextran) and their colloidal stability in various mediums is carried out. The influence of the surface functionalization of LSMO MNPs on their colloidal stability in physiological media is studied and correlated with their hyperthermia properties. Many studies have concerned the colloidal stability of MNPs coated with polymer, but their long-term stability when such complexes are exposed to physiological media is still not well understood. After zeta potential study, it is found that the dextran coating on MNPs improves the colloidal stability in water as well as in physiological media like PBS. The specific absorption rates (SAR) of these MNPs are found to be in 50-85W/g in different concentrations of glucose and NaCl; and there values are suitable for hyperthermia treatment of cancer cells under AC magnetic field. After incorporation of MNPs up to 0.2-1mg/mL in 2×10⁵cells/mL (L929), the apoptosis and necrosis studies are carried out by acridine orange and ethidium bromide (AO and EB) staining and followed by visualization of microstructures under a fluorescence microscope. It is found that there are no morphological changes (i.e. no signs of cell rounding, bubble formation on the membrane and nuclear fragmentation) suggesting biocompatibility of dextran coated LSMO nanoparticles up to these concentrations.