Dextran stabilized lanthanum strontium manganese oxide nanoparticles for magnetic resonance imaging

Dextran stabilized ferromagnetic La0.7Sr0.3MnO3 nanoparticles (Dex-LSMO NPs) have been already assessed as a potential hyperthermia agent. Herein we show for the first time by in vivo experimentation that Dex-LSMO NPs can also be used as a new type of contrast agent in magnetic resonance imaging (MRI). Interestingly, Dex-LSMO NPs (average size <= 50 nm) show both positive and negative contrast properties with r(1) relaxivity value equal to 6.741 s(-1) mg(-1) mL and superior r(2) value of 778 s(-1) mg(-1) mL. More importantly, when injected at the site of a tumor (viz. melanoma), Dex-LSMO NPs exhibit strong magnetomotive signals. Elaborate toxicity studies (such as cytotoxicity, haemocompatibility and in vivo toxicity in mice) confirm their biocompatibility and safety up to a dosage of 50 mg Kg(-1) for intravenous as well as intraperitoneal administration and 1000 mg Kg(-1) in case of subcutaneous route. Our results clearly highlight the utility of Dex-LSMO NPs as a new type of contrast agent for MRI. The possibility of their dual use in diagnostics (MRI) and therapeutics (cancer hyperthermia) can also be envisaged.