Biological Behavior of Dextran-Iron Oxide Magnetic Fluid Injected Intravenously in Rats

Dextran-magnetic iron oxide complex (CMDM) consisting of carboxymethyl dextran and a magnetite core has been synthesized. The physical and biological properties were compared with those of the conventional dextran-magnetite complex (ATDM). The CMDM exhibits a super-paramagnetic property, has high stability and low toxicity. The uptake and metabolic behavior of CMDM in live rats after intravenous (iv) administration were studied using pulsed nuclear magnetic resonance, optical microscopy and transmission electron microscopy. The ultrafine particles of CMDM were clearly observed in the lysosomes of Kupffer cells in the liver and of macrophages in the spleen. The CMDM accumulated in the lysosomes was found to disappear within two weeks after the iv-injection. The results obtained in this work suggest that CMDM is appropriate for use as a contrast agent for magnetic resonance imaging (MRI).