Abstract: Compound nano-particles of the superparamagnetic iron oxide, which are core-shell structure with iron oxide as core and dextran as shell, were prepared in the single-carboxyl
dextran water-base solution by a chemical co-deposition method. The factors of controlling the processing were investigated systematically. The compound particle’s
morphology and microstructure and the distribution of particale diameters were investigated by means of XRD, TEM and GLS. The resultes show
that the diameter of the compound nano particle can be decreased by accurately controlling the modification dextran quantity added, the drip-speed of
NH4OH and the reaction time as well as reaction temperature. Under the conditions of optimum parameters, the core-shell compound structure particle average
diameter is 7.8nm, the average core diameter of iron oxide is 5nm and the thick of dextran shell is 1～1.5nm.

Key words: superparamagnetic iron oxide compound nano particle, preparation, characterization