Objective   To explore how to prepare N-(2-aminoethyl)-3-aminopropyltrimethoxysilance (AEAPS)-Dextran-modified superparamagnetic iron oxide nanoparticles (SPION) and test the physical and magnetic properties of the nanoparticles.    Methods   Dextran-modified SPION was obtained by "one step" co-precipitation method. Then

AEAPS was added to the resultant Dextran-SPION under the condition of N2 saturation and high-speed mechanical stirring at 60℃. The size and magnetic susceptibility of the nanoparticles were measured with the aid of transmission electron microscope and Vibrating Sample Magnetometer

respectively.    Results   The AEAPS-Dextran-modified SPION nanoparticles had core-shell diameter less than 25 nm with magnetic core of less than 20 nm in diameter. The mass saturation magnetic intensity was 65.82319 emu/g Fe. Antibody conjugated with AEAPS-Dextran-modified SPION could bind to its specific antigen and were positive to Prussian Blue staining.    Conclusion   The AEAPS-Dextran-modified SPION possess the characteristics of small size and good dispersion super-paramagnetic response

and could be to bind to monoclonal antibody for possible application in disease diagnosis and treatment.