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Amino-functionalized Fe3O4and Mn3O4namoparticles （Fe3O4-NH2andMn3O4-NH2） were prepared under the premise of6-（1,3-dioxo isoindoline） hexanoicacid as precursor. The amino density of the NPs reached10-5mol/g, and the averagediameter of Fe3O4-NH2and Mn3O4-NH2NPs are respectively4.5±0.7and3.6±0.6nm. Then,2,3,5-triiodobenzoicacid with function of CT imaging, were linked withFe3O4-NH2and Mn3O4-NH2NPs for the reaction between the acyl chloride and amino,obtaining the formed Fe3O4-CT and Mn3O4-CT NPs which have the dual function of CTand MRI. The dual functional NPs have good water-solubility, biocompatibility andlow toxicity. The T1relaxivities （r1） of Mn3O4-NH2and Mn3O4-CT NPs are1.8,2.9mM-1· s-1, and the T2relaxivities （r2） of the formed Fe3O4-NH2and Fe3O4-CT NPs is15.5,31.9mM-1· s-1in a magnetic field of0.5T. Fitting line with differentconcentration of several sample and CT value obtained from the CT imaging test, wedraw a conclusion: for Fe3O4-CT NPs, the slope of the line reached10.5mM-1· HU, forMn3O4-CT NPs, the slope of the line reached11.0mM-1· HU, both of them show acertain degree of CT angiography effect. It follows that Fe3O4-CT and Mn3O4-CT NPshave the potential application ability on CT and MRI imaging.Furthermore, Mn3O4-NH2NPs were modified with the dendrimerG3PAMAM using glutaraldehyde in order to increase the amino group on the surfaceof the Mn3O4NPs.The formed Mn3O4-G3PAMAM-CT NPs show more effective CTangiography effect, the slope of the line reached22.8mM-1· HU, the longitudinalrelaxation rate （r1） decresed to1.0mM-1· s-1, more smaller than Mn3O4-NH2andMn3O4-CT due to the dendrimer G3PAMAM.
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