The invention relates to a preparation method of amphoteric
ion modified ultra-fine
iron oxide particles. The preparation method comprises the following steps: dissolving trivalent
ferric salt in solvents, adding
sodium citrate, stirring, adding
anhydrous sodium acetate, stirring, reacting for 3 to 4 hours at the temperature of 190 to 200 DEG C, cooling, carrying out
centrifugation and
drying to obtain ultra-fine Fe3O4 nanoparticles, then dispersing the nanoparticles in
ultrapure water, performing
ultrasound, and EDC and NHS activation, dropwise adding to the ultrapure
aqueous solution of Mal-PEG-NH2, reacting for 60 to 72 hours to obtain an
aqueous solution of Fe3O4-PEG-Mal, and then dropwise adding the ultrapure
aqueous solution of L-
cysteine, reacting for 60 to 72 hours, dialyzing and freeze-
drying to obtain the amphoteric
ion modified ultra-fine
iron oxide particles. The method disclosed by the invention is simple, and the prepared nanoparticles are long in half-life periods of blood in mouse bodies, and can realize
blood pool angiography in animal levels and enhance imaging for subcutaneous transplanted tumors T1 of
HeLa cells, so that the preparation method of the mphoteric
ion modified ultra-fine
iron oxide particles has potentials of industrialization and commercialization.