Superparamagnetic FePt nanoparticles (NPs) have attracted considerable attention due to their extremely promising potentials as the diagnostic and therapeutic reagent in biomedical fields.In the present study,water-soluble FePt NPs about 4 nm in diameter and oil-soluble FePt NPs about 6 nm in diameter were successfully synthesized using amino acids and oleic acid/oleylamine as the capping reagent,respectively.The component,size and magnetic property of FePt NPs were tuned through adjusting the reactant molar ratio.Furthermore,the anticancer activities of FePt NPs with different capping reagents were evaluated using different brain tumor cell lines (such as U251,U87,H4) as the model.The growth prohibition of tumor cells by NPs was measured through MTT assay,while the interaction of NPs and tumor cells was observed through transmission electron microscopy (TEM).The results show that FePt NPs capped with oleic acid/oleylamine displayed better cytotoxic effects toward brain tumor cells than L-cysteine-capped FePt NPs.It is interesting that the cellular uptake of FePt NPs seem to be similar in three cell lines.In conclusions,we synthesized successfully superparamagnetic FePt NPs with the different component using different capping reagents,which displayed different anticancer activities on Human brain tumor cells.These results also provide a promising potential of superparamagnetic FePt NPs as the multifunctional diagnostic and therapeutic reagent in biomedical fields.