Conclusion: SPIO prepared in the present study meets the requirement of MR imaging, with no acute toxicity to mice, and warrants further study for future MR gene imaging.

• 结论：自制的纳米级SPIO符合作为MR成像对比剂的要求，对小鼠无明显急性毒性，值得进一步研究以用于磁共振基因成像。