Objective:To explore the optimal transfection concentration through the study of the different mass concentrations of magnetic antibody in vitro transfection of colon cancer stem cells. Methods:The magnetic antibodies at an iron concentration of 5

10

25

50

75

100 mg/L were transfected into colon cancer stem cells. The distribution and content of iron particles in colon cancer stem cells were determined by Prussian blue staining

atomic adsorption spectrometer. Cell viability was observed and the changes of signal intensity were measured by magnetic resonance imaging(MRI). Results:Results of single factor analysis of variance showed that there were statistically significant differences between each group in the iron content of cells(F=71.709

P=0.000). It can be considered that the mean of each group was not exactly the same at the test level of α=0.05. Multiple comparisons were made between groups by the single factor analysis of variance LSD method(two-sided)

the result shows that the difference between 50 mg/L group and 5mg/L group

10 mg/L group

25 mg/L group was statistically significant(P=0.000

P=0.000

P=0.000)

but the difference was not statistically significant between 75 mg/L group and 100mg/L group(P=0.607

P=0.419). Cell activity detection was compared using single factor analysis of variance

and the difference between each group was statistically significant(F =69.306

P =0.000). It can be considered that the mean of each group was not exactly the same at the test level of α=0.05. Multiple comparisons were made between groups by the single factor analysis of variance LSD method(two-sided);the result showed that the difference between50 mg/L group and 75 mg/L group was not statistically significant(P=0.134);but the difference was statistically significant between 5mg/L group

10 mg/L group

25 mg/L group and 100 mg/L group(P=0.000

P=0.000

P=0.000

P=0.008). T2 WI signal intensity was compared using single factor analysis of variance

and the difference between each group was statistically significant(F=3 180.748

P=0.000). It can be considered that the mean of each group was not exactly the same at the test level of α=0.05. Multiple comparisons were made between groups by the single factor analysis of variance LSD method(two-sided);the result showed that the difference between 50 mg/L group and 75 mg/L group

100 mg/L group was not statistically significant(P=0.945

P=0.960)

but the difference was statistically significant between the blank group

normal cell group

5 mg/L group

10 mg/L group and 25 mg/L group(P=0.000

P=0.000

P=0.000

P=0.000

P=0.000). It can be seen that with the increase of the iron concentration of magnetic antibody(5 to 25 mg/L)

the iron content in colon cancer stem cells increased gradually. When the iron concentration of the magnetic antibody was 50 mg/L

the iron content of the cells was saturated

cell activity was decreased

the signal intensity of T2×WI was decreased obviously. Conclusion:The magnetic antibodies can effectively transfect colon cancer stem cell lines at the iron concentration of 50 mg/L

and can be detected by magnetic resonance imaging.