Examination of the iron content after simple SPION incubation with light microscopy, chemical analysis, and <i>in vitro</i> MRI.

<p>(A) No PB staining found in unlabeled cells while all the labeled ones were PB positive. (B) Little iron was detected in unlabeled cells while the labeled cells showed an averaged iron content of 5.3±1.1 pg/cell. (C) The R2* value was minimal in unlabeled cells while the labeled cells showed an averaged R2* value of 68.7±4.9 ms⁻¹. (D) The R2 value was 6.1±0.4 ms⁻¹ in unlabeled cells while the labeled cells showed an averaged R2 value of 12.8±0.8 ms⁻¹. (E) The T2* map. (F) The T2 map.