Fig. 1

Rhodamine-labeled SPIONs penetrate mouse skin. To examine the penetration of topically applied SPIONs into the skin, rhodamine-labeled SPIONs (2 mg/mL in 20 µL PBS, mouse on the right) or vehicle (20 µL, mouse on the left) were applied to the back skin of mice. One hour after application, unabsorbed solution was removed by wiping. a Mouse whole-body fluorescence images were acquired at the time points indicated. b Fluorescence micrographs of frozen fixed sections of the Rho-SPION-treated area of skin, 24 h after application, showing brightfield, nuclear counterstain (DAPI) and rhodamine signals. Representative images of 1–2 mice and experiment repeated 3 times