Superparamagnetic Iron Oxide Nanoparticles (SPIONs) with a mean size of 100 nm are clinically used as diagnostic agents. They serve as a contrast media when exposed to a magnetic field. Here, the tissue distribution of SPIONs was visualized after intravenous injection in a zebrafish embryo by synchrotron radiation-based X-ray tomography.
Agglomerates of SPIONs sequestered by macrophages are shown in a caudal direction. We are thus seemingly placed within a blood vessel of a 2.5 mm sized zebrafish looking at the surrounding soft tissue and onto embedded macrophages.