Nanoparticles may be detected through light microscopy by using chemical staining protocols that are conventionally employed in histopathology. For example, clusters of iron oxide nanoparticles can be visualized in HE-stained tissue sections as a finely granular brown material within the cells of a glioblastoma tumor (a, with kind approval of MagForce AG, Berlin, Germany). When serial sections from the same tissue were stained with a canonical stain for iron, Turnbull blue, the particles appear dark blue (b). As a second example, Alcian blue stain may be used to stain dendritic polyglycerol sulfates (dPGS) due to their negatively charged, sulfate rich shell. Organic dPGS amine accumulated in the cytoplasm of hepatic Kupffer cells (c, arrow). These liver specific macrophages are identified by their comma-shaped nuclei and their lining of hepatic sinusoids. Adjacent hepatocytes (c, asterisks) appear as light pink cells with finely stippled cytoplasm whereas erythrocytes within sinusoids can be identified by their intensely pink color.