This is an image of a mouse lymph node. It has been stained to target the main cell populations of the adaptive immune system in order to see where nanoparticles that were injected have gone. The green color is the T cells, the pink color is the B cells, and the blue color is the nanoparticles. This image shows nanoparticle penetration of the lymph node structures and cell locations from the periphery inwards.

We were trying to understand where the injected nanoparticles end up in the lymph node substructure areas in order to determine which cells they might encounter. This technique gives both spatial and cellular understanding about the biodistribution of these nanoparticles within this tissue.