 Nanoparticles have the additional advantage of enhanced transport once injected into the body as compared to microparticles.Nanoparticles are able to be transported through the porous extracellular matrix much easier and reach the lymph nodes where the T cells reside.Also, iron oxide nanoparticles have been used to take advantage of the superparamagnetic properties and to cluster both Signals to enhance T cell stimulation.