FIGURE 1.

Nanoparticle-based delivery strategies for ulcerative colitis (UC). Nanoparticles employ different targeting mechanisms to cross the epithelial barrier and reach the UC site. When delivered by such a system, nanoparticles can achieve a high local drug concentration, experience less drug degradation and loss of efficacy before reaching the site of action, and minimize systemic drug side effects. A, Following oral administration, nanoparticles target the epithelium of the inflamed colon based on its specific pH. B, Following oral administration, nanoparticles target the epithelium of the inflamed colon based on its specific level of reactive oxygen species (ROS). C, Following oral administration, nanoparticles are delivered to the inflamed colon in a hydrogel. D, Following oral administration, nanoparticles target the inflamed colonic epithelium by a ligand-receptor interaction. Abbreviation: PMN, polymorphonuclear leukocyte.