In vitro and in vivo models for the study of oral delivery of nanoparticles.

Oral delivery is an attractive route to deliver therapeutics via nanoparticles due to its ease of administration and patient compliance. This review discusses laboratory techniques for studying oral delivery of nanoparticles, which offer protection of cargo through the gastrointestinal tract. Some of the difficulties in modeling oral delivery include the harsh acidic environment, variable pH, and the tight monolayer of endothelial cells present throughout the gastrointestinal tract. The use of in vitro techniques including the Transwell ® system, simulated gastric/intestinal fluid, and diffusion chambers addresses these challenges. When studying effects after oral delivery in vivo, bioimaging of nanoparticle biodistribution using radioactive markers has been popular. Functional assays such as immune response and systemic protein concentration analysis can further define the merits of the oral delivery systems. As biologics become increasingly more important in chronic therapies, nanoparticle-mediated oral delivery will assume greater prominence, and more sophisticated in vitro and in vivo models will be required.