Transport Mechanisms of 2D Nanoparticles across a Human Follicle-Associated Epithelium Model

Oral drug delivery is the most common route for drug administration, because of its safety and convenience. Although there have been many drug delivery systems (DDS), inorganic clay-based nanosystems have been less explored. In particular, zinc basic salt (ZBS) has never been used as an oral DDS though it has high biocompatibility, anionic exchange capacity, and controlled release behavior. Here, we demonstrated the potency of ZBS as an oral DDS via an in vitro human follicle-associated epithelium (FAE) model to observe transport pathways for various-sized 2D ZBS (200 and 1000 nm) across the cellular monolayers. The decrease in transepithelial electrical resistance (TEER) for the Caco-2 and Raji B coculture monolayers incubated with 2D nanoparticles suggests that the paracellular tight junctions became loosened, confirming that the present layered nanoparticles were interacting with the epithelial cell layer and could open the tight junctions to improve drug uptake via transcellular and paracellular transport pathways also confirmed by the confocal images of the coculture cell monolayer. It is also found that the 200 nm-sized ZBS particles showed better translocation than the 1000 nm particles without any toxicity. Therefore, the 200 nm ZBS nanoparticles could be suggested as a promising oral drug delivery carrier.