Advances in the transepithelial transport of nanoparticles

• The oral absorption of nanoparticles is mainly limited by intestinal epithelium.
• The potential intestinal absorption pathways of nanoparticles.
• The characteristics governing the absorption and distribution of nanoparticles.
• Studies on the intracellular trafficking and exocytosis of nanoparticles are urgent.

The intestinal epithelium represents a barrier to the delivery of nanoparticles (NPs). It prevents intact NPs from efficiently crossing the mucosa to access the circulation, thus limiting the successful application of NP-based oral drug delivery. Recent advances in nanotechnology have provided promising solutions to this challenge. This review describes the potential intestinal absorption pathways of NPs, including the transenterocytic pathway, paracellular pathway and M-cell-mediated pathway. NP properties that influence transcytosis are summarized; and the biodistribution of NPs after oral absorption is described and the future prospects of novel NPs are explored.