Ex Vivo Studies on the Distribution and Penetration of mPEG-PLGA Nanoparticles in the Intestinal Mucosa of Rats

The surface of the gastrointestinal mucosa is covered by a three-dimensional reticular mucus layer. The mucus layer can prevent the invasion of pathogens and various toxins, however, it can also hinder the diffusion and absorption of drugs and carriers of small particles. In this study, we designed and prepared poly(lactic-co-glycolic acid) nanoparticles (PLGA-NPs), monomethoxy polyethylene glycol PLGA nanoparticles (mPEG-PLGA-NPs), and chitosan-coated PLGA nanoparticles (CS-PLGA-NPs) that were all less than 200 nm in diameter. The amounts of nanoparticles with different surface charges and hydrophilicities in the mucus and the mucosa were investigated using ex vivo rat ileum tissue. The amount of mPEG-PLGA-NPs in the mucosa was 2.1x greater than the number of PLGA-NPs and 1.4x greater than the number of CS-PLGA-NPs. In the mucus layer, the content of CS-PLGA-NPs was 17.4% greater than that of PLGA-NPs and 45.5% greater than that of mPEG-PLGA-NPs. The penetration rates of nanoparticles in the small intestine were found to follow this trend: mPEG-PLGA-NPs > CS-PLGA-NPs > PLGA-NPs. These results indicate that mPEG-PLGA-NPs can effectively penetrate and deliver drugs to the mucosa because they have high hydrophilicity, a neutral surface charge, and a suitable particle size. The mPEG-PLGA-NPs exhibited characteristics that are potentially suitable for an oral drug delivery system.