Mucus-penetrating nanoparticles based on chitosan grafted with various non-ionic polymers: Synthesis, structural characterisation and diffusion studies

Transmucosal administration offers numerous advantages for drug delivery as it usually helps to avoid first pass metabolism, provides rapid onset of action, and is a non-invasive route. Mucosal surfaces are covered by a viscoelastic mucus gel layer which acts as a protective barrier preventing the entrance of harmful substances into the human tissues. This function of mucus also inhibits the diffusion of drugs and nano-formulations and can result in a significant reduction of their efficacy. The design of mucuspenetrating nanoparticles can overcome the barrier function of mucus which may lead to better therapeutic outcomes. In this study, chitosan was chemically modified by grafting short chains of poly(ethylene glycol), poly(2-hydroxyethyl acrylate), poly(2-ethyl-2-oxazoline), or poly(N-vinyl pyrrolidone) an