Mixed mucoadhesive amphiphilic polymeric nanoparticles cross a model of nasal septum epithelium in vitro.

Intranasal administration of nano-drug delivery systems emerged as an appealing strategy to surpass the blood-brain barrier and thus, increase drug bioavailability in the central nervous system. However, a systematic study of the effect of structural properties of the nanoparticles on the nose-to-brain transport is missing. In this work, we synthesized and characterized mixed amphiphilic polymeric nanoparticles combining two mucoadhesive graft copolymers, namely chitosan-g-poly(methyl methacrylate) and poly(vinyl alcohol)-g-poly(methyl methacrylate) for the first time. Chitosan enables the physical stabilization of the nanoparticles by ionotropic crosslinking with tripolyphosphate and confers mucoadhesiveness, while poly(vinyl alcohol) is also mucoadhesive and, owing to its non-ionic nature, it improves nanoparticle compatibility in nasal epithelial cells by reducing the surface charge of the nanoparticles. After a thorough characterization of the mixed nanoparticles by dynamic light scattering and nanoparticle tracking analysis, we investigated the cell uptake by fluorescence light and confocal microscopy and imaging flow cytometry. Mixed nanoparticles were readily internalized at 37oC, while the uptake was inhibited almost completely at 4oC, indicating the involvement of energy-dependent mechanisms. Finally, we assessed the nanoparticle permeability across liquid-liquid and air-liquid monolayers of a nasal septum epithelial cell line and studied the effect of nanoparticle concentration and temperature on the apparent permeability. Overall, our findings demonstrate that these novel amphiphilic nanoparticles cross this in vitro model of intranasal epithelium mainly by a passive (paracellular) pathway involving the opening of epithelial tight junctions.