Understanding the uptake of polystyrene nanoparticles by the nasal mucosa

Nanoparticles have many proposed advantages for use in nasal drug delivery systems. Nanoparticles can improve uptake and efficacy and lower toxicity compared to the drug alone. In order to study the transport behavior of nanoparticles across nasal tissues, the uptake of non-biodegradable, fluorescently-labeled, carboxylate-modified polystyrene nanoparticles was measured. These 40 nm particles are spherical in shape and loaded with fluorescein, a fluorescent dye that can be measured spectrophotometrically, to determine the number of particles that entered the nasal tissues. In order to identify the pathways involved in the uptake of these particles, different pharmacologic inhibitors were also included in the nanoparticle transport studies. The results indicate that the nanoparticles enter the nasal tissues using several endocytosis mechanisms, namely, macropinocytosis, clathrin-mediated endocytosis, and caveolin-mediated endocytosis. These findings suggest that more than one endocytic pathway is involved in the uptake process in the nasal tissues, and these multiple pathways may help to increase the total nanoparticle uptake in the nasal tissues.