Rapid lymph accumulation of polystyrene nanoparticles following pulmonary administration.

PURPOSE: Pulmonary administration of polymeric nanoparticle drug delivery systems is of great interest for both systemic and local therapies. However, little is understood about the relationship of particle size and pulmonary absorption. We investigated uptake and biodistribution of polystyrene nanoparticles (PN) of 50 nm, 100 nm, 250 nm, and 900 nm diameters in mice following administration to lungs via pharyngeal aspiration.
METHODS: The amount of PN in tissues was analyzed by gel permeation chromatography (GPC).
RESULTS: At 1 h, larger diameter PN (250 nm and 900 nm) had the highest total uptake at around 15% of administered dose, whereas the smaller diameter PN (50 nm and 100 nm) had uptake of only 5-6%. However, at 3 h, the 50 nm PN had the highest total uptake at 24.4%. For each size tested, the highest nanoparticle deposition was observed in the lymph nodes (LN) as compared to other tissues accounting for a total of about 35-50% of absorbed nanoparticles.
CONCLUSION: PN size impacts the rate and extent of uptake from lungs and, further, the extent of LN deposition. The extent of uptake and lymph distribution of the model, non-degradable PN lends potential to pulmonary administered, biodegradable polymeric nanoparticles for delivery of therapeutics to regional lymph nodes.