Herein, we describe a simple and promising nanoparticle oral delivery phenomenon and propose pathways for oral nanoparticle absorption from the gastrointestinal tract (GIT), combining apical sodium-dependent bile acid transporter-mediated cellular uptake and chylomicron transport pathways. This strategy is proven to employ bile-acid-conjugated, solid fluorescent probe nanoparticles (100 nm diameter) to exclude any potential artifacts and instability issues in observing transport pathways and measuring oral bioavailability. The results of the in vitro studies showed that there is no interference from bile acid and no simultaneous uptake of nanoparticles and dextran. The probe nanoparticle exhibited a significantly enhanced average oral bioavailability (47%) with sustained absorption in rats. Particle-size- and dose-dependent oral bioavailability was observed for oral nanoparticle dosing up to 20 mg/kg. The probe nanoparticles appear to be transported to systemic circulation via the gut lymphatic system. Thus, we propose a pathway for oral nanoparticle absorption from the GIT, combining apical bile acid transporter-mediated cellular uptake and chylomicron transport pathways.
Keywords: bile acid transporters; nanoparticle absorption pathway; nanoparticle intestinal absorption; nanoparticle lymphatic transport; oral drug delivery.