The influence of nanoparticle shape on bilateral exocytosis from Caco-2 cells

Nanoparticles are easily to be taken up by cells but hard to be transported across epithelia, which plays an important role in absorption and toxicity. This paper aims to elucidate the effect of nanoparticle shape on bilateral exocytosis of Caco-2 cells. The fluorescent resonance energy transfer (FRET) probes (DiO and DiI) were utilized to label nanospheres and nanorods for determining and tracking nanoparticles. The results showed that more nanorods were internalized into Caco-2 cells than nanospheres. But the apical exocytosis rate of nanospheres from Caco-2 cells was faster than that of nanorods significantly. In addition, only less than 2% of intact nanoparticles were transported across monolayers for both nanoparticles, but the exocytosis behaviors between them was absolutely different. Compared to nanospheres, nanorods preferred basolateral exocytosis to apical exocytosis. Therefore, the shape is a critical parameter in cellular uptake and transport, even intracellular fate, which should be primarily considered in design of oral nanoparticles.