In vitro cellular interaction and absorption of dispersed cubic particles.

A precursor type oily liquid formulation comprising monoolein, Pluronic F-127 and ethanol has been prepared as a carrier for lipophilic drugs. When dispersed in water, the liquid precursor formulation produces sub-micron (200-500 nm) sized lipid particles, named 'nanocubicles'. The interaction between nanocubicles and Caco-2 cell was studied, and the absorption of nanocubicles by cells was observed by various microscopic techniques. Lipid droplets were observed in cytosol after incubation with nanocubicles with time. The degree of pyrene absorption encapsulated in nanocubicles was dependent on particle size and incubation time. The amount of pyrene absorbed by Caco-2 cells was ca. 20% of total at 37 degrees C after an 8-h incubation. When nanocubicles with a bigger average particle size (ca. 600 nm) were applied, the uptake rate was reduced to 10% under identical experimental conditions. The nanocubicles were easily solubilized by bile salts to produce mixed micelles. As bile salt concentration increased, pyrene absorption into the jejunum of rat everted sac in vitro increased.