Submicron complex lipid carriers for curcumin delivery to intestinal epithelial cells: Effect of different emulsifiers on bioaccessibility and cell uptake

Submicrometric lipid-based carriers were developed to encapsulate curcumin and deliver it to intestinal epithelial cells. A lipid matrix comprising monoolein, sunflower oil and water at weight ratio 1:1:1 was selected, upon screening of different combinations of amphiphilic molecules, vegetable oils and water, because of its high encapsulations efficiency of curcumin, retained over time and relatively lower content of amphiphilic molecules. Upon dispersion in aqueous phase, the carriers were stabilized by: (a) whey protein isolates (WPI), alone and (b) in combination with modified starch (WPI-MS), or by (c) polysorbate 20 (T20). Whereas T20-stabilized systems exhibited extremely fine particles (120 nm), WPI and WPI-MS stabilized carriers were characterized by a significantly larger mean particle size (270 nm). The thicker macromolecular layer of WPI and WPI-MS enabled better (a) physical stability, (b) controlled shell degradation during simulated digestion, and (c) curcumin bioaccessibility targeted at the intestinal digestion phase than T20-systems. However, uptake studies in HT29 cell lines, simulating intestinal epithelial cells, showed that WPI and WPI-MS carriers exhibited after 24 h a lower relative uptake than T20-stabilized systems (about 60% and 80%, respectively), as a consequence of smaller size and higher cell adherence of T20 carriers to the cell membrane.