Selective delivery of cargo entities to tumor cells by nanoscale artificial oil bodies

Artificial oil bodies (AOBs) are oil droplets that result from self-assembly of a mixture containing triacylglycerols, phospholipids, and membrane proteins of plant seeds. Owing to their small size, stability, hydrophobic core, biocompatibility, and biodegradability, AOBs were explored to examine their feasibility as a drug delivery carrier. This was approached by fusion sesame oleosin (Ole), the primary membrane protein of seed oil bodies, with a small domain consisting of the arginine-glycine-aspartic acid (RGD) motif. The resulting Ole-RGD fusion protein was overproduced in Escherichia coli and then isolated for reconstitution of AOBs. At the optimal condition, the size of stable AOBs was within the range of 100-400 nm. Furthermore, AOBs entrapped with a hydrophobic fluorescence dye were incubated with human tumor cells. As visualized by fluorescent microscopy and confocal microscopy, the RGD-tagged AOBs were able to selectively target cells expressing the αvβ3 integrin. Moreover, these AOBs were effectively internalized and the fluorescence dye that they carried was subsequently released inside the cells. The percentage of cells internalized by AOBs could reach 80% as analyzed by flow cytometry. Taken together, it illustrates a great promise of this proposed approach for targeted delivery of cargo entities to tumor cells.