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Endocytosis of Corn Oil-Caseinate Emulsions In Vitro: Impacts of Droplet Sizes

College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
Western Regional Research Center, Agricultural Research Service (ARS), United States Department of Agriculture (USDA), Albany, CA 94710, USA
Author to whom correspondence should be addressed.
Nanomaterials 2017, 7(11), 349;
Received: 26 September 2017 / Revised: 20 October 2017 / Accepted: 24 October 2017 / Published: 26 October 2017
PDF [3486 KB, uploaded 26 October 2017]


The relative uptake and mechanisms of lipid-based emulsions of three different particle diameters by Caco-2 cells were studied. The corn oil-sodium caseinate emulsions showed little or no cytotoxicity even at 2 mg/mL protein concentration for any of the three droplet size emulsions. Confocal laser scanning microscopy (CLSM) of Nile red containing emulsions showed that the lipid-based emulsions were absorbed by Caco-2 cells. A negative correlation between the mean droplet size and cellular uptake was observed. There was a time-dependent and energy-dependent uptake as shown by incubation at different times and treatment with sodium azide a general inhibitor of active transport. The endocytosis of lipid-based emulsions was size-dependent. The internalization of nanoemulsion droplets into Caco-2 cells mainly occurred through clathrin- and caveolae/lipid raft-related pathways, while macropinocytosis route played the most important role for 556 nm emulsion endocytosis as shown by the use of specific pathway inhibitors. Permeability of the emulsion through the apical or basal routes also suggested that active transport may be the main route for lipid-based nanoemulsions. The results may assist in the design and application of lipid-based nanoemulsions in nutraceuticals and pharmaceuticals delivery. View Full-Text
Keywords: droplet size; Nile red; endocytosis; Caco-2; transport; nanoemulsion droplet size; Nile red; endocytosis; Caco-2; transport; nanoemulsion

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Fan, Y.; Zhang, Y.; Yokoyama, W.; Yi, J. Endocytosis of Corn Oil-Caseinate Emulsions In Vitro: Impacts of Droplet Sizes. Nanomaterials 2017, 7, 349.

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