Fan Yuting, Zhang Yuzhu, Yokoyama Wally, Yi Jiang
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.
Nanomaterials (Basel). 2017 Oct 26;7(11):349. doi: 10.3390/nano7110349.
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.
研究了三种不同粒径的脂质乳剂被Caco-2细胞的相对摄取情况及机制。对于三种液滴尺寸的乳剂中的任何一种，即使在蛋白质浓度为2 mg/mL时，玉米油-酪蛋白酸钠乳剂也几乎没有或没有细胞毒性。含尼罗红乳剂的共聚焦激光扫描显微镜（CLSM）显示，脂质乳剂被Caco-2细胞吸收。观察到平均液滴尺寸与细胞摄取之间呈负相关。如在不同时间孵育以及用叠氮化钠（一种主动转运的通用抑制剂）处理所示，存在时间依赖性和能量依赖性摄取。脂质乳剂的内吞作用是尺寸依赖性的。纳米乳剂液滴内化到Caco-2细胞中主要通过网格蛋白和小窝/脂筏相关途径发生，而如使用特定途径抑制剂所示，巨胞饮途径在556 nm乳剂内吞作用中起最重要作用。乳剂通过顶端或基底途径的渗透性也表明，主动转运可能是脂质纳米乳剂的主要途径。这些结果可能有助于脂质纳米乳剂在营养保健品和药物递送中的设计和应用。
