Mechanisms of Nanoparticle Internalization and Transport Across an Intestinal Epithelial Cell Model: Effect of Size and Surface Charge

Abstract

This study investigated the effect of nanoparticle size (50 and 100 nm) and surface charge on their interaction with Caco-2 monolayers as a model of the intestinal epithelium, including cell internalization pathways and the level of transepithelial transport. Initially, toxicity assays showed that cell viability and cell membrane integrity were dependent on the surface charge and applied mass, number, and total surface area of nanoparticles, as tested in two epithelial cell lines, colon carcinoma Caco-2 and airway Calu-3. This also identified suitable nanoparticle concentrations for subsequent cell uptake experiments. Nanoparticle application at doses below half maximal effective concentration (EC₅₀) revealed that the transport efficiency (ratio of transport to cell uptake) across Caco-2 cell monolayers is significantly higher for negatively charged nanoparticles compared to their positively charged counterparts (of similar size), despite the higher level of internalization of positively charged systems. Cell internalization pathways were hence probed using a panel of pharmacological inhibitors aiming to establish whether the discrepancy in transport efficiency is due to different uptake and transport pathways. Vesicular trans-monolayer transport for both positively and negatively charged nanoparticles was confirmed via inhibition of dynamin (by dynasore) and microtubule network (via nocodazole), which significantly reduced the transport of both nanoparticle systems. For positively charged nanoparticles a significant decrease in internalization and transport (46% and 37%, respectively) occurred in the presence of a clathrin pathway inhibitor (chlorpromazine), macropinocytosis inhibition (42%; achieved by 5-(N-ethyl-N-isopropyi)-amiloride), and under cholesterol depletion (38%; via methyl-β-cyclodextrin), but remained unaffected by the inhibition of lipid raft associated uptake (caveolae) by genistein. On the contrary, the most prominent reduction in internalization and transport of negatively charged nanoparticles (51% and 48%, respectively) followed the inhibition of lipid raft-associated pathway (caveolae inhibition by genistein) but was not significantly affected by the inhibition of clathrin pathway.

Influence of Physicochemical Properties and PEG Modification of Magnetic Liposomes on Their Interaction with Intestinal Epithelial Caco-2 Cells

“…Bannunah et al have demonstrated that positively charged nanoparticles tend to stay inside Caco-2 cells, whereas negatively charge nanoparticles are more efficiently exported from Caco-2 cells. 36) Our results are similar to this observation. In addition, with respect to particle size, we observed that large magnetic liposomes were better retained in Caco-2 cells than small ones (Fig.…”

“…We think this is a reasonable result because cationic nanoparticles have been reported to strongly interact with the negatively charged region of the cell membrane surface via electrostatic forces. 36,38) In addition, we observed that the cellular associated amount of magnetic liposomes at 37°C was much higher than that at 4°C, and the highest quantitative change between 37 and 4°C was observed with magnetic cationic liposomes (Fig. 3).…”

“…36,37) Therefore, we evaluated the effect of particle size and surface charge of magnetic liposomes, focusing on their surface binding and uptake in Caco-2 cells under a magnetic field. The cellular associated amount of all the magnetic liposomes increased by 3-10 times by the presence of the magnetic field (Fig.…”

Preliminary protein corona formation stabilizes gold nanoparticles and improves deposition efficiency

“…While biomedical applications vary in function, what they have in common is the need for a high AuNP delivery rate to be effective. Current design efforts to improve colloid delivery and deposition have focused on material-based approaches, specifically through modification of particle size or surface chemistry (Bannunah et al 2014;Untener et al 2013). While these efforts have been met with moderate success, much work remains to optimize NP deposition and dosimetry (Pal et al 2015).…”

The interactions of single-wall carbon nanohorns with polar epithelium

“…40 Additionally, dynasore, a cell-permeable inhibitor of dynamin, also exhibited a significantly suppressive effect. 41,42 Generally, caveolar, CME, and macropinocytosis are responsible for the internalization of particles of different sizes. 43,44 The pathway studies demonstrated that the endocytosis of SWCNHox may be mediated via multiple mechanisms.…”