Figure 2

Interaction of nanoparticles with the cellular interface. NPs interact with cells via the protein corona. (A) Uptake of large sized NP-protein complexes, agglomerates of NP may be ingested by specialized cells such as macrophages and neutrophils via phagocytosis. It involves folding of the plasma membrane over the NP complex to form the phagosome. (B) Non-specific uptake of extracellular fluid containing aggregates of NP may also be taken up by cells via macropinocytosis which involves ruffling of the plasma membrane to form vesicles which ultimately fuse to form lysosomes. Endocytosis of NP complexes may also be directed by specific receptors involving formation of (C) caveolae that are plasma membrane indentations consisting of cholesterol binding proteins called caveolins or (D) clathrin-coated vesicles. (E) Apart from these other endocytic mechanisms, independent of clathrin or caveolae may also facilitate uptake of NP.