Nanoparticle-cell interactions: drug delivery implications.

Design strategies to enhance drug delivery at specific cellular organelle by taking advantage of the endocytotic pathways are still in the early stages of development. This review provides a summary of the endocytosis machineries and pathways, as well as their involvement in nanoparticle internalization processes into either polarized epithelial cells or nonpolarized cells, in view of the marked differences in endocytic processes occurring within those cell types. The relevance of the physicochemical properties of nanoparticles upon their entry into the cells, as well as the experimental tools used to investigate the entry of nanoparticles into cells, is also addressed. The objective of this review is to present current information and achievements for a more in-depth comprehension of the internalization process and intracellular trafficking of nanoparticulate drug delivery systems within various cells types.