Tracking the Endocytic Pathway of Recombinant Protein Toxin Delivered by Multiwalled Carbon Nanotubes

The endocytic pathway of a recombinant protein toxin. ricin A chain (RTA) delivered by multiwalled carbon nanotubes (MWCNTs) was tracked In Hela cells by tagging with enhanced green fluorescent protein (EGFP) EGFP-RTA was found to accumulate in the endosome and to be retrogradely transported to the endoplasmic reticulum, from which rt translocated into the cytosol Nuclear staining, Z axis scanning with a laser scanning confocal microscope (LSCM), and transmission electron microscopy (TEM) indicated that the RTA exerted its toxic effects Endocytosis inhibiting tests with LSCM and flow cytometry showed that MWCNT-EGFP-RTA conjugates penetrated cells principally via clathrin mediated endocytosis These studies are beneficial to understanding the MWCNT-based intracellular drug delivery mechanism and provide guidelines for designing promising MWCNT based vectors for targeting diagnostic or therapeutic compounds not only to specific cells, but even to specific cellular compartments