Figure 3.

Epifluorescent images of immortalized RAW 264.7 macrophages showing lack of role for endocytosis in cellular accumulation of C60. (A) Baseline uptake was established following 3 hrs exposures to C60, and a monoclonal antibody (red) was used to detect and quantify uptake. The effect of classical inhibitors of active membrane-mediated processes for cell entry was determined in the presence of (B) chlorpromazine (clathrin-mediated endocytosis), (C) cytochalasin A (F-actin polymerization) or (D) genistein (caveolin-mediated endocytosis, macropinocytosis and phagocytosis). (E) Statistical analysis of images supports diffusion rather than endo-/phagocytosis as the major route by which small clusters of C60 enter the cell membrane and cytoplasm. The apparent lack of statistically significant diminution in the uptake of C₆₀ induced by the pharmacologic inhibition of clathrin/caveolin-mediated endocytosis suggests that a significant quantity of material enters the cell through other mechanisms.