Figure 6. Fluorescence microscope images showing the uptake of siRNA loaded AuNP-PEI/ AuNP-PEI-EpAb nanoparticles. (A) control cells; (B) Y79 cells treated with naked siRNA; (C) Y79 cells treated with AuNP-PEI-siRNA and (D) Y79 cells treated with AuNP-PEI- EpAb-siRNA. Free FAM-siRNA was not taken up by the Y79 cells, and therefore, we did not see any detectable fluorescence. In contrast, the Y79 cells demonstrated detectable fluorescence when treated with FAM-siRNA loaded AuNP-PEI (C) and AuNP-PEI-EpAb nanoparticles (D). Increased fluorescence (white arrows show fluorescence in the Y79 cells) was seen in the Y79 cells due to the EpCAM antibody conjugation to AuNP-PEI-siRNA (FAM) when compared to cells treated with AuNP-PEI-siRNA (FAM) without EpCAM antibody conjugation.