Figure 4.

Optical microscopy images of (from left to right) HER2^– MCF7 cells after incubation with A647-aHER2-MaMAs; HER2⁺ BT474 incubated with the supernatant collected after the last washing step following synthesis of A647-aHER2-MaMAs (a control for free residual Alexa Fluor 647-labeled trastuzumab antibodies); and HER2⁺ BT474 cells after incubation with A647-aHER2-MaMAs. Note the lack of a fluorescence signal from HER2⁺ BT474 cells incubated with the supernatant; this indicates that the fluorescence after incubation with A647-aHER2-MaMAs is associated with the nanoparticles rather than with residual free antibodies. The images were acquired using a Zeiss Axio Observer.Z1m microscope equipped with a Hamamatsu ORCA-ER camera (Bridgewater, NJ) under a 40× objective lens. Fluorescence images were obtained with BP 640/30 nm excitation and BP 690/50 nm emission filters. Scale bar is 40 μm.