AS-DACA fluorescence properties. (A) Images of the intracellular distribution of AS-DACA in RD and RH30 cells captured using digital colour photography after a 4 h exposure to 2 μM drug. Images were captured at 600 × magnification. Scale bars represent 10 μm. Inset shows 4 h exposure to 2 μM doxorubicin. (B) Uncorrected fluorescence emission spectrum of AS-DACA in solution over the pH range 6.2 to 6.8. Excitation wavelength was 260 nm, λmax for absorption in the UV. (C) Fluorescent micrographs prepared using a deconvolution microscope for detection of AS-DACA. Cells were incubated for 10 min at 2 μM and show vesicle accumulation in RD (left), and RH30 (right) cells. Nuclei with reduced, or absent, staining are indicated (arrow).