Representative brightfield and fluorescence micrographs showing dead/dying MDA-MB-231 cells after treatment with a binary mixture of nucleic acid stain SYTOX Blue (5 μM) and either Tetra-Zn2BDPA-SR (a) or Bis-Zn2BDPA-SR (b) (10 μM). In each case, the cells were initially treated with etoposide (15 μM) for 11 hr, incubated with the probes for 30 min at 37 °C, then washed with HEPES buffer. Scale bar = 30 μm. Healthy cells are unstained, cells only stained red are apoptotic, and cells stained both red and green are necrotic.