Live dead vr viability cytotoxicity kit

The cell viability upon different treatments was determined by MTT assay as described in the cytotoxicity test above. To confirm the MTT assay results, MDA-MB-231 cells after PDT treatment were also fluorescently stained for viability using a Live/Dead VR Viability/Cytotoxicity kit (Invitrogen, Thermo Fisher Scientific, Waltham, MA, USA). Briefly, cells cultured on glass cover slips after PDT treatment were gently washed with HBSS and then incubated with the Live/Dead VR Viability/Cytotoxicity solution for 30 min. Viable cells were stained green by calcein acetoxymethyl (0.05%), while the nuclei of dead cells were stained red by ethidium homodimer-1 (0.2%). The stained cells were examined under a Nikon Eclipse 80i epifluorescent microscope (Nikon Instruments, Melville, NY, USA). To visualize cell morphology changes after PDT treatment, cultures were fixed with 4% formalin and stained with phalloidin (Alexa FluorH 488 phalloidin; Biotium Inc, Hayward, CA, USA) for filamentous actin and 4,6-diamidino-2-phenylindole (dilactate) for cell nuclei. The stained cells were also examined under the Nikon Eclipse 80i epifluorescent microscope.