When using the LIVE/DEAD BacLight kit for bacterial viability, with SYTO 9 and propidium iodide (PI), why are some cells detected with both dyes? Shouldn't live cells be green and dead cells be red?
SYTO 9 dye will enter all cells, live or dead. PI only enters cells with compromised membranes (dead cells or damaged cells). First, perform single color staining and examine under both filter sets. Longpass filters or the use of too much dye may result in excessive bleedthrough of the green dye emission into the red channel and the emission of PI in the green channel. Use narrower bandpass filters if possible, and use lower concentrations of the dye. Some live cells may take up PI by engulfment; avoid extended incubation times with the dye. Apply PI to a live cell culture and optimize incubation times to limit engulfment.
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.