Trypan Blue Stain is a stain used to distinguish viable from nonviable cells. Nonviable cells will absorb the dye Trypan Blue and appear blue, while viable cells will exclude the dye.
Cells should be in a single cell suspension in buffered saline before counting.
Since Trypan Blue has a higher affinity for serum protein than for cellular proteins, suspending the cells in medium containing serum will generate a dark background.
Commonly used to assess cell viability.