Crystal Violet Staining Solution

Crystal violet is a basic triphenylmethane dye. Crystal violet staining solution is commonly used in Gram staining to distinguish between Gram-positive and Gram-negative bacteria. Crystal violet can bind to the peptidoglycan in bacterial cell walls, forming a colored complex. Because Gram-positive bacteria have a thicker cell wall with a high peptidoglycan content, the crystal violet-iodine complex is difficult to wash out with ethanol, so they appear purple. In contrast, Gram-negative bacteria have thinner cell walls with less peptidoglycan, allowing the crystal violet to be removed by ethanol; after counterstaining, they appear red. In addition, crystal violet can bind to nucleic acids and acidic substances within cells to form a purple complex, thereby staining cells for visualization of colony numbers. This makes it useful in cytological experiments for assessing cell proliferation or migration activity.