AO (Acridine Orange) Staining Assay

Observed under a fluorescence microscope after staining, acridine orange can penetrate the normal cell membrane to make the nucleus green or yellow-green uniformly fluorescent; while in apoptotic cells, the chromatin shrinks or breaks into fragments of different sizes, forming apoptotic cells. Acridine orange stains dense and dense yellow-green fluorescence or yellow-green fragment particles; the yellow fluorescence of necrotic cells weakens or even disappears. Acridine orange staining is often used in combination with EB staining. EB stains only dead cells to produce orange fluorescence, which can distinguish normal cells, apoptotic cells, and necrotic cells.