Calcein-AM/PI，Live/Dead Cell Double Stain Kit

Calcein-AM is a fluorescent staining reagent for live cell labeling, which emits green fluorescence (Ex=490 nm, Em=515 nm). Non-fluorescent in its original state, Calcein-AM penetrates into cells and is cleaved by intracellular esterases to form polar, membrane-impermeable calcein. This product is retained inside cells and emits bright green fluorescence. Compared with other similar reagents such as BCECF-AM and CFDA, Calcein-AM possesses extremely low cytotoxicity, making it the preferred fluorescent probe for live cell staining. It does not affect cellular functions including cell proliferation and lymphocyte chemotaxis. As dead cells lack esterases, Calcein-AM is mainly used for cell viability detection and short-term live cell labeling. Therefore, Calcein-AM is commonly combined with dead cell fluorescent probes such as propidium iodide (PI) to achieve dual fluorescent staining of live and dead cells. Propidium iodide (PI) is unable to pass through the intact cell membrane of viable cells, but can penetrate the damaged membrane structure of dead cells to enter the nucleus. It intercalates into cellular DNA double strands and produces red fluorescence (Ex=535 nm, Em=617 nm), so PI specifically stains dead cells only. Both calcein and PI-bound DNA can be excited at 490 nm, allowing simultaneous observation of live and dead cells via fluorescence microscopy. When excited at 545 nm, only dead cells can be visualized. The working principle of this kit is based on dual staining with Calcein-AM and PI to label live and dead cells separately, so as to realize quantitative analysis of live and dead cell status.