Annexin V-Fluor 488/PI Apoptosis Detection Kit

The Annexin V-Fluor 488/PI Apoptosis Detection Kit uses Fluor 488-labeled Annexin V as a probe to detect the onset of early apoptosis on flow cytometry.

The Annexin V–Fluor 488/PI Apoptosis Detection Kit is designed to identify early apoptotic cells using Fluor 488–labeled Annexin V as a fluorescent probe and can be analyzed by flow cytometry or other fluorescence-based detection systems. In healthy cells, phosphatidylserine (PS) is localized on the inner leaflet of the plasma membrane. During early apoptosis, PS is translocated to the outer leaflet and becomes exposed to the extracellular environment. Annexin V is a Ca²⁺-dependent phospholipid-binding protein with a molecular weight of 35–36 kDa that binds PS with high affinity, allowing selective labeling of early apoptotic cells.

PI is a nucleic acid dye that cannot cross intact cell membranes but readily enters cells with compromised membrane integrity, staining their nuclei red. When used together, viable cells are Annexin V⁻/PI⁻, early apoptotic cells are Annexin V⁺/PI⁻, and late apoptotic or necrotic cells display double-positive staining (Annexin V⁺/PI⁺). This dual-labeling strategy enables reliable discrimination of different stages of apoptosis.